Tech evangelists predicted that 2016 would be “the year of virtual reality.” And in some ways they were right. Several virtual reality headsets finally hit the commercial market, and millions of people bought one. But as people begin immersing themselves in new realities, a growing number of worrisome reports have surfaced: VR systems can make some users sick.

Scientists are just beginning to confirm that these new headsets do indeed cause a form of motion sickness dubbed VR sickness. Headset makers and software developers have worked hard to combat it, but people are still getting sick. Many in the industry fear this will be a major obstacle to mass adoption of virtual reality.
“A lot of VR, people today cannot tolerate,” says Kay Stanney, a human factors engineer with a focus on VR at Design Interactive in Orlando, Fla. Search for “VR sickness” on Twitter, she says, and you’ll see that people are getting sick every day.

Around 25 to 40 percent of people suffer from motion sickness depending on the mode of transport, scientists have estimated, and more women are susceptible than men.

Count me among those women. I’m highly prone to motion sickness. Cars, planes and boats can all make me feel woozy. It can take me a day or more to fully shake the nausea, headache and drowsiness. Certain that virtual reality would also make me sick, I’ve purposefully avoided strapping on a headset. (Until this assignment came along.)
So far, avoiding VR hasn’t been much of a loss for me. A lot of the VR industry is focused on video games, vying for a chunk of an estimated $100 billion market. And most of the early adopters who are willing to pay for one of the new premium headsets — $400 for Sony’s PlayStation VR or $800 for an Oculus Rift or HTC Vive — are probably serious gamers or technophiles. I don’t fit either category.

But, avoidance promises to become harder as VR moves beyond games. The technology has already begun creeping into other fields. Car companies, including Audi, General Motors Co.and used-car seller Vroom, are building VR showrooms where you can check out cars as if you were actually on the lot. Architects are using VR to walk clients through buildings that don’t yet exist. Schools and learning labs are taking students on virtual field trips to both contemporary and historical sites.

Facebook CEO Mark Zuckerberg sees virtual reality as the next big social platform. In 2014, Facebook bought Oculus VR, maker of the Rift headset, for around $2 billion. “This is really a new communication platform,” Zuckerberg wrote in the Oculus announcement. “Imagine sharing not just moments with your friends online, but entire experiences and adventures.” New VR sites where people can socialize or play games together in virtual spaces, like AltspaceVR and Rec Room, are springing up. And some tech luminaries see a future in which VR is integrated into many more aspects of our daily lives, from movies and entertainment to work and health care.

Nobody knows if the broader public will embrace virtual reality. Sales of the expensive high-end headsets have been underwhelming — the three premium systems combined sold an estimated 1.5 million headsets in 2016. But sales of cheaper mobile headsets were more impressive. For less than $100, Samsung Gear VR, Google Daydream View, Google Cardboard and others are powered by your mobile phone. But with smaller screens and less computer power, they are far less capable than the Rift or the Vive. Still, they are selling. In January, Samsung reported that it had sold 5 million of the $99 Gear VR headset since its release in November 2015.

But VR may never really catch on if it makes people sick. And while VR companies and developers are confident that they’ll find solutions, many motion sickness experts are pessimistic. “My hunch is that [the solutions] are extremely limited,” says Steven Rauch, director of the Vestibular Division at Massachusetts Eye and Ear in Boston.

In some ways, the very premise of virtual reality makes it an ideal vehicle for motion sickness.

Cue conflict or instability
Motion sickness has probably been with us as long as we’ve had boats. References to seasickness date back to Greek mythology; the word nausea is derived from the Greek naus, meaning ship. J.A. Irwin introduced the term motion sickness in the scientific literature in 1881. Since then, an extensive body of research has accumulated.

The most widely accepted theory to emerge is that motion sickness is brought on by a mismatch between two or more of the senses that help you keep your balance. For example, when you’re below deck on a ship at sea, your eyes see a stationary room. But your vestibular system — the fluid-filled canals and specialized membranes in your inner ear — senses the motion of the ship as it rolls over waves. “You’re getting conflicting information on different sensory channels into the balance system,” Rauch says. “That is believed to be the primary cause of motion sickness.”

In virtual reality, the mismatch is there as well, says visual neuroscientist Bas Rokers of the University of Wisconsin–Madison. But the sensory cues are reversed: Your eyes see that you are moving through the virtual world — in a virtual car or a virtual spaceship, or strolling down a virtual path — but your vestibular system knows you’re not actually moving. “That gives you a cue conflict,” he says.

While most motion sickness experts think sensory mismatch is to blame, some disagree. Kinesiologist Thomas Stoffregen of the University of Minnesota in Minneapolis, who’s been studying motion sickness for 25 years, thinks instability is the culprit. On a ship, the rolling motion puts you off balance, and that makes you sick, he says. “Motion sickness situations are ones in which the control of your body is challenged somehow. If you don’t rise to that challenge, then the contents of your stomach may rise.”

This idea, known as the postural instability theory, can be applied to VR as well, Stoffregen says. If your eyes convince your brain that you’re in the virtual world, your body will respond to it instead of the real world you are physically in, which can throw your balance off. Imagine sitting in a chair in the real world while riding in a car in the virtual world. As the car approaches a turn, you’ll want to lean into it, which could land you on the floor. The more convincing the virtual world is, the more likely you are to link the control of your body to what you’re seeing, Stoffregen says. “And in a virtual car, that is a mistake.”

Gender matters
While the postural instability theory is outside the scientific mainstream, it offers an explanation for another mystery of motion sickness: why more women suffer than men.

Stoffregen and colleagues have shown repeatedly that it’s possible to predict who is likely to get motion sick in various circumstances by measuring postural sway — the small, subconscious movements people make to stay balanced while standing still. By analyzing several aspects of sway, including the distance, direction and timing of the movements, the researchers have found that people who are susceptible to motion sickness sway differently than those who aren’t. And postural sway differs measurably between men and women. The difference, Stoffregen says, can be attributed to physical differences between the sexes, such as height and center of balance.
Stoffregen’s research suggests women are also more prone to VR sickness than men . In a study published in December in Experimental Brain Research , Stoffregen and colleagues measured the postural sway of 72 college students before they were asked to play one of two VR games for 15 minutes using an Oculus Rift DK2. The first game made two of 18 men and six of 18 women feel motion sick, not enough for a statistically significant difference.
But more than half of the students who played the horror game Affected, using a handheld controller to explore a dark, spooky building, reported feeling sick. Of the 18 women playing that game, 14 felt sick. That’s nearly 78 percent, compared with just over 33 percent of the men. When the scientists compared those results against the postural sway data, just as in their previous motion sickness studies, they found a measurable difference in sway between those who got sick and those who didn’t (SN: 1/21/17, p. 7).

Rokers has another explanation for the gender difference that fits with the sensory mismatch theory. In a study published in January 2016 in Entertainment Computing, Rokers and colleagues looked at how visual acuity might affect susceptibility to VR sickness. Seventy-three people with either natural or corrected 20/20 vision completed a battery of visual tests and then spent up to 20 minutes in an Oculus Rift DK1 headset watching videos. The videos showed motion from different points of view, such as a drone flying around a bridge or a passenger in a car driving through mild traffic. Of the female participants, 75 percent felt sick enough to stop watching before the 20 minutes had passed, compared with 41 percent of the men.

People who were better at perceiving 3-D motion in the visual tests were more likely to feel sick. And on average, the women in the study performed better on the 3-D motion perception tests than the men.

It’s not clear why women would have better visual acuity for 3-D motion, but the results suggest that the more sensitive you are to sensory cues, the more likely you are to detect a mismatch, Rokers says. “If you can tell that your senses are providing you different information, then you are more likely to get motion sick.”

Just being a woman doesn’t necessarily mean you’ll be highly susceptible to motion sickness like I am. Lots of other factors are likely at play. Some research suggests Asians are more likely to suffer. People who get migraines are also unusually prone to motion sickness. Scientists at genetic-testing company 23andMe reported in Human Molecular Genetics in 2015 that they had found 35 genetic variants associated with car sickness. Age is also a factor: Infants are generally immune, susceptibility increases from age 2 to 15, and although it hasn’t been my experience, the problem subsides for many people in adulthood.

Everybody’s brain has a different capacity for processing motion, Rauch says. “Just like some people are good with languages and some people are good with math, some people are good with motion processing, of doing this complex sensory-integration task. The people who are good at it become figure skaters and divers and gymnasts,” he says. “But there are other people who throw up if they ride backwards on the metro.” That would be me.

Under the right circumstances, though, anyone with a functioning vestibular system can experience motion sickness — nearly everyone stranded on a lifeboat in choppy seas will get sick.

Very little motion sickness research has been done on the latest VR headsets available to consumers. But Rauch says the very nature of VR, which is to trick your eyes into telling your brain you’re in another world, is inviting a sensory conflict. “There’s always going to be some sensory conflict, and so the VR is going to be more successful in people who can tolerate that,” Rauch says. For me, he was clear: “It’s always going to be torture.”
Motion and movement
Some games, like theBlu: Encounter (screenshot shown on first slide) and Job Simulator (middle slide), are unlikely to cause sickness because they require little movement around the virtual world. The dinosaur-hunting game Island 359 (last slide) has a teleport option for more susceptible players.
Sprint past trouble spots
The U.S. military was the first to report, in 1957, that virtual environments could be problematic: Flight simulators were making some pilots motion sick. Since then, many studies have confirmed that simulator sickness is a real problem.

One of the biggest tech hurdles for VR has been the inherent delay between when you move your head and when the display updates to reflect that movement. If the lag is too great, you can end up with a potentially vomit-inducing sensory mismatch. Today’s high-end systems have capitalized on advances in displays, video rendering, motion tracking and computing to cut down the lag to the neighborhood of 20 milliseconds — low enough to avoid triggering motion sickness. “They’ve beaten most of the pure hardware problems,” says Steven LaValle, a computer scientist at the University of Illinois at Urbana-Champaign and a former head scientist at Oculus.

But even with the best virtual reality system, what you do in the virtual world matters. If you’re sitting or standing in one place in both the real world and the virtual world, you’re very unlikely to feel sick. And as long as a step in the real world results in an equivalent step in the virtual world, moving around is fine too. All three of the premium headsets use external lasers to track the motion of the headset within a limited space — up to 3.5 meters by 3.5 meters with the HTC Vive. But to explore further, you’ll need to use handheld controllers with buttons, triggers and directional touch pads to move your virtual self around, just as in a regular 2-D video game. That’s where things can go wrong.

“I like to joke that the controller is like a sickness generator,” says LaValle, who worked on reducing motion sickness while at Oculus. “Every time you grab onto a controller, you’re creating motions that are not corresponding perfectly to the physical world. And when that’s being fed into your eyes and ears, then you have trouble.”

The people creating the content for VR systems are taking the problem seriously, says Steve Bowler, cofounder of VR game company CloudGate Studio, based outside of Chicago. Developers “are really, really focused on zero tolerance for user motion sickness.”
One of the most successful strategies developers have hit on is using teleportation to take short skips around the virtual world. Basically you aim the controller where you want to go and the screen fades to black for a split second, sort of like the blink of an eye. When it fades back in, you’re at the new location. This, Bowler says, eliminates motion sickness even for the most susceptible people he knows. But that comfort comes at a cost: The whole point of VR is to convince you that you’re physically in this other world; if you’re magically teleporting here and there, it’s not going to feel as real, he says.

Bowler favors a technique known as “sprint” or “dash” that aims to reduce the effects of acceleration. Instead of gradually ramping your speed up and back down, a sprint bumps you up to speed almost instantaneously, maintains that speed until you reach your target and then drops you quickly back down to a standstill.

While sprinting doesn’t approximate natural movement very well, it does let you see the motion, unlike teleportation. And Bowler says he’s had about a thousand people at various events try sprinting in a dinosaur-hunting game his group built called Island 359 with almost no reports of motion sickness. Anyone who feels uncomfortable can switch to chasing dinosaurs using a teleportation option instead.

Oculus seems to have accepted that VR sickness can’t be eliminated from all VR experiences at the moment, so most Oculus-approved games come with “comfort ratings” to let users know if a game or experience is more or less likely to make them sick. Those assessments might help people like me avoid the most nauseating games.

It gets real
Bowler considers himself an ambassador for virtual reality. After almost an hour of very patiently and enthusiastically explaining how VR works, he somehow convinced me to try it. A few days later I was at UploadVR in San Francisco strapping on the HTC Vive with Bowler looking on via Skype from his office in the Chicago suburbs.

The headset was heavy and awkward, but I otherwise felt fine while creating a virtual 3-D painting or walking around on the deck of a shipwreck as an enormous blue whale swam by ogling me. I even shot at drones while dodging virtual bullets, with no hint of motion sickness. I decided I was ready to hunt dinosaurs.

First I tried teleportation mode in Bowler’s game, and as he promised, no nausea. Though the splatters of blood and guts when I slashed some attacking mini dinosaurs was almost enough to make me gag, the strangeness of teleportation made me feel more like I was inside a 2-D video game than on a dinosaur-infested island. I decided to see if I could handle sprint mode. I wanted to know if it would feel more real.

That was a mistake. I could only manage about a half dozen sprints before I felt the first hints of nausea. I had to quit. Once the headset was off I felt better. But soon, a lingering nausea and drowsiness hit, like I sometimes experience after a turbulent flight. I didn’t entirely recover until the following evening. I’m glad Bowler convinced me to give it a try, and the parts I could handle were pretty fun. But I won’t be going back for more anytime soon.

Virtual reality still has lots of room for improvement, but whether it will ever reach the point of being comfortable for everyone is an open question. The VR industry is moving at a pace science can’t match, forging ahead with its own grand experiment as millions of users test its products. Much of what we learn about how VR affects people will show up first in living rooms and on Twitter rather than in scientific labs and journals. And though the results of those experiments are still coming in, tech luminaries haven’t hesitated to declare 2017 as the real year of virtual reality.
This article appears in the March 18, 2017, issue of Science News with the headline, “Real sick: The immersive experience of the virtual world is not for everyone.”

NEW ORLEANS — Black holes and superfluids make for strange bedfellows: One is famous for being so dense that light can’t escape, and the other is a bizarre liquid that flows without friction. But new computer simulations confirm that superfluid helium follows an unusual rule known from black holes — one with mysterious significance for physics.

Scientists demonstrated that entropy, a measure of the information contained in a system, behaves in a counterintuitive way in superfluid helium. Entropy grows at the same rate as the surface area of the superfluid helium, instead of its volume — mimicking how the entropy of a black hole grows as it gobbles up matter and expands. It’s the first time the phenomenon, known as the “area law,” has been demonstrated in simulations of a naturally occurring state of matter. Physicists reported the result March 14 at a meeting of the American Physical Society and March 13 in Nature Physics.
“If you double the size of a box, you expect to be able to double the amount of information in that box,” says physicist Christopher Herdman of the University of Waterloo in Canada. But that’s not the case for black holes. Progress toward a theory that unifies quantum mechanics and general relativity, a still thorny problem, has convinced many physicists that black holes instead follow the area law.

To demonstrate the law in a superfluid, Herdman and colleagues created a computer simulation of helium. The isotope they studied, helium-4, is the same stuff that keeps birthday balloons aloft, and it becomes a superfluid at temperatures below about 2 kelvins (–271° Celsius).

In the simulation, the researchers kept track of the helium atoms’ entanglement — quantum linkages that intertwine particles. Within the superfluid, scientists selected an imaginary sphere of the material, and studied the entanglement between atoms inside the sphere and those outside of it. That entanglement gives rise to a type of entropy in the superfluid. As the researchers increased the size of that sphere, the entropy of entanglement increased as well. The rate of increase matched that of the sphere’s increase in surface area, which grows more slowly than its volume.

The superfluid sphere is analogous to a black hole’s event horizon, the region of no return surrounding the black hole, beyond which light can’t escape. In black holes, particles on one side of the event horizon can be entangled with those on the other side, creating entanglement entropy in a similar way.

“I think it’s a fascinating result,” says physicist Joe Serene of Georgetown University in Washington, D.C. But, to advance from simulations to a measurement of entanglement entropy in real-life helium would likely be difficult. “It remains to be clear how much they can actually get out of real experimental systems,” Serene says.
This area law has outsize importance in physics. The realization that a black hole’s entropy is proportional to its surface area led to the holographic principle, the idea that the information within a region of space might be completely reproduced on its surface (SN Online: 9/8/14). Scientists hope this concept could lead to a full theory of quantum gravity, uniting the physics of the very small with large-scale gravity.

What’s more, some scientists now believe that the very structure of spacetime might be the result of quantum entanglement (SN: 5/31/14, p. 16), an idea that also grew out of the area law.

“Entanglement entropy is a concept that is successful across many different areas of physics,” says physicist Markus Greiner of Harvard University. “The big problem is no one knows how to measure that in … real-world systems.”

SAN FRANCISCO — Millennials, rejoice: A winking-face emoji is worth a slew of ironic words. The brain interprets irony or sarcasm conveyed by an emoji in the same way as it does verbal banter, researchers reported March 26 in San Francisco at the Cognitive Neuroscience Society’s annual meeting.

Researchers measured brain electrical activity of college students reading sentences ending in various emojis. For example, the sentence “You are such a jerk” was followed by an emoji that matched the words’ meaning (a frowning face), contradicted the words (a smiling face) or implied sarcasm (a winking face). Then the participants assessed the veracity of the sentence—was the person actually a jerk?
Some participants read the sentence literally no matter what, said Benjamin Weissman, a linguist at the University of Illinois at Urbana-Champaign. But people who said emojis influenced their interpretation showed different brain activity in response to sentences with a winking emoji than ones with other emojis. A spike in electrical activity occurred 200 milliseconds after reading winky-face sentences, followed by another spike at 600 milliseconds.

A similar electrical pattern has been noted in previous studies in which people listened to sentences where intonation conveyed a sarcastic rather than literal interpretation of the words. That peak at 600 milliseconds has been linked to reassessment. It’s as if the brain reads the sentence one way, sees the emoji and then updates its interpretation to fit the new information, Weissman said.

This study provides more evidence suggesting that emojis aren’t just frivolous adornments to texts. “There are lots of complex linguistic functions they can serve,” Weissman said.

A puzzling neutrino shortfall seems to be due to faulty predictions, not a new particle.

In experiments at nuclear reactors, scientists have consistently found about 6 percent fewer antineutrinos, the antimatter form of neutrinos, than expected. That deficit could hint that the lightweight particles are morphing into undetectable new particles called sterile neutrinos (SN: 3/19/16, p. 14). But in a paper published online April 4 at arXiv.org, scientists with the Daya Bay experiment, located near a nuclear power plant in China, point to the calculations that underlie scientists’ predictions to explain the missing antineutrinos.

Inside nuclear reactors, multitudes of antineutrinos are born in radioactive decays of isotopes such as uranium-235 and plutonium-239. Scientists can predict how many antineutrinos each isotope should produce. If sterile neutrinos are the source of the disagreement, detectors should observe an antineutrino deficit from both isotopes. Instead, the researchers found that plutonium-239 agreed with predictions, but researchers detected fewer neutrinos than expected from uranium-235. That means there’s probably something funny with the uranium-235 calculations.

This isn’t the end for sterile neutrinos — there are other hints that they exist. If so, sterile neutrinos could constitute dark matter, an unknown invisible substance that pervades the universe.

Bacteria in the vagina affect whether a drug stops an HIV infection or is itself stopped cold.

A vaginal gel containing tenofovir, an antiretroviral drug used to treat HIV infection, was three times as effective at preventing HIV in women who had healthy vaginal bacterial communities as it was in women with a less beneficial mix. The finding may help explain why the effectiveness of these gels has varied in trials, researchers report in the June 2 Science.
“The vaginal microbiota is yet another variable that we have to take into account when we are thinking about why one intervention does or doesn’t work,” says clinical scientist Khalil Ghanem of Johns Hopkins University School of Medicine, who coauthored a commentary accompanying the study.

For women, one strategy to prevent HIV infection is to apply medicated vaginal gels before and after sex. But results have been mixed regarding how well the gels work. The hit-or-miss effectiveness can partly be explained by some patients not taking the medication as prescribed. But study coauthor Adam Burgener, a microbiologist at the Public Health Agency of Canada in Winnipeg, wondered if there might also be a biological explanation.

The main residents of a healthy vaginal microbial community, or microbiota, are Lactobacillus species. The bacteria produce lactic acid, making the vaginal tract more acidic and possibly “less hospitable for potential pathogenic organisms,” Ghanem says.

To examine the effect of the vaginal microbiota on tenofovir, Burgener and colleagues turned to a previous trial of South African women, which showed that the drug reduced HIV infections by 39 percent. During that trial, samples of vaginal mucus were taken. In the new study, the researchers measured bacterial proteins in 688 of those samples to determine the bacteria in the women’s vaginas when the samples were collected.

Just over 400 women’s vaginal microbiota mainly had Lactobacillus species; the microbiota of the other 281 women were dominated by non-Lactobacillus species, such as Gardnerella vaginalis. Within those two groups were women who had used tenofovir vaginal gel and those who had used a non-medicated gel as a placebo.
In the Lactobacillus-dominant group, the incidence of HIV was 61 percent lower in women using the medicated gel compared with those using the placebo gel. But in the non-Lactobacillus dominant group, it was only 18 percent lower. There was no appreciable difference in the consistency of the gel’s reported use between the two groups, the researchers note.

“Women with Lactobacillus had three times more protection offered by the gel,” Burgener says. “That’s a pretty remarkable difference in the efficacy of a drug.”

Looking at a random subset of 270 of the samples, the researchers found that the vaginal gel drug levels were lower in the mucus from the non-Lactobacillus group. So, in a test tube, they mixed a laboratory strain of G. vaginalis with tenofovir. After four hours, the amount of tenofovir in the tube had decreased by 50 percent. In a similar experiment with two Lactobacillus species, the amount of the drug remained about the same. It appears that the G. vaginalis bacteria “gobbled up the drug and depleted it,” Burgener says.

It’s known that microbes in the gut can impact the metabolism of medications, says clinical scientist and commentary coauthor Susan Tuddenham of the Johns Hopkins University School of Medicine. “This study tells us that when we are thinking about vaginally delivered medications, we may need to think about the vaginal microbiome as well.”

The work also shows that women closely following directions for vaginal medications “could be doing everything right and still not getting the full benefit of that medication,” Ghanem says.

Particles of light born in space have connected two cities via a quantum link about 10 times longer than any created before.

A quantum-communications satellite beamed photons to Earth, separating them by more than 1,200 kilometers. The feat showed that the particles of light can retain a strange type of interconnectedness, known as quantum entanglement, even when flung to opposite ends of a country, researchers from China report in the June 16 Science. The previous distance record was about 100 kilometers (SN: 6/30/12, p. 10). Launched in 2016, the one-of-a-kind satellite is laying the groundwork for a space-based network of quantum communication.
“It’s a huge achievement for quantum entanglement and quantum science,” says physicist Thomas Jennewein of the University of Waterloo in Canada.

Scientists have previously beamed photons up to a satellite and back again (SN Online: 6/5/16), but those particles were not entangled. Until now, no one had distributed entangled particles from space. “China is now clearly taking the world leadership in this area of quantum communication,” Jennewein says.

The technique is expected to have major technological applications. “This experiment is really important for the development of a future quantum internet,” says Anton Zeilinger, a physicist at the University of Vienna. Such a network would allow for ultrasecure communications and could connect quantum computers across the globe (SN: 10/15/16, p. 13).

An ethereal bond between two particles, entanglement is the most essential ingredient of a quantum network. Entangled particles can’t be described independently; instead, they form one unit, even when separated by large distances. Measuring one entangled particle immediately reveals the state of the other. To perform quantum communication, scientists send entangled photons from place to place. But photons can only travel so far through air or optical fibers before the material absorbs the particles, limiting the distance over which communication is possible. In the emptiness of space, however, photons can travel much farther.

Using the satellite, named Micius after an ancient Chinese philosopher, the researchers beamed intertwined photon pairs down to the cities of Delingha in northern China and Lijiang in southern China. There, telescopes aimed at the satellite detected the particles. To confirm that the particles were entangled, and that the weird qualities of quantum mechanics held, the researchers used the photon pairs to perform a Bell test (SN: 9/19/15, p. 12), which analyzes correlations between the two particles. The test reconfirmed the odd physics of the supersmall, at a larger distance than ever before.
To perform the experiment, the researchers had to update their quantum equipment to make it work in space. That technological achievement is amazing, says physicist Harald Weinfurter of Ludwig-Maximilians-Universität in Munich. “It’s a huge step from the laboratory experiments to equipment which really works on a satellite,” he says. In space, sensitive components must deal with inhospitable conditions such as fluctuating temperatures and vibrations. Plus, to fit on the satellite, the whole package must be small and lightweight.

Detecting the photons is likewise daunting. Beacon lasers helped researchers point the ground-based telescopes in the right direction to catch the photons, as the satellite zipped past, 500 kilometers above Earth’s surface. The accuracy the researchers achieved is like pinpointing a human hair on the ground from the top of the Eiffel Tower.

In the future, researchers suggest, quantum entanglement will be an important resource for communicating across the globe. “Today we pay bills: electrical bills, water bills,” says coauthor Chao-Yang Lu, a physicist at the University of Science and Technology of China in Hefei. With quantum entanglement such a basic requirement of quantum communication, “maybe someday we will need to pay some entanglement bills.”

Unusually severe storms in 2016 wrought the quickest meltdown of Antarctic sea ice ever seen during a Southern Hemisphere spring. This could explain why Antarctica’s sea ice extent hit a record low earlier this year.

Satellite images show that the extent of Antarctic sea ice decreased by an average of 75,000 square kilometers — almost the area of South Carolina — each day from September through December 2016. That was 18 percent faster than the previous record melt rate for this time of year and nearly 50 percent faster than average, researchers report online June 20 in Geophysical Research Letters.
Typically, the ring of sea ice surrounding Antarctica expands and contracts over the course of a year, usually peaking at around 18 million square kilometers in September, then shrinking to about 3 million by February. The average expanse of sea ice in a given year has increased since satellite monitoring started in 1979. So scientists were surprised that the sea ice shrank so radically this year. It hit 4.04 million square kilometers in January (SN Online: 2/17/17) and kept shrinking, dropping to about 2 million square kilometers by the beginning of March.
The new study provides the first comprehensive analysis of why this drastic decline happened, says Walt Meier, a climate scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., who was not involved in the work. Researchers examined weather data and found that a series of especially intense storms barraged the Southern Ocean during September, October and November 2016. Strong winds would have broken up the fragile sea ice, which is only about a meter thick, and bombarded it with warm air. Together, that hastened the usual springtime melting.

“People have said to us, ‘Is this global warming kicking in?’” says study coauthor Josh Turner, a climatologist at the British Antarctic Survey. But it’s impossible to pin one weird season on human-made climate change since scientists have been tracking sea ice extent for only a few decades — and it can vary widely from one year to the next.
“The big takeaway is that the Antarctic sea ice is very variable,” Meier says. “It has high highs and low lows, and we may not have seen the full range of it until now. Or maybe not even now.”

Scientists pour a lot of brainpower into understanding how their experimental equipment works.

You don’t want to be fooled into thinking you’ve made a great discovery because of some quirk in the apparatus you didn’t know about. Just the other day, a new paper published online suggested that the instruments used to detect gravitational waves exhibited such a quirk, tricking scientists into claiming the detection of waves that maybe weren’t really there.

It appears that gravity wave fans can relax, though. A response to the challenge pretty much establishes that the new criticism doesn’t undermine the wave discoveries. Of course, you never know — supposedly well-established results sometimes do fade away. Often that’s because scientists have neglected to understand the most important part of the entire experimental apparatus — their own brains.

It’s the brain, after all, that devises experiments and interprets their results. How the brain perceives, how it makes decisions and judgments, and how those judgments can go awry are at least as important to science as knowing the intricacies of nonbiotic experimental machinery. And as any brain scientist will tell you, there’s still a long way to go before understanding the brain will get crossed off science’s to-do list. But there has been progress. A recent special issue of the journal Neuron offers a convenient set of “perspective” papers exploring the current state of understanding of the brain’s inner workings. Those papers show that a lot is known. But at the same time they emphasize that there’s a lot we don’t know.

Glancing at the table of contents reveals the first lesson about understanding the brain: It’s a complex problem that needs to be approached from multiple perspectives.

On one level, there’s the dynamics of electrical currents that constitute the main signaling method of the brain’s nerve cells. Then on a higher level there’s the need to figure out the rules by which nerve cells make connections (synapses) and create the neural circuitry for processing sensory input, learning and behaving. Another challenge is understanding how nerve cell networks represent memories and how you recall what you’ve learned. And it’s essential to understand how neurobiological processing conducted by molecules and cells and electrical signaling gets translated into behaviors, from simple bodily movements to complex social interactions.

Nerve cells in the brain, or neurons, are known to communicate among themselves by transmitting electrical signals, aided by chemical signaling at the synapses connecting the neurons. But there are gaps in understanding how that process takes the brain from perceptions to thoughts to actions. Each of Neuron’s perspective papers both describes what’s already known about how the brain works and offers speculations where scientists lack full knowledge about how the brain does it jobs.

Much of the effort to explain the brain involves mapping the electrical signaling throughout the entire network of nerve cell connections. Per Roland of the University of Copenhagen, for instance, discusses how those signals vary in space and time. He emphasizes the important balance between signaling that incites neurons to send signals and the messaging that inhibits signaling, keeping some neurons quiet.
Sophie Denève and colleagues of the Ecole Normale Supérieure in Paris also emphasize the balance between excitation and inhibition in neural circuitry. That balance is important, they say, for understanding how the whole brain can learn to do things based on changes in the connections between individual neurons. Somehow the rules governing synaptic connections between cells enable such “local” activity to modify the “global” neural circuitry that carries out the brain’s many functions. Excitation-inhibition balance, plus feedback from the global network influencing synapse strength, “can ensure that global functions can be learned with local learning rules,” Denève and colleagues write.

Almost all these approaches to figuring out the brain involve how it manipulates information. In a sense, the ultimate key question is how the brain conducts the mysterious process by which it absorbs information in the form of lights and colors, sounds, smells and tactile inputs and transforms them into physical actions — ideally behaviors that are appropriate responses to the inputs. Just (OK, not “just,” but sort of) as in a computer, the brain transforms input into output; information about the external world is manipulated to produce information about how to react to it.

But because sensory input has its limits, and some of it is ambiguous, the informational variables of the external world cannot be gauged with certainty, Xaq Pitkow and Dora Angelaki of Baylor College of Medicine and Rice University in Houston point out in their perspective. So the brain’s behavioral choices must be based on some method of computing probabilities to infer the likely state of the world — and then choosing the wisest (probably) actions in response.

“It is widely accepted that the brain somehow approximates probabilistic inference,” Pitkow and Angelaki write. But nobody really knows how the brain does it. Pitkow and Angelaki propose that multiple populations of the brain’s neurons perform various computations to make appropriate behavioral decisions.

Patterns of electrical signaling by these neurons must represent the original sensory stimuli — that is, the patterns in the stimuli are encoded in the patterns of electrical signaling among the neurons. Those neural signaling patterns, in Pitkow and Angelaki’s description, are then recoded into another set of patterns; that process sorts out the important variables in the environment from those that don’t matter. Those patterns are then decoded in the process of generating behavioral actions.

In sum, the brain appears to implement algorithms for collecting and assessing information about the environment and encoding that information in messages that tell the body what to do. Somehow those algorithms allow the brain to conduct statistical computations that combine beliefs about the environment with the expected outcome of different behaviors.

Pitkow and Angelaki present sophisticated speculation about the possible ways the brain could accomplish this task. It’s clearly an unimaginably complicated process, and figuring out how the brain does it will require more sophisticated experiments than neuroscientists have so far imagined. Much research on brain function in animals, for instance, offers the animal a choice of two options, given various external conditions. But tasks of that nature are vastly simpler than the jobs that evolution optimized brains for.

“The real benefit of complex inferences like weighing uncertainty may not be apparent unless the uncertainty has complex structure,” Pitkow and Angelaki argue. “Overly simple tasks” are “ill-suited to expose the inferential computations that make the brain special.”

And so truly understanding the brain, it seems, will require better experiments — using apparatus that is more fully understood than the brain now is — of sufficient complexity to be worthy of probing the brain’s abilities.

Some deep-sea tube worms get long in the tooth … er, tube. Living several decades longer than its shallow-water relatives, Escarpia laminata has the longest known life span for a tube worm, aging beyond 300 years, researchers report in the August Science of Nature.

E. laminata lives 1,000 to 3,300 meters deep in the Gulf of Mexico, near seafloor vents that seep energy-rich compounds that feed bacteria that feed the tube worms. In 2006, biologists marked 356 E. laminata in their natural habitat and measured how much the creatures had grown a year later. To estimate the ages of tube worms of different sizes, the researchers plugged E. laminata’s average yearly growth rate — along with estimates of birthrates and death rates, based on observations of another 1,046 tube worms — into a simulation. The species’s typical life span is 100 to 200 years, the researchers calculate, but some larger tube worms may be more than 300 years old.

With few large predators, deep-sea tube worms have got it good, says study coauthor Alanna Durkin, a biologist at Temple University in Philadelphia. “Once they find a seat at the buffet, they’re pretty set for hundreds of years.” The researchers’ methodology appears robust, says ocean scientist David Reynolds of Cardiff University in Wales, who was not involved in the work. Although variable environmental conditions could affect growth rate over time, he says.

Everybody poops, but the poop of bloblike filter feeders called giant larvaceans could be laced with microplastics.

Every day, these gelatinous creatures (Bathochordaeus stygius) build giant disposable mucus mansions to round up zooplankton into their stomachs — sometimes sifting through around 80 liters of seawater per hour. Kakani Katija and her colleagues at the Monterey Bay Aquarium Research Institute now suggest that tiny plastic particles also make their way in — and out — of giant larvaceans’ guts.

Microplastics pervade the ocean. Their combined mass could reach 250 million metric tons by 2025. Scientists don’t know a lot about where microplastics stick around in open water ecosystems.

To see if plastics could end up on the larvacean menu, Katija and colleagues tried feeding the animals brightly colored microplastics. An underwater robot equipped with camera gear helped the researchers monitor plastic intake from above. Some animals did end up scarfing down the particles, and some of those particles ended up in the organism’s waste, which showers down on the seafloor, Katija and colleagues report August 16 in Science Advances.

“Plastics are sometimes seen as a sea surface issue, and more and more we’re seeing that’s not necessarily true,” Katija says.

Just how much plastic ends up passing through giant larvaceans in the wild remains unclear. But the researchers suspect that the creatures’ poop, as well as their mucus houses, could transfer microplastics from the water’s surface to the depths of the sea (along with nutrients such as carbon that cycle through the environment). And that pollution transfer may impact the ecosystems at either end.