Joel Cramer was at the pool with his kids when another dad, competing in a big splash contest, got up onto the diving board. He bounced up once, and when he landed on the board for the second time, his quadriceps muscle tore. “It rolled up his leg and balled up near the top of his thigh,” says Cramer, a professor of exercise physiology at the University of Nebraska. “[It was] like rolling up a window shade.”

That’s an extreme (and extremely rare) example of a muscle strain, a common injury that happens to high school soccer stars, recreational runners, and middle-aged racquetball players alike. “Strain” is the medical term for the condition, though it’s colloquially known as a pulled muscle. The term is a catch-all that covers everything from a small twinge to a full-on rupture.

What we call a “tear” and what we coin a “pull or strain” all boil down to the same type of injury: A rip to some part of the muscle. But some are worse than others. A mild or “grade one” strain—what many people call a “pulled muscle”—happens when you tear about 5 percent of the fibers in a particular muscle. This typically feels like an uncomfortable twinge that may force you off the court for a few weeks. A moderate sprain involves a higher percentage of fibers, and might sideline you for a month or more. A full rupture severs the muscle entirely, and usually requires surgery to repair.

[Related: Why do my muscles ache the day after a big workout?]

Okay, but how exactly do these tears occur? And why do some instances result in more muscle fiber damage than others? Cramer says three major factors contribute to this muscle busting. Muscles that cover two joints, like the hamstring which extends across the hip and knee joints, are at the highest risk. That’s because having both joints moving and stretching the muscle simultaneously adds tension, which can lead to strains.

Muscles are also more likely to strain while they are contracting. At this point, muscles are shortening and lengthening at the same time. During a dumbbell curl, for example, raising the weight up towards the shoulder compresses the bicep, and lowering it back down stretches it back out again. The muscle can create and sustain much more force during the lengthening portion of the activity, says Cramer, which makes it easier for it to strain.

Finally, muscles that have a higher proportion of fast-twitch to slow-twitch fibers strain more readily. Fast-twitch fibers contract quickly and generate more power, says Cramer. For that reason, they are the ones recruited for explosive tasks like sprinting. “It’s relatively uncommon for slow twitch [muscles] to strain,” he says. “They’re used to being active all the time.”

Technically, Cramer says, it’s possible to strain any of the skeletal muscles in your body. “For some, it’s not physiologically impossible, just very highly unlikely,” he says. “You’re probably not going to strain deep muscles with very specific functions.” The muscles in the finger, for example, are probably not going to cause much trouble, since they only have one task and don’t do much heavy lifting.

[Related: How to get muscle gains: A beginner’s guide to becoming buff]

Low flexibility and range of motion are major factors at risk for muscle strain, says Cramer. Despite the popular belief that larger muscles are tighter, Cramer says greater muscle mass is actually associated with greater give. “There’s evidence to suggest that weight training done with a good range of motion increases flexibility,” he says. And even though it may not seem like it when you’re struggling to touch your toes, Cramer says most people can teach their body to be springy enough to do the splits. So, to help keep your muscle fibers intact—pick up the weights and don’t skip your stretching routine, no matter how tedious it is.

How does a pulled muscle heal?

The post Here’s what really happens when you pull a muscle appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

In 1989, Chuck Berry and Carl Sagan partied it up at one of the biggest bashes of the summer—a celebration honoring the two Voyager spacecrafts, who were about to make a dramatic exit from our solar system. 

The twin probes, Voyager 1 and Voyager 2, launched back in 1977, with only a five-year mission to take a gander at Jupiter and Saturn’s rings and moons, hauling the Golden Record containing messages and cultural snapshots from Earth (including Chuck Berry’s music). 

Obviously, the Voyager spacecrafts have persisted a lot longer than five years: 46 years, to be exact. They’re still careening through space at a distance between 12 and 14 billion miles from Earth. So how have they lasted four decades longer than expected? Much of it has to do with a bit of vintage hardware and a handful of software updates. You can find out more (and when the crafts’ expected death dates) by subscribing to PopSci+ and reading the full story by Tatyana Woodall, and by listening to our new episode of Ask Us Anything. 

The post How is Voyager’s vintage technology still flying? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

INSIDE THE Library of Congress in Washington, D.C., there’s a living time capsule. The massive storage facility, run by the Motion Picture, Broadcasting, and Recorded Sound Division, is filled with wax cylinders, record players, and other pieces of dated audiovisual equipment. Some might see it as a junkyard of outdated technology, but Stephanie Barb likes to call this place the “land of lost toys.” 

“We used to play records all the time,” says Barb, the deputy director of IT service operations at the Library of Congress. Now, owning a record player is almost a whimsy.  

When machines become obsolete, the data they hold can be lost as well. Software and hardware fade out of general use as newer products and services replace them. It’s one of the several roadblocks technicians and archivists like Barb continuously run into in their quest to store information for long-term safekeeping. Right now, experts say there is no one storage device that can save data forever. Options like magnetic tape, Blu-ray Disc, and even DNA may provide stable but relatively temporary storage banks in which data can live while better technologies are tested and brought to market. However, each of these choices has its own shortcomings, and no one method is perfect in terms of both capacity and durability, with new innovations always on the horizon. 

The Library of Congress, for example, has a digital footprint of 176,000 terabytes, with its website catalogs of books, photos, videos, and other mediums taking up 5,350 terabytes alone (the equivalent of nearly 2 billion three-minute-long MP3s). Right now, this mountain of data is growing at around 1,500 terabytes a year. Archivists are racing against time to elongate the life of important documents and media. 

“Part of the preservation process is keeping operating systems and hardware up to date,” says Natalie Buda Smith, director of digital strategy at the Library of Congress. 

Nothing lasts forever

Preserving files in older mediums, like LP records and gaming consoles that have been discontinued, takes a bit of DIY tinkering. At the library, archivists rebuild vintage media players to recover data and transfer it to a more modern form of storage. Sometimes, the team even develops specialized technologies. For example, a system called IRENE, which the library codesigned with the Lawrence Berkeley National Laboratory, reads the depths of the grooves in broken phonograph records to convert the music to a digital format. 

This is particularly important with the materials eligible for copyright, says Barb. Books can last forever if preserved properly, but items that are submitted for copyright on more corruptible materials, like DVDs, CDs, and DVRs, can degrade over time. “That puts us in a crunch to pull that data off those obsolete technologies and preserve it digitally, because we are going to lose what’s on there,” Barb explains. Since there’s a duplicate provided with every copyright submission, the Library of Congress typically adds it to the collections with the intention to update to a more modern method. 

Back up your work

When it comes to preserving data for the future, it’s important to keep the context in which the content exists. “Content says, ‘Here are the bits’; context says, ‘Here’s all the other stuff you need to understand those bits,’” notes Ethan Miller, director emeritus of the National Science Foundation’s Center for Research in Storage Systems. The extra context includes metadata, software, and hardware such as video game emulators. It’s the modern-day equivalent of a Rosetta Stone—a key that gives meaning to written languages and symbols of the past.

A lot of the data currently being collected is “born-digital content” rather than content that had to be digitized, Buda Smith says. Artifacts gathered from internet archiving are good examples. Even though the virtual-first information may ultimately end up on a physical medium like tape, it may live in a variety of other storage forms along the way. Saving multiple backups on different mediums is also good practice. 

Held together by tape

The library preserves the majority of its data on a decades-old medium that has so far stood the test of time: simple and affordable magnetic tape. The material is a Goldilocks medium prized for its density, data-writing speeds, and low cost. 

Even though tape storage has been around since the mid-1900s, it’s still constantly being improved upon to squeeze more and more bits of data onto each inch of tape. Companies like IBM are working to double capacity per cartridge (to a maximum of 45 terabytes) in newer generations while keeping the format relevant for the future. But tape is not foolproof. If the magnetic strip is damaged or overheated, the data can be wiped out. And while tape is faster to read from and write to than more novel mediums, the data it holds is not as easy to access or edit as information stored on flash drives or hard disk drives (HDDs). 

A driving force

The way you use data, and how often, will influence which storage mediums are the best fit. HDDs—the basis of cloud infrastructure—are a good starting solution for small companies with digital collections, says Shawn Brume, IBM’s storage strategist. Take movie studios, for example. 

“We are almost 25 years into [the filming of] the Star Wars prequels,” says Brume. “Disney has never moved the raw footage from filming those off of digital technology, and has stated that it will not.” That’s because keeping them on a hard drive makes cutting footage or inserting footage, whenever the filmmakers decide they want to make changes, much easier.

But HDD becomes more expensive with time and scale, Brume adds, making its use a pricey hassle with systems that continuously pump out large batches of data, like autonomous vehicles. The average driverless car system will generate upwards of 400 terabytes a year: If you have millions of cars all doing the same, then companies will easily get crushed by HDDs. Across the industry, the total cost to store a terabyte of data on HDD deep density storage (including infrastructure operations costs) ranges from approximately $0.70 to approximately $0.80 per month, according to Brume. For tape, it’s much less, at approximately $0.08 to $0.12 per month. So with this method, the information will eventually need to be migrated to tape for lower-cost, longer-term, and offline storage. “It’s a process of ingest, collate, coordinate, and copy out to tape,” Brume says. 

IBM advises companies on how to move their data from HDDs to long-term tape infrastructure if they will need to retrieve it in the future. But the drawback of tape, unlike hard drives, is that it is pretty hard to alter. You have to erase and rewrite everything even if you want to change just one detail. 

The race to make space

An often overlooked contender may soon pull ahead of tape and cloud storage in the eternal-storage race. Many experts agree that Blu-ray, or polycarbonate optical discs, shows immense promise, especially for preserving data for decades, and maybe centuries, in an untouched box. Named after the violet laser in the reader, this system has an edge over flash or hard drives, as the parts don’t wear out, Miller explains. 

It all comes down to basic mechanics. HDDs don’t read or write very well after being powered down for a spell. Similarly, flash drives have a limited lifetime. That’s because the electrons in the device’s transistors leak out with use, passing through barriers and altering the charge of the material over months and years. “That means you have to read the flash every so often and rewrite the data,” Miller says. 

That’s where Blu-ray can excel. According to Miller, the technology needed to scan the discs is relatively simple in its construction: It’s basically a motor that spins, a reader that goes in and out, and a low-power laser. Optical drives are even simpler than those used for magnetic tapes. A lower price point of $50 to $200 per drive also sweetens the deal.  

To Miller, the question of where to store data boils down to the question of what technologies will be available in 100 to 1,000 years to read it—whether from Blu-ray or more experimental forms of storage like glass and DNA.

“If you look at history, nothing has been the forever medium except for something that’s chiseled on the wall in a cave,” Brume says. But even that information corrodes. With every new invention for record-keeping—stone, paper, code—knowledge still had to be passed down and translated to the next place. “We’ve always had to manage data,” he adds. “There’s never been a forever instance of anything.”

Read more PopSci+ stories.

The post Inside the search for the best way to save humanity’s data appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

IN 1989, Albert Wood and Peter Dunn thought they had unlocked a critical chemical door to treating hypertension and recurring chest pain. The two British Pfizer scientists reportedly created a new drug, named sildenafil, that reacts with a specific protein in muscle cells to allow for increased blood flow to the heart. 

But a few years later, human clinical trials revealed the drug was only effective when given multiple times a day and had a poor reaction with other existing cardiac treatments. What’s more, the blood rush was going to unexpected places in the body in addition to the heart. In one study, a nurse observed that most of the male volunteers were lying on their stomachs in embarrassment. The reason? Erections. Wood and Dunn had inadvertently stumbled upon the medicine that became Viagra. The small blue pill treats millions of people each year with erectile dysfunction, and further research suggests it may prove helpful for nonsexual problems such as pulmonary hypertension and altitude sickness.

Sidenafil is one of many prescriptions that treat multiple unrelated illnesses. How a drug becomes a medicinal Swiss Army knife depends on its chemical makeup. Each dose contains compounds that lock onto specific receptors, but that could also have the ability to create or suppress other reactions in the body.

“When somebody takes a medicine, it doesn’t necessarily go to the exact organ they are trying to target,” says Evelyn Huang, an emergency medicine resident physician at Northwestern Memorial Hospital. “The drug circulates through the entire body, so if there are certain receptors found in different parts, it would also affect that organ.” With sidenafil, the drug enlarges blood vessels generally and happens to prep the penis for action specifically. 

Another pill with the potential to tackle multiple conditions is mifepristone. This medicine is approved by the US Food and Drug Administration for medically induced abortions up to 70 days after a person’s last menstrual cycle starts. It works by blocking the effects of progesterone, which is needed to prepare and sustain pregnancy. (An ongoing lawsuit in a US district court in Texas could restrict its availability in pharmacies, doctor’s offices, and more.) Completely tamping down the hormone could also help prevent pancreatic cancer and melanomas, some early research shows. Additionally, at high doses, mifepristone aids in managing a condition called Cushing’s syndrome—characterized by extremely high levels of cortisol—by plugging the receptor that stimulates the production of sex and stress hormones. 

Dosage also matters in producing different drug responses. For example, barbiturates are a type of sedative prescribed in different amounts for a range of conditions from anxiety to seizures. This class of medications enhances the activity of GABA, a neurotransmitter that can slow down brain activity. At smaller doses, barbiturates can make someone feel drowsy and relaxed. But at higher amounts, they can be used as an anesthetic for rapid loss of consciousness. 

Because of the many ways a drug can affect the body, Huang warns against off-label use—taking a prescription for a condition other than the one it’s designed for. In any case, she recommends going over proper dosing, side effects, and other safety precautions with your healthcare provider. With more clinical and real-world research, it’s possible that off-label medications will be approved to target new health issues, producing formulas that pack more than one punch. Sidenafil, with its exciting possibilities, is at the top of that list.

Read more PopSci+ stories.

The post Viagra and the abortion pill can treat multiple illnesses. But how? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

How does an airplane stay in the air? Whether you’ve pondered the question while flying or not, it remains a fascinating, complex topic. Here’s a quick look at the physics involved with an airplane’s flight, as well as a glimpse at a misconception surrounding the subject, too. 

First, picture an aircraft—a commercial airliner, such as a Boeing or Airbus transport jet—cruising in steady flight through the sky. That flight involves a delicate balance of opposing forces. “Wings produce lift, and lift counters the weight of the aircraft,” says Holger Babinsky, a professor of aerodynamics at the University of Cambridge. 

“That lift [or upward] force has to be equal to, or greater than, the weight of the airplane—that’s what keeps it in the air,” says William Crossley, the head of the School of Aeronautics and Astronautics at Purdue University. 

Meanwhile, the aircraft’s engines are giving it the thrust it needs to counter the drag it experiences from the friction of the air around it. “As you’re flying forward, you have to have enough thrust to at least equal the drag—it can be higher than the drag if you’re accelerating; it can be lower than the drag if you’re slowing down—but in steady, level flight, the thrust equals drag,” Crossley notes.

[Related: How high do planes fly?]

“You can clearly feel the lift force,” Babinsky says. In this straightforward scenario, the air is hitting the bottom of your hand, being deflected downward, and in a Newtonian sense (see law three), your hand is being pushed upward. 

Follow the curve 

But a wing, of course, is not shaped like your hand, and there are additional factors to consider. Two key points to keep in mind with wings are that the front of a wing—the leading edge—is curved, and overall, they also take on a shape called an airfoil when you look at them in cross-section. 

[Related: How pilots land their planes in powerful crosswinds]

The curved leading edge of a wing is important because airflow tends to “follow a curved surface,” Babinsky says. He says he likes to demonstrate this concept by pointing a hair dryer at the rounded edge of a bucket. The airflow will attach to the bucket’s curved surface and make a turn, potentially even snuffing out a candle on the other side that’s blocked by the bucket. Here’s a charming old video that appears to demonstrate the same idea. “Once the flow attaches itself to the curved surface, it likes to stay attached—[although] it will not stay attached forever,” he notes.

With a wing—and picture it angled up somewhat, like your hand out the window of the car—what happens is that the air encounters the rounded leading edge. “On the upper surface, the air will attach itself, and bend round, and actually follow that incidence, that angle of attack, very nicely,” he says. 

Keep things low-pressure

Ultimately, what happens is that the air moving over the top of the wing attaches to the curved surface and turns, or flows downward somewhat: a low-pressure area forms, and the air also travels faster. Meanwhile, the air is hitting the underside of the wing, like the wind hits your hand as it sticks out the car window, creating a high-pressure area. Voila: the wing has a low-pressure area above it, and higher pressure below. “The difference between those two pressures gives us lift,” Babinsky says. 

This video depicts the general process well:

Babinsky notes that more work is being done by that lower pressure area above the wing than the higher pressure one below the wing. You can think of the wing as deflecting the air flow downwards on both the top and bottom. On the lower surface of the wing, the deflection of the flow “is actually smaller than the flow deflection on the upper surface,” he notes. “Most airfoils, a very, very crude rule of thumb would be that two-thirds of the lift is generated there [on the top surface], sometimes even more,” Babinksy says.

Can you bring it all together for me one last time?

Sure! Gloria Yamauchi, an aerospace engineer at NASA’s Ames Research Center, puts it this way. “So we have an airplane, flying through the air; the air approaches the wing; it is turned by the wing at the leading edge,” she says. (By “turned,” she means that it changes direction, like the way a car plowing down the road forces the air to change its direction to go around it.) “The velocity of the air changes as it goes over the wing’s surface, above and below.” 

“The velocity over the top of the wing is, in general, greater than the velocity below the wing,” she continues, “and that means the pressure above the wing is lower than the pressure below the wing, and that difference in pressure generates an upward lifting force.”

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

This story has been updated. It was originally published in July, 2022.

The post Let’s talk about how planes fly appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

THE DEVIL found his first advocate in the church. In 1587, Pope Sixtus V established the role of Advocatus Diaboli, a Vatican official whose job was to combat any biases the pontiff might hold when advancing a candidate for sainthood. The Advocatus Diaboli would present counterarguments and dissect the validity of miracles thought to have been performed by the person in question.

The role has evolved since its religious beginning into a less formal but more sinister one in our day-to-day lives. Now psychologists know that playing devil’s advocate in a public meeting or Twitter thread can prove unnecessary and, in some cases, harmful.

From the historical church to modern boardrooms, the devil’s advocate was intended to be a crusader against groupthink, a phenomenon that can hinder proper decision making, explains Jeremy Jamieson, a psychology professor at the University of Rochester. Typically—say, during a business meeting on a new marketing campaign—the person playing the role is assigned to push back on the dominant ideation. The goal is to stop the group from reaching a decision without considering unintended consequences.

But when the conflict is fabricated, it may not be helpful. The work of Charlan Nemeth, a psychology professor at the University of California, Berkeley, indicates that the devil’s advocate isn’t as persuasive as a true dissident who believes what they’re putting forth.

The role can also have adverse psychological effects on the antagonist and those being antagonized.

In a 2014 study in the Journal of Experimental Social Psychology, Jamieson and his colleagues found that those assigned to deliver negative feedback to others experienced “psychological threat” to their sense of belonging and self-esteem. This discomfiting mental state arises when the advocate feels unable to address the stressors—such as potential negative social feedback—that come from pushing back against the group. As a result, the infernal stand-ins were overly conciliatory to the people whose points of view they were attacking. The study also noted that being on the receiving end of artificial flak was even more harmful: People felt as if they were being bullied.

The researchers also saw that the person commissioned to play the devil’s advocate frequently ended up apologizing, which could be a disadvantage to the role in itself, says Jamieson. “They’ll overcompensate in future interactions with those individuals that they had to be negative towards,” he says.

When Beelzebub’s proxy appears during everyday conversations, such compassion is often lacking. In these environments, the idea of a devil’s advocate has evolved into an insidious way of airing problematic stances. This can get particularly pernicious online, whether it be in a Facebook group or the open discourse under a news article. Under a real identity or an assumed one, social media users can easily pull others into fruitless arguments, often just to serve their own interests. “Anything that involves dissent or negative commentary is typically amplified in these settings,” Jamieson says. “People are often more willing to write aggressive, critical comments online than they would be to deliver such feedback face-to-face.”

Adopting a counterintuitive persona has also become a tool to air unpopular opinions. “More recently, when people want to say something they think might offend somebody, they might add, ‘hypothetically,’ or ‘playing devil’s advocate,’” Jamieson explains. But this doesn’t align with the proper definition of the role. Rather than exploring counterarguments, these impersonators might be trying to couch disagreements in hypotheticals or get others to accept the bigoted or generally unacceptable points of view they actually hold.

For instance, in conversations about racism, hiding behind the devil’s advocate’s mask can allow someone to undermine the experience of a person of color. Or, worse, gaslight someone about their lived experience.

Maya Rupert, a political strategist, wrote about such an incident in a 2017 Slate article. After she presented at a conference, a member of the audience told Rupert, who is Black, that she’d gotten into law school because of affirmative action. Later, one of Rupert’s white friends put on his horns and asked her to consider that person’s perspective. Maybe she hadn’t earned her spot in her law school, the friend said, but he justified his claim as a counterargument, not his point of view.

Rupert shut this down by letting her friend know that her school hadn’t used race-based admissions since 1996, and she highlighted how the conversation, and others like it, taxed her emotionally. When people act as the devil’s advocate in this way, Rupert concluded in her piece, it’s to run from accountability and hide behind the guise of unbiased logic or hypotheticals.

Jamieson’s research supports this conclusion: Having a personal conversation with someone who protests without purpose only makes for a counterproductive interaction.

In most scenarios, the devil doesn’t need an advocate.

This story originally ran in the Fall 2022 Daredevil Issue of PopSci. Read more PopSci+ stories.

The post Does playing devil’s advocate do more harm than good? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

TO ALEXEI LEONOV, the colors in space were much more beautiful than those on Earth. No photograph could match what the late Russian cosmonaut experienced while floating hundreds of miles above his home planet in 1965: the distant curve of blue suspended in the deep black of space; the sunset as lines of reds, greens, and yellows skimming the horizon. Other explorers have shared this otherworldly perspective, but back then no one saw it as Leonov did—from beyond the safety of a spacecraft during history’s earliest spacewalk.

With only a 16-foot tether as his lifeline, the pilot of the Voskhod 2 mission drifted alone through low Earth orbit. But after 12 minutes, awe turned to panic when his suit ballooned to the point where he couldn’t fit back through the shuttle’s airlock door. He feared that as the first to explore the vastness of space in a suit, he might also be the first to get lost in it.

These days, spacewalks, also known as extravehicular activities or EVAs, are commonplace. Astronauts aboard the International Space Station (ISS) have conducted 250 of them since 1998, spending hours in the extraterrestrial elements to install or fix scientific equipment. But even as astronauts have become more adept at roaming outside controlled environments and the technology behind their suits has improved, the risks of accidents or death remain.

In Leonov’s case, the drop in atmospheric pressure caused the air in his suit to swell to dangerous proportions. If he tried to release the gas and reduce pressure, he risked bleeding off too much oxygen and asphyxiating himself. He decided to take the chance and quickly opened a valve in his suit to slim it down some, then slipped back indoors. Meanwhile, the Soviet space agency cut off a national broadcast of the mission to avoid public alarm. Leonov returned to a hero’s welcome on Earth, and it wasn’t until he shared his story that everyone realized the danger he’d faced.

Since Leonov’s pioneering foray, countries have stepped up safety and training standards for spacewalks. NASA astronauts practice EVA procedures in water tanks and zero-gravity airplanes, spending nearly seven hours submerged for each hour in orbit. More recently, they’ve practiced in virtual reality.

As a result, astronauts today are well prepared for EVAs, retired NASA payload commander Jeff Hoffman says. He performed four spacewalks throughout his career. His debut, in 1985, happened to be the first unplanned one in the agency’s history, when he ventured outside his shuttle to try to fix a broken satellite. “It showed how good the training [for spacewalking] was,” Hoffman said of the three-hour EVA. “I felt very comfortable, even though it was unplanned.”

Equipment has improved since Leonov’s era too, enabling astronauts to trek around for longer. Almost like individual spaceships, spacesuits supply oxygen, regulate temperature, and vent exhaled carbon dioxide. Other small additions make EVAs more secure and comfortable, including devices crewmembers use to propel themselves around in short bursts, guardrails on the facades of structures that improve maneuverability, anti-fog coating inside helmets, and warm gloves made of many layers of insulation and tough, flexible fabric.

Still, the dangers are real. In 2013, Italian astronaut Luca Parmitano almost drowned during a spacewalk when his helmet flooded with water that had leaked earlier from the suit’s cooling system. Astronauts might also face exhaustion or blood-bubbling “bends,” caused by the same rapid pressure changes that also endanger scuba divers.

Space junk, traveling at 18,000 miles per hour, poses another risk—one that Hoffman says is getting worse as stuff accumulates in Earth’s orbit. In late 2021, NASA canceled an ISS EVA because of floating debris. Though no astronaut has been hit yet, a punctured suit could turn fatal fast.

Even as spacewalks become more regular, the potential for disaster will never be fully eliminated. After all, Hoffman says, it’s part of a job that involves sitting on a loaded rocket. “I was fully confident that if anything happened that we could do something about, we’d do the right thing. And if something happened that we couldn’t do anything about—why worry?” he explains. “I took the risk because we had useful work to do.”

This story originally ran in the Fall 2022 Daredevil Issue of PopSci. Read more PopSci+ stories.

The post How astronauts pull off dangerous spacewalks appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

WHEN ACTION PARK first opened its gates on a New Jersey ski mountain in 1978, people probably showed up expecting run-of-the-mill amusements: go-karts, a lazy river, maybe a casual wave pool or two. But the 2,700-foot Alpine Slide, a track made of concrete, fiberglass, and asbestos that zigzagged through the funfair, was something else entirely. Riders plopped down on a little sled at the top—no helmets, no straps, no guardrails—and went wherever gravity took them at alarming speeds.

Eventually a park-goer did die on the Alpine Slide, and, after five additional fatalities and countless head wounds, electric shocks, and broken teeth, the entire venue shut down in 1996. New owners repeatedly tried to reopen the cult favorite destination, but after continued safety issues, the park’s operators finally decided to rebrand it a decade later.

While no other attraction can match its brazenness, Action Park lives on in the many rides that push today’s thrill-seekers to the edge of their comfort zones. Remember to read the fine print before you board these rowdy machines.

Most dimensions on a roller coaster

When Japan’s Eejanaika went up in the early 2000s, the steel coaster’s “fourth-dimension” design had to undergo multiple safety upgrades before it could start stealing people’s breath away. While it maxes out at about 75 mph (slow in extreme ride terms), it sends passengers spinning both parallel and perpendicular to the track. The seats rotate 360 degrees forward, backward, and sideways as they plunge down a 213-foot drop and swoop through 14 zero-G rolls. Since Eejanaika opened, barely more than a dozen other new 4D rollercoasters have debuted around the world.

Most sprains after going to the “rodeo”

The mechanical bull at a local dive bar may seem like the adult version of a bouncy house, but it’s a force to be reckoned with. With their aggressive torque, angular jerks, and short bursts of acceleration, the bucking plastic cattle can mangle unsuspecting (and often inebriated) bodies with every snap and toss. A survey of US hospital admissions from 2000 to 2020 estimated that mechanical bulls caused upward of 27,000 sprains, contusions, fractures, and other assorted ouchies. The majority of patients hurt their hands and arms. In other words, an iron grip could be your downfall.

Most distance falling down on your butt

Many visitors who summit Mount Kilimanjaro—that is, the 15-story-high body slide in Brazil, not the ice-capped volcano in Tanzania—chicken out when they see the drop. If you make it up 234 stairs and decide to brave the plunge, you’ll have to do without the padding of an inner tube. As bodies zing down a 60-degree angle at roughly a mile per minute, a trickle of water helps prevent friction burns. Extravagant views of tropical hills and the amusement park below almost make the wedgies worth it.

Most unpredictable carnival attraction

A Tilt-A-Whirl is essentially a giant centrifuge for humans; the clockwise and counterclockwise spinning—mixed with gravity, friction, and shifts in incline—creates what physicists call a “highly unstable” experience. Mathematical models can’t even predict the motion of the cars after a few seconds. So it’s not exactly shocking that the carnival amusement is prone to accidents like displaced cars. A report from the Consumer Product Safety Commission ranks these gyroscopes between Ferris wheels and roller coasters in terms of danger; they were responsible for about 20 percent of ride-related deaths between 1987 and 1999.

This story originally ran in the Fall 2022 Daredevil Issue of PopSci. Read more PopSci+ stories.

The post 4 of the most extreme amusement park rides on the planet appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

THE MOST IMPORTANT moments of a day on Hōkūleʻa, a 62-foot-long deep-sea canoe, are sunrise and sunset. That’s when the navigator can know for sure where the sailboat is headed. In between, the swell—the direction of the waves—helps hold course, but “you have to have known what direction it’s coming from based on where the sun rose,” says Kaʻiulani Murphy. At night, the stars are an important guide: “The sky kind of gradually changes with your latitude,” Murphy says. But on cloudy days, it is impossible to find a true path without sunrise and moonrise.

Murphy is a watch captain for the Polynesian Voyaging Society, the oldest and best-known group dedicated to the wayfinding methods that first brought humans to Hawaii as early as 300 CE. Originally from Waimea, a small community on the Big Island, Murphy’s been navigating thousand-mile stretches of open sea without so much as a compass for decades.

In 1997, as an 18-year-old undergrad at the University of Hawaiʻi at Mānoa on Oahu, she attended a lecture by Nainoa Thompson, the Voyaging Society’s chief navigator. “I was just so enthralled with the stories he was sharing,” she says. By the following spring, she was doing her first trials on the open water. “I was one of the few people who didn’t get seasick,” she recalls. She cut her teeth as an apprentice navigator in 2000, when she served on part of the return leg of a trip to the remote Rapa Nui (Easter Island). She’s spent many of the days since then following the solar rhythm that led her ancestors across the ocean.

The founding members of the Polynesian Voyaging Society—which include historian Herb Kawainui Kāne, anthropologist Ben Finney, and expert canoer Tommy Holmes—crafted Hōkūleʻa in the mid-1970s. Knowledge of Hawaiian culture was at a nadir after decades of violent colonial influence that, among other things, denied or obscured the fact that ancient Polynesians sailed thousands of miles of open waters. “Hōkūleʻa was built at a time when I think we in Hawaii needed her most,” Murphy says. The boat’s design mimics that of the double-hulled vessels that once traveled more than 2,500 nautical miles from the Marquesas Islands and Tahiti. “When you step on board you almost feel like you’re stepping back in time,” Murphy says. “I think, This is what our kupuna, our ancestors, would have been sailing.”

While no one on Hawaii knew exactly how those first epic trips had unfolded, other Oceanic communities had maintained an unbroken chain of wayfinding knowledge. Traditional Micronesian navigator Mau Piailug offered to share the techniques his ancestors had preserved as oral history. In 1976, he joined Kāne, Holmes, and Finney on their newly built vessel and guided them along the historical route, which takes 20 days or more to travel.

Piailug passed on his skills to the Polynesian Voyaging Society’s navigators, who would eventually teach Murphy how to read the stars and swells. Hōkūleʻa—named for the North Star—has now sailed more than 140,000 nautical miles and has a larger sister named Hikianalia, constructed in 2012. The two canoes have traversed the Pacific on 10 major voyages, strengthening ties between Hawaiians and other Indigenous groups such as the Maori.

Growing up in a small community and watching her family farm taro, a traditional root vegetable, made Murphy eager to connect with pre-colonial Hawaiian culture. That fascination led her to Thompson’s lecture, and then into the swells. The group is “kind of what kept me on Oahu,” she says. But it also took her around the world—quite literally, as she served on several legs of a circumnavigation of the Earth in the 2010s. She eventually started teaching, first at Honolulu Community College and then at UH Mānoa, where she oversees the same class on ancient sailing she took at 19.

At sea, Murphy’s primary kuleana, or duty, varies. As watch captain, she coordinates the movement of the canoe and its crew, which ranges in number from eight to 14. Folks work in four-hour shifts; the rest of the time, they write in journals, practice music, craft gifts, and watch the ocean.

When Murphy serves as navigator, the job starts on land. The first step is plotting a detailed reference course—complete with an estimated schedule—using nautical charts and specs like currents and average wind. It’s something her ancestors wouldn’t have had on those first trips to Hawaii, but then again, today’s voyagers lack the multigenerational experience those explorers surely leaned on.

Once at sea, Murphy relies solely on ancient methods to keep to the plan. “As a navigator, you have to be really in tune to what’s going on in nature,” she says. For example, she often takes cues from seabirds: A pale, pigeon-like Manu o Kū means the boat is probably less than 120 miles from a coastline. The small, sooty noio has a much shorter range, so it’s a reliable harbinger of land. Seeing either helps the crew confirm its location relative to the islands and continents it cruises by.

Murphy says it’s “beautiful” to watch the renaissance of traditional Polynesian navigation. “In the beginning, there was a lot of trying to prove things, especially this ability to navigate,” she says. Today, multiple groups explore the seas in canoes modeled after their kupuna’s vessels. “Now we [have relearned] this knowledge, we want to make sure it is never lost again,” Murphy says. That means maintaining boats and building new ones, continuing the practice of voyaging, and teaching it to future generations.

But it’s not just about cultural preservation, she says—it’s about a way of connecting with the planet. For Murphy it all comes down to time with Hōkūleʻa, watching the sun rise and set, keeping an eye out for birds, and relying on the natural world for guidance. “There’s so much magic in that,” she says.

This story originally ran in the Fall 2022 Daredevil Issue of PopSci. Read more PopSci+ stories.

The post Voyagers made it to Hawaiʻi thousands of years ago with no compasses. Here’s how. appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

GENERALLY SPEAKING, humans will try to eat anything at least once. Some anthropologists theorize that prehistoric people sussed out what was edible by trial and error, but we haven’t stopped pushing our palates in new, sometimes dangerous directions. The risk of illness and even death is often baked into our favorite flavors and fares. Here are some beloved bites that can kill—if things go awry.

Fugu

A dash of danger is part of the appeal of this lean and mild whitefish, which is served as slivers of sashimi in select Japanese restaurants. Tetrodotoxin, a paralysis-inducing chemical that disrupts the connections between neurons and muscle cells, collects in the liver and sex organs of this family of pufferfish. Japan’s health ministry requires fugu chefs to be certified in properly cleaning and removing the potentially deadly body parts. Yet some diners insist that a hint of risk gives the dish its allure. A possibly apocryphal tradition holds that culinary masters know just how much toxin should linger on the meat to provide a pleasing tongue tingle.

Hot dogs

Franks have long been a leading cause of choking in young US children due to the all-American food’s shape, size, and texture. Health experts advise parents against cutting dime-size medallions for tykes to chew on; instead, the sausages should be sliced into thin strips, then chopped into smaller pieces. But that’s not the only way a wiener can get you: The American Institute for Cancer Research and the World Health Organization suggest limiting consumption of all processed meats, because emerging evidence links them to an increased chance of colorectal cancer. Hot dogs may also be associated with higher risks of cardiovascular disease, according to a 2021 study in the American Journal of Clinical Nutrition.

Almonds

Wild almonds are slightly different from the domesticated seeds found in grocery stores. These bitter varieties produce amygdalin, a compound that our bodies convert to cyanide. The sweet almonds we usually eat have a genetic mutation that means they produce less of this respiratory toxin than the fatal doses found in the wild. Some foodies claim that a sprinkle of the bitter varieties is the key to deepening the taste of nutty confections. Heating or boiling them beforehand is the best way to dissipate the poison.

Potatoes

This humble root vegetable’s sprouts, leaves, stems, and flowers contain a harmful compound called solanine. Even the flesh of the spud can have high quantities of the noxious stuff—at least once you see it go green. Potatoes, like almost all plants in the nightshade family, produce solanine to ward off insects. As they make the chemical, they amp up their chlorophyll too, creating an unappetizing shade of chartreuse. But don’t fear the oft-maligned green chip: Eating the occasional off-color potato is probably fine, though it may have a slightly acrid taste. Just don’t make a habit of chowing down on taters past their prime: an excess of solanine can cause vomiting, paralysis, and even death.

Wild mushrooms

A frequently cited proverb states that “all mushrooms are edible, but some only once.” Even safe fungi can be tricky, with many poisonous look-alikes that can lead amateur foragers astray. Amanita phalloides, for example, can resemble a benign white mushroom like the paddy straw to the untrained eye. But this unassuming species is called the death cap for good reason. It contains lethal amatoxin, which holds up even after thorough boiling. And don’t trust your nose or tongue to sound the alarm in time to save you: Writer Cat Adams reports in Slate that “many people who are poisoned claim the mushroom was the most delicious they’ve ever eaten.”

Maggot cheese

Casu marzu is a Sardinian sheep’s milk cheese with an added kick: living larvae of the Piophila casei fly. As maggots eat their way through the fermented dairy, their digestion transforms it, making it softer and creamier. Many diners praise its intense and unique flavor, which is said to be tangy, nutty, and a bit bitter. It also holds the Guinness World Record for the “most dangerous cheese” because the live grubs can contaminate the product with unsavory bacteria—and, if swallowed whole, can potentially nibble on the diner’s intestinal tissue. Unsurprisingly, this product is globally banned from sale, but adventurous eaters in the know continue to indulge.

This story originally ran in the Fall 2022 Daredevil Issue of PopSci. Read more PopSci+ stories.

The post Deadly and delicious: These 6 foods can actually kill you appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

DAN BLOCK has an easy charm and a twinkle in his eye—a natural charisma that would surely serve him in all manner of glamorous professions. That makes it all the more jarring to see him stick a power drill up his nose in front of a cringing crowd of onlookers.

After taking a moment to angle the machine just so, he turns it on, the bit rotating at dizzying speeds inside his head. The terrible whirring sound is enough to make even me—a stalwart masochist and the author of a book about the pleasure of pain—nearly black out from the rushing sensation of dread. But instead of straightforward revulsion or concern, my wooziness transmutes into a celebratory high. If the shocked silence that gives way to applause and relieved laughter is any indication, I am not alone in feeling a surge of something wonderful. The terrible act thrills performer and audience alike. But why?

First, there’s the question of what would compel someone—in this case my friend Dan—to put their body in peril. When he, a sideshow performer based in Austin, Texas, gets ready to use his face drill (or set a mousetrap off with his tongue, or inflate a balloon that’s been snaked through his nostrils, or hang weights from his eyelids, or…) his body senses the impending danger, and his gray matter gets to work. According to Arash Javanbakht, a psychiatrist and director of the Stress, Trauma, and Anxiety Research Clinic (STARC) in Detroit, Michigan, the two almond-shaped areas of the brain that form the amygdala oversee “salience detection and the creation of emotions.” In the most basic terms, he says, “Every time I see something, the amygdala decides if I should run away from it, attack it, eat it, or have sex with it.”

Faced with fear, excitement, and danger, this region calls other areas of the brain into action, gearing the whole noggin to fight-or-flight mode. This means doling out a blast of neurotransmitters like dopamine, increasing focus on the task at hand, and ramping up the sympathetic nervous system. The heart pounds, and blood pressure inside the muscles juices up the limbs in preparation for a chase or a rumble. “Breathing gets faster, mouth dries, we get a little bit sweaty,” Javanbakht explains. “I’m not suggesting that the daredevil doing some stunt is terrified, but there is that excitement.”

And, lucky for us, even bystanders can enjoy a secondhand rush. “We know that if you’re watching someone doing something related to fear or anger or aggression, you will have those same areas of your brain activate,” says Javanbakht. “That’s how empathy happens.”

This mirroring applies to movement as well. Using fMRI imaging, neuroscientists and physiologists have shown that when we watch someone do something, our brains seem to simulate the witnessed action. If we see a person jump into the air, for example, neurons light up in a similar pattern to the ones firing up when we jump ourselves—even if we are perfectly still. In that way, you can think of watching a stunt as a way to microdose the experience. Remember, for example, a time you saw a rock climber dangling off a cliff or a tightrope walker teetering in the sky. As an observer, you were in no real danger, but your body gave you some of the same signals it would set off if you were.

Internalized mimicry is helpful in that humans are very social animals, and we are constantly learning by observing each other. “There are great evolutionary advantages to being able to feel empathy. We don’t all need to have a near-death experience to appreciate that something is dangerous and we shouldn’t be doing it,” explains Brendan Walker, a former aeronautics designer and self-styled “thrill engineer” who tailors rides, installations, and other experiences to make them as evocative as possible.

Seeing another person cheat the reaper can also be instructive. “In nature, nothing happens for no purpose,” adds Javanbakht. When we watch someone defy death, be it by rock climbing or sword swallowing, we are present in the moment with them, participating from afar. “I’m actively in my own head, putting myself in that situation,” he says. “I’m practicing.”

Practicality aside, what’s the fun in activating your fight-or-flight response, or, stranger still, standing in awestruck wonder as someone else tongues the membrane between existence and the abyssal cleft of death? It turns out, there are major overlaps in how fear and excitement look and feel inside the body. What distinguishes the two is the context in which we experience those sensations. After all, Javanbakht notes, even something as pleasurable as falling in love comes with a pounding heart, shortness of breath, and clammy skin.

“What makes a difference in terms of being able to enjoy [the thrill] is the sense of control that we have,” he says. “Let’s say someone with a knife is chasing me on the streets. My feeling is very different than when someone with a fake knife is chasing me in a haunted house.” The important factor here is that one of the situations comes with the logical understanding of safety. Parts of our brain—the amygdala and other areas of the limbic system, or what Javanbakht calls “the animal inside of me”—sense the danger of the chase and get very worked up. But the prefrontal cortex, where we manage our emotions and think logically about how situations are likely to play out, understands theater and Halloween props and knows we are safe. That region helps us create a pleasurable context in which to enjoy the physiological cacophony of what feels like a brush with death.

Understanding why we aren’t necessarily afraid, however, doesn’t quite explain why we enjoy the sensation. Walker posits that the euphoric rush that comes with cheating death is also about “rewarding our persistence of life.” It’s a biochemical celebration of sorts—a way to feel joy and relief at continuing to exist. Evading danger, he says, creates a surge of happy-making transmitters, like adrenaline and dopamine. “I think it’s not even an emotion, it’s actually the movement of emotions,” he clarifies. “It is that movement, that rush of changing emotional space, that is what we term a thrill.”

Those fluctuations come in plenty of flavors, but we do have some sense of how they tend to unfurl over time. For example, when it comes to roller coasters, the high begins the moment you consider getting on, and it builds every time you make the choice to pursue that desire. Driving to the park, buying tickets, craning your neck to see the peaks and loops, waiting in line for your turn, all help psych you up for thrills. In 2007, Walker and a team of researchers from the University of Nottingham’s School of Psychology used wearable monitors and video cameras to measure physiological titillation on a ride consisting of one shocking, 180-foot vertical drop. They found something extraordinary: According to heart rate and sweat data, the most nerve-wracking, exhilarating part wasn’t clearing the precipice; it was the moment when the seat belt bar clicked into place. The actual experience of the drop registered at around 80 percent of the excitement of that moment of inevitability.

Even just anticipating someone enduring chills and spills can trigger a similar rush, thanks to our brains’ tendency to echo the feelings we observe in others. Even seeing an actor in a scary movie is enough to get our bodies worked up—a discovery that has given rise to the field of neurocinematics, or the study of how films affect our brains. “It’s a vicarious thrill,” says Walker. “You can live those emotions.”

We may not be able to do what the performer does, but through observing them, we have a chance to rejoice in death defied before our very eyes. It’s a way to feel fear, yes, but followed by a heady dose of mastery and control and jubilation. “Watching a performer playing at those dangerous edges is a form of entertainment,” said Walker. “[It] allows us to quite safely experience being alive.” Through witnessing the act, we feel the same fears, trials, victories, and, yes, thrills.

The secondhand jolt of another’s improbable persistence certainly has a compulsive draw for many of us. I asked Dan the drill sniffer, known to many as “The Amazing Face,” why he thought people were drawn to his shows of pain and derring-do. “I don’t think there is a singular reason,” he mused. “I think it’s like eating candy. Everyone has a sweet tooth, but we’re all looking for different things.” In his line of work, he sees people who wish they could emulate his acts, people who get a hit of fiendish glee at the thought of how bloody a high-stakes failure could be, and people who watch on with horror at feats that they themselves would never attempt. “Whatever we get out of it individually, everyone is looking to be entertained and to see the unbelievable.” Even knowing how Dan keeps his cranium intact doesn’t curb the terror. If you’re curious: He’s worked over the years to get to know—and subtly widen—the shape of his nasal cavity, and so has learned how to angle the bit to give it enough room to whirr without making contact. The real trick is not sneezing while it’s happening, which would-be blockheads on the Internet say takes lots of practice with less-lethal insertables.

Is it any wonder that we are drawn to witness the impossible made real? We as a species are facing a climate apocalypse, wars, pestilence, and famine. As pain clown poet laureate Steve-O of the Jackass franchise reminds us, escaping death is the ultimate unattainable fantasy: “Human existence is a prank on us because we only have one instinct, which is to survive,” he opined in the midst of a hot-wing-eating gag on YouTube in 2021. “And we only have one guarantee, which is we won’t.” Perhaps we are drawn to gawking at thrills because it allows us to snatch the joy of persistence from the jaws of certain death—even if just for a moment.

This story originally ran in the Fall 2022 Daredevil Issue of PopSci. Read more PopSci+ stories.

The post Why do we love watching people defy death? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

The typical pimple is caused by clogged oil glands or bacteria in our skin, and while most pimples aren’t harmful, they can become infected (and painful), especially when they’re opened up to the outside environment. Still, so many of us cannot resist pinching them away. 

To get to the root of the pimple popping divide, we can look to one of our most basic emotions: disgust. 

Disgust evolved to protect humans from infectious diseases and poisons, Daniel Kelly, professor of philosophy at Purdue University and author of a book called Yuck! The Nature and Moral Significance of Disgust, told PopSci in an interview. For instance, we’ve learned to avoid common repulsive items, like rotten meat or poop, because they can contain microbes that are known to make us sick if ingested. Developing this internal ick-detector was important in keeping our ancestors alive, Kelly says, because we can’t actually see the tiny pathogens like viruses and bacteria that make us sick. 

However, some bodily fluids like blood, spit, or pus—including the oily ooze from a pimple—are often only seen as disgusting when they come out of our bodies. In this case, Kelly explains that our disgust is acting  like a bouncer enforcing a no re-entry policy: Once our bodily fluids are out in the big bad world, they can potentially be contaminated by bacteria or other pathogens, so we don’t want to put them back inside of us. This aversion towards disease is also why people recognize the tell-tale signs of sickness in others around them, like sweating or coughing.

But unlike snotty noses, you might be surprised to find that squeezing those angry whiteheads doesn’t always evoke the same yuck reaction—in fact, there’s a whole community of people that finds that final burst oddly satisfying.  

Popping on the brain

We obviously don’t all react in the same way when we see pus coming out of a pimple. And on a basic, primal level, even popping fanatics get at least a little disgusted. It’s all about whether your enjoyment outweighs your instinctive revulsion.

There might also be levels to one’s love (or disgust) of poking those blemishes. Some people are into watching YouTube or TikTok videos of pimple popping, but wouldn’t be tempted to squeeze their own zits. Watching it happen to someone else through a screen controls exposure—the viewer is not in any real danger of coming into contact with potential pathogens. A similar phenomena can be seen when horror fans watch scary movies. No matter how frightening or gross a film is, we know a zombie isn’t actually going to pop up and eat our brains. 

Even for people doing actual in-person popping, either on themselves or on someone else, there’s still an element of control involved. It’s not the same as suddenly coming upon an infected wound; while your conscious mind might immediately respond with an initial feeling of ick, your lizard brain and past experiences not getting sick from zit pus help you recognize that a simple pimple likely won’t put you in danger. 

[Related: The mites that breed on our faces are getting clingier by the day]

Differences in our brains also help explain why some people like pimple popping more than others. How each person reacts to pimple popping depends upon their brains, according to a 2021 paper in the journal Behavioural Brain Research. Scientists from the University of Graz in Austria had 38 popping enjoyers and 42 non-enjoyers watch 96 video clips that showed either pimple popping, water fountains, or steam cleaning. The fountain videos were used as controls because water coming from a fountain mimics pus coming from a zit, according to the researchers, while the steam cleaning videos served as oddly satisfying controls. 

The researchers had study participants complete a survey before the experiment to determine their pimple popping enjoyment, their disgust sensitivity, and their reward and punishment sensitivity. Then, participants watched the clips while their brain activity was measured in a functional magnetic resonance imaging, or fMRI, machine. 

The team found that people who liked zit squeezing videos reported a greater sensitivity to being rewarded, as well as better disgust regulation skills, than those who didn’t. In other words, pimple popping fans were more likely to feel arousal when rewarded with the satisfaction of pus spurting from a pimple and could better modulate the amount of disgust they felt while watching. Those self-reported qualities matched up with what the researchers found in the brain imaging part of the study.

[Related: What is a hangover? And can you cure it?]

The fMRI scans also revealed parts of the brain most responsible for making us a fan or hater of pimple popping: the nucleus accumbens and the insula. The nucleus accumbens is part of the brain’s pleasure system, and has been shown to modulate people’s responses to the things they dislike. When people who didn’t enjoy pimple popping watched the videos, their nucleus accumbens was deactivated and showed little to no activity. And while the nucleus accumbens was also deactivated in people who liked pimple popping videos, it was more active than in their pop-hating counterparts. The insula is another part of the brain that’s activated when we’re disgusted. The level of connectivity between the nucleus accumbens and insula also varied between the two groups, with the pimple popping fans having greater connectivity. The researchers hypothesized that the increased connectivity of the insula with the accumbens might be tied to better disgust regulation. 

Don’t worry pimple popping fans—just because you have a higher tolerance of disgust for zit squishing doesn’t mean you’re less likely to pick up on actual harmful things that will make you sick. Plus, even the most hardcore pimple popping fans still have that innate ick-response: the 2021 paper found that ultimately all participants were at least a little grossed out by pimple popping.

To pop or not to pop

Unfortunately for popping fans, dermatologists say you really shouldn’t DIY this particular task, regardless of how tempting it is to get rid of unsightly zits. Pimple popping breaks the skin and can cause infections and scarring. Blackheads and whiteheads should be left alone, although home treatments like benzoyl peroxide can help them clear up more quickly. If you’ve got a Vesuvius-level whitehead you really want to get out, go to a dermatologist because they’re trained to handle extractions properly. If you still have a squeeze craving, there are plenty of videos around the internet to satisfy you safely.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post Why some people find pimple popping so grossly satisfying appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

How does an airplane stay in the air? Whether you’ve pondered the question while flying or not, it remains a fascinating, complex topic. Here’s a quick look at the physics involved with an airplane’s flight, as well as a glimpse at a misconception surrounding the subject, too. 

First, picture an aircraft—a commercial airliner, such as a Boeing or Airbus transport jet—cruising in steady flight through the sky. That flight involves a delicate balance of opposing forces. “Wings produce lift, and lift counters the weight of the aircraft,” says Holger Babinsky, a professor of aerodynamics at the University of Cambridge. 

“That lift [or upward] force has to be equal to, or greater than, the weight of the airplane—that’s what keeps it in the air,” says William Crossley, the head of the School of Aeronautics and Astronautics at Purdue University. 

Meanwhile, the aircraft’s engines are giving it the thrust it needs to counter the drag it experiences from the friction of the air around it. “As you’re flying forward, you have to have enough thrust to at least equal the drag—it can be higher than the drag if you’re accelerating; it can be lower than the drag if you’re slowing down—but in steady, level flight, the thrust equals drag,” Crossley notes.

Understanding just how the airplane’s wings produce the lift in the first place is a bit more complicated. “The media, in general, are always after a quick and simple explanation,” Babinsky reflects. “I think that’s gotten us into hot water.” One popular explanation, which is wrong, goes like this: Air moving over the curved top of a wing has to travel a longer distance than air moving below it, and because of that, it speeds up to try to keep abreast of the air on the bottom—as if two air particles, one going over the top of the wing and one going under, need to stay magically connected. NASA even has a webpage dedicated to this idea, labeling it as an “Incorrect Theory.” 

So what’s the correct way to think about it? 

Lend a hand

One very simple way to start thinking about the topic is to imagine that you’re riding in the passenger seat of a car. Stick your arm out sideways, into the incoming wind, with your palm down, thumb forward, and hand basically parallel to the ground. (If you do this in real life, please be careful.) Now, angle your hand upwards a little at the front, so that the wind catches the underside of your hand; that process of tilting your hand upwards approximates an important concept with wings called their angle of attack.

“You can clearly feel the lift force,” Babinsky says. In this straightforward scenario, the air is hitting the bottom of your hand, being deflected downwards, and in a Newtonian sense (see law three), your hand is being pushed upwards. 

Follow the curve 

But a wing, of course, is not shaped like your hand, and there are additional factors to consider. Two key points to keep in mind with wings are that the front of the wings, also known as the leading edge, is curved, and overall, they also take on a shape called an airfoil when you look at them in cross-section. 

[Related: How pilots land their planes in powerful crosswinds]

The curved leading edge of a wing is important because airflow tends to “follow a curved surface,” Babinsky says. He says he likes to demonstrate this concept by pointing a hair dryer at the rounded edge of a bucket. The airflow will attach to the bucket’s curved surface, and make a turn, and could even snuff out a candle on the other side that’s blocked by the bucket. Here’s a charming old video that appears to demonstrate the same idea. “Once the flow attaches itself to the curved surface, it likes to stay attached—[although] it will not stay attached forever,” he notes.

With a wing—and picture it angled up somewhat, like your hand out the window of the car—what happens is that the air encounters the rounded leading edge. “On the upper surface, the air will attach itself, and bend round, and actually follow that incidence, that angle of attack, very nicely,” he says. 

Keep things low pressure

Ultimately, what happens is that the air moving over the top of the wing attaches to the curved surface, and turns, or flows downwards somewhat: a low-pressure area forms, and the air also travels faster. Meanwhile, the air is hitting the underside of the wing, like the wind hits your hand out as it sticks out the car window, creating a high-pressure area. Voila: the wing has a low-pressure area above it, and higher pressure below. “The difference between those two pressures gives us lift,” Babinsky says. 

This video depicts the general process well:

Babinsky notes that more work is being done by that lower pressure area above the wing than the higher pressure one below the wing. You can think of the wing as deflecting the air flow downwards on both the top and bottom. On the lower surface of the wing, the deflection of the flow “is actually smaller than the flow deflection on the upper surface,” he notes. “Most airfoils, a very, very crude rule of thumb would be that two-thirds of the lift is generated there [on the top surface], sometimes even more,” Babinksy says.

Can you bring it all together for me one last time?

Sure! Gloria Yamauchi, an aerospace engineer at NASA’s Ames Research Center, puts it this way. “So we have an airplane, flying through the air; the air approaches the wing; it is turned by the wing at the leading edge,” she says. (By “turned,” she means that it changes direction, like the way a car plowing down the road forces the air to change its direction to go around it.) “The velocity of the air changes as it goes over the wing’s surface, above and below.” 

“The velocity over the top of the wing is, in general, greater than the velocity below the wing,” she continues, “and that means the pressure above the wing is lower than the pressure below the wing, and that difference in pressure generates an upward lifting force.”

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post Let’s talk about how planes fly appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

The pace of our lives are closely intertwined with so many things: hormonal changes, literal growing pains, and (of course) dental development. Most of us don’t remember teething, but plenty recall having our wisdom teeth erupt and, if you live in a place that regularly removes them, getting them yanked out of your jaw. It’s just one dental milestone and one of three molar milestones, but until recently we had no idea why wisdom teeth emerged so late in life.

A new study in Science Advances suggests a reason: our jaws are simply late bloomers.

“It turns out that our jaws grow very slowly, likely due to our overall slow life histories and, in combination with our short faces, delays when a mechanically safe space—or a ‘sweet spot,’ if you will—is available, resulting in our very late ages at molar emergence,” said Gary Schwartz, a paleoanthropologist at the Institute of Human Origins at Arizona State University, who co-authored the paper, in a press release. It’s easy to forget that our teeth undergo quite a bit of mechanical pressure as they chomp down on food, as does your entire jaw structure. And that means your jaw needs to be developmentally ready to have teeth all the way at the back of our mouths nearest the joint. If wisdom teeth emerged earlier, the molars could actually damage the jaw they’re growing out of.

[Related: Ancient dental plaque shows humans have always loved carbs.]

All of this is the result of two fundamental things about humans: we have prolonged lives and short faces. Life, short as it may seem, is pretty stretched out for humans in comparison with other creatures, even other primates. We develop slowly—we take our time—and we spend an inordinately long period just becoming adults. And, unlike our primate cousins, our faces are quite flat and squashed. Just take a look at chimpanzees or gorillas; you’ll notice that their jaws protrude outwards such that their mouths are mostly in front of their brain (though you probably never thought of it that way). Our faces are pulled in, sitting beneath our braincase.

The combination of these factors means that our jaws can’t accommodate that final set of molars until fairly late in life.

Lots of people in the US get their wisdom teeth taken out, which might make you think that they’re some kind of evolutionary leftover—some artifact of a prehistoric life that’s no longer relevant. But the truth is that you don’t necessarily need to get them removed. In the UK, for instance, wisdom teeth are only removed if they become problematic, as the National Health Service notes that there is otherwise no proven benefit (but there is the added complication of having a minor surgery).

Either way, the teeth are not so much a leftover as they are a sign of our evolutionary progress. Our squashy faces and slow development are part of what makes us human, weird dental development and all.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post We finally know why we grow wisdom teeth as adults appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Around 15 years ago, a slogan began to appear on bumper stickers, license plate holders, and tote bags: Save the bees. The sense that these pollinators—and the food system they support—were in critical condition was all-pervasive. In 2014, an online poll in the UK found that respondents ranked the decline of bees as a more serious environmental threat than climate change.

But do we still need to save the bees?

The answer is complicated: The public began worrying about bees at a time when western honeybees were dying in alarming numbers from a mysterious syndrome, colony collapse disorder. Now, their populations are much more stable. However, wild bees, which play an entirely different role in our food system and environment, are still in trouble. 

Colony collapse

The recent intense focus on honeybee health began after the fall of 2006, when beekeepers from Pennsylvania began to notice that their hives were dying off over winter. “Those were colonies that had, a couple weeks earlier, looked healthy, full of strong bees,” says Nathalie Steinhauer, science coordinator of the Bee Informed Partnership, a national nonprofit that monitors honeybee populations. “And they came back and the apiary was basically just full of empty hives.” What made the event especially mysterious was that there was no discernible cause. There were no dead bees around to suggest starvation, nor traces of parasitic mites. The bees had simply vanished.

Over the winter, other beekeepers experienced the same die-offs, losing anywhere from a third to more than half of their hives. “It really acted like an epidemic,” says Steinhauer. Affected hives showed no obvious signs of stress, and scavengers strangely avoided the abandoned honey. The cluster of symptoms came to be known as colony collapse disorder, or CCD. The disorder was alarming enough that it led to a wave of research on honeybee health, including the monitoring now led by the Bee Informed Partnership.

But the last verified case of CCD occurred in 2008. Entomologists still don’t know exactly what caused this bee epidemic, but the most likely explanation is that exposure to pesticides, fungicides, and parasites made hives more vulnerable to some kind of pathogen—like a virus. “[The disorder] appears to have existed,” says Geoff Williams, president of the Bee Informed Partnership, and a bee pathologist at Auburn University. “But it just for whatever reason didn’t persist.”

Die-offs, but stability

So why is there a lingering sense that bees are still in trouble? Well, says Williams, honeybee mortality is still high—but not because of colony collapse. The term has been misapplied in the years since. CCD was a galvanizing force for bee conservation within the industry, and quickly captured public attention. Both beekeepers and the media have used the term to describe unrelated die-offs.

Bee hives can naturally collapse during the stress of winter. Entomologists don’t know what the baseline rate of collapse looked like before the 2006 CCD outbreak, because national counts only began in 2007. But over the last 15 years of data, there are no obvious trends. “On average, winter loss hovers around 30 percent,” Steinhauer says.

“Some years are worse, some are slightly better,” she says. “Overall, it’s higher than what beekeepers tell us is acceptable.”

Williams says it’s likely that honeybee losses each winter did increase over the last 20 or 30 years, before baseline data was gathered.

In the late 1980s, a parasitic mite called Varroa destructor arrived in the US. As it spread, Varroa put extra strain on hives—Williams says it’s hard to get exact numbers, but that old-time beekeepers say that they remember times when losses were about three times lower, around 10 or 15 percent. The damage from mites are compounded by the continuing spread of monocrop agriculture. Soybean farmers have taken over regions of the northern prairie, where honeybees often summer—which has reduced the variety of the bee’s diet, likely making them more vulnerable to illness. And the proliferation of neonicotinoid pesticides, which are particularly toxic to bees, adds even more stress.

[Related: Want to help the bees? Keep these out of your garden.]

Despite of winter losses, overall honeybee populations in the US have remained stable over the last 15 years, and have even grown globally. 

The key to understanding how populations can be stable through losses is to recognize that honeybees are a domestic species. They’re more like cattle than butterflies. Every year, American farmers spend hundreds of millions of dollars to rent honeybee hives to pollinate almonds, blueberries, cherries, and more. To get there, the hives travel across the country on the back of semi-trucks, usually following the growing season from Florida to California.

Losing hives can devastate a beekeeper (“picture 30 or 40 percent of cows or chicken dying every winter,” Williams says) but they can be regenerated.

Honeybee hives reproduce by fission, a lot like the way a cell divides. In the spring, a healthy queen can fly away with half of the workers to form a new hive, leaving queen-eggs behind to pick up the baton in the original colony. A beekeeper can start this process manually, but it takes time, cutting into the bottom line.

So the pressures on honeybees have real stakes for the livelihoods of beekeepers, and possibly the food system more broadly. In theory, a bad year could knock out enough honeybees to screw up fruit harvests across the country. But honeybees aren’t at risk of dying off and leaving entire ecosystems without pollination.

Wild bees

Western honeybees are just one of hundreds of bee species in North America. Threats to domestic honeybees also hit wild bees, which don’t have farmers nursing them back to health.

And this is where the slogan “save the bees” becomes confusing. While honeybee populations are currently stable, wild bees and other pollinators, including flies and moths, are in immediate trouble. The loss of these pollinators have ramifications for both agriculture and ecosystems.

Of the 46 species of bumblebees in North America, more than a quarter are in decline or threatened, says Jess Tyler, who works on pollinator conservation and science with the Center for Biological Diversity. “If bumblebees are representative of bees at large, that could be hundreds that are in decline, potentially,” he says. The data on wild bees is fairly sparse in comparison to honeybees, but plenty of once-common species, like the rusty-patched bumblebee, have been reduced to tiny remnant populations.

Both wild bees and domestic honeybees are critical in our food supply—one study estimated that wild pollinators provide roughly the same crop value as domestic honeybees. Honeybees aren’t especially efficient pollinators, especially for North American crops like tomato and sunflower. They’re used because they’re portable, easy to breed, and convenient for farmers who need pollination on a schedule. (Over the last 50 years, apiarists have tried to get the best of both worlds by domesticating new species, like the eastern bumblebee and the solitary blue orchard mason bee.) The benefits of wild bees go beyond agriculture: They also pollinate native plants, creating the backbone for diverse, non-agricultural landscapes. 

Wild and domestic bees require different kinds of support. And wild bees might need to be protected from domestic honeybees. Honeybee hives, for instance, can drive other bee species off of flowers after they’re done pollinating a crop. Even when they don’t compete, they can pass along diseases. “Honeybees are very messy,” says Tyler. “They’ll poop on flowers, and if another bee visits the same flower it can pick up a virus.” 

As a 2018 commentary in Science pointed out, some efforts to shore up honeybee populations that put hives in wildland far from crops might have actually hurt other types of bees.

[Related: City gardens are abuzz with imperiled native bees.]

According to another provocative commentary in the Journal of Insect Science earlier this year, honeybees are both a victim and driver of intensified agriculture. The author concludes that focusing on mites, malnutrition, or CCD as individual causes of honeybee decline misses the bigger picture. They’re actually suffering from industrialization, the model of farming that relies on large monocultures and off-farm inputs, like pesticides, fertilizers, seeds—and domestic pollinators.

“Honeybees are livestock,” says Tyler. “They’re cared for by humans. Their health is the result of what humans do to them.” And when industrial farms bring in high densities of honeybees, it might be inevitable that they will get sick.

Steinhauer thinks that while this framing is useful for understanding the problem, it shouldn’t be used to dismiss the struggles of working beekeepers. “In a lot of entomology departments, we are trying to improve industrial agriculture,” she says. Her work with Bee Informed Partnership pushes to reduce pesticides or improve farm diversity to improve the health of bees even within industrial farm contexts. “That’s going to be helping beekeepers next year.” She also points out that non-agricultural forces, like suburban construction and lawn chemicals, put pressure on both wild and domestic species.

If the critique from the Journal of Insect Science is right, more diverse, less chemical-drenched farms would make for healthier honeybees. Farms just might not need as many of them, because they’d also have wild pollinators.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post Do we still need to save the bees? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

LEFT TO THEIR OWN DEVICES, most children won’t hesitate to, say, lick a doorknob or wipe snot with their sleeve. But is there any truth to the idea that their affinity for getting dirty can be beneficial to their health?

That theory dates to the 1800s, when European doctors realized that farmers suffered fewer allergies than city slickers. However, it didn’t gain widespread attention until 1989, when British epidemiologist David Strachan discovered that youngsters with older siblings were less susceptible than other kids to hay fever and eczema. Strachan suggested that early childhood infections “transmitted by unhygienic contact” helped foster a robust immune system.

His theory, called the hygiene hypothesis, provides a convenient explanation for why allergies and asthma, as well as autoimmune disorders like multiple sclerosis and Crohn’s disease, have increased 300 percent or more in the US since the 1950s. Maybe Western societies have become too clean for their own good, and parents too fearful of a little dirt. “Whatever it is that’s happening in the modern world, it’s causing the immune system to be active when it doesn’t need to be,” says microbiologist Graham Rook of University College London.

As Rook notes, however, the hygiene hypothesis has its flaws. For example, some viral infections appear to trigger asthma, not prevent it. Most research now blames changes in the human microbiome, not a dearth of childhood infection, for at least some of the sharp rise in chronic diseases, from digestive disorders to kidney failure.

[Related: This pseudoscience movement wants to wipe germs from existence]

Getting a bit messy can help cultivate the thousands of microbial species that call the body home and keep it healthy. Providing that boost can be as easy as having pets, tending chickens, or playing in a green space. In fact, a 2020 study published in Science Advances found that when daycare centers in Finland replaced gravel yards with soil and vegetation, tykes saw almost immediate benefits to their immune systems, including an increase in disease-fighting T-cells. Eating a varied diet high in fiber helps too. And vaginal childbirth and breastfeeding promote healthy guts in newborns and nursing babies.

It’s also wise to go easy on the antibiotics. Although they can be lifesavers for patients with severe bacterial infections, there’s “a real risk of harm” from overuse, says John Lynch, a doctor at the University of Washington School of Medicine. “Regaining your native microbiota can be extremely hard to do,” he explains.

All this is not to say tots should be slobs. You definitely want them washing their hands regularly, and scrubbing high-touch surfaces is imperative to avoid unpleasant infections like norovirus, Rook and a colleague advised in a recent paper. Just don’t go overboard and sterilize everything. As it turns out, kids probably do need a few germs to stay healthy.

This story originally ran in the Spring 2022 Messy issue of PopSci. Read more PopSci+ stories.

The post Children are grimy, and that’s (mostly) ok appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

OUR ENTIRE SOCIETY runs on garbage, at least in a manner of speaking. Eons-old junk—coal and oil that began as ancient plants and dinosaur remains, among other dreck—has powered our electric grid since the beginning of the industrial age. Of the 3.8 trillion kilowatt hours of electricity the United States used in 2020, most came from fossil fuels. The problem is that this trash isn’t meant to keep lights on or charge up EVs; it’s supposed to stay deep beneath the surface, locking away the gases that now flood our atmosphere and cause disastrous warming.

The good news—and bad news—is that we’re making new batches of carbon-rich refuse all the time. In 2018, the average American generated an unsavory 4.9 pounds of waste every day. Could these fresh trash heaps help replace our dependence on dead dinos?

We already know, of course, that we can burn carbon-based products for energy. But simply setting trash aflame has its own nasty side effects. Incineration plants, which have been running in the US since 1885, emit nitrogen oxides, sulfur dioxides, particulate matter, lead, mercury, and dioxins, among other toxins. They also belch greenhouse gases out the wazoo: more than half of what coal spews. The process isn’t even very efficient, extracting just a fraction of the refuse’s potential power. “A lot of energy escapes in the process,” says Johan Enslin, executive director of the Energy Systems Program at Clemson University.

Luckily, firing up trash, be it new or millions of years old, isn’t the only way to turn it into fuel. Take natural gas: Deep beneath the earth, organic matter breaks down and compresses to form methane (chemically, CH₄). We call that byproduct natural gas, which has run a chunk of the grid since the 1960s, and which today contributes more power than coal and oil combined.

Our heaps of castoffs mean we’ve got that same gas topside too. Deprived of oxygen in landfills and manure ponds, modern waste breaks down into methane more or less the same way as the ancient subterranean stuff. There’s plenty of incentive to trap that gas: Methane is more than 25 times as potent as carbon dioxide in terms of trapping heat in the atmosphere, and municipal solid waste landfills are the third-largest source of human-related CH₄ emissions in the US.

Enter biogas, a combination of the carbon dioxide and methane that naturally creep up out of moldering garbage. Humanity has tapped these landfill burps in various forms since the late 1800s, and today more than half of the EU’s biogas production goes toward generating electricity.

There are a couple of different methods for turning that junk into voltage. The oldest involves a vessel called an anaerobic digester: Organic matter goes into an oxygen-deprived tank, where it breaks down over the course of days or months. The resulting gas is often used to power internal combustion engines or turbines that produce electricity and heat. Biogas can also generate voltage through fuel cells, which tap a chemical reaction to separate hydrogen atoms into electrons and protons. The negatively charged particles then run through a circuit, creating energy with fewer emissions than combustion.

Right now, biogas producers fall into three categories—biodigesters, landfill gas recovery systems, and wastewater treatment plants. Trash-heap-based projects currently make up the primary source of biogas production nationwide, bringing in some 17 billion kilowatt hours—less than half a percent of our annual usage.

Farms and wastewater treatment facilities could hold the key to boosting American usage. At present, just 20 dairies and livestock operations around the country turn their dung into power, which nets only around 173 million kilowatt hours—scarcely enough to keep the country alight for 30 minutes. But the EPA estimates there are more than 8,000 farms across the US that could plausibly recover biogas. That would rake in another 16 billion kilowatt hours of energy each year. And as of 2017, just 860 wastewater treatment plants in the States used their gold mine of garbage for biogas energy, leaving more than 15,000 other facilities to send similar sludge off to dumps and incinerators instead.

Sure, closing that gap still wouldn’t give us close to all the juice we need. But toasted trash could fill in a missing piece of the renewable energy puzzle. On days when the sun barely shines and the wind doesn’t blow, animals—and humans—will continue to poop.

Unlocking that potential will largely come down to making policy changes. The rest of the world has already shown us how it’s done. In 2009, the EU mandated that 20 percent of the bloc’s energy come from renewables, and as early as the 1990s, countries like Germany were using incentives to get greener power on the grid. So it’s no surprise that in 2015, the EU produced around half of the globe’s total biogas. With the Biden administration’s new goals of making the stateside power sector “carbon pollution-free” by 2035, the US may have a chance of catching up.

Even before White House mandates, the number of renewable-natural-gas-to-pipeline projects shot up from 219 to 312 between early 2019 and late 2020. According to the Environmental and Energy Study Institute, renewable methane and biogas sources could one day replace 10 percent of the natural gas used in the United States.

So could we ever run the entire electrical grid using nothing but garbage? Probably not. And wind, solar, and hydro arguably have the potential to power the whole thing on their own. But tapping the planet’s junk could help us make the most of methane that would otherwise keep filling our atmosphere. We just need to make sure we learn from the mistakes we made powering all our cars and factories on dinosaurs.

This story originally ran in the Spring 2022 Messy issue of PopSci. Read more PopSci+ stories.

The post Is trash a form of renewable energy? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This post have been updated. It was originally published on January 2, 2020.

The holidays are officially over, and many of us are recovering from reconnecting with loved ones and take in some well-earned R&R. And while the vacation time could mean different things to people—catching up on competitive sports, consuming inordinate amounts of food, or finally confronting your racist uncle—one thing is almost ubiquitous: the looming sentiment of “oh no, I have to go to work again.”

It’s easy to understand why we get a little bummed at the prospect of reverting back to everyday life—dealing with the debilitating effects of jet lag is enough to take a person out of a good mood. But for a lot of folks, ever the most seasoned jet setters, the post-vacation blues can have actual health effects. “I absolutely feel sad after returning home from a trip,” says freelance journalist and travel writer Nneka Okona. “For me, the deflation starts around the last 24 hours of a trip. I feel really down and sometimes even teary; the more of a sensational experience, the harder and deeper the deflation tends to be.”

[Related: What is a toxin?]

But if vacations are supposed to be a significant boon to our happiness and wellbeing, why do we crash mentally afterwards?

Know the reason for the post-vacation blues

Jeroen Nawijn, a psychologist at the Breda University of Applied Sciences who’s studied vacations as they relate to quality of life, says that though people generally see a blissful boost on their days off, those benefits taper off quickly after returning home. “They most likely feel best during vacation because they have more freedom to do what they want,” he explains.

Suzanne Degges-White, a therapist and chair of the Department of Counseling and Higher Education at Northern Illinois University, echoes this sentiment. “Once we get back into the work world, the majority of us have to answer to someone about what we’re doing, how we’re doing it, and when we’ll be done,” she says. She also attributes the difficulty of reacclimating to the fact that quandaries and responsibilities don’t disappear when we go on vacation. “Many people dread the return as they know that problems may have stacked up in their absence. There may be a pile of new requests of their time on top of the unfinished tasks they left behind,” Degges-White adds.

[Related: For better sleep, borrow the bedtime routine of a toddler]

She also cites the influence of transitioning from a looser sleep-wake pattern on vacation to a more strict and regimented bedtime schedule. That, combined with sluggishness from overeating (and drinking, if that’s your style) can put a real drag on a person’s wellbeing, she says. Thankfully, there are ways to keep the vacation high going after you’ve put the good times past you.

Get ready for work before you return

Prepare yourself in advance for the sharp adjustment by adding some extra padding between your travel and work dates, Nawijn says, even if it’s just a day or half a day. Thinking ahead could also include making a to-do list for your first week back, keeping your work and living spaces clean and organized for you return, and prioritizing relaxation as you get back into the swing of things, Degges-White says.

Take another break soon

One more tip: start planning your next vacation right away. “The only thing that has continually worked for me is booking another trip as quickly as possible,” Okona says. “My blues are diminished greatly if I know I have something else to look forward to.” She also recommends nabbing a useful souvenir so that you have something to tie your new experiences with your life back home. (Instead of kitschy magnets and shot glasses, she opts for spice blends, unique snacks, and jams or jellies.)

[Related: The coolest science-themed destinations in all 50 states]

Checking off these little tasks should overall, prepare you better for the reality that awaits post-vacation. And hey, if all else fails, you can always try manipulating your memories to trick yourself into happily ever after.

The post Why you hate going back to work after vacation appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

With millions of podcasts streaming online these days, it’s easy to get overwhelmed by the amount of variety in the audio-storytelling space. That’s why it’s sometimes better to stick with what you know, like PopSci’s two hit shows, “The Weirdest Thing I Learned This Week” and “Ask Us Anything.” Not convinced? We put our best episodes from this year into a fun, listenable list—and included other science podcasts we adore to help get you hooked. Bottoms up.

The Weirdest Thing I Learned This Week

Moose crash test dummies, famous ferrets, and deadly planets

This wonderful episode features science author Mary Roach, who joined the show to talk about her new book FUZZ: When Nature Breaks the Law. Her fact, which comes straight from the book, is all about why (and how) researchers created moose crash test dummies.

Ancient brain surgeons, the crows have eyes, and why radiators are so annoying

Actor and famous Schitt’s Creek impersonator Michael Judson Berry joined this episode, and it was a downright blast. Listen to Berry impersonate many members of the Rose family and learn all about why we’ve always drilled holes in heads, how radiators saved people during outbreaks, and why crows are, terrifyingly, even smarter than we thought.

Haunted vaginas, fairy floss, and books made of human skin

Halloween episodes of Weirdest Thing are always bangers, and this one is no exception. We learned that ectoplasm is real, but it’s not really the pink or green gooey slime we imagine. More dramatically, the material has been linked to a lot of scams and scandals through history.

Art crime doesn’t pay, canines cooking meat, and eggs done wrong

The comedian (and downright wonderful human) Josh Gondelman made this episode a giggly delight. From unsolved art heists to dogs cooking their humans dinner, this one’s a must-listen.

Science meets magic, high-tech murders, and bees

Jonathan Sims from the riveting horror fiction podcast the Magnus Archives joined the Weirdest Thing for this special recording. The group spun a (true!) story about the first murder reported via telegraph, discussed whether bees can tell time, and blurred the lines between science and magic.

Q&A: Punkin chunkin, mysterious shipwrecks, and midwestern scorpions

In the break between Season 4 and Season 5, host Rachel Feltman and producer Jess Boddy hopped on Zoom to listen to some listener voicemails. What ensued was, as always, wonderful and weird—but to Boddy’s delight, somehow Midwestern-themed. (Did you know scorpions live in Illinois?) The episode is a refreshing change of pace from the typical show format.

See the full list of Weirdest Thing episodes here.

Ask Us Anything

How can you safely send nude photos?

Guest-hosted by Associate DIY Editor Sandra Gutierrez G., the first episode of “Ask Us Anything” Season 2 was juicy and informative. From metadata to camera angles, Gutierrez explains everything you need to know about sending a steamy pic in the safest way possible.

What did dinosaurs taste like?

This is one of those questions that you might never consider—but once you hear it being asked, you’ll be ravenous for the answer. DIY Editor John Kennedy gets into the grisly details of how dinos might have tasted if you tossed them on the grill.

Why can’t we see more colors?

Most humans see the world in a generally consistent way. But other animals see even more colors than we can—so what’s the deal? Is it possible for us to perceive these “invisible” colors too? Science Editor Claire Maldarelli explains what is (and isn’t) possible.

See the full list of Ask Us Anything episodes here.

Other best science podcast episodes

The Outdoor Life Podcast: The mysterious chronic Lyme disease nightmare

Our sister magazine Outdoor Life launched their new podcast this year and took several deep dives on hot topics in the hunting and fishing worlds. This episode focusing on the latest research on chronic Lyme disease, however, felt relatable to a lot of people.

Flash Forward: What is the future of gender?

Former PopSci contributor Rose Eveleth’s podcast is a perennial go-to for our staff. This year’s gender episode really stood out to us, largely because of how it built off a thought experiment Eveleth ran six years ago. A lot has changed in gender science and policies since then, but at the same time, a lot of misunderstandings and questions remain.

Donut Podcasts: How these electric vehicles sparked the Tesla

Another sister publication of ours, Donut Media recently turned its popular YouTube channel into a freewheeling podcasting space. Their episode on the classic tech that fuels modern EVs was fascinating, especially with all the battery-powered trucks and sports cars that were unveiled this year.

For the Wild: Moral landscapes amidst changing ecologies

Indigenous science keeps growing in stature as a way to seek solutions against climate change, extinction, and other environmental problems. This episode, featuring Cal State University East Bay professor and biodiversity expert Enrique Salmón, combines philosophy, chemistry, and deep analysis to help humans rejigger their role in the natural world. It has the power to change minds and practices.

Apple News Today: Does blood hold the key to the fountain of youth?

PopSci writer Kat McGowan chatted about her magazine feature on reverse aging on one of Apple’s premiere podcasts. Listen to her dissect the sensational research that neurobiologists from Harvard and Stanford have been tinkering with for decades. What is fact and what is still fantasy at this point?

Radiolab: Elements

Here’s a nerd fest that you won’t want to miss. WNYC’s “Radiolab” stole our hearts with an entire episode dedicated to illuminating the more obscure parts of the periodic table through poetry, musical theater, and old-fashioned yarn spinning. Turns out, livermorium rhymes pretty well with zirconium.

The post Our favorite science podcast episodes of 2021 appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This post has been updated. It was originally published on 5/28/2018.

Food is an excellent way to celebrate life’s adventures. From weddings to birthdays, and backyard summer barbecues (when safe from a public health standing, of course), good cooking is at the center of so many celebrations. Still, in the presence of such abundant deliciousness, we humans tend to—on occasion—overdo it. That’s where good old Tums antacids come in.

Too much fatty, rich, or fried food can lead to that dreaded indigestion and heartburn that sidelines you from the merriment and keeps you up at night. Many people, in these situations, turn to Tums and other similar antacids to relieve their symptoms. The Tums label advises taking only a few in one sitting, not exceeding 7,500 milligrams, which depending on the dosage (it comes in 500, 750, and 1,000 mg doses) can range anywhere from 7 to 15 tablets.

But what if you have like really, really bad heartburn, and you want to just nip it in the bud? Can you just take the whole bottle? In other words, can you overdose on Tums?

While death by Tums overdose is exceedingly rare, downing a bottles’ worth of Tums is ill-advised.

The reason we have so much acid in our stomachs in the first place is because it’s a key component to digestion. Without it, we wouldn’t be able to break down food and therefore wouldn’t be able to absorb nutrients from it.

But it’s also true that acid plays a key role in heartburn, caused by acid reflux. This condition occurs when the valve that covers the bottom of the esophagus (the tube of muscle that connects your mouth to your stomach) relaxes when it shouldn’t, allowing acid to flow back up the esophagus and cause that burning feeling in your chest.

Over time, this can lead to inflammation of the stomach lining, known as gastritis, as well as erosive sections, known as ulcers (though it’s far more common to get these two conditions via infection with a bacteria known as H. pylori).

All that—heartburn, acid reflux, gastritis, and ulcers—is painful. What do Tums do? The reason Tums work so well is because their main ingredient, calcium carbonate is basic and when exposed to the hydrochloric acid in your stomach, the carbonate group binds to the hydrogen. This gets rid of the free floating acid, but in the process frees up calcium ions, allowing them to be absorbed by the body.

That leads to the main potential downside to the question of how many Tums can I take: a decent amount of readily absorbable calcium. The mineral is vital to bone and overall good health, but too much can be toxic to the body, particularly the heart and kidneys.

We know about this link between calcium and health problems partially because it used to be quite a common syndrome. Back in the day, the only method we had to treat peptic ulcer disease (in which an ulcer forms in the stomach lining) was with a combination of milk and sodium bicarbonate, and then later calcium bicarbonate. It was not uncommon for this to lead to something doctors dubbed “milk-alkali syndrome,” which causes high blood calcium levels (hypercalcemia), which can cause irregular heartbeat, metabolic alkalosis (too basic of a pH in the blood), and acute kidney injury. Researchers think the kidney problems result from too much calcium and neutralizing agents building up in the kidneys, which prevents them from being able to filter these compounds out.

[Related: Is it safe to take expired medication?]

Once we invented newer drugs, like Pepcid, Nexium, and Prilosec, that block acid from being excreted into the stomach rather than neutralize it when it’s already there, the cases of milk-alkali syndrome plummeted.

However incidental case reports show that milk-alkali syndrome still pops up from time-to-time, and often it stems from taking far too much calcium carbonate, or Tums.

Sign up for PopSci’s newsletter and receive the latest science and tech updates to your inbox.

So how many Tums can you take and how often can you take Tums? According to one report on recent cases of milk-alkali syndrome, the question is almost impossible to answer for the general population. When calcium carbonate was used to treat peptic ulcers, doctors often gave patients 20 to 60 grams of the neutralizing agent per day, and they noted, on average, that up to 35 percent of patients developed toxic symptoms. Other case reports show that people who took just 4 to 12 grams a day (that’s even less than the recommended maximum for Tums) went on to develop the syndrome. That same case report of milk-alkali syndrome found instances of the syndrome in people taking calcium carbonate daily to supplement their calcium intake.

In the reports, doctors note that certain individuals are far more susceptible to this syndrome than others. Those with impaired kidney function are at a higher risk, but sometimes, they note, it’s not easy to tell who is most susceptible.

Because of the variability in the number of grams of calcium carbonate it takes to lead to certain conditions like milk-alkali syndrome, it’s impossible to say how many Tums are too many Tums. As such, erring on the side of caution is best, taking only the recommended amount, and only supplementing for extra calcium if recommended by a doctor, is best. And if you find yourself taking that recommended maximum on a frequent basis, it could be a good idea to see a doctor to discuss how to improve your digestive ailment.

Have a science question you want answered? Email us at ask@popsci.com, tweet at us with #AskPopSci, or tell us on Facebook. And we’ll look into it.

The post What happens if you eat too many Tums? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This story has been updated. It was originally published on September 12, 2017.

The bottle of NyQuil always seems to be grimy, faded, and buried beneath layers of toiletries when you come down with a sudden cold. Tired and sniffling, you peer at the label. The medication expired six months ago. At that moment, it’s easy to question the number printed on the bottle: How solid is that expiration date, exactly?

Gina Bellottie, a professor of pharmacology at Thomas Jefferson University in Philadelphia, says that, as a general rule, people shouldn’t take drugs past their expiration dates. But whether or not those dates set in stone, she says, is a loaded question.

The Food and Drug Administration (FDA) requires that drug companies put an expiration date on all prescription and over-the-counter medications. The date that gets stamped in is the result of numerous tests run before the medications even hit the market: Researchers store the drugs under the recommended conditions (room temperature or refrigerated), and check them over time to see if their potency remains intact or if their chemical compounds break down. But companies don’t keep an eye on the drug forever, so if the medications still work until the end of the test period—which is usually between six months and two years—drug makers call it a day. That makes the resulting expiration date simply the last point where the company has data.

“Beyond that date, the drug company doesn’t guarantee it,” Bellottie says. And without further testing, she says, it’s impossible to know if a drug will continue to work just as intended.

But some recent evidence suggests at least some drugs might still be okay. In 2017, ProPublica published an in depth investigation into the research and policy on drug expiration dates, noting that when expired medications are tested, even years later, many of them still retain their potency. The inquiry found that piles of expired drugs, with price tags of thousands of dollars, are thrown out every year, even though testing shows that they work just fine.

But until drugs actually go through longer testing regimens (and there’s nothing to suggest they will anytime soon), day-to-day medication management practice stays the same. “In terms of what I would recommend for one of my patients, it doesn’t change,” Bellottie says: Don’t take an expired drug without checking with a pharmacist first.

A multitude of factors, like storage conditions or the time since the container was opened, could impact the safety and potency of a drug, says Bellottie. It’s possible some drugs may be okay years later, but it’s difficult to say which of those would be without further testing.

If you absolutely must take an expired drug, Bellottie advises against taking one for a life-threatening problem. “For some drugs, the only risk would be well, maybe it won’t work as well,” she says. “If you have a headache, maybe that’s not a big deal. But if it’s for an emergency problem, there’s a risk when a drug doesn’t work the way it’s supposed to.” Further, she says, old medications, especially if they’re open, and especially if they’re liquid, could also become contaminated after a long period of time.

When in doubt, she says, just throw the entire contents of the medicine cabinet into a bag and take them to the nearest pharmacy. The pharmacist can tell you what’s okay to keep taking and what’s not—and let you know about any possible drug interactions or side effects to boot.

The post Is it safe to take expired medication? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

WHEN FEIGE WANG was growing up in Shandong province, China, he liked gazing up at the night sky to look at the stars. Now, as a NASA Hubble fellow at the University of Arizona’s Steward Observatory, he looks much deeper into the darkness to contemplate the most distant objects ever studied.

His targets, quasars, are black holes surrounded by disks of gas and stars—the nuclei of primitive galaxies. Their dark hearts suck in nearby matter and crush the absorbed material into a superhot disk, which burns bright as it shoots out immense amounts of energy. That’s the feature that allows us to spot them from so far away. But because it takes billions of years for their light to reach Earth, we see these beacons in the blackness as they existed eons ago.

[Related: How old is the universe? Our answer keeps getting better.]

As one of today’s foremost quasar watchers, Wang uses them to gaze into the universe’s ancient history. “In the past couple years, I have been pushing to find the most distant ones,” he says, since every additional light-year of distance equals another year of cosmic time travel.

In 2021, using a trio of telescopes in Chile and Hawai’i, Wang and his colleagues discovered the farthest quasar yet. Dubbed J0313-1806, it’s more than 13 billion light-years away, which means Wang saw it as it was just 670 million years after the Big Bang—when it was practically a newborn.

Wang finds the quasar’s black hole particularly fascinating, because according to our current understanding of astrophysics, it shouldn’t exist.

J0313-1806 confounds scientists’ current theories. Black holes of its size are thought to grow from relatively small “seeds” that then suck up mass over time. One model states that the very first stars might have left such seeds in their wake after living fast and burning out young. Otherwise, clusters of stars collapsing in on themselves could come together to make good fodder.

But neither scenario can explain J0313-1806. Its center is around 1.6 billion times the mass of the sun, and about 500 times more massive than the black hole at the core of our own galaxy. At that point in the universe’s history, the cosmos simply hadn’t churned out enough stars to explain the sheer size of J0313-1806’s immense center.

Instead, Wang and his colleagues think that raw hydrogen may have seeded the massive object. It’s possible that a cloud of gas collapsed, eventually becoming dense enough to birth a black hole, which then ate up stars and other gas. But without other quasars of comparable age to observe, the black hole’s provenance remains a mystery.

“We have very little information about the large-scale environment of the earliest quasars,” Wang says, since observers are limited by the reach of current instruments.

[Related: Flickering light could help astronomers weigh supermassive black holes]

But he is optimistic that the next generation of sky-watching machines will help us uncover these secrets. The long-awaited James Webb Space Telescope, set to launch in late 2021 and take the throne of the 30-year-old Hubble, will allow astronomers to peer farther back into time than ever before—and take a closer look at J0313-1806. Other incoming scopes will help as well. Chile’s Vera C. Rubin Observatory, expected to open in 2023, will scour Earth’s southern skies for new quasars, among other things. The Nancy Grace Roman Space Telescope should enter orbit in 2025, where it will peer at infrared wavelengths to spot far-out matter.

Wang hopes such tools will reveal much more about how the earliest black holes grew. “The next decade will be a great time for studying the most distant objects in our universe.”

This story originally ran in the Fall 2021 Youth issue of PopSci. Read more PopSci+ stories.

The post What we can learn from baby black holes appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This story has been updated. It was originally published on October 20, 2017.

Before the mile run each year in middle school, on the dreaded walk down from the classroom to the course, my classmates would argue over the best way to prevent a side stitch. More so than turning an ankle or coming in last, that repetitive stabbing pain is what the majority of us dreaded most. Our cures ranged across the map from taught techniques, like breathing in through the nose and out through the mouth and not eating for three hours prior, to my favorite: Punching yourself in the stomach at the slightest hint of pain (don’t try it, it doesn’t work).

There’s a medical term for that stabbing side cramp: exercise-related transient abdominal pain, or ETAP. And it’s far from rare. Around two-thirds of runners experience them every year. But unfortunately for middle schoolers, elite athletes, and weekend joggers everywhere, this medical term does not come with a medical solution. There’s no standard advice for how to prevent a side stitch, says sports chiropractor Brad Muir, because we don’t know the mechanism that produces the pain in the first place. “It’s still up in the air.”

That’s partly because, even though side stitches are common, researchers haven’t really studied them. In 2015, a review article noted that after a few studies in the 1940s and 50s, there was a nearly 50 year gap in research on side stitches. Despite that, there are some basic things that we do know about ETAP: It’s more common in younger people; the number of reported cases tends to drop off as people get older. The pain is more common in activities where the upper body twists, like swimming, running, and horseback riding. Athletes of all levels get side stitches—elite athletes get them less often, but their stitches are no less painful than the ones in amateur exercisers.

About half of athletes said that they thought their stitches were triggered by eating or drinking, and some studies back this observation up. In the lab, drinking liquids with high concentrations of sugar were more likely to trigger a painful cramp than beverages with little or no sugar. Things like body mass index, body type, and gender haven’t been connected to the frequency or severity of ETAP.

What we do know about side stitches, the symptoms and risk factors, don’t provide much information about the underlying cause of the pain. One common theory posits that, during exercise, not enough blood (and therefore oxygen) gets to the diaphragm and causes the pain—but side stitches still occur in activities like horseback riding, which don’t tax the respiratory system. “The explanation of it being just the diaphragm never really held up to more scrutiny,” Muir says.

[Related: Why do my muscles ache the day after a big workout]

Another explanation is that jolting movements during exercise put stress on the ligaments in the abdomen that hold the organs in place. That explanation accounts for the role of food and drink in ETAP—putting something in the stomach would make it heavier, forcing those ligaments to work even harder. But it doesn’t account for the high rate in an activity like swimming, where muscle movements are smooth.

Bad posture or problems with a runner’s gait could also be a factor in ETAP, Muir says. There’s some evidence that playing around with certain vertebrae in the spine could reproduce the particular pain from a side stitch, indicating that biomechanical fixes could help with the problem. Friction and irritation in the tissue of the abdominal wall is yet another explanation.

One of the reasons it’s difficult to pin down an explanation for ETAP, Muir says, is that there are so many different components of the problem, and not all of them apply to each case. Four people might come in with their pain on the right side, for example, and then the next three all have the problem on the left. Muir says that it’s rare to have no clear explanation for an abdominal pain. “It seems to be in a class almost of its own.”

Because we don’t know exactly what causes a side stitch, Muir says there’s no standard advice for how to prevent it. The best thing to start with, he says, is a quick rundown of your history: Did you drink a lot of water before that run where you had a particularly bad cramp? Is there something you usually eat on days you’ve had an issue? If you play a sport, he says, the next step might be to have someone check out your form, and make any biomechanical adjustments.

Typically, ETAP will stop when you stop the activity. If it doesn’t, or the pain gets worse, Muir says it’s best to check in with a doctor to rule out any other gastrointestinal or abdominal problems unrelated to exercise.

But usually, side stitches, while incredibly annoying, are innocuous. And there’s no gold standard to make them go away, Muir says. “It’s all sort of trial and error.”

The post When you get a stitch in your side, what’s really going on? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This article was originally published on November 2, 2017.

In 2014, a woman visited a California doctor’s office complaining of a year and a half of watery diarrhea. She seemed healthy—she hadn’t lost weight and was in excellent shape. In fact, she had started running marathons two years prior, and typically ran about 20 miles every weekend. She also mentioned that she had noticed a correlation between her long runs and the uncomfortable bowel movements, which seemed to become less formed and more frequent as her intense training months dragged on. Her doctors advised the woman to stop running such long distances, and her gastrointestinal issues stopped within a month.

Kim van Wijck, a Netherlands-based physician and triathlete herself, remembers a similar experience with one a patient who was a professional middle-distance runner. The athlete tried everything—giving up caffeine and dairy as well as performing pre-race relaxation techniques—to make her gut less sensitive. But nothing eased the discomfort.

These women are not alone in either their grueling athletic pursuits, or their resulting intestinal distress. On November 5, more than 50,000 runners will gather for the TCS New York City Marathon, and the portapotties will absolutely be vital to a successful—and bearable—race.

Running causes a span of digestive issues that range from heartburn and acid reflux to frequent bowel movements. The most common, however, are those in the lower digestive system, which includes the small and large intestines. These issues can be as mild as bloating and flatulence to as severe as bloody stools. Doctors and researchers don’t know exactly how many runners experience these belly aches, but they estimate it’s around a third to a half at any given time. One study out of the British Medical Journal found that almost half the participants in the 1985 Drammen marathon in Norway reported some degree of runner’s diarrhea during and immediately following the race. Many physicians estimate that most people suffer some form of intestinal trouble eventually.

The good news is that these gut issues, while uncomfortable, are (usually) transient. Understanding why they occur might help some runners deal with the problems, or at least give them comfort in knowing why it’s happening and that they aren’t alone.

One reason for the distress could be that our delicate digestive organs aren’t getting enough blood during exercise; a condition known as ischemia. At any given moment, the heart pumps oxygen and nutrients to whatever organs need it most, which changes depending on the activity at hand. During an intense run, the skin and large muscles are the most urgent recipients, whereas the intestines don’t get as much attention.

That makes sense. While running, our glutes have more of a need for oxygenated blood than our stomachs. In fact, during peak physical exercise, blood flow to the internal organs can decrease by up to 80 percent. While that resource reallocation may be necessary during a track race or to flee from danger during a zombie apocalypse, the lack of blood compromises the mucus that lines the intestines, making it more permeable and prone to disturbance. In one review, Brazilian scientists found that lack of blood flow to the digestive system was the most significant factor in runner’s nausea, vomiting, abdominal pain, and bloody diarrhea.

The tummy troubles don’t end at the finish line, either. The morning- and day-after effects that runners often experience probably have to do with some slight intestinal tissue damage from the lack of blood flow, says van Wijck, though she makes it clear this injury is minor. “It’s kind of like a scraping of the skin,” she says. “Afterward there are new cells and no lasting problem.”

Why is it so common for runners to have runny poop?

There must be more to runner’s diarrhea than ischemia, or else the athletes would experience it at the same rates as those in other sports. The Brazilian researchers showed that the fleet-footed racers dealt with these problems almost twice as often as athletes from other endurance sports, like cycling or swimming. (Other athletes can get digestive issues, but they are usually much different than runner’s trots and are not as common. Swimmers, for example, sometimes deal with excessive burps.) Professional runners were also three times more likely to undergo a bout of diarrhea than recreational runners. Researchers think that the mechanics of sloshing your organs around for hours at a time is likely what amplifies the effect of exercise alone. Some studies have found that the constant gastric jostling for more than 52,000 steps can lead to an urgent needs to use the facilities, as well as flatulence and diarrhea.

Sadly, there aren’t many strategies a runner can use to direct blood flow towards their intestines, or to keep them steady during the race (marathon corsets are not advised). However, athletes can control their diets and how much water they drink—and this could make a difference in how a person’s digestive system performs during long runs. One study found that Ironman participants that ate foods that were high in fiber, fat, protein, and dense carbohydrates during and shortly before the race were more likely to experience problems. Those foods are all more difficult to digest than simple carbohydrates like straight table sugar. The intestines have to work harder to break them down, which is not ideal for an already weakened digestive system. Indeed, all the men who ate thirty minutes before the race threw up during the mile-long swim. (The study did not include women, which is frustrating to the writer, who is an Ironman 70.3 finisher.)

It’s probably best to stay away from hard-to-digest foods prior to racing, but researchers still aren’t completely sure what’s better. The carbohydrate-rich energy gels that are frequently distributed throughout races and that runners consumer before and intermittently during the race might not be any better.

While these are essentially simple carbohydrates in the form of sugar and are supposedly an easy-to-digest, quick energy source, studies looking into the effects they have on runners’ guts are mixed. One small study found that runners who frequently consumed these packets while racing did not experience significant gastrointestinal problems during a ten mile run. But another larger study found the opposite: For both men and women running triathlons and both half and full marathons, there was a correlation between these high-carb gels and reports of nausea and flatulence. Though, when researchers compared the finish times of competitors who consumed the gels to those who didn’t, they found that the ones who used the gels did, on average, achieve faster times. Some scientists recommend drinking beverages with more than two types of carbohydrates—like glucose and fructose—as opposed to a juice with a large amount of one kind of carbohydrate, which seems to make gastrointestinal symptoms worse.

Usually, runner’s problems have to do with the jostling effects of the sport and the decreased blood flow. However, a common habit of long-distance runners can also be exacerbating or triggering the symptoms: The frequent use of non-steroidal anti-inflammatory drugs (NSAIDS), such as ibuprofen. While useful for muscle pain, these can cause problems anywhere along the GI tract, from the esophagus to the colon. In a healthy gut, epithelial cells in the gastrointestinal tract, similar to those in our skin, hold tightly together to protect large molecules from passing through the intestines and into the bloodstream. A small study at the 1996 Chicago marathon hinted that ibuprofen made the mucus lining of the intestines more permeable, which could lead to gut trouble over time, and later studies back up these findings.

These drugs partly work through reducing blood flow to the digestive system, which is a problem that’s exacerbated through exercise, according to van Wijck, who led a study that found that damage markers in the digestive system were twice as high in runners who took these anti-inflammatory meds. And this isn’t just for runners. Its well known that NSAIDs, when taken in high quantities for an extended period of time, can cause gastrointestinal effects, like an inflamed gut, known as gastritis, and even small sores in the stomach lining, called ulcers. Heat and alcohol can also cause gaps between these epithelial cells as well.

While there is no foolproof method to prevent the runner’s runs, staying hydrated and eating foods that won’t aggravate the condition is probably best. And, just as runners practice the race course and the distance, they should also rehearse when to eat and remember when they will need to use the bathroom so that there are minimal to no surprises on race day. “You have to really listen to your body, which people already do when they have muscle pain,” says van Wijck. Paying attention to your gastrointestinal system with the same attentiveness, she says, could help to minimize the amount of discomfort you feel.

Have a science question you want answered? Email us at ask@popsci.com, tweet at us with #AskPopSci, or tell us on Facebook. And we’ll look into it.

The post Why do marathon runners get the runs? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This post has been updated. It was originally published on October 9, 2018.

When he was a child, Donald Unger’s mother and aunts warned that he shouldn’t crack his knuckles, because he would develop arthritis. To prove them wrong, he set out on a half-century long experiment, cracking the knuckles on his left hand at least twice a day, while leaving the right knuckles (mostly) uncracked.

After 50 years, Unger (then a doctor in Thousand Oaks, California) examined his hands—and found no evidence of arthritis in either one, and no other differences between them, either. He wrote to the journal Arthritis & Rheumatology with his findings in 1998. “This preliminary investigation suggests a lack of correlation between knuckle cracking and the development of arthritis of the fingers,” he wrote.

This particular “study” wasn’t exactly scientific—a sample of one isn’t nearly enough to reach a a research-backed conclusion for the entire human population, and Unger wasn’t a neutral observer. But since then, there’s been more rigorous research conducted into the same question, and it’s to largely the same conclusion: Cracking your knuckles probably won’t give you arthritis.

Kevin DeWeber, a sports and family medicine physician at PeaceHealth Southwest Medical Center in Vancouver, Washington, ran one such study—largely because he, too, is a knuckle-cracker. “I’ve been cracking my knuckles for my whole life. Once I developed a scientific mind, and once I got a job that put me in a position where I could do some research, I looked into it,” he says.

The study, published in the Journal of the American Board of Family Medicine in 2010, looked at x-rays of the right hands of over 200 people. About 20 percent of those people reported that they cracked their knuckles routinely, but they were not any more likely to have arthritis in their hands than the people who did not crack their knuckles.

Despite the results of that study and a handful of others, all reaching the same conclusion, the myth that knuckle-cracking will lead to arthritis persists. Why? DeWeber thinks the fracturing sound might have something to do with it. “Knuckle cracking is really annoying to the people who are not doing it,” DeWeber says. “The people who are annoyed want it to stop, so they come up with a story that will dissuade the knuckle-cracker.”

That fictitious story isn’t entirely unreasonable, DeWeber says, even though it’s probably wrong. Joints crack because tiny bubbles of air form in the fluid that surround them, and then rapidly collapse, producing the distinctive sound. Bubbles form and pop in a similar way in ship’s propellers, and in that environment they do cause damage, so it’s possible to make the argument that they’d harm joints, as well. “But the mechanics of a ship’s propellor and the mechanics of a knuckle are different,” DeWeber says.

[Related: You can injure yourself stretching—but it’s not easy]

Trauma to a joint can be a risk factor for arthritis, and the loud sound of a knuckle cracking might sound to some people like it’s a traumatic event. “You’re doing something forceful, so it seems like it’s hurting the joint,” DeWeber says. “It’s a natural conclusion people might come to, but it doesn’t have any supporting evidence.”

DeWeber is careful to note, though, that there isn’t a 100 percent conclusive answer to the knuckle-cracking arthritis query. It’s pretty likely that it doesn’t, and there isn’t a scientific reason that could explain a connection between the two. But to find out for sure, scientists would have to assign people to be knuckle-crackers or non-knuckle crackers, make sure they stuck to their instructions, and follow them for most of their lives, to see if arthritis develops. That’d be incredibly difficult, DeWeber says, so the research we have now is likely the best we’re going to get.

Unger won a 2009 Ig Nobel prize, which honors silly (but still significant) science, for his query into his own knuckle-cracking habits. During his own de-bunking of a well-meaning parental warning, he also questioned some other decrees he was given as a child—like that eating spinach was important. Unfortunately for Unger, though, that one isn’t a myth.

Have a science question you want answered? Email us at ask@popsci.com, tweet at us with #AskPopSci, or tell us on Facebook. And we’ll look into it.

The post Will cracking my knuckles give me arthritis? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This post has been updated. It was originally published on August 23, 2017.

Urinary tract infections are insanely common. Alone, they make up almost 25 percent of all infections, and more than half of women will get at least one in their lifetimes. In parallel, they’re also becoming increasingly harder to treat as the bacteria become resistant to antibiotics. Some urinary tract infections (UTIs) now manage to survive multiple rounds of antibiotic treatment, require bacterial cultures, and last much longer than the usual few days. How can you tell if your or a loved one has an antibiotic-resistant UTI, and what can you do about it?

A classic UTI goes something like this: You feel a burning sensation when you pee, so you see a doctor who diagnoses it and prescribes an antibiotic, which kills the bacteria and clears up the infection in a number of days. Throw in a little cranberry juice for good measure, some extra water, and annoying trips to the bathroom about every 20 minutes, and that pretty much sums up your run-in with the unpleasant infection.

But what happens when your symptoms come back—or refuse to ever really go away in the first place? About 25 percent of women with acute UTIs experience another within six months of the first infection. If you’re an otherwise healthy person, this means the bacteria weren’t totally wiped out, and have regrown to once again wreak havoc on your urinary system (and life). Assuming you’ve taken the entire course of antibiotics, that means the strain of bacteria you were originally infected with is resistant to the particular antibiotic you took. If you’re lucky, a doctor can fix this by having your urine tested, so they can select a second round of antibiotics that’s known to work against the offending bacteria. If you’re really unlucky, it may take two or more rounds of this to knock the UTI from your system.

If you have two UTIs in a three month period, or more than three UTIs in a single year, you officially have a recurrent UTI (RUTI). But the reasons for developing a lingering one isn’t the same for everyone. And not all of them are the result of impervious bacteria. For example, people who are chronically dehydrated (as is often the case with seniors, especially the mentally impaired) are at an increased risk because they aren’t flushing out bacteria at a normal rate. Those who have catheters for other medical reasons are also at an increased risk, because the catheter itself can introduce new bacteria to sensitive areas. Postmenopausal women often have lower estrogen levels, which can harm the good bacteria that should remain in the vaginal flora. Finally, those with physical irregularities that lead to voiding dysfunction (or an incomplete release of urine) are also at risk, since this can keep bacteria from getting flushed out during trips to the bathroom.

[Related: Is urine actually sterile?]

With this in mind, most preventative measures are fairly intuitive. Things that are more likely to introduce bacteria into the urinary tract are risk factors. This includes sex more than three times a week, having multiple partners, using spermicides and diaphragms, or skin allergens like bubble bath, oils, deodorants, or sprays. Good hygiene is important to prevention (though less proven in medical data). This includes wearing cotton underwear, avoiding tight pants, and always peeing after sex. Evidence is mixed about the value of drinking cranberry juice, but doctors agree there is little risk, so go at it. There’s a ton of sugar in most cranberry juice products, however, so popping cranberry pills or pure cranberry juice is better than drinking juice cocktail.

Do RUTIs have anything to do with superbugs? Each time the bacteria in your system survive a round of antibiotics, it means that bacteria is resistant to that drug. Doctors start out prescribing relatively mild antibiotics on a three or five day regimen, at the first tier of “strength,” for your first UTI visit. But they escalate to the second and third tiers (and for longer regimens) as the infection persists. Last year, a woman in the U.S. was treated for a UTI, and the bacteria in her infection were found to be resistant to colistin—one of the strongest “last resort” antibiotics we have. Luckily the infection was susceptible to other drugs lower on the antibiotic ladder, but it’s certainly forced us to confront a reality where antibiotics may actually run out.

The fact that a colistin-resistant bacteria was found in a UTI case shouldn’t be looked over, many experts say. UTIs are such a common problem that they often aren’t taken seriously. They also disproportionately affect women—whose pain we tend to not take as seriously. But if left untreated, they can escalate until a patient urinates blood and experiences extreme discomfort and fever. If the infection reaches the kidneys, it becomes life-threatening. At least one scientist estimates that 8 million UTI cases occur in the US every year, probably 10 percent of which are antibiotic resistant.

[Related: Please stop freaking out about flesh-eating STIs]

Dr. Jeffery Henderson, Associate Professor at Washington University in St. Louis and part of the school’s Center for Women’s Infectious Disease Research, says that he’s noticed UTIs are becoming harder to treat. And he’s surprised by how quickly the antibiotics used to treat common infections are becoming unreliable. One class of them, he says, called fluoroquinolones, went from being almost completely reliable at the beginning of his medical education, to now working only 30 to 50 percent of the time. “We lost an entire class of antibiotics,” says Henderson.

Cases like UTI antibacterial resistance highlight the necessity of new antibiotic development, Henderson says. He and other researchers around the country are currently trying to understand the underlying mechanisms that sustain bacteria. This knowledge could lead to drug therapies that would target that process and stop bacterial growth.

UTIs and even RUTIs are almost never a life-threatening condition, and are not contagious (unless caused by an otherwise infectious sexually transmitted disease). And you can rest assured that, for now, even the most stubborn RUTIs eventually go away with continued communication and treatment—although like many medical conditions, you may always be at elevated risk. However, this increase in RUTIs serves as a reminder that bacteria are powerful and constantly evolving.

The post Why your UTI keeps coming back appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This post has been updated. It was originally published on July 31, 2017.

Ever woken up the day after a workout and wondered what you did to deserve such pain?

I’m talking about muscle soreness. That pain can stem from several sources, and understanding what’s behind yours will help you best remedy it—and find ways to potentially prevent it in the future.

Why is my body in so much pain after a day at the gym?

“There’s muscle soreness that could be due to, say weight training, which can cause what we call delayed onset muscle soreness, which is kind of a diffuse soreness in the muscle,” says Thomas Brickner, head team physician for a number of sports at the University of North Carolina. “It usually starts a day or two after a new workout, or a workout that you’re not typically accustomed to.”

Delayed Onset Muscle Soreness (DOMS) is the kind that happens the day after you dive into your first barre class, first run in a few months, or first time trying out weights. And though it can feel like you can barely move, when worst comes to worst you can straighten your arms if need be.

We experience DOMS because of diffuse microscopic injuries to the muscles themselves and the inflammation that results from it. (It’s a common myth that it results from the build up of lactic acid. Lactic acid does cause that intense burning feeling during your last rep or right when your muscles are about to give in. But your body is able to eliminate it from your blood in a few minutes.)

[Related: How to work out for your mental health]

“Usually the delayed onset muscle soreness is just kind of a discomfort in the muscles themselves that is somewhat diffuse, but the pain is usually just kind of mild and [the muscles] won’t typically lose much in the way of motion,” says Brickner. You don’t typically have much in the way of swelling in the area either, he says. For example, if you did some bicep curls a day earlier, your biceps might feel sore, but you’d still be able to straighten your elbows.

How can I make the pain stop?

For DOMS, certain types of exercise may make you more sore than others, especially workouts that include what are called eccentric contractions—ones that cause the muscles to tighten and lengthen at the same time. A good way to visualize this would be to picture doing a squat: the quadricep muscles in your thighs are starting to lengthen as you lower your body, but they are also tightening so you don’t go down too fast. Running downhill can cause this too, Brickner says.

Usually, this type of muscle soreness goes away on its own in a couple of days. But when you are feeling the brunt of it, there are steps you can take to make yourself feel better while it runs its course, and potentially allow the muscles to heal faster, too. Brickner says staying hydrated is extremely important. Your muscle cells need water to properly repair damaged tissue through protein synthesis. If you are bold, he says, and have access to multiple bath-sized bodies of water, a contrast bath—going from a warm bath to a cold one—could be helpful as well. Contrast baths work by opening and closing blood vessels, which creates a “pumping action” that decreases pain and inflammation in the area. You also can’t go wrong with gentle massage of the muscles in pain, which research has shown to switch on genes that decrease inflammation as well as activate mitochondria-producing genes.

When do muscle cramps become more serious?

DOMS is painful, and can really wreck havoc on your daily activities. But you should still be able to do things, albeit a little more slowly. However, if you literally can’t straighten your arm a few days after a round of bicep curls, it’s probably time to call the doctor. Brickner says that this is a sign of rhabdomyolysis, a severe injury to the muscles from an excessive workout. Extreme exercise can actually cause cell death of the muscles themselves. When the cells die, they release toxins into the bloodstream, which can cause immobility of the muscles in question, stiffness, swelling, and a release of myoglobin into the kidneys, which can make your pee look bloody. Not so good.

“A lot of people go and they work out hard and they think, ‘Oh, the muscle soreness is normal, it’s normal soreness from working out,’ but it might not be,” says Bricker. “It might be rhabdomyolysis, which is an abnormal type of muscle soreness. If you have that awareness of what rhabdo is, that is very important thing.” Rhabdo is rare, but if you have intense muscle stiffness, pain and swelling paired with red or brown urine, it’s best to see your doc or head to the emergency room.

Sign up for PopSci’s newsletter and receive the latest science and tech updates to your inbox.

Can I prevent my muscles from getting sore in the first place?

Anyone can fall victim to muscle soreness, whether you are a national championship-earning basketball player or someone who gets wiped out just walking up the stairs (I fall into the latter category). It all comes down to not pushing yourself too hard, especially if you are just now getting back into the swing of things when it comes to working out.

“I see that in our athletes every so often,” says Brickner. Oftentimes they are in great shape, division one athletes, but maybe they just got back from winter or summer break and do a ton of pull ups, more than they had done in weeks or months. Even though they are in great shape, he says, they just overdo it. And the result is muscle soreness.

How do you know not to overdo it and spend the next few days feeling stiff as a board? For the first few times doing a new workout, you should feel like you could keep pushing a little bit harder if you wanted to. For lifting, Brickner recommends picking a weight that doesn’t fatigue you. The weight that you lift should make you think ‘hey, I could go further’ the first few times. As for beginning runners, Brickner says, if you’ve never jogged before, start on an every-other-day basis, and maybe trying something like jogging for a mile and then walking for a mile to gradually build up your distance.

[Related: Here’s what would happen if you worked out like a strongman.]

“Almost all of these things occur because somebody goes into a program too quickly without training the body for it,” he says.

Beyond not wearing yourself out on round one, hydrating and having good nutrition for the workout you’re taking on might help (carbs for aerobic exercise like running, or protein for weight lifting). Warming up and cooling down is also essential to protecting yourself from injury, Brickner says.

“Muscle soreness can happen in the best trained athlete, it can happen in the least trained athlete,” he says. “I think that it can happen to anyone, but the prevention, no matter who you are, is to start off small with any activity that you’re not used to.”

The post Why do my muscles ache the day after a big workout? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This is probably a question that you might have heard once or twice in conversations: Did food taste better in the past? It’s one of those things that just kind of gets tossed around as common sense sometimes—the idea that food, and particularly produce, just isn’t like it used to be. 

Unfortunately, we can’t go back in time and pluck a strawberry from a 1960s grocery store and compare it to one found in a supermarket today. Even if we could do that, it’s unlikely that everyone would agree that today’s strawberries are less flavorful than a fresh berry from decades ago. 

In some ways, taste is pretty objective. There are currently five recognized kinds of taste—sweet, sour, salty, bitter, and umami. When we eat food, various receptors (otherwise known as taste buds) react to those tastes and send a signal to the brain telling us what’s going on. But, in other ways, taste can be perplexingly subjective. Certain types of health conditions can impair your sense of taste, as can your mood, along with plenty of other environmental and genetic factors. For example, some people are more sensitive to bitter tastes, making foods that are particularly bitter less palatable. And this is often because of their genetics: Some folks who are more sensitive to bitter flavors—often dubbed supertasters—have a gene named TAS2R38, which heightens their perception of bitterness.

Your taste buds also change as you get older. Most significantly, evidence shows that the number of taste buds we have decreases as we age, and the ones that stick around shrink in size—all of which can affect our ability to detect the five tastes, and can alter our perception of food. 

The way we perceive food can change even by the day. A 2015 study in the journal Appetite analyzed the effect of mood on various tastes by collecting data from 550 people who attended a men’s hockey team season, which encompassed 4 wins, 3 losses, and 1 tie. Analysis showed that positive emotions during the game were associated with heightened sweet perceptions and diminished sour intensities. On the other hand, negative emotions were associated with spiked sour perceptions and decreased sweet sensations. 

On top of all this subjectivity, taste is just one component of what’s known as flavor, which is an incredibly complex mixture of what the tongue literally tastes, what the nose smells, things like texture, and how all that comes together to determine our perception. 

One thing we do know is that the way we produce and consume foods has changed a lot over the past half-century, and that can definitely affect taste.   

Perhaps the best example is the tomato. They’re incredibly popular and are often considered the highest value vegetable crop worldwide. A tomato’s flavor is determined by sugars and acids, which activate our taste receptors, and a set of volatile compounds, which trigger our smell receptors. The combination of the two creates the unique flavor that makes a perfect fresh pasta sauce or BLT so delectable.

Over the years, food scientists have realized the importance of those volatile compounds in particular in making tomatoes taste great. Today, tomatoes are bred to travel long distances without getting bruised and sit in storage without going bad. According to a 2017 study published in the journal Science, this genetic shift has led to a significant drop in the volatile compounds that contribute to a tomato’s aroma, which means we’re getting a less tasty product.

While the tomato has gotten a lot of attention, there are a number of other crops that have been bred similarly to accommodate for the demands of modern agriculture, which means that they’ve likely also lost some of their flavor they once had.

Still, there are other factors that contribute to how much we love one food over another that are far more difficult to study but are nonetheless important. Because flavor and taste have such a strong subjective quality, the nostalgic element of food can’t be ignored. My sister, mom, and I have attempted countless times to make my grandmother’s lemon bread, which we would devour every year around the holidays during my childhood. We always get compliments on it, but to us it tastes nothing like the real thing. It could be nostalgia; I’m also convinced she doubled the amount of lemon syrup. 

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post Did food taste better 50 years ago? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

If you put a steamy cup of coffee in the refrigerator, it wouldn’t immediately turn cold. Likewise, if the sun simply “turned off” (which is actually physically impossible), the Earth would stay warm—at least compared with the space surrounding it—for a few million years. But we surface dwellers would feel the chill much sooner than that.

Within a week, the average global surface temperature would drop below 0°F. In a year, it would dip to –100°. The top layers of the oceans would freeze over, but in an apocalyptic irony, that ice would insulate the deep water below and prevent the oceans from freezing solid for hundreds of thousands of years. Millions of years after that, our planet would reach a stable –400°, the temperature at which the heat radiating from the planet’s core would equal the heat that the Earth radiates into space, explains David Stevenson, a professor of planetary science at the California Institute of Technology.

Although some microorganisms living in the Earth’s crust would survive, the majority of life would enjoy only a brief post-sun existence. Photosynthesis would halt immediately, and most plants would die in a few weeks. Large trees, however, could survive for several decades, thanks to slow metabolism and substantial sugar stores. With the food chain’s bottom tier knocked out, most animals would die off quickly, but scavengers picking over the dead remains could last until the cold killed them.

Humans could live in submarines in the deepest and warmest parts of the ocean, but a more attractive option might be nuclear- or geothermal-powered habitats. One good place to camp out: Iceland. The island nation already heats 87 percent of its homes using geothermal energy, and, says astronomy professor Eric Blackman of the University of Rochester, people could continue harnessing volcanic heat for hundreds of years.

Of course, the sun doesn’t merely heat the Earth; it also keeps the planet in orbit. If its mass suddenly disappeared (this is equally impossible, by the way), the planet would fly off, like a ball swung on a string and suddenly let go.

This article originally appeared in the November 2008 issue of Popular Science magazine.

The post What would happen if the sun went out? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

THERE’S PERHAPS nothing more ancient and unchanging than the sun, a yellow dwarf star that has illuminated Earth for over 4 billion years.

But our star, too, shall pass. And scientists are actually pretty certain about what will happen when it does. 

The sun powers itself by fusing, or combining, extremely hot hydrogen atoms inside its core. That creates helium and a lot of energy. But just as a music box will wind itself out, the hydrogen in the sun’s core will run dry. When that happens, in around 5 billion years, the sun will have to find a new power source. 

At first, that’s not a problem. Today, fusing hydrogen also lets the sun’s core push back against the outer layers pressing down. When the core can no longer hold out, hydrogen from those outer layers will flood in and heat up—giving the sun more fuel to fuse. All will seem well.

But this will come at a cost. The side effects of these events will cause the sun to redden, cool, and inflate to more than a hundred times its current size, swallowing the orbits of Mercury, Venus, and even Earth. The sun will transform into a red giant, just like the stars Arcturus or Aldebaran that we can see in our sky.

[Related: We still don’t really know what’s inside the sun—but that could change very soon]

It’s all for a fix of hydrogen that will only buy the sun an extra billion years of life. When that, too, runs out, the sun will be forced to reach for the next best thing: that helium it’s produced all this time.

When the sun begins to fuse helium, it might seem a return to normal. The helium will partly rebuild the ruins of the core, and the bloated star will lose much of its size. Astronomers call this the helium flash. But there’s a catch: The flash will burn off nearly a tenth of the sun’s perfectly good helium in mere minutes.

Afterwards, the increasingly geriatric sun faces a fatal problem: As fuel, helium just doesn’t compare to hydrogen. Fusing helium isn’t nearly as energy-efficient as fusing hydrogen, and it produces carbon and oxygen. It’s possible to fuse those, but it’s far more difficult and far more inefficient.

The remaining helium will only buy the sun another 100 million years or so.

When the sun can no longer fuse helium, it will enter another troubled time. It’ll puff back up, desperately flailing for any pockets of hydrogen or helium it can fuse. Even as the core starts to collapse, the star might push its outer rim ever farther away, maybe all the way past the asteroid belt.

This can only go on for so long. In the end, the sun will throw off all of its outer layers. Observers in the next star system might see a spectacular display, like a bright halo. For the sun we recognize, these 10,000 years are its moment of death.

It will leave behind a sort of celestial tombstone called a planetary nebula, even though planets aren’t involved—unless the dark, dead husks of what were once Jupiter, Saturn, Uranus, and Neptune manage to stop themselves from being blown away.

But for the sun, death is not the end. While about half its mass will flood out, the rest will crush together at the very center of the planetary nebula. This will turn into a tiny, bright, ultra-dense ember of the sun’s core, no larger than the Earth. This kind of smoldering remnant is called a white dwarf star.

So begins the sun’s long, last, lonely form. Over trillions of years, over a time that’s hundreds of times longer than the current age of the universe, that white dwarf will—very, very slowly—lose its remaining heat and fade to black.

This story originally ran in the Summer 2021 Heat issue of PopSci. Read more PopSci+ stories.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post What happens when the sun burns out? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This story has been updated. It was originally published on July 24, 2013.

Of all the bodies in our solar system, the sun is probably the one we want to give the widest berth. It gushes radiation, and even though its surface is the coolest part of the star, it burns at about 9,940 degrees Fahrenheit, hot enough to incinerate just about any material. As such, there are no plans to send a manned mission in its direction anytime soon (Mars is much more interesting, anyway), but it can’t hurt to figure out at what distance a person would want to turn back. You can get surprisingly close. The sun is about 93 million miles away from Earth, and if we think of that distance as a football field, a person starting at one end zone could get about 95 yards before burning up.

That said, an astronaut so close to the sun is way, way out of position. “The technology in our current space suits really isn’t designed to withstand deep space,” says Ralph McNutt, an engineer working on the heat shielding for NASA’s Messenger, a new robotic Mercury probe. The standard space suit will keep an astronaut relatively comfortable at external temperatures reaching up to 248°. Heat coming off the sun dissipates over distance, but a person drifting in space would begin encountering that kind of heat (the five-yard line) some three million miles from the sun. “It would then be a matter of time before the astronaut died,” McNutt says. Above 248 degrees, the suit would transform into a close-fitting sauna—the temperature would climb above 125 degrees and the person would become dehydrated and pass out, eventually dying of heatstroke.

Riding in the space shuttle, though, someone could get much closer to our star. The ship’s reinforced carbon-carbon heat shield is designed to withstand temperatures of up to 4,700 degrees to ensure that the spacecraft and its passengers can survive the friction heat generated when it reenters the atmosphere from orbit. If the shield wrapped the entire shuttle, McNutt says, astronauts could fly to within 1.3 million miles of the sun (roughly the two-yard line). But the integrity of the shield degrades rapidly above 4,700 degrees, and the cockpit would begin to cook. “I would advise turning away from the sun well before that point,” McNutt says. Much hotter than that, the shields would fail altogether, and the vehicle would combust in less than a minute.

Of course, just getting that close to the sun would be quite an accomplishment, says NASA radiation-health officer Eddie Semones. The constant exposure to cosmic radiation during the voyage would most likely prove fatal before the astronauts crossed the 50-yard line.

This article originally appeared in the August 2010 issue of Popular Science magazine.

The post How close can you get to the sun? Closer than you’d think. appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

As a middle schooler, one of my life goals was the Presidential Fitness Award—an accolade given to those who passed a series of gym-class tests that included doing a number of pull ups, running a mile, and, among other things, the sit and reach: A flexibility test in which one sits with their legs outstretched in a V position and reaches their fingertips as far past their ankles as they can manage. That’s where things went sour for me. I could never reach quite far enough to be a presidential fitness scholar.

The sit and reach is essentially a modified version of another popular stretching exercise: touching your toes. For many people, such a maneuver is an easy way to begin or end any sort of workout. It’s part of the warm up or cool down routine in countless youth sports programs and gym classes.

And for good reason. For most people, toe touching is among the easiest stretching exercises to do, and it incorporates a number of different muscle and joint groups. But for me (and many of my peers) it’s sheer agony. Why? It turns out that the ability to touch your toes is the summation of a number of different physiological factors, many of which we have no control over.

“The two biggest factors are the flexibility of your hamstrings and and the range of motion of your hip joints,” says Jeffrey Jenkins, a physiologist at the University of Virginia School of Medicine. “But the other big factor is the relative length of your arms and your torso to your legs.”

Hamstrings are the set of three muscles that rest behind the thighs, running from your pelvis and hip area down to your knees. When you bend down to touch your toes, hamstrings do the most work. The range of motion of your hips is equally important. When you bend down to actually reach the ground, you have to be able to bend your hip joints forward. In conjunction with that, Jenkins says, you also have to be able to flex your lumbar spine. If you have an arched or a stiff back or a lot of injuries to your spine that inhibit your ability to bend forward, that could also alter how far down you can reach.

To a certain degree, you can work your hamstring muscles to make them more flexible. However, the flex your hips is beyond your control and unfortunately can’t be altered with any stretching program.

The other major physiological attribute that can’t be changed is the span of your arms and length of your torso compared to the height of your legs. Someone like Michael Phelps, who is famous for his long torso, long arms, and relatively short legs, would likely have no problem touching their toes without doing a single hamstring stretch. “On the other hand,” says Jenkins, “someone can be really flexible, but if their arms and hands are short relative to their legs, then even at their maximum flexibility they might still not be able to touch their toes, because their arms and fingers aren’t long enough to reach.”

Life is so unfair.

Why does the stretch even exist then?

Jenkins says that although there are some unjust aspects, overall the toe touch is not the worst measure of flexibility. There are ways to directly measure range of motion of specific muscle groups by using something called a goniometer, which calculates the exact angle of specific joints. But the toe touching exercise can also measure the flexibility of the whole body—to a certain degree.

“It involves the hamstrings, the hips, and the spine,” he says. “And, though it has it’s faults, I can’t really think of anything that’s that much better than it, in terms of easily measuring someone’s flexibility health.” Perhaps, he says, the straight leg raise—starting in a supine position, a person raises one outstretched leg as far as possible while keeping the other leg straight and using a goniometer to measure the angle between the legs—is a better measure of just hamstring flexibility than touching the toes, since it takes the confounding variables of leg and arm length out of the equation.

But if you are flexibility inept like me, there are some thing you can do to improve the elasticity of the body you have. It might not get you that coveted Presidential Fitness Award (though apparently President Obama did away with that back in 2012 anyway), but it could at least help you reach your ankles without experiencing excruciating pain and humiliation in your yoga classes.

Your muscle groups contain cells called muscle spindles. Whenever you stretch a muscle, these sensory receptors tell neurons within the muscle to fire a signal back to the central nervous system through the spinal column. This causes your muscles to contract, tighten, and resist the force to be stretched, resulting in that annoyingly painful feeling that most of us get when we first reach down to touch our toes or attempt to stretch other muscles. However, Jenkins says, if you are patient, this too shall pass.

If you hold the stretch for a minimum of six seconds, you can actually conquer the reflex. Around that time, the muscle’s golgi tendon organs—spindles of neurons that sit on the muscle fibers—kick in and inhibit muscle contractions, allowing your muscles to relax and lengthening the stretching you can do.

“That’s why we tell people to hold a stretch for at least 15 seconds. Often, it’s even better to hold it for 30 or 60 seconds,” says Jenkins. “The extra time ensures the the golgi tendon organ mechanism to kick in.” In fact, Jenkins says, there’s some preliminary evidence that holding static stretches for 30 seconds results in greater improvement in flexibility than holding it for 15 seconds, and just as much improvement as 60 seconds. And that one stretching session a day gave the same results as three times a day.

But for some people, the pain that accompanies those six seconds is just too severe. Certain folk’s central nervous systems interpret stretching as a more noxious stimulus than others. If you can get past that pain, then you can probably improve your flexibility. However, Jenkins cautions against enduring too much pain: If you’re in agony, you could be tearing a muscle. That’s not a good thing. And it’s hard to tell someone how to differentiate muscle tearing from the discomfort of the muscle contraction, Jenkins says, because experiences of pain are so subjective.

If you are able to push through what feels like a reasonable amount of pain and keep up a good stretching program, several studies suggest that you can actually elongate your muscle and build more sarcomeres and other structural units of muscle tissues. But most of what you are doing in a stretching program, Jenkins says, is training your nervous system to lose those intense inhibitory factors so your muscle fibers can relax more easily.

Okay, but how important is flexibility? Does it improve your overall health?

Generally speaking, more flexibility is a good thing. It promotes blood flow and, according to Jenkins, flexibility training and muscle elasticity itself can prevent certain kinds of injuries in sports and other recreational activities. “But in terms of specifically touching your toes, I am dubious about its effect on fitness and health because there are so many factors beyond your control,” says Jenkins.

He told me that I shouldn’t feel too bad about my toe touching deficiency. As a lifelong runner, I was concerned that perhaps my inflexibility could be affecting my running performance. But the opposite could also be true: There’s some evidence that improving flexibility in the lower limbs can actually decrease muscle strength and running efficiency.

So the next time I’m reminded of my inability to touch the floor, I’ll just remember that: My inflexibility might be making me a stronger, faster runner.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

Have a science question you want answered? Email us at ask@popsci.com, tweet at us with #AskPopSci, or tell us on Facebook. And we’ll look into it.

The post Why can’t we all touch our toes? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

The final frontier smells a lot like a Nascar race—a bouquet of hot metal, diesel fumes and barbecue. The source? Dying stars, mostly.

The by-products of all this rampant combustion are smelly compounds called polycyclic aromatic hydrocarbons. These molecules “seem to be all over the universe,” says Louis Allamandola, the founder and director of the Astrophysics and Astrochemistry Lab at NASA Ames Research Center. “And they float around forever,” appearing in comets, meteors and space dust. These hydrocarbons have even been shortlisted for the basis of the earliest forms of life on Earth. Not surprisingly, polycyclic aromatic hydrocarbons can be found in coal, oil and even food.

Though a pure, unadulterated whiff of outer space is impossible for humans (it’s a vacuum after all; we would die if we tried), when astronauts are outside the ISS, space-borne compounds adhere to their suits and hitch a ride back into the station. Astronauts have reported smelling “burned” or “fried” steak after a space walk, and they aren’t just dreaming of a home-cooked meal.

The smell of space is so distinct that, three years ago, NASA reached out to Steven Pearce of the fragrance maker Omega Ingredients to re-create the odor for its training simulations. “Recently we did the smell of the moon,” Pearce says. “Astronauts compared it to spent gunpowder.”

Allamandola explains that our solar system is particularly pungent because it is rich in carbon and low in oxygen, and “just like a car, if you starve it of oxygen you start to see black soot and get a foul smell.” Oxygen-rich stars, however, have aromas reminiscent of a charcoal grill. Once you leave our galaxy, the smells can get really interesting. In dark pockets of the universe, molecular clouds full of tiny dust particles host a veritable smorgasbord of odors, from wafts of sweet sugar to the rotten-egg stench of sulfur.

This article originally appeared in the February 2011 issue of Popular Science magazine.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post What does space smell like? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

When you’re a kid, your stance on homework is generally pretty simple: It’s the worst. When it comes to educators, parents, and school administrators, however, the topic gets a lot more complicated. 

Collective educational enthusiasm toward homework has ebbed and flowed throughout the 20th century in the US. School districts began abolishing homework in the ‘30s and ‘40s, only for it to come roaring back as the space race kicked off in the late ‘50s and drove a desire for sharper math and science skills. It fell out of fashion again during the Vietnam War era before it came back strong in the ‘80s.

As the country mostly transitions back to full-time, in-person schooling, the available research on homework and its efficacy is still messy at best. 

How much homework are kids doing?

There’s a fundamental issue at the very start of this discussion: we’re not entirely sure how much homework kids are actually doing. A 2019 Pew survey found that teens were spending considerably more time doing schoolwork at home than they had in the past—an hour a day, on average, compared to 44 minutes a decade ago and just 30 in the mid-1990s. 

But other data disagrees, instead suggesting that homework expansion primarily affects children in lower grades. But it’s worth noting that such arguments typically refer to data from more than a decade ago. 

How much homework are kids supposed to be doing?

Many schools subscribe to a “rule of thumb” that suggests students should get 10 minutes of homework for each grade level. So, first graders should get just 10 minutes of work to do at home while high schoolers should be cracking the books for up to two hours each night. 

This once served as the official guidance for educators from the National Education Association, as well as the National PTA. It also serves as the official homework policy for many school districts, even though the NEA’s outline of  the policy now leads to an error page. The National PTA also now relies on a less-specific resolution on homework which encourages districts and educators to focus on “quality over quantity.”

The PTA’s resolution effectively sums up the current dominant perspective on homework. “The National PTA and its constituent associations advocate that teachers, schools, and districts follow evidence-based guidelines regarding the use of homework assignments and its impact on children’s lives and family interactions.”

Even with these well-known standards, a study from researchers at Brown University, Brandeis University, Rhode Island College, Dean College, the Children’s National Medical Center, and the New England Center for Pediatric Psychology, found that younger children were still getting more than the recommended amount of homework by two or three times. First and second graders were doing roughly 30 minutes of homework every night. 

Does homework make kids smarter?

In the mid-2000s, a Duke researcher named Harris Cooper led up one of the most comprehensive looks at homework efficacy to-date. The research set out to explore the perceived correlation between homework and achievement. The results showed a general correlation between homework and achievement. Cooper reported, “No strong evidence was found for an association between the homework–achievement link and the outcome measure (grades as opposed to standardized tests) or the subject matter (reading as opposed to math).” 

The paper does suggest that the correlation strengthens after 7th grade—but it’s likely not a causal relationship. In an interview with the NEA, Cooper explains, “It’s also worth noting that these correlations with older students are likely caused, not only by homework helping achievement but also by kids who have higher achievement levels doing more homework.”

A 2012 study looked at more than 18,000 10th-grade students and concluded that increasing homework loads could be the result of too much material with insufficient instructional time in the classroom. “The overflow typically results in more homework assignments,” the lead researcher said in a statement from the University. “However, students spending more time on something that is not easy to understand or needs to be explained by a teacher does not help these students learn and, in fact, may confuse them.”

Even in that case, however, the research provided somewhat conflicting results that are hard to reconcile. While the study found a positive association between time spent on homework and scores on standardized tests, students who did homework didn’t generally get better grades than kids who didn’t. 

Can homework hurt kids?

It seems antithetical, but some research suggests that homework can actually hinder achievement and, in some cases, students’ overall health. 

A 2013 study looked at a sample of 4,317 students from 10 high-performing high schools in upper middle class communities. The results showed that “students who did more hours of homework experienced greater behavioral engagement in school but also more academic stress, physical health problems, and lack of balance in their lives.” And that’s in affluent districts. 

When you add economic inequity into the equation, homework’s prognosis looks even worse. Research suggests that increased homework can help widen the achievement gap between low-income and economically advantaged students; the latter group is more likely to have a safe and appropriate place to do schoolwork at night, as well as to have caregivers with the time and academic experience to encourage them to get it done. 

That doesn’t mean financially privileged kids are guaranteed to benefit from hours of worksheets and essays. Literature supporting homework often suggests that it gives parents an opportunity to participate in the educational process as well as monitor a child’s progress and learning. Opponents, however, contest that parental involvement can actually hurt achievement. A 2014 research survey showed that help from parents who have forgotten the material (or who never really understood it) can actually harm a student’s ability to learn. 

The digital homework divide

Access to reliable high-speed internet also presents an unfortunate opportunity for inequity when it comes to at-home learning. Even with COVID-era initiatives expanding programs to provide broadband to underserved areas, millions of households still lack access to fast, reliable internet. 

As more homework assignments migrate to online environments instead of paper, those students without reliable home internet have to make other arrangements to complete their assignments in school or somewhere else outside the home. 

How do we make homework work?

Some experts suggest decoupling homework from students’ overall grades. A 2009 paper suggests that, while homework can be an effective tool for monitoring progress, assigning a grade can actually undercut the main purpose of the work by encouraging students to focus on their scores instead of mastering the material. The study recommends nuanced feedback instead of numbered grades to keep the emphasis on learning—which has the added benefit of minimizing consequences for kids with tougher at-home circumstances. 

Making homework more useful for kids may also come down to picking the right types of assignments. There’s a well-worn concept in psychology known as the spacing effect, which suggests it’s easier to learn material revisited several times in short bursts rather than during long study sessions. This supports the idea that shorter assignments can be more beneficial than heavy workloads. 
Many homework opponents add that at-home assignments should appeal to a child’s innate curiosity. It’s easy to find anecdotal evidence from educators who have stopped assigning homework only to find that their students end up participating in more self-guided learning. As kids head back into physical school buildings, the homework debate will no doubt continue on. Hopefully, the research will go with it.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post Kids are onto something: Homework might actually be bad appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

There are many luxuries in life, but water is decidedly not one of them. Most of us are aware that we all need the liquid to survive, but exactly how much of it is necessary is surprisingly complex. 

There’s a popular notion that we all need to be chugging eight cups of water everyday for optimal health. While it is true that staying hydrated will certainly help contribute to your body working at its best, there’s no evidence to suggest that consistently drinking eight glasses of water a day is needed. 

In reality, each person’s water intake needs vary, and they depend on a number of factors, including how much exercise you get, the weather conditions of where you are, what you eat, and other health conditions you might have. Taking all these factors into account, the purported eight glasses a day just doesn’t work for most people. And our bodies already have an easy way to tell us if we need water: thirst. You can quickly replenish your lost fluids with a good helping of water. The human body has a carefully calibrated system for deciding when it needs more hydration and by listening to its cues, you can ensure you stay on top of your hydration needs. 

The amount of water you need depends on your body size. According to a 2018 review, infants need less water (in the form of breastmilk or formula, of course) than young children, who need less water than teens and adults who generally need the same amount of the liquid, on average. There are other factors to consider in this equation, too. For instance, people who are lactating need the most baseline water than most other groups. 

Your activity level also plays a large role. If you are exercising a lot, then you are more likely to sweat more, which forces you to need more water to replenish that lost amount. This is especially true if you are exercising in a particularly hot or humid environment, or your workout is long or intense. 

Additionally, water is not the only source of hydration. In fact, according to a highly-cited 2005 report from the ​​Institute of Medicine, we get about 20 percent of our hydration from the food we eat. Some foods, like watermelon, are almost exclusively water. It also might surprise you that consuming caffeinated beverages, such as tea or coffee, which are often considered diuretics, don’t actually dehydrate you. While caffeinated beverages will likely make you have to pee, that effect is temporary, and won’t have a considerable effect on your overall hydration balance. In other words, all those cups of coffee you down every day are indeed contributing to your daily hydration needs.

Given that you don’t need to be chugging all those glasses throughout the day, how can you tell if you are staying on top of your hydration needs? The answer is surprisingly simple. Follow your thirst.  

While it is true that you can drink water to excess, it is incredibly hard to do. Hyponatremia occurs when your body does get too much water and the amount of water in your blood becomes so high that it throws your electrolytes, particularly sodium, off balance. The condition, whose symptoms include headaches, confusion, nausea, and muscle weakness, is incredibly dangerous, but thankfully rare. Listening to your body’s thirst—and noting when weather, exercise intensity, or other factors, might make you more likely to need extra hydration—will ensure you are getting all the water you need, no counting required. 

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post How much water should you drink in a day? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Unless someone finds well-preserved dinosaur DNA and decides to breed, say, free-range Velociraptors in an agricultural twist on the standard Jurassic Park scenario, we’re probably not ever going to taste the flesh of the roughly 700 species of extinct dinos. But we can hypothesize, and the answer is a lot more complicated than “dinosaurs probably tasted like chicken.”

Let’s get one thing out of the way first: If you’ve eaten any type of bird, you’ve eaten dinosaur. Modern birds are the last living therapods—the same group of animals that includes Tyrannosaurus rex and Velociraptor—so they’re not simply “descended from” dinosaurs, they are dinosaurs.

So yes, chicken (a dinosaur) tastes like chicken. Crocodilians (like alligators), which share a common ancestor with dinosaurs, also kind of taste like chicken. And that’s a good starting point when you’re thinking about what Stegosaurus or Compsagnathus might’ve tasted like.

“In evolutionary biology terms, there is an extant phylogenetic bracket of chicken-tasting animals—crocs and birds—surrounding the dinosaurs on the family tree, making it reasonable that the dinosaurs had a chicken taste too,” says Steve Brusatte, a paleontologist and professor at the University of Edinburgh.

But it’s not that simple. Every bird has a unique taste. If you’ve eaten duck in the US, it was probably the American Pekin, a domesticated mallard with a mild, somewhat gamey taste. Merganser, another type of duck, is quite fishy and some people find it unpalatable. Extinct dinosaurs likely had similarly varied flavor profiles.

There are also countless factors that go into making something taste the way it does, but two of the most important are muscle usage and diet.

Triceratops and Allosaurus likely had fast- and slow-twitch muscles like people and other animals do. Slow-twitch fibers are associated with dark meat—thanks to reddish hues linked to the oxygen-carrying protein myoglobin—while fast-twitch fibers are associated with white meat.

Smaller predatory dinosaurs probably had to move quickly to ambush prey and dart away from threats, so they might’ve had a fair amount of white meat. Velociraptor may have truly tasted like chicken. Larger dinos, on the other hand, likely had large muscles that were constantly moving and needed a lot of oxygen, so they might’ve more closely resembled beef or venison.

Animals can also take on the flavor of things they eat. Grass-fed beef can be a bit more earthy than corn-fed cattle, for example. Dinosaurs, however, probably didn’t eat much grass, as it didn’t evolve until the very end of their 165 million-year reign. Therapods had a varied diet, while herbivores chowed down on ferns, cycads, and conifers, to name some ancient plants that are still around today.

Today, deer eat a similar diet, so some dinosaurs could’ve tasted like venison. They also may have been gag-inducing—the spruce grouse, a chicken-like bird, spends its winters munching almost exclusively on conifer needles. If you eat one at that time, it can taste heavily of spruce, almost like turpentine, says Hank Shaw, a chef and outdoorsman who specializes in wild foods.

Ultimately, there’s no definitive answer for what extinct dinosaurs might’ve tasted like, but we can let our imaginations run wild. And if someone ever does acquire the ability to bring dinosaurs back from extinction, we’d do well to remember that the Jurassic Park movies don’t end with people eating their creations—more often, it’s the other way around.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post What would a dinosaur taste like? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

The Guinness book of world records states that Michel Lotito died at age 57, of natural causes. But not before this competitive eater had consumed 18 bicycles, 15 supermarket carts, seven TV sets, six chandeliers, two beds, a pair of skis, a low-calorie Cessna light aircraft, and a computer.

It’s unclear what compelled Lotito to do this, and whether he was aware of the many ways he was jeopardizing his health.

First things first: No nutritionist, doctor, or even the trendiest of dieters would recommend or applaud eating a computer. But it begs a ridiculous yet perhaps equally intriguing question: Is consuming one really that dangerous? Many of the same metals that are found inside electronic devices—magnesium, iron, and sodium—are also found inside the human body. In the event of a dare, would consumption be possible?

Unfortunately, the benefits of eating a computer do not come close to outweighing the risks, many of which include death. The first potential peril is the choking hazard. Even competitive eaters have been unable to swallow much softer foods. In fact, last year, two Nathan’s contestants died after choking on a doughnut and a pancake, respectively, according to Metro News. Silicon and fiberglass are much harder to gulp down. Even Lotito cut his metallic meals into pieces that were one to two centimeters long. On top of that, anything that is long or sharp has the potential to scratch or tear the eater’s esophagus, the long tube that connects the mouth to the stomach.

If you did somehow manage (like Lotito did) to pulverize the computer and then swallow it without issue, heavy metal poisoning would be your next obstacle. Circuit boards sometimes contain tiny amounts of arsenic — not enough to kill you immediately, but if you ate several computers, the dose would add up. Aluminum, a common component found in the casings of both the computer and its hard drive, has no biological function in the human body and seems to gum up normal body processes. Some case reports have described that people in the end stages of liver disease who are no longer able to flush aluminum out of of their bodies suffer nerve damage, presumably from the metal. Older computer monitors also contain up to eight pounds of lead, as well as mercury, arsenic, cadmium, and beryllium, according to the Long Island manufacturing center, a recycling and e-waste drop-off site.

Most people are aware that lead isn’t great for you—immediate side effects can include nausea, vomiting, and abdominal pain. If the lead poisoning continues, the victim can eventually die, typically from kidney failure. In 2006, a child died after swallowing a small lead charm—eating an entire computer’s worth of the metal is a viable way of ingesting enough to kill. So how did Lotito survive? In the child’s case, the lead charm got stuck in the kid’s stomach, where acids slowly broke it down. If it hadn’t, the piece of metal would have passed through the digestive system quickly and would have caused less damage, according to Helen Binns, a professor of pediatrics and preventative medicine at Northwestern University’s Feinberg School of Medicine. “If you had a fishhook that got stuck in your intestines, that would cause problems,” she says. “If you swallow a bead or something like that, it just passes through your bowel.”

But metals aren’t the only form of toxic indigestion you might endure. The optical drive, the part that allows you to read CDs (unless you have a new Mac), is covered with a light-sensitive substance called a photoresist application. Studies have shown that this doesn’t seem to be very good for lab animals, though it was not fatal. When scientists gave it to mice and rabbits, it caused inflammation around their eyes and skin, as well as weight gain.

The flame retardants that keep your electronics from easily combusting are not delicious or nutritious, either. These substances surround the computer’s copper wires and drift into the atmosphere if burned or crushed as waste. In addition to disrupting fertility, some evidence suggests these flame retardant chemicals might also disrupt human hormone systems, according to the National Institute of Health, and some studies have shown a correlation between certain types of flame retardant and cancer.

Eating computers, though still not safe, has become less deadly over time. The European Union banned cadmium and lead from computers in 2006 and newer circuit boards are less likely to contain arsenic. In 2009, the Institute of Electrical and Electronics Engineers created environmental guidelines that companies and institutions can adhere to, and the even more recent Green Electronics Council grades companies according to how recyclable they are. However, old computers still turn up at recycling centers. “Sometimes people will hold onto things for a long time — we get 40 or 50 year old TVs,” says Jason Linnell, executive director at the National Center of Electronics Recycling. “They might have the lead, the mercury, cadmium. These are the types of materials that you want to prevent from going into the landfill.”

In the future, humans may eat computers on purpose. Right now scientists are developing nanocomputers that patients will be able to swallow like a pill. These tiny robots will be able to monitor your vital signs from the inside, and may also, in the future, be able to fill in one of your hundred hard-to-remember passwords. Prototypes already exist for people like astronauts, firefighters, and football players, whose caretakers want to make sure they do not overheat. Scientists are working on developing computers that are more biodegradable — like this computer chip made of wood-based nanocellulose.

Since most of us lack Lotito’s steel-crushing stomach, recycling is the much more appealing (and safer) option. “Things have definitely gotten better,” says Linnell. “We have a lot more well-qualified recyclers.” In some cities, you can even be fined for putting old computers in the pile with normal trash. Instead, many manufacturers take back old products and many cities offer e-waste deposit locations. There is no need to eat your computer.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post What would happen if I ate my computer? Asking for a friend. appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

When so much of our communication happens online, sexting and sending nude photos are as healthy and natural as having sex. 

A 2018 survey revealed 40 percent of Americans have sent at least one naked picture of themselves, while data from 2015 shows nine out of 10 adults have sexted. Contrary to popular belief, these activities are not restricted to single people on dating apps, but are very much a part of committed bliss. The same 2015 survey found that three out of four sexters were in long-term relationships, and they were more likely to say they were sexually satisfied than single people.

Being able to instantaneously swap photos with someone no matter the distance can be really fun, but ease can make you ignore potential complications. Just like having sex, sending nudes can have unintended lifelong consequences you might not be willing to deal with. But you can easily minimize risks and protect yourself by being safe.  

Sending nudes 101

Let’s go over the basics. Even if you sent your first nude decades ago with an original Motorola Razr, there might still be something you can learn to make the experience better and safer for you and the recipient of your sexy pics. 

There’s no such a thing as completely safe nude

We’re just going to go ahead and say it: Once you hit that send button, you’ve lost total control of your photo.

“Technology can’t fix untrustworthy humans, but it can help you express your boundaries and make it a little harder to violate them,” says Jacob Hoffman-Andrews, a senior staff technologist at the Electronic Frontier Foundation.

Sure, some apps will notify you when someone takes a screenshot of your picture, but they won’t actually prevent them from doing so. A recipient may also simply use another device to take a photo of the screen without alerting you. 

Are you or your partner underage? Do not take, send, receive, share, or store nudes.

There’s no nuances about this one—naked pictures of minors are child pornography, and their production, storage, and distribution is against federal law. 

Even if an image exchange was enthusiastically consensual, and you were the one who took a naked selfie, some states might still consider it a serious crime just because you’re a minor. Sorry. 

Abide by basic sext etiquette

This may go without saying, but there are basic rules of decency when it comes to sending nudes. First, if you receive one, don’t share it with anybody else—it is for you and you alone. When you share a private photo, you’re not only violating the trust of the person who sent it, but also making it more likely to end up in the wrong hands, or worse—on the internet. In some states, sharing naked pictures of people without their consent may also be a felony. Just don’t do it. 

[Related: An expert guide to love and sex during a pandemic]

Second, don’t post someone else’s nudes online. Same principle: Don’t be a jerk. 

Third—as with all sexy things—consent is key. Respect it. Don’t send unsolicited nudes, especially to people you don’t know. If you’re in a relationship with someone, no matter how casual, have a conversation about how they feel about unsolicited nudes. Some might welcome a sexy photo in the middle of their workday, while others might not. Talk to your partner about their likes and limits, and honor them.   

When in doubt, abstain

Send nude photos only to those you know and trust. This excludes people you’ve matched with on dating apps but never actually met, online contacts you’re not even sure are real, or people who give you the slightest hint they’re untrustworthy. 

“The biggest risk in sending a nude is that the person on the other end is less trustworthy than you think. Or that they are trustworthy today but become less so in the future—after a breakup, for instance,” says Hoffman-Andrews. 

Knowing who to trust is far from a perfect science, but just asking yourself the question before you send them a naked picture of yourself might save you some trouble. 

Yes, this sounds scary, but it doesn’t mean you should embrace full-on nihilism or stop sending nudes altogether. Instead, focus on managing the things you can control.

How to safely take a nude photo

The best way to keep a nude pic safe is to keep it anonymous. That way, even if your photos end up online, it will be hard to identify you. 

Crop out or cover your face 

Going faceless is the foundation of anonymity. If this doesn’t work with your artistic vision, be creative and opt for other ways to make you unidentifiable. Use sharp angles to keep your visage out of frame or shrouded in shadow, or shoot with a bright flash in a mirror, for example. 

If you wear a mask, make sure it covers enough of your face.

[Related: Take better selfies with these lighting and angle tips]

If you need tips, check out boudoir photography content on YouTube and TikTok. This will not only help you perfect the poses and angles that will show off your beautiful body, but you’ll also learn how to make your surroundings work in your favor. 

Consider your environment

If someone took a peek inside your room, they’d probably figure out a lot about you. Don’t let your unique style give you up. Find anything that may reveal personal information about you and make sure it’s not in the frame. This includes photos, diplomas, and sticky notes. 

Keep in mind that something doesn’t have to have your social security number on it to be revealing. People who’ve been to your home could easily identify it by a band poster or a painting on your wall. 

When choosing a setting for your nude, keep it as stripped-down as possible (pun very much intended). Blank walls and nondescript bathroom tiles are perfect backgrounds for sexy pics. 

Finally, stay away from large, open windows. Well-known landmarks could peek through and be enough to trace the photo back to your home and to you. Plus, you might want to keep the neighbors out of your photo session—unless you’re into that.  

The healing tool (an icon that looks like a bandage) will help you blur out information in the background, along with small tattoos, birthmarks, beauty marks, blemishes, and anything else you’d like to airbrush out.

[Related: Edit gorgeous photos right on your phone]

Downloading apps such as Snapseed (free for Android and iOS) or Photoshop Express (free for Android and iOS) to your phone or computer will help you tweak all the things you might have forgotten about while taking the picture. They will also provide you with a wide library of filters to get you looking even more like a snack. 

If you’re using a mobile device, turn off location services before taking the photo. On Android, swipe down from the top of the screen to open up the quick settings menu, and tap on the location icon to turn off your GPS signal. Additionally, open your camera app and tap the cog icon to go into its settings. Once you’re there, tap on the toggle switch next to Save location to stop the app from adding your whereabouts to your metadata.

On iOS, go to Settings, then Privacy, and select Location services. There, find the camera app and under Allow location access choose Never.

If you forgot to do this, you can remove location metadata from your picture later using macOS. Open the photo using Preview and hit command + I, or go to Tools and click on Show Inspector, which will show you all the information attached to your file. Under the More info tab (second to the right), choose the GPS tab (third to the right). Then, at the bottom of the dialog box, click on Remove Location Info. The GPS tab should disappear. 

You can do the same on Windows. Right-click on one or more files, select Properties, and go to Details. At the bottom of the dialog box, click on Remove Properties and Personal Information, and then check the box next to Remove the following properties from this file. At the bottom, click Select All, and then hit OK. This will erase all metadata from the selected files.

Turn of automatic syncing with your cloud services

Sending photos straight from your camera roll to your personal space in the cloud is handy, but it’s a liability when nudes are involved. 

Before you take your naked portrait, make sure to turn off syncing between your device and all connected cloud services. On Android, open the Google Photos app, tap on your avatar (top right) and then on Back up. Once there, turn off the toggle switch next to Back up & sync. On iOS, turn off iCloud photos by going to Settings, tapping on your name, choosing iCloud, then Photos, and turning off the toggle switch beside iCloud Photos.

Make sure to delete your photos from your camera roll and your trashcan, or move them to a secure folder before turning syncing back on. 

How to safely send a nude

You got the money shot. Now it’s time to deliver your sexy pic and rock your partner’s world.

Choose a secure platform

Anything that doesn’t have end-to-end (E2E) encryption—which protects your content from interception on its way to the recipient, and prevents the company that owns the platform from accessing it—is out of the question. This means no Facebook Messenger or Instagram. Snapchat uses E2E encryption on photos and videos, but not on messages, and although it lets you know when someone took a screenshot of your photo, it doesn’t prevent them from doing so. 

Your safest bet is Signal. It’s E2E encrypted, you can have messages disappear a minimum of five seconds after viewing, and secure chats prevent users from taking screenshots. It’s worth noting that this doesn’t prevent someone from taking a picture of the screen, but as far as traditional messaging apps go, Signal may be your best option. 

[Related: 6 secure alternatives to WhatsApp]

If you’re willing to spend money on your privacy, Disckreet is a messaging app designed to share racy texts and images. Available for iOS and Android, this platform is E2E encrypted, protected by a passcode, and gives users unilateral control over their content. This means you decide when your partner can see a photo you sent, and you can remotely delete the image from their phone. Diskreet’s free version limits the size and number of files you can share in one day, but you can subscribe for $1 a month for unrestricted sharing.

Even if they don’t do it, this will make it clear that when you shared those pictures, they were meant for your partner’s eyes only. If they share them or post them online, it legally constitutes a violation of your privacy. 

Exercise some good ol’ cybersecurity essentials

Make sure you’re being safe online overall. Start by securing all of your accounts and devices with unique and secure passwords, patterns, PINs, passcodes, or biometrics. If keeping track of all that information is too hard for you, download a password manager, and don’t forget to enable two-factor authentication on all of your accounts. 

[Related: How to do two-factor authentication like a pro]

You should already be doing all of this, but it is especially important if you’re swapping nudes. You want to make it as hard as possible for anyone to gain access to your sexy content by breaking into your accounts or devices.  

How to safely store a nude

What you do after you send a nude will depend on whether you want to delete it or add it to your personal archive. 

If you can, delete the picture on the platform you used to send it so neither you nor the recipient have access to it. If you want to leave absolutely no trace, you should also delete the file on your device. 

But maybe you took a very good nude and you don’t want it to be lost in oblivion. This is when you need to secure your file. Cloud storage services are susceptible to hacks and data leaks, so you may want to store your nudes locally. 

The easiest way is to move your photos to a password-protected folder on your device. On Android, go to the Files app, and then Images and Pictures. Select your nude by long-pressing on it, tap on the three dots in the top right corner of the screen, and choose Move to Safe folder. To access that folder, you’ll need to provide a security pattern, passcode or biometric feature, which can be the same one you use to unlock your phone or something completely different. You can also hide the folder, so if someone were to break into your device, they wouldn’t be able to see it or search for it. 

Windows 10 has a similar feature that allows you to use File Explorer to protect any file or folder with a password. Just right-click on the item, go to Properties, and then Advanced. Click on Encrypt content to secure data at the bottom of the dialog box, and click on OK, then Apply. From the next dialog box, pick whether you want to encrypt only the file or the entire folder where it’s located, then click OK. 

Apple’s computer operating system also allows you to create password-protected folders. Save your nudes inside a folder, open Disc Utility, and go to File, New image, and Image from Folder… Then, use the emerging Finder window to find the folder with your nudes, and click Choose. Under Encryption, pick your protocol, then enter and verify your password. Finally, under Image Format, choose read/write and hit Save. You can also protect single files on Preview as long as they’re saved as PDFs, and use the Notes app to create protected files with embedded photos.

There’s no built-in solution for iOS, but you can download a free file locker app that will do the same job as Android’s “safe folder” on your iPhone.  

[Related: Rip out your computer’s guts and craft an external hard drive]

Another alternative is moving your nudes to an external hard drive, which you can encrypt and store in a safe location. 

Safe nudes are a team effort

Nothing you do to ensure safe sexting will be truly secure if the recipient of your naked pictures cannot be bothered to set up a passcode to lock their phone.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post A complete guide on how to safely take, send, and store nudes appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Even though some end-of-summer festivities might be limited this year, that doesn’t mean celebrations (and drinks) are, too. Within our households or over video calls, lots of us are planning to raise our glasses and forget about how terrible 2021 has been to the world.

It’d be nice if we could do all that without a horrible, head-wracking hangover, though.

Before you start scheduling some recovery time on your calendar, know you can try to avoid them, and but if things get rough, you might be able to make that bottle-ache a bit milder. But that’s the best-case scenario, because we’re sorry to tell you one cold, hard fact: there is no cure for hangovers. Like, none. Zero.

What do you mean there’s no cure for hangovers?

Exactly that, actually. For starters, science still doesn’t quite know what causes a hangover. Literature on the subject has identified three possible culprits: the direct effect of alcohol on the brain and other organs, the effects of alcohol withdrawal from these organs; and other non-alcoholic factors, such as the physiological effects of compounds created when the body processes alcohol, like methanol.

It’s also challenging to define what a hangover is. The definition researchers generally agree upon is that it’s a condition characterized by a feeling of misery that can last up to 24 hours after the amount of alcohol in your blood drops to zero. As anyone who’s ever experienced a hangover will tell you, symptoms can vary both in nature and intensity, going from headache, nausea, and fatigue, to muscle aches, vomiting, lack of concentration, and anxiety.

The symptoms you experience after a night of drinking will depend on multiple factors, like how much you drank, for how long, what it was, if you ate, what kind of food you devoured, if you danced, or smoked, and more. And that’s not even taking into account genetic predisposition to hangovers or family history regarding alcohol addiction.

Considering these effects vary widely from person to person—and even from one event to another—it is very hard to study them, which makes hangovers a tough nut to crack. And then there’s the morality of curing them.

“A possible explanation for the lack of scientific interest is that many physicians and researchers regard the alcohol hangover as an adequate punishment for unwanted behavior,” Utrecht University researchers Joris C. Verster and Renske Penning wrote in their 2010 paper Treatment and Prevention of Alcohol Hangover.

According to them, it is possible that part of the scientific community may not want to find a cure for hangovers because doing so would make binge drinking that much easier.

Ok, so how do I deal with a hangover?

Since we don’t know what causes hangovers, there’s no drug or homemade remedy that will get rid of one entirely. In fact, the only scientifically proven method to avoid a hangover is moderate alcohol consumption or good old abstinence.

But since it is likely you will eventually have to deal with at least one hangover in your life, it’s a good idea to know there are things you can do to make the day after a party a little less miserable.

Rehydrate

Dehydration is one of the main symptoms of hangovers. Alcohol inhibits the production of antidiuretic hormone, preventing the kidneys from reabsorbing water and resulting in the overproduction of urine. Add that to sweating, vomiting, and diarrhea (all possible hangover symptoms), and you end up with a sure case of dehydration.

Drinking one glass of water for every alcoholic beverage you consume is a great way to prevent a bad hangover. If that ship has already sailed and you’re experiencing hangover-induced dehydration, you can always opt for a sports drink or make your own oral rehydration salts. All you need to do is mix two tablespoons of sugar and a 3/4 teaspoon of salt in four cups of water. Doing so will not only help you get that precious water back into your body, but will also restore your electrolytes.

Beware of congeners

If you’ve ever experienced a red wine-induced hangover, you know they’re some of the worst you can get, and congeners are to blame. These are the biologically active compounds that give alcoholic beverages their distinct taste, smell, and color. Research shows a higher concentration of congeners may have something to do with more severe hangovers, whereas drinking distilled spirits containing purer ethanol, such as vodka or gin, will result in milder or fewer hangover effects.

When it comes to avoiding hangovers, the lighter the color, the better—stay away from rum, whiskey, tequila, and red wine, which are among the alcoholic drinks with higher amounts of congeners.

Sleep well

Fatigue and muscle aches are two of the most common hangover symptoms, and you don’t have to be a doctor to know the best way to treat them: rest. But alcohol consumption disrupts sleep patterns, resulting in both less and worse sleep. Drinking also alters your circadian rhythm, which raises cortisol levels and causes a feeling similar to jet lag.

It might be difficult, but a good way to combat a hangover is just to sleep. Give yourself the time to get some rest and bounce back. And if you made the horrible decision of making plans for early the next day, God help you.

Be careful when taking Aspirin or paracetamol

When you’re suffering from a hangover that features an intense headache, your first instinct may be to take Aspirin or paracetamol. Studies have shown alcohol can cause an inflammatory response in the body, so anti-inflammatory drugs such as these could have a positive effect.

The problem is there’s no peer-reviewed evidence supporting Aspirin’s ability to fight a hangover, and research has found the use of the drug in combination with alcohol can result in stomach bleeding and liver damage. Before you think about taking any pills to fight off the consequences of a long night of partying, consult with your doctor—they may be able to recommend a better course of action considering your particular situation.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

The post What is a hangover? And can you cure it? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

The healthiest way to eat a dessert (or any type of added sugar) is to not eat it. That being said, what is life if you don’t live it? For me, a life without the occasional glazed doughnut for breakfast or Sour Patch Kids at the movies is a life not fully lived. Most Americans, including doctors and nutritionists, would likely agree. Nevertheless, studies show that sugar, in excess, can contribute to the development of diabetes, obesity, and heart disease. So when you inevitably consume foods loaded with sugar, is there a way to do so that minimizes the impact on your health?

Recent studies suggest there could be.

First of all, there’s no reason to cut sugar completely out of your diet. That’s a pretty hard thing to do, says Leslie Bonci, a registered dietician and sports nutritionist. She says it’s unlikely that most people will stick to a sugar-free diet. Everyone, to a certain extent, has a desire for sweet-tasting foods—and for good reason. Sugar provides us with needed energy. So, if we eat a diet completely devoid of sugar, “psychologically, that can be devastating.” It’s much more productive to think about how to keep your sugar intake as healthy as possible.

Sugar often gets a bad rap because we eat it alone, in the form of soda and candy, or with other carbohydrates in various baked goods. Since these foods are loaded with simple carbohydrates, they spike our bodies’ blood glucose levels. When this happens, we immediately try to bring those spikes back down to normal levels by increasing the production of glucose-lowering hormones such as insulin and incretin. If we increase them too much too often, this mechanism stops working as it should, which can lead to type 2 diabetes.

But there are ways to try to prevent this. People can start, Bonci says, by simply eating less sugar, or eating it with other foods to avoid letting it become the focal point of a meal (goodbye, Sour Patch Kids lunch). Bonci says perhaps the best type of food to eat sugar with is protein. The consumption of protein triggers the release of glucagon, another hormone, which stabilizes insulin levels. So when eaten together, protein and sugar can sort of regulate each other. “Our bodies are pretty darn smart in that way,” she says.

An ideal way to implement this is with your morning coffee (that is, unless you drink it without any sugar). Coffee can be pretty bitter on its own, so rather than add a bunch of sugar to offset that, try mixing it with milk in the form of a latte, cappuccino, or cafe au lait. That way, Bonci says, you get that ideal mix of sugar and protein (from the milk), resulting in more balanced hormone and glucose levels.

Some recent research suggests that we should take it one step further: Eating all carbohydrates, including sugar, last. Studies on post-meal glucose and insulin levels in people with type 2 diabetes show that the order in which you eat various types of food matters. The most recent one, out in September of this year, had participants—all with type 2 diabetes—eat the same exact meal on three different days, but in various order. One day, they ate carbohydrates first, followed 10 minutes later by protein and vegetables, then protein and vegetables first, followed by carbs 10 minutes after, and finally everything eaten together at the same time.

Researchers measured their blood glucose, insulin, and glucagon levels just after the meals and every 30 minutes for the next three hours. They found that peaks in glucose levels when carbs were consumed last were all around 50 percent lower than when they were consumed first. Even eating everything at once produced a spike 40 percent higher than that seen when carbs came last.

That’s a pretty significant difference. In fact, according to the study, the effect of food order on postmeal glucose and hormone levels is comparable to the effect of drugs meant to regulate glucose. Many people with diabetes are told to limit the carbs and added sugar they consume. But this research suggests that just switching the order could be as good as limiting their intake altogether.

While the study was done on diabetics and it’s intended goal was to find a best practice for that group, study author Louis Aronne, a professor of metabolic research at Weill Cornell Medical Center, says everyone could use the information gained. Generally speaking, he says, “ I think it would be best to have salad, vegetables, and a protein, followed by dessert.”

Bonci adds that this method could also work, logically speaking, to help you eat less of the dessert or carb in general. If you’ve already loaded up on other foods, especially fiberful vegetables, then you will probably be less hungry when dessert comes around.

It’s probably fruitless to promise yourself you won’t eat any sugary treats this holiday season. Instead, try to eat the bird and Brussels sprouts first, followed by the stuffing and mashed potatoes, and then use whatever room you have left to dig into that delicious homemade apple pie.

Have a science question you want answered? Email us at ask@popsci.com, tweet at us with #AskPopSci, or tell us on Facebook. And we’ll look into it.

The post How to eat sweet foods on a healthy diet appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

This week, we investigated whether you can survive by eating a single type of food. While we wouldn’t recommend this as part of a healthy diet—and why would you when there are so many delicious foods out there—we made sure to answer the question accurately and scientifically. While you’ll have to listen to the entire episode for proper context, I will say that it’s not easy and it would take a lot of that single food item. We’re talking dozens and dozens of potatoes. 

The main reason this would be so hard is that there are many micronutrients, including various vitamins and minerals, that we need to survive. All foods have more of some and less of others, so relying on just one form of sustenance for all our nutritional needs is really challenging. There’s a reason that the U.S. dietary guidelines recommend eating a variety of fruits, vegetables, grains, meats, and cheeses.

Perhaps taking a deep dive into one food item is the easiest way to show that a varied diet is really the best thing you can do for your body. So if you want to know how many potatoes you’d need to eat to survive, be sure to tune in to this week’s episode of Ask Us Anything. Tune in here, and read the article that inspired this episode here.

The post Ask Us Anything: Can you survive on a single food forever? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This post has been updated. It was originally published on October 30, 2017.

From a basket of warm focaccia on the table at a restaurant, to flat loaves of naan accompanying a curry, bread is incorporated into many, if not most, meals around the world. Everyone loves carbs, especially bread. So, wouldn’t it be awesome if we could literally live off of this beloved food group? The short answer is yes, yes, it would, but the larger question is; is it even possible?

You could probably survive on quality whole grain bread that’s been fermented for a while. But eventually you would run into nutritional deficiencies, and in all likelihood, you’d eventually get sick of the carb-laden substance.

Many people have wondered whether humans can survive on just one food item. The question is valid: Eating just one thing would probably save a lot of time and effort and potentially a good deal of money. Plus, many food items do pack a considerable nutritional punch. But none can contribute everything, which is the main reason humans have evolved eating a varied diet. For example, technically potatoes contain all the essential amino acids you need to survive. But many of those amino acids are present in such small amounts that even if you consumed far more than a day’s worth of calories in potatoes, you would eventually run into many nutritional deficiencies.

The same goes for bread, though not all kinds are nutritionally sliced equal. Unlike potatoes or rice which are stand-alone plants, this carb is created from the combination of grains and water and some type of microbe. These microbes, yeast and certain types of bacteria, break the grains down, exposing the nutrients within them that humans normally wouldn’t be able to access. As the environmental news outlet Grist points out, the end product, bread, is far more nutritious than its main ingredient, whole grain.

If you compared the nutritional benefits of porridge, which is essentially whole grains soaked in water, to traditionally-made bread, the latter would come out on top because the porridge didn’t go through that fermentation process which releases key nutrients from the grains. But that’s if you made the bread the traditional way. Many breads made today are created with a combination of white flour and commercial yeast—leaving out the whole grains and the nutrients they provide.

[Related: Can you survive on a single food forever?]

So, if you wanted to attempt to survive just on bread alone, it would need to be made with whole grains and probably a yeast/bacteria combination that’s been proven to ensure the proper combination and diversity of bacteria are there to break those whole grains down. Perhaps one of the best breads that achieve this is traditionally-made sourdough, which is created with a combination of yeast and lactobacilli, a type of bacteria. The fermentation process is slow, ensuring the nutrients inside the whole grains are exposed.

But even sourdough might not be enough to survive. Eventually, just like the potato scenario, you would probably run into nutritional deficiencies. Even sourdough bread made with wild yeast, bacteria, and whole grains likely will not provide enough nutrients like vitamin C, B12, and D, as well as calcium. Without these key players, humans would run into some serious problems. With no vitamin C source, a person could develop scurvy, which results in weakness of the muscles and fatigue. Calcium is necessary to prevent osteoporosis, which results in weakened bone mass. Plus, humans need fat to survive as well, which sourdough bread doesn’t have.

If you did attempt to eat one food for an extended period of time, you would probably get sick of eating the item far before you gave yourself any severe nutritional deficiencies. That’s due to a psychological phenomenon called sensory specific satiety. Scientists have found that the more you eat something, there’s a corresponding decline in pleasantness. But some foods are more prone to this than others (like high protein foods), and some researchers have found that bread might be in fact fairly resistant to this phenomenon.

[Related: Learn your sourdough starter’s funky secrets]

While sourdough and other whole grain breads are extremely nutritious, they cannot provide everything. And sure, it might sound easy to eat the same thing for the rest of your life, but, for most people, it’s also probably incredibly boring. But if you want to simplify your diet, don’t fret. There’s plenty of simple food combinations, like rice and beans, yogurt and nuts, and pasta and vegetables that provide a more complete nutritional profile. But even with those, it’s always best to change those up as well. Eating the rainbow is still a pretty foolproof method.

The post Can you live on bread and water alone? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Sleep is a time suck. If you multiplied the average recommended number of hours we should sleep in a day—eight for a typical adult—by the number of days in an average lifespan (78.8 years in the United States), that would amount to about 9,587.3 days. That’s one third of your life spent unconscious. From an evolutionary standpoint, sleep is quite literally a waste of your time, yet it’s fought its way through countless years of adaptation in nearly every living animal on Earth. So it must be important, right?

In fact, researchers have found that sleep plays a vital role in the functioning of nearly every organ system in the body. At the same time, medical conditions, a busy schedule, and even the simple unavoidable act of aging constantly challenge the number of hours we allow ourselves. But that begs the question: how much sleep do we actually need? And can we train ourselves to need less?

First, let’s talk about that eight hour figure that gets tossed around. It’s far from some arbitrary number. It’s truly the number of hours we naturally crave, and there are two pretty strong pieces of evidence for it. In a series of experiments, researchers took study participants into a laboratory with no sunlight or other visual cues and, at night, gave them a non-negotiable, nine-hour-long opportunity to sleep. They did this each night for a number of weeks, and the results were always the same: even when provided with more time, humans will typically spend an average of eight hours catching up on their Zzz.

And that wasn’t the only study to support the eight-hour sleep schedule. Back in 1938, a sleep researcher named Nathaniel Kleitman and one of his students spent 32 days living in Mammoth Cave in Kentucky, one of the longest and deepest caves in the world—an environment completely void of sunlight. When they analyzed their sleep patterns, they found that they, too, slept about eight to eight and a half hours per night.

But what happens when we deprive ourselves, as many Americans do, of all or some of these recommended hours? It turns out, a lot. In 2003, David Dinges and Gregory Belenky, both sleep researchers at the University of Pennsylvania and the Walter Reed Army Research Institute, performed some of the most pivotal studies on the consequences of sleep deprivation thus far. Their goal was to figure out how little sleep a person could get away with, without having it affect their cognitive performance.

The two studies involved two-week-long experiments where researchers deprived participants of varying hours of sleep. Before they did so, they first allowed subjects to receive eight hours of sleep, followed by a series of cognitive tests the next day—which measured things like someone’s speed of response, how well they could interpret a written passage, and the number of times they dozed off for a second or two (what science calls a microsleep). All of this gave them a baseline for each subject’s normal cognitive performance.

The researchers on Dinges’ team then assigned the participants to one of four groups: one group was allowed eight hours of sleep for the following two weeks, the next six, then four, and the last group received zero hours of sleep for up to three days straight.

That last group, says Matthew Walker, the director of the sleep and neuroimaging lab at the University of California, Berkeley, showed just how much your cognitive performance suffers after just one night of total sleep deprivation. What Dinges and colleagues found (and what subsequent studies have confirmed) is that to your brain, one sleepless night is the cognitive equivalent of being legally drunk, says Walker.

The rest of the groups weren’t so far behind. While the group that received eight hours of sleep saw virtually no change to their cognitive performance throughout the two-week study, after just 10 days the participants that slept six hours each night were as cognitively impaired as those suffering from a night of total sleep deprivation. And the group that got four hours? It only took them three days before they reached that same level of impairment. By 10 days in, they were as cognitively impaired as if they had gone two days with no sleep. As the days went by, these detriments didn’t slow down. “If you looked at the data graphs, there’s no end in sight. That was the frightening thing,” says Walker.

When Dinges compared his results to his colleague’s at Walter Reed—who had done the same exact study but with odd hours (meaning seven, five, and zero hours of sleep), their findings were basically identical. Even the group that slept seven hours a night—which some people think of as a luxury, says Walker—were dozing off at a rate three times greater than the group sleeping eight hours a night just five days into the experiment. So, how much sleep can you take away before someone becomes cognitively impaired? Sorry, but the answer is less than one hour.

Okay, so that’s sadly settled: we should all be getting no less than eight hours of sleep per night. No exceptions. But we all lead extremely busy lives, especially during the workweek. Can we make up any of those hours lost during the week on the weekends (similar to those weekend warrior who still receive health benefits from only exercising on twice a week) so that you average eight hours a night? The researchers asked the same question.

After the sleep deprivation part of the study was done, the researchers then gave the participants three nights of “recovery sleep” where they were allowed as much as they wanted (unsurprisingly, most slept way more than eight hours). After those three days, they took the same cognitive screening tests. But the participants hadn’t returned to the baseline levels they had at the beginning of the study. In other words, if you are sleep deprived—meaning you are sleeping seven hours or less each night—then it takes you longer than a weekend to get back to baseline. And no one’s figured out how long it actually takes.

“People think that sleep is like the bank. That you can accumulate a debt and then hope to pay it off at a later point in time,” says Walker. “And we now know that sleep is not like that.”

The brain has no capacity to get back all that it has lost, Walker explains. Why is this? Why haven’t we evolved a way to make up for lost sleep the same way we can make up for days of starvation by storing calories as fat? The answer, Walker says, is simple: “Human beings are the only animal species that deliberately deprive themselves of sleep.” There is no storage system for sleep in the brain because life never needed to create one.

Undoubtedly, many of you are reading this and scoffing. If you regularly get six hours of sleep and feel just fine, why should you waste your time trying to squeeze in more?

Consider this: after the first night of reduced sleep, researchers in Dinges’ study asked the participants in the six-hour-a-night group how well they thought they did on the day’s cognitive tests. They replied that they did well—great, even. However, when the study researchers actually compared the two performances, the tests completed after six hours of sleep were significantly worse than the ones done after eight hours of sleep.

“You don’t know you are sleep deprived when you are sleep deprived,” says Walker, “That’s why so many people fool themselves into thinking they are one of those people who can get away with six hours of sleep or less.” Walker argues that there’s no way you can effectively train yourself to need less sleep. You may get used to feeling tired all the time, he says, but that does not mean you can suppress that tiredness and perform as well on cognitive tests as you would if you received eight hours.

But perhaps there is a positive twist—in the form of a mid-afternoon nap backed by science. Researchers who have looked at cultures that remain completely untouched by electricity, such as the Hadza of Tanzania, found that, especially in the summer, these groups tend to sleep biphasically: packing in six hours a night, and then a few hours again in the afternoon. This begs the question, Walker says, of whether human beings should stay awake for sixteen hours straight. In fact, everyone goes through an afternoon lull. Biologists have actually been able to measure this physiological dip in our alertness—what science calls a postprandial dip—through changes in our metabolic system, as well as adjustments in our brain waves, and in our cognitive reaction times. The universal cognitive pause means we might benefit from a nap around this time. “Perhaps human beings need to sleep biphasically for truly optimal performance, though that’s still unclear,” Walker says.

One thing science knows for sure, however, is that the less sleep you get each night, the less cognitively aware you are the next day, the day after, and every day after that. Simple.

In fact, Walker says, if you ever want proof of how much of an effect just one hour less sleep can have on human beings, just remember how you feel the days after daylight savings begins every March, when nearly the entire country has intentionally deprived themselves of an hour of sleep.

But perhaps the most relevant thing to remember, Walker says, is this: When someone tells you the reason they can only get five hours of sleep is that they simply have too much to do, “I tell them, I’m sorry, but there’s an irony in your statement. The reason you are left with so much to do could likely be because you are only getting five hours of sleep and your cognitive functioning is deficient, so it’s taking you forever to do everything.”

The post How many hours of sleep do you actually need? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This post has been updated. It was originally published on June 1, 2019.

Stretching is good for your muscles—no newsflash there. Research shows that an active warmup before a workout prepares them for the intense activity, and a static cool down (you remember those circle-up and stretch exercises from elementary school?) helps the body relax and recover.

But is it possible to overstretch? We’ve all had that moment: You stand up or lean back to stretch, and, all of a sudden, extreme pain hits. Can a benign extending and lengthening session turn detrimental?

It’s entirely possible that you could stretch so much that you strain, or even tear, a muscle, but more likely than not, that pinch is probably just a startled nerve. Muscles contain special sensory receptor cells called muscle spindles. When you stretch, these cells send a signal to the neurons within the muscle to tell the central nervous system that you’ve gone too far. As a result, those muscles contract, tighten, and resist the pull. That reaction is what causes the initial painful feeling that people get when they attempt to stretch. It’s also the reason that some people feel such agony when they try to touch their toes: The quick pain caused by that neural cascade is just too great.

There is hope, though. You can prime your muscles to avoid the painful twinge of startled neurons, according to Jeffrey Jenkins, a physiologist at the University of Virginia School of Medicine. It’s simply a matter of patience. If you hold a stretch for 6 seconds or more, the reflex lessons. That’s because, at that point, the muscle’s golgi tendon organs (spindles of neurons that rest on muscle fibers) react and inhibit those ouchy muscular contractions. Finally, your muscles can relax, stretch, and lengthen.

Jenkins notes that if you have the mental fortitude to get past that those 6 seconds, you no longer feel the pain and can indeed improve your flexibility. However, if you are enduring a ton of agony, stop, as you could be tearing a muscle. In fact, it’s quite difficult to differentiate between a tear and the pain that comes along with the first moments of a good stretch.

The best thing to do is to know yourself—and your pain threshold. If you feel like you are in a level of discomfort that is far beyond what you normally experience, you should probably stop. At that point, the likelihood of you benefiting from the stretch versus the likelihood of you pulling or tearing a muscle tips. Indeed, in a small study published in 2017, researchers tested and compared the benefits and risks of static stretching to the point of pain in 22 physically active women. One group stretched to the point of true pain, whereas another group went only to the point of discomfort. Pushing yourself to the point of pain, the study found, had no advantages.

So, of course stretch however it benefits you, but remember that if you are experiencing agonizing pain, it’s far more likely to be doing harm than it is to be doing good. And don’t worry, the ability to touch your toes—or not—has little to do with your overall well being.

The post You can injure yourself stretching—but it’s not easy appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Australian Boomerangs

The boomerang is one of humanity’s oldest heavier-than-air flying inventions. King Tutankhamen, who lived during the 14th century BC, owned an extensive collection, and aboriginal Australians used boomerangs in hunting and warfare at least as far back as 10,000 years ago. The world’s oldest boomerang, discovered in Poland’s Carpathian Mountains, is estimated to be more than 20,000 years old.

‘When the boomerang spins, one wing moves through the air faster than the other’

Anthropologists theorize that the first boomerangs were heavy projectile objects thrown by hunters to bludgeon a target with speed and accuracy. They were most likely made out of flattened sticks or animal tusks, and weren’t intended to return to their thrower—that is, until someone unknowingly carved the weapon into just the right shape needed for it to spin. A happy accident, huh?

Darren Tan is a PhD student in physics at Oxford University. He donned a ninja suit as the “Science Samurai” in a video for high school science students about boomerangs. In his video, he demonstrates how to fashion a boomerang from three strips of cardboard, by crossing and stapling them together so that they jut radially outward from the center.

Proper wing design produces the lift needed for boomerang’s flight, says John “Ernie” Esser, a boomerang hobbyist who works as a postdoctoral researcher at University of California and Irvine’s Math Department. “The wings of a boomerang are designed to generate lift as they spin through the air,” Esser said. “This is due to the wings’ airfoil shape, their angle of attack and the possible addition of beveling on the underside of the wings.”

But a phenomenon known as gyroscopic precession is the key to making a returning boomerang come back to its thrower. “When the boomerang spins, one wing is actually moving through the air faster than the other [relative to the air] as the boomerang is moving forward as a whole,” explains Tan. “As the top wing is spinning forward, the lift force on that wing is greater and results in unbalanced forces that gradually turns the boomerang.” The difference in lift force between the two sides of the boomerang produces a consistent torque that makes the boomerang turn. It soars through the air and gradually loops back around in a circle.

Protip: To really make a boomerang soar, hold it vertically and give it a good spin—and be careful where you aim!

The post What Makes A Boomerang Come Back? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Lava Splatter

Great question. Glad you asked. While volcanoes might seem like the ideal natural incinerator for our massive amounts of garbage, there are a few obstacles between us and a magical geological trash chute to the center of the earth.

Americans generate about 4 and a half pounds of trash per person, per day, or 254.1 million tons total per year. In order to dispose of all that trash in a volcano, you’d need to first locate an active volcano, and lug the trash there. That’s the first problem. Not many people live near active volcanoes, so transporting trash to a volcano would cost time, money, and a whole lot of fuel. Then there’s the fact that an even smaller number live near the right kind of active volcano.

That sounds like a volcanically snobby thing to say (oh, we don’t associate with those sorts of geological formations) but it’s the truth. When you picture throwing garbage into a volcano, you’re probably thinking of a nice, friendly cone shaped volcano with a hole at the top. Something like this:

And in the middle of the crater, you’re probably picturing a lovely lava lake that looks like this:

Perfect for throwing trash into, right? But not all volcanoes are cooperative like that. The ideal trash incinerator would be a slow-erupting volcano that gradually spews lava out onto the surface of the earth, like the volcanoes in Hawaii, called shield volcanoes. But the majority of volcanoes on Earth are stratovolcanoes which occasionally have lava flows like Kilauea, but also have the unfortunate tendency to explode when the pressure of hot gas and magma inside the volcano gets to be too much. Long story short, you don’t want to throw trash into an explosive volcano (think Mount St. Helens) when it’s erupting. If you’re close enough to throw trash into the exploding mass of molten rock, ash, and gases, you’re already dead.

But say you happen to live in Hawaii, close enough to haul your trash up to the summit of your friendly neighborhood active volcano every day. In addition to worrying about your house getting destroyed by lava, there’s also some danger to you (or a garbage truck) that’s dumping trash into a placid lake of lava. See, in addition to the poisonous gases and lava splatter which are already normal hazards at the summit of a volcano, when cold trash hits a large mass of lava, it can cause some spectacular explosions, as a group of researchers discovered in Ethiopia in 2002.

Awesome, right? But that was a 66-pound bag of trash, about three and a half days’ worth for a U.S. family of four. Imagine if that was a larger amount. Rockfalls into lava lakes in Hawaii have sent lava 280 feet into the air, splattering fences and scientific webcams with molten rock. That’s a little too much danger associated with taking out the trash.

Not to mention the fact that you’ll be burning a bunch of trash, and any smoke generated will go straight into the atmosphere, creating a lot of air pollution. Today, trash incinerators are governed by a web of regulations that make sure the smoke from burning trash doesn’t get into our air (they try to filter out major pollutants like ozone, carbon monoxide, sulfur dioxide, etc).

So throwing the mass detritus created by human civilization into a volcano isn’t an option. But what about more specialized waste, like medical or nuclear? Things that tend to be really dangerous? Unfortunately, volcanoes aren’t hot enough to melt nuclear fuel or sterilize medical waste. Temperatures of lava range from 1292 to 2282 degrees Fahrenheit, which is hot, but not hot enough.

It is, however, hot enough to devour a can of Chef Boyardee in a spectacular manner. Enjoy:

The post Why don’t we just throw all our garbage into volcanoes? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This post has been updated. It was originally published on April 6, 2020.

Before the invention of antibiotics, most of our dealings with bacteria—at least, the dangerous ones—ended in death. At least partly because of that, we have viewed hand sanitizer, the powerful bacterial annihilator that it is, as something we should use liberally without fear of health consequences. Now, after more than a year of living with the threat of the novel coronavirus (SARS-CoV-2), the stuff has become a steady fixture of daily life. Its role as destroyer-of-all-microbes has become a vital component to public health. But where do our delicate microbiomes fit into this microscopic battlefield?

Over the past decade, microbes have taken on a new, positive role in our lives. We’ve figured out that in addition to the bad microbes that can infect us, our bodies are teeming with good bacteria that help us digest food, potentially prevent autoimmune diseases, and even stave off infections from happening in the first place. Unfortunately, antibacterials don’t discriminate bad from good. And that puts users at a crossroads: Should we continue using things like hand sanitizer to avoid disease, or should we embrace germy hands for the sake of our health?

Under normal circumstances, the question of whether and when to use hand sanitizer comes down to a judgement call, as outlined in detail below. But in light of recent events—namely the presence of SARS-CoV-2, which causes the respiratory disease COVID-19—the guidelines for using hand sanitizer are far clearer: As long as the virus continues to spread throughout communities in the United States and around the world, apply hand sanitizer liberally and often. While washing your hands is best, using hand sanitizers that are at least 60 percent alcohol are a close second to killing any viruses that might be lurking on your hands. The benefits of using hand sanitizer to prevent COVID-19 far outweigh the potential risks to our skin’s microbiome, the delicate balance of bacteria, viruses, and fungus that live on our skin everyday.

[Related: The future of probiotics and gut microbiomes is bright]

But in a world in which SARS-CoV-2 stops being an immediate threat—and hopefully the currently available safe and effective vaccines will continue to help get us there—there are positives and negatives to the liberal use of hand sanitizer.

“One aspect of hand sanitizers that is usually overlooked is that they can affect bodies’ microbiomes in a few ways, and some of these ways could be bad,” says Jonathan Eisen, a microbiologist at the University of California at Davis. While they are killing potentially dangerous microbes, they are also altering the communities of beneficial bacteria on the skin.

While we can’t see any of them, millions of bacteria reside on our hands, skin, and inside our guts. Recently, scientists have begun to understand that every person has a proper balance of bacterial colonies that, among other things, keeps the body in check. When we use hand sanitizers, we are attempting to kill off almost every microbe that resides on our hand—the good and the bad.

In addition to killing off potentially beneficial bacteria, Eisen says, hand sanitizers could also contribute to antibiotic resistance. “Even though they generally do not contain standard antibiotics, when microbes become resistant to some of the sanitizers this can make it easier for them to be resistant to more important antibiotics,” Eisen says. You might just want to make sure you aren’t eating any harmful bacteria with your burrito, but doing this repeatedly—and as a general population—could come back to haunt us later. Antibiotic resistance is already a serious threat, and it’s getting worse.

So should we disinfect or not?

“I recommend that people use hand sanitizers with caution, and only if really needed,” says Eisen.

Consider what your hands have recently touched. If you just spent time in a hospital, a doctor’s office, or on the subway next to someone coughing and sneezing, grabbing the Purell is not a terrible idea. But if you’re just going about your normal day without touching too many other humans, it’s probably not necessary to sanitize yourself. That’s especially true if you have the opportunity to use regular ol’ soap. One 2009 study found that typical soap, when scrubbed on properly, is just as good at killing potentially infectious bacteria and viruses.

There’s still a lot of work that needs to be done to better understand the skin microbiome, especially the microbes that reside on human hands. While we know a lot about what types of bacteria typically live on us, we know less about what each one’s specific function is. If we can figure out how some microbes keep us healthy, then we might have a better answer as to how often, and in what situations, using a hand sanitizer is best. For now, follow Eisen’s advice and use it as sparingly as possible. Think of it as a last line of defense against the world’s grime.

Have a science question you want answered? Email us at ask@popsci.com, tweet at us with #AskPopSci, or tell us on Facebook. And we’ll look into it.

The post You might be overusing hand sanitizer appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Monkey Business

Ah, the age-old question. When animals are going at it like, uh, animals, how does it end? Is there an animal version of the Big O?

It’s a bit hard to say, actually. “The short answer is that we don’t know much about orgasms in other species — in fact, scientists are still studying the significance/evolution of female orgasms in humans,” Marlene Zuk, a professor of ecology, evolution and behavior at the University of Minnesota, wrote me in an email.

Unlike humans, animals can’t tell us they’re having orgasms, so we can’t truly know what their experience is like. For the most part, we assume that male animals orgasm because there’s an ejaculation–though one can happen without the other, they usually go hand-in-hand. (Or something in hand.) The question of female orgasm is, as usual, more hotly contested, though all female mammals have clitorises.

Scientists can infer that animals–mostly primates–orgasm through recording physiological or behavioral aspects, like muscle contractions or changes in vocalization. Studies of primate orgasm have often focused on macaques, a subset of monkeys which are used often in research because they’re genetically similar to humans and have similar reproductive systems. According to Alfonso Troisi, a clinical psychiatrist in Rome who has studied female orgasm in Japanese macaques, they’re easier to study in the lab than gorillas or chimps. Macaques species tend to have longer copulations than other primate species like gorillas, which is a bonus if you’re trying to observe their mating behavior.

“In the lab, by artificial stimulation, it is possible to trigger female orgasm in virtually any primate species.”In a 1998 study, he and his co-author wrote that “Under specific circumstances, nonhuman primate females may experience orgasm.” But, the rate at which the females orgasmed was variable, and they weren’t exactly sure what caused them. Their study found that the level of dominance of the male macaque might play a role, for instance. But, as Troisi wrote me via email, “In the lab, by artificial stimulation, it is possible to trigger female orgasm in virtually any primate species.”

At the Institute for Primate Studies in Norman, Okla., psychologist William Lemmon and his grad student, Mel Allen, argued that “the female chimpanzee manifests most, if not all, of the indices of sexual arousal and orgasm that occur in women.”

They get more specific in the 1981 study:

sexual responses detected included transudate secretion, clitoral tumescence, vaginal thickening and expansion, hyperventilation, involuntary muscle tension, arm and leg spasms, clutching, facial expressions (eg, low open grin, low closed grin, eversion of the lips, protrusion of the tongue), and a panting vocalization.

Allen manually stimulated the clitorises and vaginas of female chimps in the course of writing his master’s thesis at the University of Oklahoma, “Sexual response and orgasm in the female chimpanzee (Pan troglodytes).” (Surely he had fun describing his work at parties.) As he and Lemmon wrote in their later paper, “Most of these females permitted stimulation to continue to sexual arousal. One of them allowed stimulation to continue to orgasm on ten separate occasions.” As they so dutifully recorded, the average number of “digital thrusts” required (performed “at an approximate rate of one to two per second”) before the onset of vaginal muscle contractions: 20.3. Poor Allen.

Stanford University anthropologist Suzanne Chevalier-Skolnikoff, in 1974, writing on homosexual encounters between female stumptail macaques:

On three recorded occasions, the female mounter displayed all the behavioral manifestations of orgasm generally displayed by males: a pause followed by muscular body spasms accompanied by the characteristic frowning round-mouthed stare expression and the rhythmic expiration vocalization.

And yes, drawings were involved.

Stumptail Monkey Orgasms

So, when it comes to primates, orgasms definitely seem to occur. What about the rest of the animal kingdom?

“Who knows whether it feels like a human [orgasm], but the external behaviour looks like it.”The male red-billed buffalo weaver is the only species of bird we know of that exhibits orgasm-like behavior, according to Tim Birkhead, a professor in Sheffield University’s Department of Animal and Plant Sciences. Birkhead spent years trying to observe the birds getting down, culminating in a study published in 2001. The buffalo weaver, a native of sub-Saharan Africa, has a fake penis–it has no sperm duct and doesn’t become erect, but when Birkhead and his colleagues manually stimulated a buffalo weaver’s mock member, the bird had what seemed to be an orgasm. As Birkhead described to me via email, “the bird shudders its wings and clenches its feet as it ejaculates– who knows whether it feels like a human [orgasm], but the external behaviour looks like it.” He says the organ is purely stimulatory, but they’re currently investigating its anatomy further.

And what of dolphins, widely touted as the only other species to have sex for pleasure?

First of all, orgasms aside, animals don’t get it on because they really want to make babies. They do it because it feels good (which ends up being good for the propagation of the species, too). As Daniel Bergner puts it in his book What Women Want:

The rat does not think, I want to have a baby. Such planning is beyond her. The drive is for immediate reward, for pleasure. And the gratification has to be powerful enough to outweigh the expenditure of energy and the fear of injury from competitors or predators that might come with claiming it. It has to outweigh the terror of getting killed while you are lost in getting laid. The gratification of sex has to be extremely high.

“Nowadays, there is little money around (even in the US), field researchers get no funds, and scientists working in the lab face the opposition of animal rights activists.”Tadamichi Morisaka, an assistant professor at Kyoto University’s Wildlife Research Center, says that dolphins do engage in masturbation without ejaculation “a lot,” as well as other non-breeding-related genital touching, called socio-sexual behavior, especially between males. However, “We have no idea that dolphins feel orgasm or not because there is no study to measure brain response during sexual activity in dolphins,” he told me via email.

Morisaka did catch the first spontaneous ejaculation ever recorded in a dolphin, which he published (with a mildly NSFW video) in a hyper-readable study in PLOS ONE. Spontaneous ejaculation has thus far been recorded in drowsy rats, guinea pigs, domestic cats, warthogs, horses and chimpanzees, according to the study.

As fun as this kind of research is to read about, watching animals get down in the hopes of detailing their climaxes in a scholarly manner appears to have gone out of style.

“The 1970s and 1980s were the golden years for primate research and animal ethology,” according to Troisi, who left primate research a decade ago. “Nowadays, there is little money around (even in the US), field researchers get no funds, and scientists working in the lab face the opposition of animal rights activists. In addition, this the era of neuroscience and molecular genetics. Few people pay attention to behavioral observation,” he wrote.

Hooking monkeys up in a dog-harness contraption and stimulating them with essentially a silicon monkey dildo, for instance, might be tough to get approved these days.

Other researchers echoed the sentiment. Kim Wallen, a professor of psychology at Emory University, says “animal studies have essentially disappeared.”

According to Wallen, there have been a variety of factors involved in the demise of animal orgasm research. For one thing, it’s easier to study human orgasms now that we can stick people in an fMRI scanner. Studying animal sex is hard–as evidenced by Birkhead’s account to Nature of what it was like to chase around mating birds: “I’d run after them, sweating profusely with my binoculars steaming up.”

Plus, the type of animal studies approved in the ’70s and ’80s might not make it past research review boards today. University of Toronto researcher Frances Burton’s 1970 work, which involved hooking monkeys up in a dog-harness contraption and stimulating them with essentially a silicon monkey dildo, for instance, might be tough to get approved these days.

And though it’s likely that most non-human primates have the ability to orgasm, we can’t really know for sure if it’s analogous to the human variety. As Zuk wrote me, “what all this points to is our own inability to know what other animals experience.”

Have a science question you want answered? Email us at ask@popsci.com, tweet at us with #AskPopSci, or tell us on Facebook. And we’ll look into it.

The post Do animals have orgasms? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Warm Santa

At the yearly Rottnest Channel Swim in Western Australia, participants often smear their bodies with animal fat for insulation against the 70-degree water. But their own body fat also helps to keep them warm, like an extra layer of clothing beneath the skin. When scientists studied aspects of the event in 2006, they found that swimmers with a greater body mass index (BMI) appear to be at much lower risk of getting hypothermia.

The same effect has been demonstrated in hospitals where patients who’ve suffered cardiac arrest are treated with “therapeutic hypothermia” to stave off brain injury and inflammation. Studies have shown that it takes longer to induce hypothermia in obese patients than in their leaner counterparts. The extra fat seems to insulate the body’s core.

Under certain conditions, though, overweight people might feel colder than people of average weight. That’s because the brain combines two signals—the temperature inside the body and the temperature on the surface of the skin—to determine when it’s time to constrict blood vessels (which limits heat loss through the skin) and trigger shivering (which generates heat). And since subcutaneous fat traps heat, an obese person’s core will tend to remain warm while his or her skin cools down. According to Catherine O’Brien, a research physiologist with the U.S. Army Research Institute of Environmental Medicine, it’s possible that the lower skin temperature would give fatter people the sense of being colder overall.

But O’Brien points out that many other factors beyond subcutaneous fat help determine the rate at which we chill. Smaller people, who have more surface area compared to the total volume of their bodies, lose heat more quickly. (It’s often said that women feel colder than men; average body size may play a part.) A more muscular physique may also offer some protection against hypothermia, partly because muscle tissue generates lots of heat. “We have a joke around here that the person who’s best-suited for cold is fit and fat,” says O’Brien.

This article originally appeared in the January 2014 issue of Popular Science.

The post FYI: Do Fat People Stay Warmer Than Thin People? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

For all of 2016, Andrew Taylor ate only potatoes. There were a few caveats to his potato diet: He ate both white potatoes and sweet ones, and sometimes mixed in soymilk, tomato sauce, salt and herbs. He also took B12 supplements. But, overall, he ate potatoes for breakfast, lunch, and dinner. He took four blood tests over the year which he claims all came back normal. He even lost weight and felt more energized.

“If you have to choose one food, if you’re one of the people that’s getting sent to Mars, choose potatoes,” says Taylor. “I’m not trying to be evangelical about potatoes, but it was a really good experience for me.”

First and foremost, it’s not a good idea to only eat one kind of food. To survive, we need 20 amino acids—of which nine are essential, meaning we can’t make them ourselves and must get them from food—as well as a plethora of minerals and vitamins. (And, obviously, we need water in addition to food to keep our cells hydrated so they don’t wither and stop functioning.) Throughout history we’ve often combined foods, like rice and beans, yogurt and nuts, and even macaroni and cheese to a certain extent, in an attempt, or by accident, to intake the proper balance of nutrients that you usually can’t attain from eating a single food item. But in times of famine, fasting, or strange double-dog-dares, there are a couple of foods a human could survive on…at least for awhile.

The potato diet

The potato is one good example. Andrew Taylor isn’t the only person in history who has relied almost exclusively on potatoes for sustenance. In the beginning of the 1800s, about a third of the Irish population got most of their calories from spuds. The average American ate about 113 pounds of these starchy tubers in 2015. “For the money and your blood pressure, you can’t beat a traditional baked spud,” says Joan Salge Blake, a clinical nutrition professor at Boston University.

Technically, the traditional white potato contains all the essential amino acids you need to build proteins, repair cells, and fight diseases. And eating just five of them a day would get you there. However, if you sustained on white potatoes alone, you would eventually run into vitamin and mineral deficiencies. That’s where sweet potatoes come in. Including these orangey ones in the mix—technically, they belong to a different taxonomic family than white potatoes—increases the likelihood that the potato consumer will get their recommended daily dose of Vitamin A, the organic compound in carrots that your mom told you could make you see in the dark, and Vitamin E. No one on a diet of sweet potatoes and white potatoes would get scurvy, a famously horrible disease that happens due to a lack of Vitamin C and causes the victim’s teeth to fall out.

Even with this combo, you’ll still need to eat a lot of spuds before you intake the right levels of everything. Consuming five potatoes would give you all the essential amino acids you need to build proteins, repair cells, and fight diseases. But unless you ate 34 sweet potatoes a day, or 84 white potatoes, you would eventually run into a calcium deficiency. You would also need 25 white potatoes a day to get the recommended amount of protein. Soybeans have more protein and calcium—but they don’t have any Vitamin E or beta-carotene.

Of course, there are a lot of health disadvantages to potatoes, especially when you eat them en masse. White potatoes are high in a kind of carbohydrate that causes your blood sugar to spike and then dip, which puts a strain on the insulin system. People who ate a lot of these tubers were more likely to get diabetes and become obese, according to multiple studies.

Andrew Taylor actually lost weight—probably from eating less overall and giving up sugar—which wasn’t his ultimate goal. He quit eating most food to train himself to get comfort and joy from other areas of his life. But now even though his spud experiment is over, he still gets pretty excited about potatoes. “It was just an experiment and turned out to be exactly like I wanted,” he says.

Foods you can survive on

No nutritionist would get on board with an all-potato diet. Nor would they recommend an all coconut, kale, seaweed, or yogurt one either. There’s a reason that the U.S. dietary guidelines recommends eating a variety of vegetables, grains, proteins, fruits, and oils. Eat any of these just by themselves and you would soon run into the same nutritional deficiencies that you would with a potato. Variety is important, and in this case, it’s vital. So don’t just eat a baked potato, load it with other healthy stuff, too.

**This article originally stated that we need 20 essential amino acids to survive, when, in fact, we need 20 amino acids in total, of which nine are essential. The article has been updated to reflect that. We regret the error.

The post Is there a single food that you can survive on forever? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Everyone pees in the pool. That’s the safe and well-informed assumption that many chemists studying the safety of public, chlorinated swimming pools make. But let’s face it: once you jump in the pool and smell and feel the chlorine surrounding you, you quickly forget about any potential pool-peers and trust the power of the chemicals in the water. That’s probably not the best idea, though. The chemical byproducts that result from your urine and the chlorine aren’t as benign as you may think. And in the end, everyone would be doing a great public service if they would just stop peeing.

“If this was just one person peeing in the pool, then clearly that would not be a problem,” says Ernest Blatchley, an environmental engineer at Purdue University. “But we have evidence to suggest that there are circumstances where the concentration of these compounds could, in some cases, or in fact have, reached the concentrations that are detrimental to human health.”

First, let’s start with a little chemistry. Urine is made up of tons of different substances, all of which can interact with chlorine. But uric acid and a handful of amino acids pose the biggest threat. When each of these react with chlorine, they create are trichloraminen (sometimes called nitrogen trichloride) and cyanogen chloride. Both of these can be harmful in high enough concentrations.

The problem, says Blatchley, is that it’s incredibly difficult to determine just how concentrated these chemicals are in pool water at any given time. It depends on a whole bunch of other factors: How many people are using the pool, how well mixed it is, how warm the water is, and how long it’s been since someone changed the water.

The amount of trichloramine can be measured, but the tools used to do so aren’t generally available at pools. And cyanogen chloride is even harder to measure. “[It’s] a very dynamic chemical. It forms very rapidly but it also decays very rapidly, and it’s quite volatile,” says Blatchley. What that means, he says, is that once it forms in a pool, it doesn’t stick around very long. Of the two substances, Blatchley says cyanogen chloride is the most concerning. It’s a toxic substance, and once it reaches a high enough level, it can be detrimental to human health. But the problem is that because it forms and decays so quickly, it’s very hard to figure out how high those levels in a pool can get.

Trichloramine can caused respiratory problems when inhaled, especially in folks who already suffer from problems like asthma. It also causes irritation—it’s what creates that sometimes-overwhelming pool smell, and makes your eyes burn. Cyanogen chloride is an irritant too, and can actually affect the body’s ability to use oxygen. You’re not going to get a fatal whiff of the stuff in a pool—no matter how full of pee it is—but breathing it in definitely isn’t good for you.

Blatchley says that for the majority of swimming pools, and the majority of the time, the levels of cyanogen chloride won’t reach toxic levels. However, he says, that there are certain conditions in which that chemical could accumulate to unacceptably high concentrations—when you have a really crowded pool, for example.

“I think pretty much any pool that you put people in, you can count on people peeing in [it],” Blatchley says. Based on data that he and his team have conducted, as well a multitude of other studies done, he estimates that the average swimmer leaves behind somewhere between 50 and 80 milliliters of urine—”essentially a shot glass full of urine per swimmer.”

Young couple in swimming pool on sunny day. Water slide.

If everyone is peeing, why don’t we just chlorinate our pools more? Blatchley says that’s not the solution. The more chlorine you add, the more likely the chemical reactions that create those volatile compounds are to occur. Instead, he says, we should actually be working to disband this culture that it’s okay to pee in the pool.

Blatchley thinks that if people just understood the chemistry, they would think twice before urinating in a pool they’re sharing with others. He says he often relates it to secondhand smoking. It wasn’t that long ago that it was culturally acceptable to smoke in public in this country. That changed largely as a result of public pressure that grew out of a scientific understanding of the negative effects of secondhand smoke. “I think we as a culture have evolved to make it unacceptable. If people understood [the same] for pool chemistry, no one would subject their neighbors to cyanogen chloride.”

Even Michael Phelps—a swimming icon and symbol for both competitive and recreational swimming—has admitted to peeing the pool, commenting that chlorine kills it, so it’s not bad. But in reality, science says the opposite.

What Blatchley suggests is that people stop treating swimming pools like a cleaning machine—take a shower before getting in the pool, and step out to the restroom if you need to urinate. If we can stop this culture of routinely peeing in the pool, we can cut down on our chlorine usage— that would reduce the burden of organic compounds that react with chlorine, which would, in turn, result in less chlorine usage as well as improved water and air quality. In the future, Blatchley says “I’d like to see us take a proactive approach, rather than reactive.”

Have a science question you want answered? Email us at ask@popsci.com, tweet at us with #AskPopSci, or tell us on Facebook. And we’ll look into it.

The post Peeing in the pool is actually really bad for you appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

Human height can vary quite a bit, with the tallest folks reaching peaks of six, seven, and even eight feet tall, and the shortest people standing at two, three, and four feet in height. But most people will fall into an average range of between five and six feet. Why did we land at that particular height—and why aren’t we taller?

Natural selection and millions of years of time helped humans land at the heights we are at today. It’s clear that early humans with certain anatomies were more likely to survive and thrive, thus pushing the Homo sapiens population to the shape it is today.

Paleontologists know that body size and height shifted upward about 2 million years ago when early Homo species evolved from their ancestors, Australopithecus. In fact, as one 2012 study published in the journal Current Anthropology points out, “body size is one of the major features that distinguish australopiths from early Homo and early Homo from Homo erectus”.

But how we reached our modern heights and why our species isn’t still growing is still fairly a mystery. We explain all this and more on this week’s episode of Ask Us Anything. Tune in here, and read the article that inspired this episode here.

The post Ask Us Anything: Why do humans stop growing? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

A glowing sunset. A field of wildflowers. A rainbow peeking out of the clouds. The world is teeming with colors we see everyday. But humans don’t see every color on the light spectrum. There is a whole world of color that we can’t recognize. 

Why can’t we spot these hues? We see colors thanks to our eyes and brains. Our eyes contain two types of cells called cone cells and rod cells. Rod cells enable us to see in grayscale, which comes in handy at night when hues are more subdued. Cone cells, on the other hand, enable us to see in color. Our two eyeballs contain a total of about six or seven million cone cells. Actually processing and seeing color also requires the use of our brains. When a certain wavelength of light passes through the cornea it hits one of those cone cells. The cells then send a signal through neurons up to the optic nerve which relays a message to the brain and processes that data.

These cone cells only pick up on a select range of colors. It’s likely we can only see this selection and nothing more because honestly, we’ve been able to survive and thrive just fine with just these hues. But it is true that detecting light with shorter wavelengths than we currently can now, for example, would allow us to see more purplish hues. On the other hand, seeing longer wavelengths, like in the infrared spectrum, would enable us to have the ultimate night vision. 

Hear more about the colors we can and can’t see and why on this week’s episode of Ask Us Anything.  

The post Ask Us Anything: Why can’t we see more colors? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

Warmer weather is upon us here in the Northern Hemisphere. While it’s a welcome reward for surviving the winter to peel a few layers of clothing off, springtime is also when those unwelcome spring allergies start to blossom. If you do suffer from recurrent seasonal allergies, you aren’t alone. According to the American College of Allergy, Asthma, and Immunology, more than 50 million Americans experience various types of allergies each year. In fact, according to that same report, allergies are the 6th leading cause of chronic illness in the U.S. But that begs the question, what exactly is an allergy?

An allergy is a condition in which the immune system generates an abnormal reaction to an otherwise harmless substance. That substance is called an allergen, and it can take countless forms—dust mites, mold, grass, pollen, and different types of food can all illicit reactions in some people while having zero effect on others.

When you have an allergy to something, your immune system sees this substance as potentially harmful, and it reacts in a similar way to how it would respond to a dangerous virus or bacterium—however this time there’s nothing dangerous out there. Find out why the immune system performs this unnecessary act of rebellion in this week’s episode of Ask Us Anything. 

The post Ask Us Anything: What are allergies? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

At some point, almost every human has experienced daydreaming. It often happens in the late afternoon slump when thoughts of relaxing on the beach or curling up on your living room couch with a good movie are far more pleasing than looking at spreadsheets or meeting your deadlines. And while daydreaming almost certainly gets a bad rap for snatching up our productivity, the act itself might actually be good for our brains. 

So what is actually going on in our brains when we mentally doze off? While neuroscientists haven’t fully pinned down all the mechanisms through which our brains work when we daydream, what we do know is that we likely form these alternate-reality thoughts with the assistance of a cluster of brain regions called the default mode network. Researchers have found that this network is most active when we aren’t focused on any concrete thing in the world around us. 

While nothing is for certain, neuroscientists and psychologists surmise that this type of creative thinking may be helping our brains reflect on the past and plan for the future. Other researchers suggest that it might reduce anxiety, boost creativity, and improve memory. And while perpetually working and improving oneself is popular these days, there’s research to suggest that daydreaming and doing nothing is also really important for our brains.

For more of the nitty gritty details on daydreaming, listen to this week’s episode of Ask Us Anything. 

The post Ask Us Anything: What happens in your brain when you daydream? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

Viruses have been the talk of the town this past year, and for good reason. A fairly deadly one—SARS-CoV-2, which causes COVID-19—has found its way to every corner of the globe. This pandemic has shown just how dangerous viruses can be, and it’s definitely not the first to do so. But the world isn’t necessarily black and white, and viruses are no different. So in this episode of Ask Us Anything, I’m excited to give a spotlight to the do-gooders of the virus world. 

Yes, good viruses do exist. In fact, all sorts of microorganisms, from viruses to bacteria and fungi, exist in and on our bodies without harming us. Researchers have dubbed our resident viruses the “virome.” But viruses are a bit different from the bacteria and fungi that call our bodies home. Namely, they can’t replicate without a living host. They enter cells and hijack their controls to make copies of themselves. Pretty gnarly and sneaky, but even so, they can still confer benefits to the living beings they depend on—human or otherwise. 

For example, the development of the placenta was helped in part by a group of special viruses called ancient retroviruses. To hear about the numerous other ways that viruses have helped shape who we are today and what researchers are still discovering about how they help us thrive, listen to this week’s episode. 

The post Ask Us Anything: Can viruses be good for us? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

ON JULY 21, 1969, when the Apollo 11 crew was due to depart the lunar surface after a 22-hour visit, two speeches were placed on President Richard Nixon’s desk. “Fate has ordained that the men who went to the moon to explore in peace will stay on the moon to rest in peace,” read the contingency speech. Would Buzz Aldrin and Neil Armstrong live out the rest of their days staring at the blue glow of Earth from 250,000 miles away?

We’ve lost only 18 people in space—including 14 NASA astronauts—since humankind first took to strapping ourselves to rockets. That’s relatively low, considering our history of blasting folks into space without quite knowing what would happen. When there have been fatalities, the entire crew has died, leaving no one left to rescue. But as we move closer to a human mission to Mars, there’s a higher likelihood that individuals will die—whether that’s on the way, while living in harsh environments, or some other reason. And any problems that arise on Mars—technical issues or lack of food, for example—could leave an entire crew or colony stranded and fending for themselves.

No settlement plans are being discussed at NASA (leave those to pie-in-the-sky private groups like Mars One for now), but a crewed mission has been on the docket for some time, and could touch down as early as the 2040s. NASA’s “Journey to Mars” quotes an estimated three-year round-trip, leaving plenty of time for any number of things to go wrong.

“The real interesting question is, what happens on a mission to Mars or on the lunar space station if there were [a death],” says Emory University bioethicist Paul Wolpe. “What happens when it may be months or years before a body can get back to Earth—or where it’s impractical to bring the body back at all?”

Today’s astronauts travel to space by way of the Russian Soyuz, then spend a few months on the International Space Station. Because astronauts are in impeccable health at the time of launch, a death in the ISS crew would likely result from an accident during a spacewalk.

“In the worst case scenario, something happens during a spacewalk,” says Chris Hadfield, Canadian astronaut and former commander of the ISS. “You could suddenly be struck by a micro-meteorite, and there’s nothing you can do about that. It could puncture a hole in your suit, and within a few seconds you’re incapacitated.”

This hypothetical astronaut would only have about 15 seconds before they lost consciousness. Before they froze, they would most likely die from asphyxiation or decompression. 10 seconds of exposure to the vacuum of space would force the water in their skin and blood to vaporize, while their body expanded outward like a balloon being filled with air. Their lungs would collapse, and after 30 seconds they would be paralyzed—if they weren’t already dead by this point.

The likelihood of death on the ISS is low, and it’s never happened before. But what would surviving astronauts do if it did?

Prepare for the Worst

ISS and shuttle astronaut Terry Virts served two expeditions on the space station and one mission on the space shuttle. In total he’s clocked 213 days in space. But the astronaut says he’s never been trained to handle a dead body in space. “I did quite a bit of medical training to save people, but not for this.”

NASA’s official statement to Popular Science on the subject left a lot to be desired:

“NASA does not prepare contingency plans for all remote risks. NASA’s response to any unplanned on-orbit situation will be determined in a real time collaborative process between the Flight Operations Directorate, Human Health and Performance Directorate, NASA leadership, and our International Partners.”

“In my 16 years as an astronaut I don’t remember talking with another astronaut about the possibility of dying,” Virts says. “We all understand it’s a possibility, but the elephant in the room was just not discussed.”

But NASA’s out-of-sight-out-of-mind policy on death may not be the norm. Commander Hadfield tells Popular Science that all international partners who train for missions to the ISS (including JAXA and ESA) do in fact prepare for the death of a crewmember.

“We have these things called ‘contingency simulations’ where we discuss what to do with the body,” he says.

Hadfield discusses these ‘death simulations’ in his book An Astronauts Guide to Life. He sets the scene—”Mission control: ‘we’ve just received word from the Station: Chris is dead.’ Immediately, people start working the problem. Okay, what are we going to do with his corpse? There are no body bags on Station, so should we shove it in a spacesuit and stick it in a locker? But what about the smell? Should we send it back to Earth on a resupply ship and let it burn up with the rest of the garbage on re-entry? Jettison it during a spacewalk and let it float away into space?”

As Hadfield points out, a corpse in space presents some major logistical problems. The fact that a dead body is a biohazard is definitely the biggest concern, and finding the space to store it in is a close second.

Since NASA lacks a protocol for sudden death on the ISS, the station’s commander would probably decide on how to handle the body. “If someone died while on an EVA I would bring them inside the airlock first,” Hadfield says. “I would probably keep them inside their pressurized suit; bodies actually decompose faster in a spacesuit, and we don’t want the smell of rotting meat or off gassing, it’s not sanitary. So we would keep them in their suit and store it somewhere cold on the station.”

If submarines lose a crew member and can’t make it to land right away, they store bodies near the torpedoes—where it’s cold, and separate from the living quarters. The crew of the ISS already stores trash in the coldest spot on the station; it keeps the bacteria away from them and makes smell less of an issue. “I would probably store them in there until a ship was going home, where they would take the third seat on the Soyuz,” Hadfield says. They could also store a body in one of the airlocks.

Freeze-Dried Funerals

NASA may not have specific contingency plans for a sudden death, but the agency is working on it; in 2005 they commissioned a study from Swedish eco-burial company Promessa. The study resulted in a yet-to-be-tested design called “The Body Back.” The creepy-sounding system uses a technique called promession, which essentially freeze-dries a body. Instead of producing the ash of a traditional cremation, it would turn a frozen corpse into a million little pieces of icy flesh.

During the study, Promessa creators Susanne Wiigh-Masak and Peter Masak collaborated with design students to think about what this process might look like while en route to Mars. On Earth, the promession process would use liquid nitrogen to freeze the body, but in space a robotic arm would suspend the body outside of the spaceship enclosed in a bag. The body would stay outside in the freezing void for an hour until it became brittle, then the arm would vibrate, fracturing the body into ash-like remains. This process could theoretically turn a 200-pound astronaut into a suitcase-sized 50-pound lump, which you could store on a spacecraft for years.

If freeze-dried cremation isn’t an option, you can always “jettison” the body out on a forever path into the void. While the UN has regulations about littering in space, the rules may not apply to human corpses. “Currently, there are no specific guidelines in planetary protection policy, at either NASA or the international level, that would address ‘burial’ of a deceased astronaut by release into space,” says Catherine Conley at NASA’s Office of Planetary Protection.

But the laws of physics might trump the laws of humankind on this one. Unless we strapped a mini rocket to the deceased, they would end up following the trajectory of the spacecraft from which they were ejected. As the years went on and the bodies accumulated, that would make for a morbid trip to and from Mars.

Martian Burial Rituals

But the risks of dying along the way are nothing compared to the inevitability of dying once you get there. In promoting his own future space settlement plans, SpaceX’s Elon Musk has openly cautioned that, “If you want to go to Mars, prepare to die.” Which begs the question: if someone dies on the Red Planet, where do you put them?

If someone were to perish on the spaceship en route to Mars (or beyond), cold storage or a round of promession could be a fine solution. But there isn’t a morgue on the surface of Mars, and spaceships are usually low on extra space.

So what would Martian explorers do with a body? “I would expect that if a crew member died while on Mars, we would bury them there rather than bring the body all the way home,” Hadfield says.

That makes sense because of the long journey back, but it poses some potential contamination problems. Even the rovers exploring Mars are required by law not to bring Earth microbes to their dusty new planet. Spacecraft are repeatedly cleaned and sanitized before launch to help protect potentially habitable locales from being overtaken by intrepid Earthly microbes. But the bugs on a rover are nothing compared to the bacteria that would hitch a ride on a dead body.

This makes the issue of planetary protection even more nuanced, but a Martian graveyard might not be so far-fetched. “Regarding the disposal of organic material (including bodies) on Mars,” NASA’s Conley says, “we impose no restrictions so long as all Earth microbes have been killed—so cremation would be necessary. Though planetary protection does require documentation of disposal, to ensure that future missions are not surprised.”

But not everyone who dies in space will be treated like inconvenient cargo. Some of those corpses will actually save lives.

Worst Case Scenario

Space may be the final frontier, but it wasn’t always that way. Humans have spent millennia traversing difficult landscapes and putting themselves in bizarre and dangerous situations in the name of discovery. Thousands of lives have been lost in this pursuit, and on occasion the deceased have actually saved the lives of their comrades. Not through acts of deadly heroism, mind you, but through acts of cannibalism.

Don’t think for a second that this couldn’t happen in space. In the book The Martian, author Andy Weir wrote in a scene (spoiler) in which the Ares crew decides to go back to Mars to save a stranded Mark Watney. Johansen, the Ares systems operator and smallest crew-member (requiring the least amount of calories) on the mission tells her father that the crew has a last-ditch plan to make it to Mars if NASA won’t send them supplies for the trip. “Everyone would die but me, they would all take pills and die. They’ll do it right away so they don’t have to use up any food,” she explains. “So how would you survive?” her father asks. “The supplies wouldn’t be the only source of food,” she says.

While extreme, the crew’s plan to commit suicide so one member could save Watney is not totally unheard of. “That’s a time-honored tradition,” says bioethicist Paul Wolpe. “People have committed suicide to save others, and in fact religiously that’s totally acceptable. We can’t draw straws to see who we’re going to kill to eat, but there are many times when we’ve considered people heroes who jump on the grenade to save their buddies.”

Wolpe says the school of thought on cannibalism for survival is split. “There are two kinds of approaches to it. One says even though we owe the body an enormous amount of respect, life is primary, and if the only way one could possibly survive would be to eat a body, it’s acceptable but not desirable.”

Mars boasts a landscape so barren and dead, it would put the frozen mountains that drove the famous Donner party to cannibalism to shame. If anything interrupted the mission’s food supply, they’d quickly run out of alternatives.

But no space agency has an official policy on Martian cannibalism—yet.

A Journey Into the Void

Humans have only been traveling to space for a short time relative to our existence, but we’ve been pushing the boundaries of exploration for thousands of years—and we will no doubt continue to do so despite the risks. Every astronaut or space tourist wishing to embark on a journey to Mars will ultimately be forced to grapple with the reality of deaths both sudden and slow.

NASA may never have officially published a contingency plan for the Apollo moonwalkers, but they were prepared to lose the crew. In his biography, Nixon speechwriter William Safire recalled the tenuous Apollo 11 liftoff. “We knew disaster would not come in the form of a sudden explosion,” he wrote. “It would mean the men would be stranded on the moon in communication with Mission Control as they slowly starved to death, or deliberately ‘closed down communication,’—the euphemism for suicide.”

In fact, NASA had planned to shut down communication with the stranded astronauts and issue them a formal “burial at sea.” But even given that morbid hypothetical turn of events, everyone knew they would keep going to the moon. “Others will follow, and surely find their way home,” Nixon’s back-up speech read. “Man’s search will not be denied. But these men were the first, and they will remain the foremost in our hearts.”

As we enter an age of space exploration sure to be filled with rocket launches and crewed missions, the thought of death looms over every crew-member and decision maker.

Astronaut Terry Virts may never have casually chatted about dying over coffee with his friends, but he knew what was at stake when he launched into space. “I believe that it is worth it, and that any great endeavor will involve risk,” he says. “We consciously accept the unavoidable hazards that we face.”

Like most explorers, shuttle astronaut Mike Massimino is quick to say that the risk is worthwhile. “It’s about increasing our understanding,” he tells PopSci. “I think it’s worth the risk we take. Exploration has always taken lives and I’m sure it always will.”

The realistic options for a deceased crewmember—cannibalism, cold storage in the trash room, being freeze-dried and shaken into a million frozen flakes—lack the dignity we associate with the majestic endeavor of spaceflight. But Wolpe doesn’t think humankind will have a hard time adjusting to the harsh realities of posthumous treatment in space. We already accept that Earthbound explorers may suffer indignities if they die in the field. Wolpe sees Mount Everest as a perfect Earthly analogue for the future Mars missions: when people die, their bodies just stay there. Forever.

Every year around 800 people attempt to reach the summit of the mountain. Every year, some of those people die. And then another 800 people try the next year. These people want to be first, to be the best, to explore something marvelous and rare. And with this determination comes the risk of paying the ultimate price.

“If you climb Everest, you know that if you die you’re being left there,” says Wolpe. There’s no fancy method of cremation on Everest, no respectfully somber place to stow a body, no way to reasonably pick up a corpse for burial back home. Over 200 bodies lay across the mountain, some of them still visible on days when snow cover is light. Everyone who climbs past them is reminded that they’re risking their lives—and their chance at a proper burial—for a chance at reaching the summit. “You just accept that,” Wolpe says. “That’s part of climbing Everest.”

The post Ask Us Anything: What happens to your body when you die in space? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

At first glance, a volcano’s hot lava seems ideal for incinerating our trash. But, like so many things in science, it’s so much more complicated than that. And the short answer is, the effort might not be worth the reward. 

If you did try to turn a volcano into a dump, you would likely run into a number of obstacles. First, humans produce a lot of trash. Americans alone generate, on average, about 4.9 pounds of junk per person per day. That’s 292.4 million tons of waste in total for the US annually, according to the Environmental Protection Agency’s most recent report in 2018. 

In addition to the giant load of trash we create, volcanoes ideal for rubbish dumping aren’t exactly easy to come by. The ideal trash incinerator would be one that erupts slowly and ever so gently spews hot lava onto the surrounding area. Those are called shield volcanoes, and they are common in Hawaii. An ideal example is Kilauea, which is located on the Big Island and is one of five volcanoes that together form the Big Island. Unfortunately, the majority of volcanoes on Earth are stratovolcanoes.

The last obstacle is a big one: Getting too close to hot lava is downright dangerous.  

For more details on this exhilarating albeit dangerous hypothetical journey from dumpster to volcano and back listen to this week’s episode of Ask Us Anything. 

The post Ask Us Anything: Why can’t we burn our trash in volcanoes? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

From a nutty, aged cheese to the floral finish of dark chocolate, delicious tastes perpetually bombard our tongues. Here’s how a tongue takes these flavors from the plate to the mind.

The tongue, which anchors the body’s system of taste, is a piece of muscular flesh covered in a mucous membrane. To the human eye, our tongues appear dotted with tiny bumps called papillae. Often mistaken for taste buds themselves, these bulb-like dots actually contain groups of taste buds.

Three types of taste-sensing papillae dot the tongue. Fungiform papillae, concentrated mostly at the tip and sides of the muscle, usually contain one taste bud on their mushroom-shaped tips. Foliate papillae, arranged into reddish folds on the sides of the tongue, contain many taste buds organized around these crevices. Larger, dome-shaped vallate papillae sit toward the back of the tongue and, like foliate papillae, can house as many as 250 taste buds each.

A fourth type—filiform papillae—is the smallest and most numerous on the tongue. This type contains fine hairs that connect to nerves associated with touch, allowing you to feel the texture of what you’re eating, but they don’t contain any taste buds.

While these different types of papillae vary in structure, they typically organize taste buds around crevices, which collect broken-down food chemicals released when you chew. These crevices also house glands that secrete saliva.

Taste buds are complex little growths, too. Each one contains a collection of between 50 and 150 taste receptors and supporting cells, all nested together like cloves in a bulb of garlic. While each person’s taste bud count varies, humans tend to have between 2,000 and 5,000.

Each taste receptor is specialized to detect one of five flavor types: sweet, sour, bitter, salty, or umami. Contrary to what you may have learned in school, different areas of the tongue don’t detect different flavors—instead, each taste bud has all five taste receptors built in. Each receptor has small hair-like proteins called microvilli, which bind to specific chemical compounds corresponding to the flavor type it specializes in—and scientists are still figuring out how chemicals fit into the receptors. Deeper into the tongue’s flesh, these cells attach to nerves specifically involved in taste, which connect them to the rest of the nervous system.

The post How your tongue tells your brain what you’re tasting appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Almost nothing looks more orderly than chess pieces before a match starts. The first move, however, begins a spiral into chaos. After both players move, 400 possible board setups exist. After the second pair of turns, there are 197,742 possible games, and after three moves, 121 million. At every turn, players chart a progressively more distinctive path, and each game evolves into one that has probably never been played before.

According to Jonathan Schaeffer, a computer scientist at the University of Alberta who demonstrates A.I. using games, “The possible number of chess games is so huge that no one will invest the effort to calculate the exact number.” Some have estimated it at around 10100,000. Out of those, 10120 games are “typical”: about 40 moves long with an average of 30 choices per move.

There are only 10^15 total hairs on all the human heads in the world, 10^23 grains of sand on Earth, and about 10^81 atoms in the universe. The number of typical chess games is many times as great as all those numbers multiplied together—an impressive feat for 32 wooden pieces lined up on a board.

The post FYI: How Many Different Ways Can a Chess Game Unfold? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

When Edgar Allen Poe had to find a bird annoying enough to drive a man insane, the choice was easy: a raven. Corvids—the avian family that includes ravens and crows—are notorious for causing mischief to humans and animals alike. They steal food, knock over trash cans, harass dogs, tailgate raptors, raid nests for eggs, and engage in all kinds of behaviors that have people wondering, “Why are these birds such jerks?”

Kaeli Swift, a corvid researcher and lecturer at the University of Washington, knows all about birds’ devious reputation. Of the behaviors she’s asked about most, her explanation usually boils down to, “they’re smart.”

Corvids are famous for their intelligence. Ravens can use tools to get food (and even use other crafty birds as tools), and plan ahead like apes and small children. Crows have demonstrated the ability to recognize individual human faces and harass people who have harmed them. In the process, both birds might come of looking a little … dickish.

Swift talked us through some of the rude corvid behavior she hears about most often, and explains why it happens.

Mobbing

Mobbing is perhaps the most noticeable of the bullying corvid behaviors. A hawk or owl will be hanging out in a tree, not bothering anyone, when a group of crows will come along and harass it—dive-bombing and screeching—until it’s forced to fly away. Jerks!

Swift says we should cut corvids a break on mobbing, though, given that lots of birds do it. “It’s simply a prey species responding to a predator,” she says. “We just notice it more with crows because they’re big and loud.” Even tiny birds like chickadees, titmice, and wrens are known to hound potential threats on the wing. And while the behavior can be seen all year round, corvids tend to get more wary and protective during the spring-to-summer breeding season.

But what about when crows harass a bird that isn’t a predator, like a fish-eating osprey? In those instances, Swift says the birds may just be responding to a species that fits the general frame of a predator—a “better safe than sorry” approach, she calls it. Mobbing may also serve a social purpose: one corvid showing off to others that it can handle danger.

Pulling tails

Crows and ravens have a particular knack for stealing food away from other animals, often just by annoying them. Both groups are omnivorous, so they can adapt their wits to most any scenario involving dinner. For instance, a flock of ravens might swoop in when a pack of wolves is enjoying a fresh kill, even if the hunters aren’t into sharing. Instead of waiting around for the scraps, the birds have learned to sneak up behind feeding wolves and nip them on the tail. The mammal turns and gives chase, leaving the carcass open for other ravens to feast. This sort of parasitism can be a real problem for wolves: Swift says “the theft rate is so high that it actually determines pack size.” Jerks!

Crows and ravens also use their tail-pulling trick on a host of other animals, including domestic dogs. Pets that feed outside often serve as the best targets, like the poor sled dogs Swift first saw victimized in Alaska—but some corvids will pull the tails of dogs just minding their own business. In fact, Swift has observed so many other creatures, from cats to eagles to parakeets, getting goosed by a corvid, she’s started a #PullAllTheTails hashtag on Twitter to put the impish behavior on display in one place.

Raiding nests

About half of the diet of an urban crow comes from human trash, Swift says, both in landfills and from the revolting pile at the end of your driveway. Believe it or not, nearly 40 more percent comes from bugs. Eggs make up just a small part of a crow’s meals, but Swift says she hears from an inordinate amount of people concerned with protecting their backyard nests from hungry corvids.

It’s another unfair bit of a corvid’s rotten reputation. “Lots of animals eat eggs,” Swift says, ”everything from deer to bunnies. Because crows are obvious and large, we notice them at nests instead of smaller animals that eat eggs more often, like snakes or squirrels.”

Crows and ravens use their big brains in all sorts of ways to outsmart other creatures to survive. How much longer do they deserve to carry around a badge for being the jerks of the bird world? Quoth the Raven: “nevermore.”

The post Why are crows and ravens such jerks? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Most of us learned what we know about eye color from a chart in grade-school biology. You know, the one that shows that two brown-eyed parents will likely have brown-eyed kids, and two blue-eyed parents are pretty much destined to have blue-eyed kids. It might have come with little color codes, clear-cut percentages, and neat lines of inheritance. But the story of how eye color is passed down is more complicated—and unpredictable—than we’re taught.

Why eyes look different colors

Humans get their eye color from melanin, the protective pigment that also determines skin and hair shades. Melanin is good at absorbing light, which is especially important for the iris, the function of which is to control how much brightness can enter the eyes. Once it passes through the lenses, the majority of the visible light spectrum goes to the retina, where it’s converted to electrical impulses and translated into images by the brain. The little that isn’t absorbed by the iris is reflected back, producing what we see as eye color.

Now, that color depends on the kind and density of melanin a person is born with. There are two types of the pigment: eumelanin, which produces a rich chocolate brown, and pheomelanin, which renders as amber, green, and hazel. Blue eyes, meanwhile, get their hue from having a relatively small amount of eumelanin. When the pigment is low in stock, it scatters light around the front layer of the iris, causing it to re-emerge are shorter blue wavelengths. This makes blue an example of what is called “structural color,” as opposed to brown and to some extent, green and hazel, which would be defined as a “pigment colors.” It’s in part the same reason the sky is blue—an atmospheric light trick known as the Rayleigh effect.

Green eyes are interesting because they combine light scattering and two kinds of pigment: They hold slightly higher amounts of eumelanin than blue eyes, as well as some pheomelanin. Hazel eyes come from the same combination, but they have more melanin concentrated in the outer top layer of the iris. Red and violet eyes, which are much rarer, come from a minute to complete lack of pigment. In fact, red eyes have no melanin whatsoever, so all we’re seeing is the reflection of the blood vessels. When there’s some pigment, but too little to cause wavelengths to scatter, the red and blue interact to produce a rare violet.

An imperfect circle of genes

Though we used to think eye color came from a relatively simple pattern of inheritance, in recent years scientists have found that it’s determined by many genes acting in tandem. What’s more, tiny tweaks on a gene can result in different shades in the iris. “When you have mutations in a gene, they’re not just acting in a vacuum,” says Heather Norton, a molecular anthropologist who studies the evolution of pigmentation at the University of Cincinnati. “The proteins that they produce don’t just do what they do independently.”

The two genes currently thought to be most strongly associated with human eye color are OCA2 and HERC2, which are both located on chromosome 15. OCA2, the gene we used to think to be the sole player in eye color, controls the production of the P protein and the organelles that make and transport melanin. Different mutations in the OCA2 gene ramp up or tamp down the amount of protein that’s produced in the body, changing how much melanin is sent to the irises. (If you’re wondering why some kids are born with blue eyes but end up with green or hazel ones later in life, it’s because these organelles take a while to mature and start shuttling melanin around).

The HERC2 gene, meanwhile, acts like a helicopter parent for OCA2. Different mutations in this gene act as a switch that turns OCA2 on and off and determines how much P protein it encodes.

Those are just the two genes we know about in detail so far. Newer studies have linked as many as 16 genes to eye color, all of which pair with OCA2 and HERC2 to generate a spectrum of different iris colors and patterns. With all these variations in the interaction and expression of genes, it’s hard to say for sure what a child’s eye color will be based on their parents’. “While what you might have in your HERC2 genotype matters, it also matters what you have at [other parts of chromosome 15],” Norton says. “Even though you might have two copies of the allele that’s more commonly associated with blue eye color, if you have a mutation somewhere else in your genome that does something to modulate how that P protein is produced or distributed, that’s going to influence phenotype.” What she means is, if a kid does shockingly end up with brown eyes, there’s no need to flip out and reach for the paternity test. It’s just the rich tapestry of genes.

Norton notes that most of what we know about the complicated genetics of eye color, we know through genome-wide association studies (GWAS), which track visible traits in subjects with varying DNA profiles. But she also points out that there are huge gaps in the range of populations we’ve documented to figure out how eye color is genetically influenced. “Given that most of what we know about how these genetics have been done in studies of Europeans, when you think about some of these genetic interactions, there may be mutations that influence eye color, skin color, or hair color that are more common in other parts of the world,” Norton says. “We don’t know about them because we don’t look.”

There are several research groups around the world trying to flip this bias by conducting GWAS studies in Latin American and South African populations; some have even found novel gene segments affecting skin pigmentation in different communities. One day, the same may be revealed about eye color.

Why choose one …

Now you might be wondering, what causes people—and sometimes really cute huskies—to have a different color iris in each eye? The condition is called heterochromia for short, and there are several kinds: partial heterochromia, where part of the iris is a different color; central heterochromia, where the inner portion of the iris is a different color than the outer ring; and complete heterochromia, where one iris is a completely different color than the other.

The vast majority of cases of congenital heterochromia (when people are born with the condition) are completely benign, but in rare cases it can occur as a symptom of disorders like Horner or Waardenburg syndromes. If heterochromia develops later in life, it’s most often the result of eye injury, head trauma, melanoma, or sporadically, glaucoma treatments. But in the majority of people it happens by random mutation, leading to one eye getting more or less melanin than it should. Try and put that in a chart.

The post How do we get our eye color? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Every year, a handful of the wet weather events in the tropics swell into hurricanes. These monster storms crash into coastlines and can inflict billions of dollars of damage, earning their reputation as some of nature’s scariest disasters. They have the potential to kill thousands and wreak ongoing environmental and economic chaos. So why not try to hit them before they hit us?

Since the dawn of nuclear explosives, citizens and scientists alike have speculated that the government might be able to repurpose weapons of war as weapons of weather. Most recently, President Donald Trump asked why we couldn’t just nuke hurricanes out of the sky. Meteorologists are wincing at the reappearance of this all-too-familiar myth.

“It doesn’t make sense at all,” says Falko Judt, a meteorologist who specializes in hurricanes at the National Center for Atmospheric Research.

“It is a spectacularly bad idea,” says Gary Lackmann, a meteorologist and professor at North Carolina State University’s department of marine, earth and atmospheric sciences.

Okay, so the concept inspires the meteorological equivalent of a massive eye-roll. But why is the idea of nuking a hurricane such a dud—and what explains the myth’s longevity?

First, a refresher on hurricanes, AKA tropical cyclones. They’re among the most powerful storms on the planet, and with good reason: They harness the heat of Earth’s oceans and turn it into whirling tempests. Hurricanes are fueled by warm ocean water (at least 80°F throughout) and usually develop over tropical seas. They take place when a weather disturbance, like a thunderstorm, literally spirals out of control. The storm’s winds pull warm air toward it. As it interacts with warm sea water, the water evaporates and starts to rise. Clouds form above, and more air rushes into the low-pressure zone created below. Soon, the swirling mass gains momentum and begins to move, dragging water along with it and growing larger and larger until it hits land. It’s the weather equivalent of a steam engine that converts water into mechanical work.

The results can be terrifying. The low-pressure systems whip up winds and shove water toward the shore, where torrential rains and gales of wind crash into beaches, landscapes and people. Severe flooding, property damage, and loss of life follow.

We know hurricanes need warm ocean temperatures to get going. But how can you get them to slow down? That’s hard, Judt explains. To really stop a hurricane from forming, he says, you’d need to cool down the ocean, suck the humidity from the air, or blow strong winds against the grain of the storm. And the jury is still out on what really causes smaller storms to turn into hurricanes. Some smaller disturbances can peter out, but others get out of control quickly. The factors that tip the balance either way aren’t entirely clear. “We’re not really sure yet,” he says. “About 90 percent of precursor disturbances do not become hurricanes.”

Storm modeling has become more and more advanced over the years, and the dynamics occurring inside storms are being demystified by data-gathering daredevils who fly planes directly into their centers. But there’s still a way to go, says Judt, and many questions about storm dynamics and formation remain unanswered. Without knowing exactly what factors lead to runaway growth, it’s difficult to know exactly what methods might stunt a would-be hurricane’s development.

But Judt’s list of potential hurricane busters doesn’t include nukes, because nuclear weapons are puny compared to nature’s wrath. If you nuked a hurricane, he explains, the resulting shockwave would do nothing to disrupt the storm. “A nuclear weapon is very powerful, but it’s not nearly as powerful as the hurricane itself,” he says.

That’s an understatement. The massive energy inside a hurricane is the equivalent of a 10-megaton nuclear bomb exploding every 20 minutes, he says. During its brief lifespan, a single hurricane generates wind energy equivalent to half of the energy consumed by the entire population of Earth in one year. The energy it releases in the form of clouds and rain is the equivalent of 200 times world’s energy-generating capacity. It would simply take too many nuclear bombs to defang a storm, says Judt—and more than likely, the cyclone would just turn from a spiraling menace to a nuclear spiraling menace.

That hasn’t kept scientists from giving it serious consideration. During Project Plowshare, a program designed to test peaceful uses for nuclear explosives beginning in the 1950s, the U.S. detonated 35 warheads in the hope they could help with everything from mining to, yes, weather control.

Jack Reed, a scientist at Sandia National Laboratories, ran with the concept of halting a hurricane with a nuclear weapon in 1959. At the time, it was still unclear just how powerful a punch these storms could pack, and Reed was convinced that nuke-shooting submarines could reduce wind speed enough to kill the circulation that pushes storms ashore.

But though he called for a test of the concept, writes historian Vince Houghton, “Not a single person with any kind of authority was willing to even entertain the idea of nuking hurricanes. Later in life, Jack Reed bitterly chalked this up to his idea being ‘politically incorrect.'”

The incorrectness of the idea isn’t just a function of public mistrust of nuclear weapons. “Spreading around a bunch of radioactive contamination for no real reason doesn’t seem like a good idea to me,” says Edward Waller, a professor at the Ontario Tech Energy Systems and Nuclear Science Research Center who studies nuclear emergency preparedness and response.

Though it’s unclear just how much material a nuclear hurricane could spread, says Waller, it’s not something anyone should be prepared to risk. In the nuclear world, he explains, there’s a concept called “ALARA,” or “as low as reasonably achievable,” that calls for people to use as little radiation as possible in the name of protecting as many people as possible.

“There are justifications for using radiation all the time,” he says. “But if a task or if a process can be done without using radiation, you don’t [use radiation].” And if the laws of physics make it extremely unlikely that a nuclear warhead will circumvent a deadly storm, you don’t shoot one into the sky. Since the idea strikes storm experts as preposterous, there has been little ink spilled on how exactly a nuke-icane would play out as it hit land. But it’s easy to envision the potential outcomes. “Can you imagine radioactive rain from a nuclear hurricane?” asks Lackmann.

People who lived in Europe in 1986 don’t have to. That’s when the Chernobyl disaster belched a cloud of radioactive contamination that dispersed across virtually the entire continent. Areas that experienced rainfall during the disaster saw higher deposits of radioactive contamination, and people as far as Asia and North America were dosed with fallout, too. However, the health effects were mostly endured by those who were close to the reactor when it melted down.

Depending on where a hypothetical hurricane attack took place, some of the contamination might not hit land. But even if the rainfallout didn’t bring severe harm, says Waller, it could hurt people anyway. “It would be putting undue stress on the population,” he says. Large-scale evacuations could put lives at risk through accidents or leave vulnerable populations uncared for—and the sheer stress of worrying about the unknown effects of hurricane nukes could cause additional health problems.

People who live through hurricanes are already at risk for depression, anxiety, and PTSD, and those who are evacuated during natural disasters experience emotional and mental impacts, even when their homes don’t end up getting destroyed. After the hasty evacuation of people from the area near the Fukushima nuclear plant in 2011, for example, more than 1,000 people died, and displaced locals experienced a range of health problems due to the disruption.

Bottom line: The suggestion that scientists turn weather into war is past its expiration date. But thanks to the scary possibilities presented by the world’s ever-more-modern nuclear arsenal, it’s doubtful the cry to nuke clouds will die down any time soon.

The post Nuking hurricanes out of the sky ‘doesn’t make sense at all’ appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

We all know the families populated by towering basketball players versus the petite households with builds best suited for, say, horse jockeying or wrestling. There’s probably a fair amount of height variation within friend groups, too: The tallest friend takes the selfies, while the shortest struggles to fit in the frame. But despite these drastic variations, humans pretty much fall within a normal height range: In the United States, healthy men are, on average, 5 feet and 9 inches tall while women are typically 5 feet and 4 inches. Thanks to middle school science class, we know that we inherit height from our parents. Why, though, do most people stay within these standard limits? Why don’t we all grow to be 10 feet tall?

Why we will likely never reach extreme heights

We can thank evolution for this, says Terence D. Capellini, a human evolutionary biologist at Harvard University. “Height is not just about height,” Capellini says. “It’s about the overall biological growth of an organism, at least in humans.” Researchers surmise that how tall we become isn’t an isolated piece of our extremely intricate genome. Rather, it’s intertwined with other growth processes, like organ development. Over millions of years, natural selection has forged the blueprint for the human genome and therefore influenced body and organ growth through linked genes and subsequent tissue growth. Our height, then, is simply a byproduct.

Besides genetics, environmental factors like proper nutrition and modern healthcare can impact height. Still, genes take on the lion’s share of the work, accounting for 70 to 80 percent of the result. Height generally evens out around puberty and that’s when those evolutionary mechanisms step in. When we reach our predetermined heights, a biological mechanism called programmed senescence eventually turns off the genes responsible for growth. Most people grow taller until puberty ends, their bones continuously lengthening. This process occurs at the growth plates, two layers of cartilage located in children’s vertebrae and long bones, such as the femur and tibia.

We grow quickest as fetuses, says Jeffrey Baron, a pediatrician and head of Growth and Development research at the National Institutes of Health. The added centimeters generally decrease afterwards. In fact, fetuses grow about 20 times faster than five-year-olds. Infants’ growth plates are also highly active, causing them to grow rapidly. As a child gets older, growth plate activity slows down. Eventually, in mid- to late-adolescence, the growth plate activity ceases and teenagers reach their adult height.

Compare the growth process to a wind-up toy train, Baron says. Winding up the train’s spring causes the coil to tighten with potential energy. Upon release, the train zooms forward but gradually slows and putters out as the spring winds down. When we use up our genetically programmed growth potential, like the unwinding spring in the toy train, our growth slackens and eventually stops.

What scientists know—and don’t know—about height inheritance

Hundreds of genes likely influence height. In fact, a study out in 2018 found over 500 height-related genes. These genes manipulate the behavior of growth plates and control bone length.

“For most of us, it’s not just one gene that makes us short or tall,” Baron says. “It’s many, many different genes.”

Though rare, mutations in height-related genes can trigger unusually tall stature. “The Princess Bride” actor André the Giant had pituitary gigantism, a condition in which the pituitary gland produces too much growth hormone, which controls height. There are other conditions that affect height, too, such as skeletal dysplasias, which result in shortened and often malformed bones.

The conditions that result from excess growth hormones also carry serious health risks, according to a February 2019 Endocrine Society study. These include heart failure, bone disease, and an overall “impaired quality of life.”

By recording thousands of people’s heights in genome-wide association studies, which look for genetic variations that occur more frequently in groups of people who all share the same physical traits, researchers aim to better understand the links between height inheritance and disease susceptibility.

Clarifying the mysterious relationships between genomes could transform how we treat diseases. For example, genetic variants causing short stature may also make it more likely for someone to develop coronary artery disease (CAD), according to a 2015 NEJM study. And, if we are able to pin down certain genetic variations more precisely, then in the future, genome editing techniques like CRISPR, which can correct faulty genes, may facilitate new growth disorder therapies.

If you’re still hoping that humans someday reach greater heights, keep a close eye on the Nordic region. Last year, researchers concluded that populations in Denmark, Finland, Norway, and Sweden have grown progressively taller each generation.

The post Why don’t we grow to be 10 feet tall? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Most of us have become used to sitting for extended periods of time suspended in 60-ton metal machines. Aside from hearing the compulsory airplane safety warnings at takeoff, most people don’t think much about how flying impacts our bodies and minds. But some pretty weird stuff happens when we’re seven miles above sea level: Air pressure drops, our taste buds go partially numb, our skin dries out, and some of us cry. Actually, many of us do. Virgin Atlantic conducted a Facebook survey in 2011 that found 55 percent of respondents said their emotions were heightened on flights. In response, the airline introduced “weepy warnings” before particularly sad movies in-flight. But why do we weep once in the air?

While peer-reviewed studies on the science behind the “Mile Cry Club” are few and far between, scientists across fields from film to psychology to medicine have taken interest in the topic. And while they haven’t identified a definitive cause, researchers think it’s likely a combination of oxygen deprivation, dehydration, and stress.

As planes ascend to their cruising altitudes, air pressure drops–that’s why our ears pop–to levels equivalent to the outside air pressure you’d experience while hiking through the mountains in the Swiss Alps (6,000-8,000 feet above sea level). This resulting low cabin air pressure causes a reduction in the amount of oxygen carried in our blood, a condition called hypoxia. Hypoxia has a slew of potential symptoms, including fatigue, confusion, impaired decision-making, and notably, it wreaks with our ability to handle emotion.

On top of this, the air conditioning systems on airplanes dries the air until there’s 25 to 30 percent less humidity, causing dehydration (which explains why we get drunk more quickly inflight).

While mild hypoxia won’t impair a healthy person very much (a good thing, considering pilots operate under these conditions routinely), Jochen Hinkelbein, a Berlin-based medical researcher and president of the Society for Aerospace Medicine, says that hypoxia makes us more vulnerable to psychological and physical changes. He added that though he’s perfectly healthy, he often falls asleep during takeoff because of these dramatic pressure and humidity changes, which both can make you feel dizzy and tired.

These physiological changes may then lay the groundwork for our brains to start considering our uncomfortable surroundings. Though passengers may not be conscious of their emotional vulnerability, our brains are working overtime on airplanes due to claustrophobia, travel stress, and fatigue, according to clinical psychologist Jodi De Luca of Erie Colorado Counseling.

“We have little control over our environment while we are traveling by plane,” says De Luca, who studies the impact living in a high-altitude mountainous region has on mental health. All of these stressors trigger some people’s fight-or-flight response, she says.

This causes the body to produce more stress hormones called cortisol which influence our emotions by increasing our blood pressure and heart rate, making us less able to cope with them. Couple that with some oxygen deprivation, dehydration, and a corny movie, and it’s no wonder Virgin Atlantic reported that “41 percent of men surveyed said they hid under blankets to hide their tears.” It might also explain why toddlers, who are prone to temper tantrums anyway, are even more likely to fall into a deconstructive crying fit while on board a flight. Though, no studies have explicitly studied this connection.

Stephen Groening, a professor of Comparative Literature, Cinema, and Media at the University of Washington, has been studying this phenomenon in the context of in-flight entertainment for years. He says the content of films people report crying during doesn’t matter. Most recently, his friend told him that he wept watching Thor on a flight to Australia. He thinks another contributing factor is the environment travelers find themselves in. When we watch movies on the plane, we’re much closer to screens—and people—than we’re used to.

“It’s not so much about the content, it’s about being in a situation where you’re isolated, but at the same time you’re surrounded by strangers,” Groening says. “You have this physical closeness for an extended period of time that you don’t have in any other situation.”

While there’s no definitive mechanism scientists can point to just yet, most researchers surmise that it might just be a combination of all these factors that give us the weeps. This subconscious discomfort, combined with the physical changes Hinkelbein describes, likely explains why we cry on planes, explains Groening.

De Luca concurs: “Emotions govern our lives more than we know, and our environment influences our emotions more than we realize.”

The post Why you’re more likely to cry on an airplane appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

People forego eating meat for a variety of reasons. Some do it in an attempt to eat healthier meals while others make the shift because they think cows and pigs are simply cuter than they are delicious. Some might even switch over because they think it will help the planet. But what would happen if every single human decided to become a vegetarian? Would we be harming or helping our planet? It turns out, reducing our animal product intake (especially red meat) might not be such a terrible place to start.

How exactly does meat consumption affect the environment?

Red meat production, which includes all of the steps that go into supplying the animals that turn into hamburgers, takes a toll on the environment in the form of greenhouse gases and the land we use.

“Red meat production has major impacts on almost every aspect of [the] environment,” says Walter Willett, a Professor of Epidemiology and Nutrition at Harvard. “The greenhouse gas production is probably one of the most serious and acute because it’s apparent that our planet is warming faster than anybody anticipated even just a few years ago.”

Willett says this comes from two steps in the cattle production process. The first is that we lose a lot of energy in the process between growing the grains that we feed the cattle and using the animals for food. That’s because many farm animals, especially cattle, are inefficient converters, meaning that they consume more food than they are able to provide. The second problem is the amount of methane that cows create. On average, cows produce around 100 to 500 liters of methane per day in the form of flatulence. That methane is about 30 times more potent as a heat-trapping, or greenhouse gas.

“The biggest piece of grain use is about 45 percent, which is fed to animals, largely cattle,” says Willett. “We produce a huge amount of carbon dioxide and methane in that process. Then we eat the red meat, and the red meat itself is very damaging to human health in the amount that we consume it. That is both damaging planetary and human health at the same time.”

So, to sum up, cow farts plus the massive amount of grain production needed to feed them is pretty disastrous for both land use and greenhouse gas production.

“Certainly the way that we produce meat currently and in the quantities that we produce meat, it’s much more impactful on the environment from a variety of indicators including carbon footprint, land use, and water use,” says Martin Heller of the Center for Sustainable Systems at the University of Michigan.

What if we all became vegetarians?

If meat, especially red meat, is so bad, what if we just stopped eating it all together? Would that solve all of these problems?

Switching from an omnivorous to vegetarian diet could reduce a person’s carbon footprint by about 30 percent, says Martin Heller, an engineer at the Center for Sustainable Systems at the University of Michigan. However, he says, some meat might not be a terrible thing if you’re struggling with the idea of giving it up.

“The caveats to why a vegetarian diet may not be the lowest. There are opportunities [for] using ruminant animals to eat grass on land that isn’t suitable for cultivation of other crops,” he says. “There’s kinds of small niche types of productions systems that are rather atypical in our current agricultural production that could offer situations where significant high quality calories could be produced at a lower impact than growing a field of beans.”

In other words, if there’s grazing land that couldn’t sustainably grow anything, that land could be used for cattle. That way, cattle could be raised in a way that doesn’t destroy our environment. And if we only raised cattle on this type of land, that would end up reducing our worldwide consumption of red meat dramatically, says Willett.

There’s also the concern for human health. Just because a plant based diet is in fact plant based, that does not mean it’s necessarily healthy.

“You do need to be careful there, because not all plant foods are health foods,” Willett says. “Coca Cola and Dunkin Donuts are plant-based foods and are obviously bad for human health. But, a plant-based diet should really focus more on fruits, vegetables and whole grains, and for protein sources, legumes and seeds would be much better for human health than the average American diet.”

So, if I’m a vegetarian, am I at least environmentally off the hook?

Giving up meat, especially red meat, isn’t a bad start to making your dietary carbon footprint shrink a bit. However, even if you’ve done that, there’s other ways to make sure that you are making the most sustainable choices.

“For example, a vegetarian may be eating a diet with major environmental impacts because they are eating berries flown in from South America or tomatoes grown in greenhouses in January,” Willett says. “Those have very big environmental impacts and greenhouse gas production.”

You’ve probably heard about eating locally and in season, but sometimes this isn’t a perfect system either. Willett recommends looking not just at the distance your food has traveled, but also at the transportation involved, especially when it comes to fruits and veggies.

“There’s no single factor that captures all of this. Local has value, but not all local is the best sometimes,” Willett says. “Driving a truck in from 100 miles away is relatively local but may have much more adverse environmental impact than bringing some fruits [in from] several hundred miles away by train in large amounts.”

Additionally, it may be worth it to think about your region and the stress that certain types of foods have on the local environment, both in the cases of animal-produced food and plant-based food.

“There’s big differences in water use for producing dairy, milk, in California versus Wisconsin, right?” says Heller. “Not only because there’s water shortages in California so they don’t get enough rain so it requires more irrigation, but also because the region is under water stress. Using that irrigation water in those regions is much more impactful both for environmental systems as well as other users of the water.”

Eating right for the environment is certainly enough to make your head spin, but the moral of the story is reducing the amount of meat (especially red meat) and thinking twice about where your favorite foods come from and how they got there is a pretty good start.

The post If everyone became vegetarian, would the planet actually be better off? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Men do go through hormonal cycles. That much is established. Their testosterone levels tend to peak first thing in the morning, perhaps in concert with circadian rhythms, and then diminish over the course of the day—though exercise can cause fleeting spikes. What science has yet to show is whether hormones dip and rise over weeks or months, as women’s do.

Some researchers believe that male hormones vary with the seasons. A 2003 study found that the testosterone levels of men in one Norwegian town bottomed out in summer and reached a high in late fall. A study of Danish men found similar seasonal variations (on a slightly different schedule). If these rhythms are real, they might have to do with sun exposure, summer workouts, or winter weight-gain. But studies done in sunny San Diego and snowy Boston failed to replicate the Scandinavian findings. In a 2012 review, urologists at Baylor College of Medicine in Houston concluded that some “evidence exists to support the notion” of seasonal cycles but cautioned that more research was needed.

Endocrinologist Peter Celec of Comenius University in Slovakia, thinks that men have a straight-up monthly hormonal cycle too. In 2002 he published a study showing that both men and women experience roughly lunar rhythms of testosterone; the levels in men’s saliva peaked dramatically on day 18 of a 30-day cycle. Celec’s findings have not been replicated or accepted in the field, yet he remains convinced: “I have searched the literature for negative findings, but I have not found anything.”

Celec adds that if women didn’t bleed, the research establishment would likely be skeptical of their monthly cycles too.

This article was originally published in the October 2015 issue of Popular Science.

The post Do men have hormonal cycles? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Walk along a California beach on a warm summer day, and there are sure to be dozens of men and women, spread out on their towels, soaking in as much sun as they can. Sure enough, about six months later, in the cool months of January, February, and March, that same tan they worked so hard to obtain is… gone. What happened?

The short answer: it fell off.

The long answer? Let’s start with how we tan. Put simply, a tan is a protective mechanism for the skin according to Dr. Ali Hendi, a skin cancer specialist from Georgetown University.

There are a few cells in the basal (bottom) layer of the epidermis (or outer layer of skin) called melanocytes which produce a pigment called melanin. These cells are interspersed within the skin and make up about 1 percent of the skin. Dr. Hendi compares them to octopuses with little tentacles delivering packets of melanin to surrounding skin cells. “The job of the melanin is to protect the skin, specifically the nucleus,” Dr. Hendi says. “It sits right on top of the nucleus almost like a little cap.” The “cap” of melanin on top of the nucleus helps protect the skin from UV radiation by absorbing some of the excess rays, which can cause mutations in skin cell DNA that can lead to skin diseases.

Melanocytes can detect Ultra Violet (UV) radiation from the sun which triggers production of the pigment. There is even some new evidence that melanocytes have eye-like abilities to help begin melanin production. Scientists at Brown University found evidence of rhodopsin in melanocytes which is a photosensitive protein found in the eye’s retina used to detect light changes. Further testing led the study to conclude that these photosensitive receptors help start melanin production in the skin much faster than previously thought.

People with darker skin have more active melanocytes that produce more melanin than those with fair skin, Hendi says. Therefore, black skin and white skin will have an almost identical number of melanocytes, but the cells in black skin produce much more melanin.

The reason you lose your tan, however, has nothing to do with melanocytes. It disappears for one simple reason: humans shed.

You lose about one million skin cells in a 24-hour period. The outside layer of human skin replaces itself every 28 to 30 days. Cells on the surface continually flake off over time; new ones grow in the bottom layers of the skin. This cell death is known as apoptosis, according to Dr. Jeffrey Banabio, a dermatologist certified by the American Academy of Dermatology. The dead cells on the surface, made of mostly fat and protein, provide the most protection against the environment and the sun. “It is a normal process that is actually optimized to protect us. It is productive to have nonliving protein and fat there rather than having living cells on the surface.” The melanin in these dead cells absorbs some of the UV radiation hitting the skin.

During the winter, this cycle of regrowth and shedding continues, but the production of melanin drops off. “In the winter, the amount of UV radiation reduces significantly, so the melanocytes stop putting out so much pigment.” Over the course of weeks or months, the more heavily pigmented skin cells mature and fall off. The new cells produced in the basal layer of the epidermis are exposed to less radiation in the winter and thus have less pigment making them lighter in color. This gradual change in skin cells is responsible for lighter winter skin colors.

Some scientists estimate that you lose about one million skin cells in a 24-hour period. These skin cells make up most of the dust you see on your computers, windowsills, or tables. Therefore, whenever you decide to clean your house (let’s hope more often than not), you could be slowly but surely sweeping your tan right out the door.

This story was produced in partnership with Northwestern University’s Medill School of Journalism.

The post FYI: Why Do You Lose Your Tan In The Winter? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

In the science of staleness (yes, there is such a science), you have “crust staling” and “crumb staling.” Crust staling is the process by which the outside of a loaf of bread goes from crisp to soft. Crumb staling is when the inside turns hard.

It’s easy to explain the first: Crust absorbs moisture from inside the loaf. Potato chips, which absorb moisture from the air, are all crust, so they completely soften.

Crumb staling is more complicated. Over the years, food scientists have published hundreds of papers on the subject. Many have come to believe the process has to do with starch within the gluten structure. “Starch granules exude amylose during baking,” says Bill Atwell, professor of grain science at the University of Minne­sota. Spiderwebs of amylose then attach to the gluten network. As the crumb sheds moisture, these webs stiffen. Some bread manufacturers extend shelf life by adding enzymes that sever these amylose strands, or by way of additives that inhibit starch from interacting with gluten.

Staleness can also be a state of mind. In a 2004 study, Oxford University researchers asked people to eat Pringles while sitting in a soundproof booth wearing headphones that amplified their munching. When researchers cranked up the crunching, subjects rated the chips as fresher.

This article was originally published in the December 2015 issue of Popular Science.

The post Why Does Stale Bread Turn Hard, But Stale Chips Turn Soft? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Modern touchscreens like the one on an iPhone work by measuring the change in charge and voltage across a grid of hair-thin electrodes, aka capacitance. “When you touch your finger to the screen, it sucks out some of the charge,” says Geoff Wilson, a mobile-technology consultant and former touch technologist at Intel. That’s because your body is made mostly of water, which is extremely conductive. The touchscreen locates your finger on the grid by measuring how much the charge drops between two intersecting electrodes, a process called “mutual capacitance.”

The problem is that drops of sweat or rain can reduce the charge too by providing another conduit between the electrodes. Thankfully, over the past few years, touchscreen engineers have solved the water problem by drawing on a different mode of touch sensing called “self-capacitance.”

Instead of measuring the charge across pairs of electrodes, the touchscreen measures the increase in charge between an individual electrode on the screen and the ground you’re standing on. Because water droplets aren’t grounded, the phone’s firmware is better able to ignore them.

However, this method alone won’t work for most smartphones because it can’t handle multitouch gestures such as pinches and zooms. The signal corresponds to rows or columns of the electrode grid, as opposed to individual points. With more than one touch, a phone might register ghost points in addition to real ones.

The solution? Combine the two methods in a single touchscreen. If the device checks for both signals, it can pick up multitouch gestures while controlling for sweat, rain, and other moisture. “It’s the same electrodes and the same controller,” Wilson says. “The only difference is the firmware, which has to be smart enough to combine the measurements.”

Some phones already come equipped with the combo, but that’s rarely advertised. It’s tough to make “mutual and self-capacitance” sound sexy in an ad.

This article was originally published in the November 2015 issue of Popular Science

The post Why Does A Drop Of Water Confuse My Touchscreen? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Perhaps as many as a quarter of us sneeze when we look at a bright light, a condition scientists have been calling “photic sneeze reflex” since 1954. But the condition goes back millennia. Aristotle proposed that the sun’s heat dries nasal fluid, causing the nose to tingle. (The ancient Greeks also suggested sneezing is divine and should occur only during sexual excitement.) Modern science has put forth a few more likely explanations.

For starters, the effect has been observed in babies, so it’s probably not a learned response—but it could be genetic. One Swedish study found that in families where one parent had the condition, more than half of the children had it too. A separate research team even found two places in the human genome where the trait might reside, though they’ve yet to prove it.

On a mechanistic level, the condition might result from crossed signals in the brain’s wiring. Scientists have speculated that intense activation of the optic nerve, such as you’d get from stepping into bright sunlight, could leak into the nearby trigeminal nerve, which responds to nasal irritation—thus triggering the sneeze.

Or the cause might lie elsewhere in the brain. A few years ago, researchers at the University of Zurich recruited 10 photic sneezers and 10 nonphotic sneezers to test another theory. They measured brain waves using electroencephalogram (EEG) while flashing bright lights at their subjects. The photic sneezers displayed more activation in their visual cortices, suggesting that this extra sensitivity to light extends this reflexive process beyond the brainstem.

This article was originally published in the December 2015 issue of Popular Science.

The post Why Does Bright Light Make Me Sneeze? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

We could all use an extra hour in the day, but clocks won’t need to be extended anytime soon. The time the Earth takes to make a complete rotation on its axis varies by about a millionth of a second per day, says physicist Tom O’Brian of the National Institute of Standards and Technology. While some days are shorter than average, the planet’s rotation shows a long-term slowing trend, ultimately leading to a longer day.

Scientists have reliable data on the Earth’s rotational speed, based on observations of the sun’s position in the sky during solar eclipses, going back some 2,500 years. Although the rotational rate hasn’t declined smoothly, over that period the average day has grown longer by between 15 millionths and 25 millionths of a second every year. Even at the faster rate, it will take 140 million years before the Earth’s rotation slows enough to necessitate a 25-hour day.

You don’t need to worry about having to add another day to your calendar, either. Although the planet’s rotation around its own axis is lagging ever so slightly, we’re revolving around the sun just as quickly as ever, and showing no signs of slowing down.

The post I’ve Heard That The Earth’s Rotation Is Slowing. How Long Until Days Last 25 Hours? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Here’s why you might be worried: Burning oil, coal, gas, wood or other organic materials uses molecular oxygen, the O2 we breathe, to break carbon-hydrogen bonds and release energy. This reaction, better known as combustion, also pairs each broken-off, positively charged carbon atom with two negatively charged oxygen atoms, forming carbon dioxide, or CO2.

Although that does cut into the amount of O2 in the atmosphere, there’s no need to fill your basement with oxygen tanks. Nitrogen accounts for 78 percent of the gas in the atmosphere, but molecular oxygen, the O2 that we breathe, is the runner-up, at 20.94 percent. The remaining 1 percent and change falls into the “other” category, predominantly water vapor but also argon and hydrogen gas; CO2 accounts for just 0.04 percent.

Because of this relative bounty of oxygen, scientists such as Pieter Tans of the National Oceanic and Atmospheric Administration don’t fear that carbon emissions will cut off our oxygen supply. “Even if we were to burn another 1,000 billion tons of fossil fuels, we would only decrease the oxygen in our atmosphere to 20.88 percent,” he says. And even then, the effects that action would have on the environment—more particulate pollution, hotter temperatures—would be far worse than oxygen depletion.

The post Will We Run Out Of Breathable Oxygen If We Produce Too Much Carbon Dioxide? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

In October of 2019, three strong earthquakes hit the Philippine municipality of Tulunan, Cotabato. With multiple active fault lines snaking around the southern island, residents three hours away in Davao City felt the ground shaking. The first round of tremors kept me up at night. The second came two weeks later, and then the third just two days after. That’s when I lost count.

As people in Tulunan shared photos and videos of the destruction, I felt helpless. The anxiety of not knowing what to do or what would come next flooded my mind. Little did I know, my worries were just beginning.

“The vast majority of earthquakes are caused by the sudden release of stresses built up by movements of tectonic plates,” says Morgan Page, a research geophysicist with the U.S. Geological Survey. The “instrumentally detectable aftershocks,” she adds, typically go on for months to years. That’s exactly what happened in Tulunan and Davao City—we experienced hundreds of aftershocks throughout November. Page also notes that “the rule of thumb following a large earthquake is that there’s about a five percent chance that it will trigger an even larger earthquake.” “So in most cases,” she says “the aftershocks remain smaller than the mainshock. But everyone should be aware that sometimes an even larger earthquake can occur.”

The earthquakes in the Philippines may not have been all natural. The region around Tulunan is rife with mining activity, which could lead to “induced earthquakes,” says James Gaherty, a professor at the School of Earth and Sustainability at Northern Arizona University. Induced earthquakes are “are almost always very small and very rarely damaging,” he explains, but they can build up to larger events. On November 18, a magnitude 5.9 earthquake hit the municipality of Kibawe, Bukidnon, about 70 miles away from Davao City. This time sleeping was next to impossible.

Just as continued aftershocks take a toll on infrastructure, they can also eat away at people’s mental health. Earthquakes and post-traumatic stress disorder (PTSD), a condition that affects upwards of 7 percent of the world’s population, both manifest over time. I, for example, have have been grappling with anxiety for a decade; the recent earthquakes just brought out the worst of it. Now, I feel like I need to get ahead of everything, be prepared for everything, have back-up plans for everything. It’s a fight-or-flight response, cranked up to the nth degree.

Indeed, that description might not be too far off, according to medical experts. Anxiety is “a completely normal response to an abnormal situation, and more specifically, a frightening situation,” says Molly Ansari, an assistant professor of counseling at Bradley University in Peoria, Illinois. “The anxiety that develops following something such as an earthquake serves as a warning signal to our bodies to protect us from future danger. For example, ‘helpful anxiety’ may urge individuals to make earthquake safety kits, install mechanisms to make their homes more stable, purchase insurance, etc.”

The thing is, it’s not easy to predict how earthquake-induced anxiety may affect an individual—or how someone who’s still learning to cope with anxiety might fare with aftershocks. For me, after four strong tremors, it didn’t feel like “helpful anxiety” anymore. The difficulty in sleeping topped a long list of symptoms that Ansari highlights: excessive worrying, irritability, flashbacks, and constant fear of the next disaster. I checked at least three of those adverse effects.

Ansari, who’s a licensed clinical counselor specializing in trauma, says that earthquakes can indeed cause worry and fear, even in those who’ve already survived and thrived after one. But she also notes that it can be tough to tell if those reactions are a result of anxiety or PTSD, which is a more specific expression of anxiety. “The symptoms often overlap and can be mistaken for the other,” she explains. “It’s common for someone who is diagnosed with PTSD to [broadly] experience anxiety.”

So how does one parse the two? Ansari says a clinician would look at the etiology, or set of causes of the symptoms. “Typically, when a diagnosis of PTSD is given, an individual has experienced an intense feeling of anxiety in response to an event, such as a natural disaster.” With general anxiety, on the other hand, Ansari says the symptoms likely have “presented themselves in a variety of circumstances” and have a more longstanding history.

In short, if the anxiety was a direct result of a traumatic experience and triggers severe behavioral and psychological symptoms—agitation, hyper-vigilance, social isolation, flashbacks—it may be diagnosed as PTSD. Ansari also stresses that someone with pre-existing anxiety who hasn’t received treatment or support “may be more susceptible to developing PTSD following a traumatic event.”

While earthquakes do fall in the category of traumatic events, there’s little research on how widely they can cause PTSD and general anxiety. Last year, the Asian Journal of Psychiatry published a study connecting the 2016 Aceh Earthquake in Indonesia with a statistically significant rise in comorbidity from PTSD, depression, and anxiety. A public health scientist at the University of Miami conducted similar research on Puerto Ricans displaced by Hurricane Maria. He’s currently examining how island residents fared when hundreds of aftershocks hit their homes earlier this year.

As Ansari puts it, “there’s still so much to research” with PTSD following natural and human-made disasters. “I think the most interesting factor is when I get asked ‘who will get PTSD’ or ‘will I get PTSD’? The answer to that is, ‘we don’t know.‘ But it’s always interesting to see what common factors exist with those who get PTSD and those who do not. The same can be asked about general anxiety disorder.”

For residents of the southern Philippines, a region whose fault geology is still poorly understood, according to Gaherty, there’s still the question of whether they’ll ever be able to sleep with ease. But as Ansari points out, there are ways to cope and get help for general anxiety and PTDS. In addition to counseling and prescribed medications like Buspirone, Ansari suggests joining support groups for survivors of natural disasters, practicing relaxation techniques like meditation, and establishing life routines that build predictability. She also says it’s wise to engage in activities that foster a sense of empowerment and control, including creating art and journaling. The latter has done wonders for me: Every time I can put how anxiety affects me into words, I feel empowered.

It’s been eight months now since the first strong tremor in Davao City and a few weeks since the aftershocks eased up. The anxiety still creeps in every now and then, but I’m learning to calm my mind and continue on with life. That might not hold true for my neighbor, however, or the person who lost their home in the hills of Tulunan. Everybody experiences mental health disorders differently, and because of that, we each have to find our own way of coping with disaster. The important part is that we acknowledge the struggles, no matter what the aftershocks might look like.

The post Earthquakes can cause serious psychological aftershocks appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

“Spending money on others might represent a more effective route to happiness than spending money on oneself,” says Elizabeth Dunn, a University of British Columbia psycho­logist. In 2008, she conducted a survey of 632 Americans to study their spending habits and happiness. The subjects reported spending a lot more on themselves than on friends or relatives: $1,714 versus $146, on average.

But their happiness correlated more strongly with the gifts they gave.

Receiving gifts also has a strong effect. A 1998 study led by Charles Areni, now of Macquarie University in Australia, asked 174 college students, half male and half female, to write down a memorable gift-related experience. The majority, about 71 percent, described receiving a gift. The results were even more pronounced along gender lines: Among females, 92 percent focused on getting versus giving. Among males, it was 55 percent.

Gad Saad, an evolutionary psychologist at Concordia University in Montreal, is not surprised to see gender differences. In the animal kingdom, he observes, the male typically gives food to the female. In a 2003 experiment, in which Saad asked people to explain their gift-giving motives, he found men were more “tactical.” They wanted their gifts to convey a message, such as “I’m rich.” Women were more likely to gift for reasons like a birthday.

This article was originally published in the December 2015 issue of Popular Science.

The post Does It Feel Better To Give Or Receive A Gift? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Global warming, holes in the ozone layer, and lush golf courses in the desert all reveal mankind’s ability to mess with the planet. But the Earth’s core, protected by an outer core consisting of some 1,000 miles of 8,000˚F liquid metal, appears safe from our meddling.

Geothermal energy systems don’t drain heat directly from the core. Instead, they pull radiant heat from the crust—the rocky upper 20 or so miles of the planet’s surface—either by sucking up pockets of heated water or by circulating water through the hot rock. Power plants then use steam from the hot water to spin turbines to make electricity. Geothermal energy generates 7 to 10 billion watts worldwide, barely enough to account for 0.05 percent of global energy consumption and far less than the estimated 44 trillion watts the planet produces.

But drawing energy from the crust won’t send it into a deep freeze: Its heat is constantly renewed by the virtually continuous decay of radioactive elements sprinkled throughout it. “Cooling the Earth’s core by drawing geothermal energy from the crust is like trying to cool the western end of Lake Superior with a few ice cubes,” says Paul Richards, a professor of natural science at Columbia University.

It’s a good thing that we can’t cool the core. The spinning metal there generates Earth’s magnetic field, which protects us from deadly cosmic radiation. If the outer core cooled, the liquid would solidify, and both it and the solid inner core would grind to a halt, the magnetic field would dissipate, and high-energy cosmic radiation would bombard the planet, essentially turning Earth into a giant microwave and ending life on the surface.

The post Could Tapping the Planet for Geothermal Energy Cool the Earth’s Core? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

You might guess that magma or tumbling rocks fill the void, but the truth is much more prosaic: water. Petroleum deposits, which are naturally mixed with water and gas, lie thousands of feet below the earth’s surface in layers of porous rock, typically sandstone or limestone. (Contrary to what you might imagine, drilling for oil is more like sucking oil from a sponge with a straw than from a giant pool of liquid.)

At such depths, these liquids are under very high pressure. Pump petroleum out, and the pressure in the well drops. Water in the surrounding rock, which is also packed under high pressure, then pushes its way into this low-pressure pocket until the pressure reaches equilibrium. “It’s just like digging a hole at the beach, where water in the sand around it flows into the lower pressure zone of the hole,” explains Chris Liner, a professor of petroleum seismology at the University of Houston.

Unless you drill in a volcanically active region (which would be unwise), magma typically flows miles below the deepest oil wells, which tap out around 30,000 feet down. And although some shifting of rock and deep sediment can occur, it wouldn’t spur a major earthquake. Typical drilling-induced quakes register between –2 and –4 on the Richter scale, which is one thousandth as forceful as the rumble of a tractor-trailer driving by.

The post What Fills the Space Left in Wells When Oil is Extracted From the Ground? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

When the Apollo astronauts drove around on the moon, they had to settle for a little buggy. But if you want to tour the Sea of Tranquility in the family SUV or a Ferrari, well, you’re looking at more than a few weekends under the hood.

“Your average car faces several major problems on the moon,” says Brian Wilcox, who heads the development of NASA’s new manned rover, called Athlete [see NASA’s Gilded Chariot]. Chief among those is the small matter of combustion. There’s no oxygen on the moon, so your engine can’t burn fuel to generate power. In addition, your rubber tires would crack or melt on the surface, where temperatures range from that of liquid nitrogen to boiling water.

The upgrades are fairly straightforward. You could swap your Firestones for a set of NASA’s metal mesh lunar-grade tires. You’d need to get rid of that combustion engine, too. An electric engine running on hydrogen fuel cells would perform best in the lunar environment, Wilcox says.

You’d want to keep your trips brief, though. On the surface of the atmosphere-free moon, there’s no protecting yourself from cosmic rays, which at lunar-intensity levels can increase your risk of developing cancer by 3 percent in just six months. If you’re the cautious type, you might consider two-inch-thick, water-filled panels to block the protons spewed from the occasional solar flare, which could kill you in less than an hour.

Once you’d made these modifications, you would reap some nice benefits. Because gravity on the moon is one sixth that of Earth, your engine wouldn’t have to work as hard to propel your car, so you’d score six times as many miles per charge as you would here. And there’s never any traffic. Of course, you’d have to get your car up there. NASA’s going freight rate to the moon runs around $25,000 a pound, so delivering a one-ton car would cost $50 million. Those two-seater buggies left behind from the Apollo missions don’t sound so bad after all.

The post What Modifications Would I Need to Make to My Car So I Could Drive It On The Moon? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

The makers of Deo Perfume Candy claim that if you eat a few of their pink lozenges, the odor compounds contained therein will travel through your body and start oozing out of your pores, giving you a vague and pleasant rose-smelling aura. That’s right. It’s edible deodorant. But don’t throw out your Speed Stick just yet. I tried it for a week, and suffice it to say “pleasant” is a wild overstatement.

First, how it’s supposed to work: The theoretical mechanism of action is pretty easy to grok if you know something about chemistry. The “active ingredient” in the candy is geraniol, a monoterpene alcohol found in rose oil, citronella and geraniums. It is used in perfumes and in artificial flavors such as raspberry, peach and lime. Those who read my BeerSci column will remember me talking about terpenes, as they pertain to hops and cannabis active ingredients. Well, geraniol is another terpene. If you look at geraniol, you’ll see that it’s mostly carbon and hydrogen; as such, it’s at least moderately fat-soluble, and thus it should pass easily through cell walls and therefore through your skin.

geraniol structure

To test if this candy really does make one smell like roses, I agreed to 1.) eat them for a week and 2.) not use antiperspirant. I also refrained from using any perfume or scented lotions during the testing period. I did shower every day, though. My lucky (read: brave, foolish, insane) coworker Susannah agreed to smell-test me during the week.

Day 1
Test smell before the experiment. Susannah reports that I smell “normal” (whatever that might mean). The instructions that came with the candy say to eat four pieces of candy to get enough geraniol in your system. So I do. I don’t eat them all at once, but over the course of an hour. By the third candy, I am already dreading piece number four. It’s not that the candy tastes bad–it’s tart-sweet with a rose-raspberry character–but more that I don’t actually have a sweet tooth. After I pop the fourth candy, I wait for an hour or so, then demand to be smelled. It’s probably a mercy that Human Resources is on the other side of the building, otherwise I might have been answering some rather pointed questions about my shouting in the middle of a cube farm, “Susannah! Smell my rose-inflected funk!”

Result: I do not smell like a rose.

Day 2
Same as Day 1, except that I eat candies about once an hour, all day. Again, I have Susannah smell-test me before I shove the first candy into my piehole. By 3 p.m., I figure I’ve had enough geraniol-laced sugar to be stencherific. I stand up and present my arm for the smell test.

Result: I do not smell like a rose.

Day 3
I’m starting to really despise that bag of candy. I haven’t looked at a sweet with that much hate since the last time I got a Bit O’ Honey while trick-or-treating. In 1983. I dutifully eat more candy and make other people in the office smell me pretty much constantly. I start feeling nauseated due to general sugar overload, and I am pretty sure my pancreas is planning a bloody coup against my hands and my mouth. Susannah shakes her head sadly and reports that, no, I do not smell any different. She says, and I quote, that I “smell like a girl,” and that I’d been smelling like a girl since before the experiment. Needless to say, I do not smell like a rose.

After that, I give up.

Two, or even four, pieces of Deo candy aren’t bad. In fact, I actually like the flavor of it. The problem is that it just doesn’t work–at least it didn’t for me. If you already “smell like a girl,” the candy will not likely make much difference to your personal odor. Susannah, who, it should be noted, also smells like a girl, did a follow-up study of her own the following weekend, and came to the same conclusion. I would love to say I’d forgo the shower for a week on behalf of science, but I am pretty sure my colleagues would lock me in a closet. It’s one thing to “smell like a girl.” It’s something else entirely to smell like feet and onions, even with the vaguest hint of rose scent on top of it.

The candy, which is made in Bulgaria, is imported to the U.S. by Ecodeum LLC. You can buy it from Amazon.

The post Does Edible Deodorant Work? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Tune into a Colorado Rockies game, and you’re bound to hear one of the announcers mention the team’s most famous piece of lore: They keep their baseballs in a humidor. Cigar aficionados keep their cigars in a humidity-controlled environment to prevent the tobacco leaves from drying out, but the Rockies are more concerned about dried-out balls carrying farther and driving up scores. So far, it’s worked, having quelled the offensive binges the park was known for when it first opened. But scientists still can’t say exactly why it’s so effective.

From the 1995 to 2001 seasons, National League pitchers at Coors Field recorded a horrendous earned-run average (ERA) of 6.50, more than two runs a game higher than the 4.37 ERA recorded at other stadiums. Fans and the media attributed the numbers to Denver’s mile-high thin air. But in the winter of 2002, based on a hunch that the balls might be drying out and losing weight in Denver’s arid climate, engineers at Coors Field installed a humidor for storing game balls. Since then, N.L. pitchers have posted a 5.46 ERA at Coors.

According to a 2004 study by physicist David Kagan of California State University at Chico, keeping the balls at 50 percent relative humidity lowers their coefficient of restitution, a.k.a. bounciness. This means that the balls don’t bounce off the bat as powerfully as dried-out ones do. In December, Edmund Meyer and Alan Bohn, physics professors at the University of Colorado, found that the added moisture does not change a ball’s size and shape — and thus, its aerodynamics — which seems to verify Kagan’s explanation for the humidor’s success.

Yet the pitchers might know something the scientists don’t. Former Rockies pitcher Shawn Chacon griped that pre-humidor balls were as slippery as pool balls, making it difficult to impart enough spin to execute breaking pitches. Lloyd Smith, a professor of mechanical engineering at Washington State University who tests bat materials, and physics professor Alan Nathan of the University of Illinois are investigating this effect and have qualitatively corroborated Kagan’s findings. “We’re fairly confident that the effects are small,” Smith says. “But in baseball, even small effects can be important.” Just ask the Rockies’ pitchers.

The post Why Do the Colorado Rockies Keep Their Baseballs in a Humidor? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

About six “Santa months,” according to Larry Silverberg, a professor of mechanical and aerospace engineering at North Carolina State University. He’s a Santa math specialist (really) whose students took on the problem.

Here’s how he got there: Santa has to deliver gifts to around 200 million children spread over 200 million square miles. Because each household has 2.67 children, there are about 75 million homes to visit and the average distance between homes is about 1.63 miles, Santa needs to cover 122 million miles.

To cover that distance in 24 hours on Christmas, Mr. Claus’s sleigh would need to travel at a whopping average speed of 5,083,000 mph. Silverberg argues that the feat is possible because the sleigh would have to travel 130 times more slowly than the speed of light, which is 300 million meters per second, or 669,600,000 mph. Because something already moves that quickly, it would be difficult, but not impossible, for Santa to travel at 5,083,000 mph.

Traveling at 5,083,000 mph seems a bit fast for a plump old man so Silverberg and his students found a more realistic scenario: relativity clouds. Relativity clouds, based on relative physics, allow Santa to stretch time like a rubber band and give him months to deliver gifts, while only a few minutes pass for the rest of us. (Silverberg theorizes that Santa’s understanding of relative physics is far greater than our own.)

Silverberg’s theory is plausible, says Danny Maruyama, a doctoral candidate researching systems physics at the University of Michigan. If Santa were to travel at about the speed of light, share the delivery work-load with his elves and makes use of relativity clouds, he would be able to deliver the presents in about five minutes Earth time, Maruyama says. “While I don’t know much about relativity clouds myself, I think it’s very possible that a man who flies in a sleigh, lives with elves, and has flying pet reindeer could have the technology needed to utilize relativity clouds,” he says.

And what if Santa deployed multiple sleighs? Silverberg says if Santa and his elves use 750 sleighs to deliver the gifts and, using their knowledge of relativity physics, take roughly six Santa months (to us humans, only 24 hours), each sleigh only needs to travel about 80 mph, a much more realistic scenario. “At 80 miles per hour, you just throw a couple jetpacks on either sides of the sleighs and you’re there,” Silverberg says.

The post FYI: How Long Would It Take Santa To Deliver Presents To Every Kid On Earth? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Earlier this fall, a forensic chemist at the Massachusetts-based crime lab William A. Hinton State Laboratory was charged with obstruction of justice. Annie Dookhan allegedly mixed drug samples, neglected to test them properly and forged colleagues’ signatures throughout her nine-year career to drive up her productivity. She might not have even received the master’s degree she claimed to have (University of Massachusetts officials are denying her credentials). Now a grand jury is investigating the case and is expected to return indictments against the disgraced chemist some time after today. The story is like something straight out of “Law & Order.”

Which got us wondering: What exactly do forensic chemists do? And why might some feel compelled to cheat?

In crime television shows, investigators brush evidence into tiny baggies in leaky warehouses, then send the samples off to the crime lab. Minutes later, the results magically materialize, the bad guy gets convicted, and everyone else lives happily ever after.

But as Dookhan’s case suggests, the reality is much less tidy and offers a dark portrait of the perverse incentives of a key aspect of the criminal justice system.

Forensic chemists are, first and foremost, scientists. These technicians usually have degrees in biology, chemistry, biochemistry or forensic science, and are trained in the sanctity of the scientific method. They specialize in either drug analysis, toxicology or arson and explosives. Adam Hall, an instructor at Boston University’s School of Medicine, says drug analysts examine the five Ps: pills, plants, paraphernalia, powders and precursors (substances obtained from chemicals that are synthesized into new drugs.)

Hall says crime labs find that the three most commonly abused drugs are marijuana, cocaine and heroin. Marijuana, in particular, is easily identifiable. But even in the face of glaringly obvious evidence, lawyers don’t simply present the sample as is. Each sample must be weighed, tested and confirmed as the drug in question. Dookhan was accused of “dry-labbing,” looking at samples and slapping on labels without testing, which Hall says isn’t considered an appropriate practice in crime labs.

“An untrained analyst would say that a white powder must be cocaine in drug analysis, but it could be almost anything,” Hall says. “You certainly could group like items together but they would still require analysis to be able to determine what each of those items are.”

Why does that matter? Because in a court of law, some drug convictions result in harsher sentences than others. A forensic chemist’s tests could mean the difference between a misdemeanor and a felony; whether the case is tried on the state or federal level; and even whether the DEA gets involved.

You have to be there for 15 years before you get a bag of cocaine from Paris Hilton.

That helps explain the severity of Dookhan’s alleged malfeasance, resulting in an estimated 60,000 tainted drug samples. Why would someone risk it? Dr. James Woodford has worked in crime labs all over the country since 1975, noting how for many technicians, the job is heavily bound by politics, hierarchy, money, and plain old boredom.

There are three tiers of forensic chemists. Woodford says that forensic chemists in the lowest tier have the tedious job of filling out thick stacks of drug-analysis documents for minor cases simply to please the prosecution. “The technician hands them all in and what happens–nothing,” Woodford says. “Most of the cases get worked out or dropped.”

Woodford adds that crime labs have a high turnover rate for low-level technicians because the job doesn’t pay well and isn’t nearly exciting as the crime shows would have you believe. The incentive is to either quit or work your way up through the tiers as quickly as you can. The high-profile, glamorous cases are usually saved for the top-tier technicians. “You have to be there for 15 years before you get a bag of cocaine from Paris Hilton,” Woodford says.

Therein lies one possible motivation to cheat: Flying through your casework offers a fast track to the top-tier work–to big cases that aren’t likely to be dropped. Dookhan admitting she forged colleagues’ signatures because, as the Boston Globe reported, she “wanted to get the work done,” which is a daily struggle for lower tier technicians.

“Out of the hundreds of drug tests you do in a week almost all of them go away–you feel like you’ve done nothing,” Woodford says. “It’s just exasperating. It’s grunt work. And the technicians start taking shortcuts.”

The post FYI: What Do Forensic Chemists Do, And Why Would They Cheat? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Why a strand of hair bends or falls the way it does may sound like a simple question, but the answer is rather convoluted. On one level, the texture of a person’s hair derives from his or her genes. A 2009 study looked at the genetics of waves and curls and reported a heritability of between 85 and 95 percent. (That means about nine tenths of the variation in hair texture within the sample could be ascribed to DNA.) How does this play out at the level of a single hair? Research shows that the curvature of a strand depends on the nature of its follicle. When a follicle is asymmetrical, the hair that it produces is oval in shape and tends to curl. When it’s symmetrical, the strand that emerges grows round and straight.

A curly hair can also be described according to its composition and structure. A research team based in Clichy, France, and working for the cosmetics firm L’Oréal, used electron microscopy to compare straight and curly hair fibers. The former were circular in cross section and symmetrical in structure. The latter, though, had an uneven distribution of a particular type of keratin. This protein—which, along with other varieties of keratin, serves as the primary component of hair—accumulated near the inside edge of a curled hair, beneath the curve.

Even if you’re born with symmetrical follicles, there are some ways in which straight hair can turn curly. Scientists have found that a cellular receptor called EGFR clusters on the outer root sheath of a follicle and appears to regulate the growth of hair. Certain cancer drugs that inhibit these receptors may cause a patient to develop curly hair as a side effect.

Have a burning science question you’d like to see answered in our FYI section? Email it to fyi@popsci.com.

The post FYI: What Makes Hair Curly? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Aristotle reasoned that stars twinkle because people need to stretch their vision to see them, and that vision wavers. Centuries later, scientists guessed that stars spin like diamonds, twinkling as they turn through different facets. It wasn’t until the early 18th century that Isaac Newton determined Earth’s atmosphere was to blame. The question was how.

Today, the generally accepted explanation is “stellar scintillation.” Lorne Whitehead, a physicist at the University of British Columbia, describes it like this: A bright light, positioned far away, projects as a tiny point through the varying air densities of our atmosphere. Hundreds of these pockets act as lenses, refracting the light so that it moves like the light on the bottom of a swimming pool on a sunny day. The changing swells on the pool’s surface correspond to the turbulent shifting of our atmosphere.

Though this theory is widely accepted, John Kuehne of the University of Texas believes the “lens-and-prism” model gets it wrong: “Everybody forgot the wave theory of light!” he says. We shouldn’t think of starlight as a ray bending through the atmosphere, he says, but rather as a set of light waves that travel perfectly in sync. “The atmosphere puts wrinkles and crenelations into that wavefront,” he says, knocking light out of phase and creating random patterns of interference. Thus, twinkle.

But Whitehead says it isn’t necessary to complicate things in this way. “The ray model for light is a perfectly reasonable model for stellar scintillation,” he says. “It gives the same exact answer.”

This article was originally published in the November 2015 issue of Popular Science

The post Why Do Stars Really Twinkle? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Bears wide receiver Brandon Marshall caused a great engorgement in the wit of the sports commentariat when he admitted that he’s “heard (of) guys using like Viagra, seriously” to gain a competitive edge on the field.

It wouldn’t be the first time. Cyclists, runners, and football players have been allegedly popping the little blue pill to improve their athletic ability for years–but does it help? The short answer is that no one knows for sure. Correlations between Viagra and better performance (on the field) have been found in some studies, but not in others.

Here’s the theory of why it would work: Viagra chemically relaxes muscles and opens arteries to help blood flow more easily. (To help it flow easily all over the body, but, you know, there’s the primary mission.) With the blood flowing more easily, oxygen moves to the muscles more easily, which can (theoretically) improve endurance during competition. That’s something like the idea that altitude training will improve your oxygen flow and help you move longer distances without tiring, which it does.

So you can imagine why it’d appeal to certain athletes like cyclists and endurance runners hoping to get the oxygen pumping. Don Catlin, former director of the UCLA Olympic Analytical Lab and researcher at the nonprofit Anti-Doping Research, Inc., adds a couple more athletes to that list: mountain climbers and skiers. While studies have not found a link between Viagra and athletic performance at sea level, other studies suggest Viagra improves results at a high altitude, like 6,000 feet or above, which would make it more attractive to high-climbing mountaineers and cross-country skiers. And athletes in those sports do use it, Catlin says.

Some researchers have argued that playing a contact sport at a higher altitude on Viagra would help, too, but Catlin has not found evidence to confirm that. Even researchers who are convinced that Viagra gives athletes an edge say it might only deplete the deficit already caused by competing at a high altitude.

Catlin also suggests that any improvement would be miniscule (although minuscule can sometimes matter). More to the point, athletes could gain that minuscule advantage elsewhere, without having to ask their doctor for erectile dysfunction pills. Altitude training, the process of switching between living at high altitudes and training at low altitudes, could improve performance by 1 to 1.5 percent. That doesn’t sound like much, but even that might be more useful than Viagra. Beyond that, illicit substances would make for a relatively major increase in performance, much higher than what an athlete would get from Viagra.

So if that increase is so small, why would athletes use Viagra? Because players have heard (incorrectly, maybe, especially in the case of football players) it increases performance, even if just a smidgen. That’s enough of a reason for some athletes. Plus, it’s not banned in competitive use. Without some major evidence, Catlin says, official organizations like the World Anti-Doping Agency won’t place a ban on a medication for a necessarily discreet problem. (“Excuse us, but we need to make a formal display of this condition before you compete.”)

That might be the most convincing evidence that the jury’s out on Viagra in sports: officials are unable to make a move when they’re between a rock and a hard place.

Sorry.

The post FYI: Can Viagra Make You A Better Athlete? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Orb-weavers, arachnids that capture their prey using sticky webs, make up more than one fourth of all known spiders. These species spin their creations with spiral crossbeams dotted with drops of viscous goo. (The webs’ radial and framing threads are left clean.) When an insect brushes against these drops—each thread can carry several dozen per millimeter—it gets stuck, and the spider rushes over to inject it with venom or cocoon it in silk. The question, of course, is how does the predator escape its own glue traps?

Naturalists have only recently worked out the mechanics of the sticky web—and of avoiding it. “It’s surprising how little attention the topic has gotten despite how many people wonder about it,” says Brent Opell, a biologist at Virginia Tech who has researched spiders’ capture threads. Opell has shown that when a bug tries to pull away from a web, the droplets divide the force across a length of stretchy silk, so that no single point bears all the strain.

As for how spiders avoid their goo, scientists have plenty of ideas but not much data. One hypothesis, that spiders simply skip over the sticky threads, has been more or less discredited. In fact, orb-weavers sweep their hind legs across the goo hundreds or thousands of times as they make their webs. They also brush their bodies against the drops while they’re subduing prey. Another, more promising theory originated in 1905, when a French naturalist named Jean-Henry Fabre noted that the orb-weavers frequently ran their legs across their mouthparts. He wondered if they might be spitting up or otherwise secreting some sort of lubricant that protected them from their own web. Fabre tried washing spider legs with solvent, and reported that many became ensnared.

Spiders seem to use an oily coating to protect themselves.
Early last year, a team of researchers at the Natural History Museum in Bern, Switzerland, re-created Fabre’s experiment, albeit under more controlled conditions. They installed spiders in laboratory boxes and left them to build webs. The scientists then pulled off the spiders’ legs and pressed them very carefully against the adhesive silk. When washed in water or left untreated, the legs barely stuck at all. But when treated with an organic solvent, the legs seemed twice as prone to sticking. Fabre had been right, they said: Spiders seem to use an oily coating to protect themselves.

There may be more to the story, though. Another study published in 2012, this one done in Costa Rica, came to a similar conclusion about the oily coating. But the Costa Rican study also used video analysis, which showed other adaptations: A spider moves its hind legs across the capture threads at an angle that minimizes the glue’s effects, and tiny barbs on the bristles of its feet, or tarsi, help keep its legs from sliding into the goo. The idea that a spider might have multiple ways of avoiding snaring itself doesn’t surprise Opell. “If it’s an important thing to the spider,” he says, “there probably are several mechanisms that have evolved to contribute to the nonsticking ability.”

All of the above applies to orb-weavers, but their webs aren’t the only ones that stick their prey. A related family of spiders, called Deinopidea, makes use of an older method that predates the evolution of viscous goo. Dry cribellar threads catch on the stout bristles of an insect’s body, or adhere to it through capillary and van der Waals forces. What tricks do Deinopidea use to escape their cribellar yarns? The arachnologists haven’t yet worked that one out.

Have a burning science question you’d like to see answered in our FYI section? Email it to fyi@popsci.com.

The post FYI: Why Don’t Spiders Get Trapped In Their Own Webs? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

On January 8, 1989, a Boeing jetliner crashed during an emergency landing near East Midlands airport in England, killing one-third of the passengers on board. As doctors tended to survivors, they found that people who had adopted a “brace position” prior to the crash—heads bent forward, feet planted on the floor—were less likely to have sustained severe head trauma or concussions, no matter where they sat on the plane.

The Federal Aviation Administration has been using test dummies to study brace positions since 1967. While the recommended postures have changed a bit over the years, the underlying principle remains unchanged: It’s best to lean forward in advance of a plane crash so your head is close to the seat in front of you. To press yourself toward the back of that seat, the theory goes, reduces the risk of deadly “secondary impact,” wherein your head whips forward and slams into a hard surface.

Passengers in car accidents, who might have less time to act before a crash, reflexively brace for impact too. One study found that at least half the victims in head-on collisions press their heads and torsos back against their seats, locking their arms against the steering wheel or dashboard. While this position might increase the risk of breaking an arm or leg, it helps protect the head and chest from severe injuries.

Of course, the safest crash position depends on the nature of the accident and the design of the vehicle. Dipan Bose, a transport specialist with the World Bank, has studied emergency bracing positions using computer simulations. “This is all very directional,” he says. “You have to know exactly which way the body will move.” Easier said than done when it comes to car accidents, which are, by nature, unpredictable.

This article was originally published in the November 2015 issue of Popular Science.

The post Does ‘Bracing For Impact’ Really Protect You In A Crash? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

An unexpected cold breeze, almost tripping over your own feet, a particularly high note hit by a singer. All are vastly different experiences, but they share one thing in common: They can cause goosebumps. But what exactly are goosebumps, and why do we get them? Scientists have a good understanding of the first question, but why they happen is still a bit of a mystery.

The most straightforward thing about goosebumps is their name. When geese are freshly plucked, their skin creates raised bumps where the feathers were. The mechanism that creates goosebumps on humans is also pretty simple. At the end of hair strands closest to the skin, known as the root, are tiny muscles called erector pili. When these muscles tense up, or contract, they cause the hair to stand straight up.

Surprisingly, scientists are not entirely sure why we get goosebumps. But they think they are likely a hand-me-down survival mechanism from our ancestors. Somewhere in the human lineage, we were once covered in much thicker, longer hair than we are now. When early humans would get cold, their hairs would lift and separate slightly. This would trap a small amount of air close so to the skin, effectively creating a layer of insulation.

That all makes perfect sense, but why do we get goosebumps when experiencing something pleasurable, like the sound of beautiful music?

Dr. Mitchell Colver, a researcher at Utah State University, studies goosebumps and why they form in scenarios when people aren’t cold. Specifically, he studies “frisson”, or the waves of pleasure running over the skin. It’s a sensation as many as two-thirds of humanity feels.

The latest theory, he says, is that it’s a part of our fight-or-flight response, an innate survival mechanism that causes us to react within milliseconds to stimuli like unexpected noises—think sticks snapping nearby while walking in the woods at night. Without having to think about it, those snaps immediately cause our body to deploy adrenaline, a chemical that stimulates increased breathing, sweating, and a racing pulse. All of these physical responses primes our bodies for action (flight or, as they say, fight).

Adrenaline also triggers goosebumps. Colver says our brains are so fine-tuned to keep us alive that our ancestral habit of anticipating snapping sticks carries over to our experience of music and art.

“The vocal cords of a skilled singer are trained to scream in tune. So some of the ways vocal cords vibrate when singing are similar to the vibrations of someone screaming bloody murder,” says Colver. So if you’re listening to music and something unexpected happens in a song (a high note, chord change), and our fight-or-flight response reacts. Something is wrong! Goosebumps deployed. Once we our cognitive abilities kick in to tell us to settle down and enjoy the art, the fight-or-flight response is halted. We even get a flush of dopamine, a happiness-inducing chemical, out of the experience.

No longer sensing the tune as a warning call, we recognize it as something beautiful and pleasing, says Colver. “It’s like evolution is rewarding us for figuring out something isn’t a threat.”

The post Why do we get goosebumps? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Mean people are attractive because of their meanness, not in spite of it. What I call meanness is more officially known as the “Dark Triad” of personality traits—narcissism, Machiavellianism and psychopathy. A recent study shows that people who exhibit these traits are better than people who score lower on the Dark Triad at making themselves appear more attractive.

The meanies aren’t necessarily more physically attractive than anyone else, they are just better at using what the study calls “adornments” (clothes, makeup and the like) to make themselves seem more appealing. The researchers, Nicholas Holtzman and Michael Strube at Washington University in St. Louis, had their subjects remove all makeup, pull long hair back into a ponytail and don a white T-shirt and grey sweatpants. They were rated on their attractiveness in this unadorned state, set loose to adorn themselves to their hearts’ content, and rated again. All three Dark Triad traits were associated with higher attractiveness in the adorned state, when controlling for attractiveness in the unadorned state. So you can take some small comfort in knowing that mean people are just as ugly as the rest of us, they’re just better at fooling everyone into thinking they’re hot.

Mean people are just as ugly as the rest of us, they’re just better at fooling everyone into thinking they’re hot.

The study suggests a possible reason why these subjects were compelled to make themselves more attractive: “When people high in Dark Triad traits dress-up, they may experience greater increments in self-esteem or derive more satisfaction from the additional attention they receive, compelling them to continue dressing well.”

And it has been well-documented that the physically attractive are seen as more likeable, further explaining the popularity of the bad boys in their motorcycle jackets who make the ladies swoon, and the cruel, selfish high school girls with expensive hair and logo-emblazoned t-shirts. As “Mean Girls”—yet another incisive cultural study—put it: “The weird thing about hanging out with Regina was that I could hate her, and at the same time, I still wanted her to like me.”

The inexplicable pull of Regina George, the cruel, popular ringleader, goes beyond just her physical beauty, artificial or not. Her Dark Triad personality traits may actually be helping her. Psychopaths have long been characterized as outwardly charming, and research suggests that narcissists tend to make better first impressions. Studies show that after brief exposure to a new person, people rated those who ranked high for narcissism as more likeable.

But whether your personal Regina George gets hit by a bus or not, beauty will fade with time, and even the strongest first impression can’t hide a truly dark interior forever. So chin up, because someday you’ll be living in a big old city, and all they’re ever gonna be is mean.

Scientific American

The post FYI: Why Are Mean People So Hot? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

People who live north of the Arctic Circle experience two months each year with no direct sunlight. During the dark winters, the only natural illumination people experience is twilight, which tends to have a bluish color. So in 2007, cognitive neuropsychology specialist Bruno Laeng set out to see how this might affect the vision of these northernmost inhabitants.

Laeng and his colleagues gathered about 250 people, mostly undergraduates from the Arctic University of Norway (where Laeng, now at the University of Oslo, was a professor at the time), and split them into two groups: those who were born above the Arctic Circle and those born below it. Both groups took a test measuring color discrimination, in which they had to arrange more than 85 color tabs according to the progression in their hues.

Those born in polar regions made more mistakes arranging the yellow-green and green tabs, but far fewer mistakes arranging the blueish ones. (Perhaps not surprisingly, the prevalence of red-green color blindness is higher in populations that live farther from the equator.)

Language also supports Laeng’s findings: Ohio State University psychologist Angela Brown looked at dictionaries for various populations—more than 450 languages in all—to see which ones had distinct words for the color “blue.” She found that the closer people lived to the poles, the more they distinguished between the blues.

This article was originally published in the January/February 2016 issue of Popular Science.

The post Do People Who Grow Up In The Arctic See Better In The Dark? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

In today’s featured reader question, DiGMEH from Montreal wonders “Why not send someone again [to the Moon] now? Technology is better and they have more experience and money for it…”

It’s an interesting question. Is it a matter of priorities, of money, of something else?

Submit your science and technology questions to fyi@popsci.com.

The post So Near And Yet So Far appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

The feeling you get as soon as you step off a merry-go-round is a hard one to forget. You crash to the ground only to look up and watch the sky continue to spin. You’ve stopped moving, but this dizzying feeling continues. Why?

No matter what method you use to spin—run around rapidly in circles, whirl in an office chair, or spend some time on the merry-go-round with your friends—your body reacts in the same way.

When you spin around quickly, your eyes see a lot of different information in a very short time, which can be disorienting. But your body is ready for sudden changes like that, and it tries its best to keep its visual field looking normal. If what you saw started spinning with every movement your body made, the world would be a very befuddling place. In fact, it would be pretty hard to do anything.

The process that keeps you oriented doesn’t have much to do with your eyes at all. Instead, it all begins inside your ears. Way past the outer area that you can see, rests three semicircular canals (think elbow pasta shape). They are each situated at 90 degree angles of each other. The canals are lined with extremely tiny strands of hair. Inside each canal (where you would normally find the cheese in your elbow-shaped mac n cheese meal), is two layers of thick gelatinous fluid.

Scientists call them endolymph and cupula. As you move around, these fluids slosh inside the ear canals. That sloshing hits those itty bitty strands of hair, making them move back and forth. Those hair movements are key. The ear picks up on what direction the hair cells are moving and uses nerve cells to send a signal to the brain with all of that information.

Once you stop moving, the fluids stop sloshing and the hairs no longer pick up movement and that alert signal to the brain halts. However, that process is far from perfect. When you move really fast, like if you spin around in circles a bunch of times or spend far too long on a merry-go-round with your friends, that fluid in your ears swishes around at an even more rapid speed. That makes sense because you are spinning really quickly.

The problem comes when you stop. Your muscles are able to start and stop really quickly without any issues. But that fluid doesn’t work as fast. Even though you stopped, that fluid is still moving. And it takes some time for it to finally stop. While it’s still moving, those hairs are still picking up on the motion and sending signals saying, “I’m moving” to the brain. The brain receives that signal but at the same time knows the body is perfectly still. The resulting feeling? An extreme case of dizziness. Luckily, it’s only temporary.

The post Why do I feel dizzy after spinning? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Well, it’s never a great idea to stand next to a machine that could create black holes, but the magnets that steer the proton beams around the planet’s most powerful particle accelerator would probably spare you from excess radiation. Then again, there is the off chance that some 300 trillion protons could erupt from the device and kill you on the spot.

Even though the LHC’s twin beams will travel in protective isolation through 17-mile-long, two-inch-wide pipes sucked to a near-perfect vacuum, some of those protons—potentially billions—will inevitably wander off the track. When they do, they will slam into the magnets that steer and focus the beam, or hit other hardware, gas molecules or protons. These collisions will generate a mess of secondary radioactive particles, explains Mike Lamont, an LHC machine coordinator, filling the tunnel with a field of radiation roughly equivalent to that of a full-body CT scan. That’s not a dangerous amount of radiation to be exposed to for a few minutes, but longer than that, and you might suffer some cellular damage. (It’s important to note, though, that the security measures in place at the LHC make it virtually impossible to sneak into the tunnel when the beam is on.)

If engineers were to lose control of the beam, however, watch out. The beam is only one millimeter wide, yet it contains 320 trillion protons moving just shy of the speed of light. (That gives it about the same momentum as a 400-ton train speeding at 95 mph.) It would plow through the magnets and unleash a fatal cascade of high-energy particles and radiation.

And that’s just if you were near a runaway beam. If you stood in its way, it would burn a hole right into you, Lamont says. “A human body wouldn’t stand a chance.”

The post Say I’m Inside the Large Hadron Collider and It’s Revving Up. Should I Be Concerned? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

An ostrich-like dinosaur known as an ornithomimid would probably yield the most consumer-friendly cut of meat, while still maintaining a unique dinosaur taste.

Much of the flavor in a cut of meat comes from its fat composition, and an animal’s diet contributes significantly to this. However, due to the average consumer’s taste for meat that is not too strong-tasting, it is more important to figure out what we don’t want the animals we consume to be eating. Dinosaurs that ate marine animals would definitely be off the list, not only for their fishy flavor, but also because the high amount of oil in fish would make the meat more susceptible to oxidation, which would give it a rancid taste. In fact, any carnivorous dinosaur would not fare too well in the supermarket. Most people prefer meat that comes from herbivorous animals—think cow, deer, bison— since animal fat found in a carnivore’s diet adds a significant amount of “gamey” flavor. And some dinosaurs’ diets are far too unappetizing to consider.

“When people ask me if a T-Rex would be good, well, I don’t think so,” David Varricchio, professor of paleontology at Montana State University, says. “They’ve found jaw abnormalities that suggests they were eating fetid meat and had diseases that came about from prey items. They would be pretty parasite-laden.”

Just as important in the search for the best cut of dinosaur meat would be the level and type of activity for which the dinosaur was built.

As for exactly which dinosaur would be most appetizing, one with red meat would have just enough flavor as compared to one with blander white meat. Theories that dinosaurs would have tasted like chicken abound since dinosaurs are so closely related to birds, but for many land-dwelling dinosaurs, beef may be a closer guess. The kind of activity an animal does determines what kind of meat it yields. Red meat is composed of slow-twitch muscle fibers, which are built for sustained periods of activity, so animals that are active for longer amounts of time throughout the day would be composed of mostly red meat. Those who ambush their prey or move quickly for short periods of time would have white meat, which is composed of fast-twitch muscles that allow for quick bursts of activity. So dinosaurs taking part in extended periods of activity would probably have muscles less like a chicken (or even a fast-acting predator like a cheetah) and more like a steady-moving cow.

The tasty–yet accessible!–ornithomimid

Ornithomimosaurs were a group of ostrich-like dinosaurs that were part of the suborder Theropoda from which modern birds evolved. They were close enough to birds that they likely had feathers and were warm-blooded, but they were very active animals with large hind legs for prolonged periods of running, so their muscles would probably have been mainly slow-twitch, less like modern birds. Though most theropods were carnivorous, ornithomimids were unique in that they had no teeth, a fact that has led most to believe they ate mostly plant matter.

“About 80 percent of the ornithomimids were hindquarters, and they were really well-suited for running,” Varricchio says. “I’ve also done a little work on their bone histology and it’s safe to say they’re relatively fast-growing. I think it would be a lean, slightly wild-tasting red meat.”

That’s not to say other dinosaurs wouldn’t make a tasty meal either. Velociraptors, being wild ambush predators, may have had gamier-tasting white meat comparable to a carnivorous bird such as a hawk. Taking into consideration activity level and diet could yield a huge variety of possibilities were dinosaurs ever to roam our pastures and grocery stores.

“You could get into cuts of meat. Armored dinosaurs mainly used their tails for defense, so that would probably be a lot of good white meat. Hadrosaurs were quadrupedal and spent much of their time on the move; I suspect they would be largely red meat,” Varricchio says. Sauropods, the largest animals to ever walk the earth, may have made for an interesting meal as well. Their long necks, used to reach high-up food sources, could have resulted in a unique cut of sturdy red meat weighing several tons. Says Varricchio, “Sauropod neck could be a delicacy.”

Florida native Erin Berger is a junior at Northwestern University. She is studying journalism and anthropology with a special interest in health, social justice and, of course, dinosaurs.

The post FYI: What Kind Of Dinosaur Meat Would Taste Best? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

PopSci reader aaronmrosen wonders: “when it comes to wind farms, can too many props actually slow down the wind, and cause a change in weather patterns?”

What do you think? Wind power: good or evil? Discuss in the comments section.

Submit your science and technology questions to fyi@popsci.com.

The post Readers Ask . . . appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Motion sickness is a mismatch between what your body and your brain is experiencing, says Dr. Sujana Chandrasekhar, director of New York Otology and ENT surgeon at the New York Head and Neck Institute.

It’s experienced when the central nervous system receives conflicting information from the inner ear, eyes, and both the pressure and sensory receptors, found in our joints, muscles, and spine. Our sense of balance is controlled by the interaction of these systems.

“In motion sickness the fluids of the inner ear are moving along with you in the moving vehicle. The brain is interpreting that movement, [and] instead of saying ‘yes you are in a moving car,’ it’s interpreting it as an incorrect stimulus,” Chandrasekhar says. This will often cause some sort of nausea.

Unfortunately, motion sickness is one of those things that just can’t be “cured.” On the bright side you can use medication to reduce the sensation. “Medication will blunt the effects but there’s no way to get rid of it,” says Dr. Hamid Djalilian, director of Neurotology at the University of California Irvine.

What you should do, if you’re in a car for example, is sit up front. This way you’ll be able to anticipate motion and fix your eyes on a point.

People often think they should close their eyes when they’re experiencing motion sickness. But this action won’t really reduce the sensation, says Dr. Chandrasekhar, and it’s just about the worst thing you can do. “Closing your eyes shuts off a very powerful override. If you open your eyes and focus, either on a single point in the distance, or focus as if you’re driving the car, you can actually override the incorrect interpretation of the ear input.”

Another prevention mechanism that doesn’t work is wearing those magnetic bracelets that supposedly help with balance, “[they] actually have not been found to be effective,” Djalilian says. It’s a psychological relief; it doesn’t really get rid of your symptoms.

But there is a more natural approach to relieving the sensation of motion sickness: ginger. All you have to do is suck on it. It’s very effective, says Chandrasekhar, and it will calm your stomach down.

Have a burning science question you’d like to see answered in our FYI section? Email it to fyi@popsci.com.

The post FYI: What Causes Motion Sickness, And How Do You Cure It? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Will drinking carbonated beverages weaken my bones?

Maybe—but only if you’re drinking several gallons of seltzer a day. Here’s the chemistry that has soda drinkers worried: As carbon dioxide hits the water in your blood, it turns into carbonic acid. Too much acid in the blood can lead to a condition called acidosis, which could intercept small amounts of calcium from food as it makes its way to your bones, or steal it from them directly. Your greater concern, though, says endocrinologist Robert Heaney of Creighton University, should be the vomiting, headaches and impaired organ function that result from extreme acidosis.

The acid content in a carbonated beverage is 5 to 10 percent of what the body’s metabolism naturally produces, Heaney has found, which is far too little to interrupt the calcium absorption of bones. In general, he says, the carbonation in soda has no ill effect on bone-mineral content.

Other ingredients in soda might rob a small amount of calcium from bones. Caffeine causes the kidneys to pull sodium from the blood using proteins that accidentally scoop up calcium ions as well. The body reverses this effect within 24 hours, however. Another commonly cited culprit is phosphoric acid, an ingredient in colas. Studies have indicated that if the ratio of phosphorus to calcium in your body tips too far toward phosphorus, it can cause bone loss over time. So although a “Coke and a smile” once in a while won’t a brittle bone make, Heaney urges drinking a tall glass of milk to keep your bones good and strong.

The post Will Drinking Carbonated Beverages Weaken My Bones? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Humans haven’t fared well against IBM computers.

Record-holding Jeopardy! champions Ken Jennings and Brad Rutter lost to IBM’s Watson last year on national television. Garry Kasparov, often considered history’s greatest chess player, fell to IBM’s Deep Blue in 1997.

Machines outsmarted men, but which machine would outsmart the other?

In some sense, neither. Comparing smarts is slippery business, especially with an English major like Watson and a math guy like Deep Blue.

“They were both significantly smarter than similar systems of their type when they appeared, but the nature of their intelligence is very different,” says Doug Downey, a machine learning and artificial intelligence researcher at Northwestern University. Like Johnny Unitas and Willie Mays, Deep Blue and Watson weren’t programmed to compete with each other. They played and succeeded at very different games.

Still, the two systems don’t defy comparison, and there is one very important difference: Deep Blue stayed in computers’ comfort zone; Watson walked on awkward terrain for a machine.

“The easiest thing for computers is super advanced math,” says Stephen Baker, former BusinessWeek technology writer and author of Final Jeopardy, an inside look at the creation of Watson. “The hardest thing for them is kindergarten.” Chess kept Deep Blue in the realm of what computers are good at, using statistics and probabilities to determine strategy. Jeopardy!, on the other hand, pushed Watson into an unfamiliar world of human language and unstructured data.

Though it seems counterintuitive from a human perspective, “Watson is a far more sophisticated program than Deep Blue, because it’s closer to mastering kindergarten (though still far away),” Baker says.

In the future, advanced computers will likely merge Watson’s mastery of knowledge and language with Deep Blue’s computational power. “That’s kind of where we’re going as field: a system that’s as broad as Watson but as deep as Deep Blue,” Downey says.

These types of computers could have far-reaching applications. “Imagine if we could do that in the medical domain,” Downey says. “It would just be tremendous.” For difficult or rare diagnoses, computers could potentially connect dots between symptoms, diagnoses and treatments that doctors don’t always see. Such technology would become a doctor’s ultimate sidekick, but you shouldn’t expect a walking, talking Dr. Watson to replace your family physician in the exam room any time soon. Chess and Jeopardy! seem like benchmarks of human intelligence, but “Deep Blue didn’t actually play chess,” Downey says. “It generated chess moves but it required a person to sit at the table and actually execute moves.” And with Watson, “There wasn’t a robot that walked up to the podium, picked up the buzzer and rang in on time.”

Downey goes on: “It turns out, sensory motor skills and also just common sense that people have, those have been the tougher hurdles for AI.” What comes easiest to humans comes hardest to computers, and vice versa.

Deep Blue and Watson might have defeated brilliant champions at chess and Jeopardy!, but neither could compete with a toddler at some of the most basic forms of human cognition.

Have a burning science question you’d like to see answered in our FYI section? Email it to fyi@popsci.com.

The post FYI: Which Computer Is Smarter, Watson Or Deep Blue? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

Last week, Hostess Brands, Inc. announced it was going out of business, raising fears of an orphaned Twinkie the Kid, inciting Twinkie runs on eBay, and turning up home-made recipes for the snacks. (So many recipes.) It’s since been reported that mediation will save the company, but we still need to know: Can you really make a homemade Twinkie taste the same as the version with the Hostess stamp of approval?

The abundance of recipes available online will yield a similar but not identical treat. Twinkies, notoriously, make use of an arsenal of industrial ingredients like sodium caseinate to ensure an exactly reproducible and shelf-stable texture and flavor. Chances are, you don’t have a full stockpile of sodium caseinate in your cupboard waiting for you to recreate childhood memories, but that sort of thing is more and more available.

The industrial baking process is tough to replicate at home as well, says Steve Ettlinger, author of Twinkie, Deconstructed. There’s a lot you can do at home, but a precisely-timed, industrialized mold-release system isn’t in the budget for most families. Neither is a continuous over that quick-bakes them in just a few minutes, or a line to immediately package the snacks as soon as they’re done.

For the majority of home cooks, then, those recipes that use more-common ingredients–pound cake mix, powdered sugar, a reasonably large number of eggs–are a safer bet. Nothing wrong with those. In fact, Ettlinger writes in Twinkie, Deconstructed, the original Twinkies were probably closer to the ones produced through such processes; the recipe was only changed later, to increase the shelf life.

So what is it about the way an industrial Twinkie tastes that’s so hard to copy at home? The way Twinkie filling leaves a coating on the tongue, Ettlinger says by way of example, might be a result of the polysorbate 60 used as an emulsifier. The flavor of the cake itself comes from artificial vanilla flavor (as opposed to actual vanilla extract). Dextrin is used as a crispness enhancer. The more exotic ingredients in Twinkies also help keep moisture out, something that the sponge-cakey version made with home ingredients can’t replicate as easily. “They have perfected the art of stabilization,” Ettlinger says of the commercial bakers. Only one of the ingredients on the list is a true preservative — sorbic acid — but as a result of the moisture barrier, says Ettlinger, a Twinkie stays fresh much longer than it would if it were made with traditional dairy-based ingredients, which spoil easily and need to be served relatively quickly (but arguably taste better).

The post FYI: Can You Make An Authentic Twinkie At Home? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

It goes without saying that global warming is one of the thorniest problems of our time. If only we had some kind of sponge to just soak up all that carbon dioxide! The Metal Organic Frameworks (MOFs) developed by UCLA researchers might not be a catchall solution. But as the most porous materials on earth, they can be used to store, separate or convert molecules–and could help absorb harmful gases before they reach the air.

MOF-210

Lead researcher Omar Yaghi discovered a way to make highly porous MOFs in 1999, and his team continues to update that work today–their most porous materials to date are called MOF-200 and MOF-210. The pore aperture measures of these materials is 32 by 24 angstroms (ten billionth of a meter). The internal diameter is 47 angstroms. We’re talking in pretty tiny terms here, but those are the largest reported MOF pore measurements we know of. Other materials like mesoporous silica and porous carbon have very large aperture and pore sizes, too. One difference: they don’t have the same flexible structure as MOFs. The researchers found that the pore aperture of MOFs can be controlled on the angstrom level by increasing the number of atoms in the organic links of its design.

Even though MOF-200 and 210 are the most porous materials on earth by a long shot, other materials in this category are still pretty impressive gas absorbers. Check out how a chemical company in Germany, applies MOFs ability to store gases for an application in vehicle fuel tanks.

Fun fact: MOFs also have very high surface area. (After all, more pores equal more surfaces.) Northwestern University researchers designed two MOFs that hold the award for greatest internal surface area. Is there a world record for the material with the most world records?

The post FYI: What’s The Most Porous Material On Earth? appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.