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Young children travel to fantasy worlds every day, packing just imaginations and a toy or two.

Some preschoolers scurry across ocean floors carrying toy versions of cartoon character SpongeBob SquarePants. Other kids trek to distant universes with miniature replicas of Star Wars robots R2-D2 and C-3PO. Throngs of youngsters fly on broomsticks and cast magic spells with Harry Potter and his Hogwarts buddies. The list of improbable adventures goes on and on.

Parents today take for granted that kids need toys to fuel what comes naturally — outlandish bursts of make-believe. Kids’ flights of fantasy are presumed to soar before school and life’s other demands yank the youngsters down to Earth.
Yet some researchers call childhood fantasy play — which revolves around invented characters and settings with no or little relationship to kids’ daily lives — highly overrated. From at least the age when they start talking, little ones crave opportunities to assist parents at practical tasks and otherwise learn how to be productive members of their cultures, these investigators argue.

New findings support the view that children are geared more toward helping than fantasizing. Preschoolers would rather perform real activities, such as cutting vegetables or feeding a baby, than pretend to do those same things, scientists say. Even in the fantastical realm of children’s fiction books, reality may have an important place. Young U.S. readers show signs of learning better from human characters than from those ever-present talking pigs and bears.
Studies of children in traditional societies illustrate the dominance of reality-based play outside modern Western cultures. Kids raised in hunter-gatherer communities, farming villages and herding groups rarely play fantasy games. Children typically play with real tools, or small replicas of tools, in what amounts to practice for adult work. Playgroups supervised by older children enact make-believe versions of what adults do, such as sharing hunting spoils.
These activities come much closer to the nature of play in ancient human groups than do childhood fantasies fueled by mass-produced toys, videos and movies, researchers think.
Handing over household implements to toddlers and preschoolers and letting them play at working, or allowing them to lend a hand on daily tasks, generates little traction among Western parents, says psychologist Angeline Lillard of the University of Virginia in Charlottesville. Many adults, leaning heavily on adult-supervised playdates, assume preschoolers and younger kids need to be protected from themselves. Lillard suspects that preschoolers, whose early helping impulses get rebuffed by anxious parents, often rebel when told to start doing household chores a few years later.

“Kids like to do real things because they want a role in the real world,” Lillard says. “Our society has gone overboard in stressing the importance of pretense and fantasy for young children.”

Keep it real
Lillard suspects most preschoolers agree with her.

More than 40 years of research fails to support the widespread view that playing pretend games generates special social or mental benefits for young children, Lillard and colleagues wrote in a 2013 review in Psychological Bulletin. Studies that track children into their teens and beyond are sorely needed to establish any beneficial effects of pretending to be other people or acting out imaginary situations, the researchers concluded.

Even the assumption that kids naturally gravitate toward make-believe worlds may be unrealistic. When given a choice, 3- to 6-year-olds growing up in the United States — one of many countries saturated with superhero movies, video games and otherworldly action figures — preferred performing real activities over pretending to do them, Lillard and colleagues reported online June 20 in Developmental Science.
One hundred youngsters, most of them white and middle class, were tested either in a children’s museum, a preschool or a university laboratory. An experimenter showed each child nine pairs of photographs. Each photo in a pair featured a boy or a girl, to match the sex of the youngster being tested. One photo showed a child in action. Depicted behaviors included cutting vegetables with a knife, talking on a telephone and bottle-feeding a baby. In the second photo, a different child pretended to do what the first child did for real.

When asked by the experimenter whether they would rather, say, cut real vegetables with a knife like the first child or pretend to do so like the second child, preschoolers chose the real activity almost two-thirds of the time. Among the preschoolers, hard-core realists outnumbered fans of make-believe, the researchers found. Whereas 16 kids always chose real activities, only three wanted to pretend on every trial. Just as strikingly, 48 children (including seven of 26 of the 3-year-olds) chose at least seven real activities of the nine depicted. Only 14 kids (mostly the younger ones) selected at least seven pretend activities.

Kids often said they liked real activities for practical reasons, such as wanting to learn how to feed babies to help mom. Hands-on activities also got endorsed for being especially fun or novel. “I’ve never talked on the real phone,” one child explained. Reasons for choosing pretend activities centered on being afraid of the real activity or liking to pretend.

In a preliminary follow-up study directed by Lillard, 16 girls and boys, ages 3 to 6, chose between playing with 10 real objects, such as a microscope, or toy versions of the same objects. During 10-minute play periods, kids spent an average of about twice as much time with real items. That preference for real things increased with age. Three-year-olds spent nearly equal time playing with genuine and pretend items, but the older children strongly preferred the real deal.

Lillard’s findings illustrate that kids want and need real experiences, says psychologist Thalia Goldstein of George Mason University in Fairfax, Va. “Modern definitions of childhood have swung too far toward thinking that young children should live in a world of fantasy and magic,” she maintains.

But pretend play, including fantasy games, still has value in fostering youngsters’ social and emotional growth, Goldstein and Matthew Lerner of Stony Brook University in New York reported online September 15 in Developmental Science. After participating in 24 play sessions, 4- and 5-year-olds from poor families were tested on empathy and other social skills. Those who played dramatic pretend games (being a superhero, animal or chef, for instance) were less likely than kids who played with blocks or read stories to become visibly upset upon seeing an experimenter who the kids believed had hurt a knee or finger, the researchers found. Playing pretend games enabled kids to rein in distress at seeing the experimenter in pain, the researchers proposed.

It’s not known whether fantasy- and reality-based games shape kids’ social skills in different ways over the long haul, Goldstein says.

True fiction
Even on the printed page, where youngsters gawk at Maurice Sendak’s goggle-eyed Wild Things and Dr. Seuss’ mustachioed Lorax, the real world exerts a special pull.

Consider 4- to 6-year-olds who were read either a storybook about a little raccoon that learns to share with other animals or the same storybook with illustrations of human characters learning to share. Both versions told of how characters felt better after giving some of what they had to others. A third set of kids heard an illustrated storybook about seeds that had nothing to do with sharing. Each group consisted of 32 children.

Only kids who heard the realistic story displayed a general willingness to act on its message, reported a team led by psychologist Patricia Ganea of the University of Toronto in a paper published online August 2 in Developmental Science. On a test of children’s willingness to share any of 10 stickers with a child described as unable to participate in the experiment, listeners to the tale with human characters forked over an average of nearly three stickers, about one more than the kids had donated before the experiment.

Children who heard stories with animal characters became less giving, sharing an average of 1.7 stickers after having originally donated an average of 2.3 stickers. Sticker sharing declined similarly among kids who heard the seed story. These results fit with several previous studies showing that preschoolers more easily apply knowledge learned from realistic stories to the real world, as opposed to information encountered in fantasy stories.

Even for fiction stories that are highly unrealistic, youngsters generally favor realistic endings, say Boston University psychologist Melissa Kibbe and colleagues. In a study from the team published online June 15 in Psychology of Aesthetics, Creativity and the Arts, an experimenter read 90 children, ages 4 to 6, one of three illustrated versions of a story. In the tale, a child gets lost on the way to a school bus. A realistic version was set in a present-day city. A futuristic science fiction version was set on the moon. A fantasy version occurred in medieval times and included magical characters. Stories ended with descriptions and illustrations of a child finally locating either a typical school bus, a futuristic school bus with rockets on its sides or a magical coach with dragon wings.
When given the chance, 40 percent of kids inserted a typical school bus into the ending for the science fiction story and nearly 70 percent did so for the fantasy tale. “Children have a bias toward reality when completing stories,” Kibbe says.
Hands on
Outside Western cultures, children’s bias toward reality takes an extreme turn, especially during play.

Nothing keeps it real like a child merrily swinging around a sharp knife as adults go about their business. That’s cause for alarm in Western households. But in many foraging communities, children play with knives and even machetes with their parents’ blessing, says anthropologist David Lancy of Utah State University in Logan.

Lancy describes reported instances of youngsters from hunter-gatherer groups playing with knives in his 2017 book Raising Children. Among Maniq foragers inhabiting southern Thailand’s forests, for instance, one researcher observed a father looking on approvingly as his baby crawled along holding a knife about as long as a dollar bill. The same investigator observed a 4-year-old Maniq girl sitting by herself cutting pieces of vegetation with a machete.

In East Africa, a Hadza infant can grab a knife and suck on it undisturbed, at least until an adult needs to use the tool. On Vanatinai Island in the South Pacific, children freely experiment with knives and pieces of burning wood from campfires.

Yes, accidents happen. That doesn’t mean hunter-gatherer parents are uncaring or indifferent toward their children, Lancy says. In these egalitarian societies, where sharing food and other resources is the norm, parents believe it’s wrong to impose one’s will on anyone, including children. Hunter-gatherer adults assume that a child learns best through hands-on, sometimes risky, exploration on his or her own and in groups with other kids. In that way, the adults’ thinking goes, youngsters develop resourcefulness, creativity and determination. Self-inflicted cuts and burns represent learning opportunities.

In many societies, adults make miniature tools for children to play with or give kids cast-off tools to use as toys. For instance, Inuit boys have been observed mimicking seal hunts with items supplied by parents, such as pieces of sealskin and miniature harpoons. Girls in Ecuador’s Conambo tribe mold clay balls provided by their mothers into various shapes as a first step toward becoming potters.
Childhood games and toys in foraging groups and farming villages, as in Western nations, reflect cultural values. Hunter-gatherer kids rarely engage in rough-and-tumble or competitive games. In fact, competition is discouraged. These kids concoct games with no winners, such as throwing a weighted feather in the air and flicking the feather back up as it descends. Children in many farming villages and herding societies play basic forms of marbles, in which each player shoots a hard object at similar objects to knock the targets out of a defined area. The rules change constantly as players decide among themselves what counts and what doesn’t.

Children in traditional societies don’t invent fantasy characters to play with, Lancy says. Consider imaginative play among children of Aka foragers in the Central African Republic. These kids may pretend to be forest animals, but the animals are creatures from the children’s surroundings, such as antelope. The children aim to take the animals’ perspective to determine what route to follow while exploring, says anthropologist Adam Boyette of Duke University. Aka youngsters sometimes pretend to be spirits that adults have told the kids about. In this way, kids become familiar with community beliefs and rituals.
Aka childhood activities are geared toward adult work, Boyette says. Girls start foraging for food within the first few years of life. Boys take many years to master dangerous tasks, such as climbing trees to raid honey from bees’ nests (SN: 8/20/16, p. 10). By around age 7, boys start to play hunting games and graduate to real hunts as teenagers.

In 33 hunter-gatherer societies around the world, parents typically take 1- to 2-year-olds on foraging expeditions and give the youngsters toy versions of tools to manipulate, reported psychologist Sheina Lew-Levy of the University of Cambridge and her colleagues in the December Human Nature. Groups of children at a range of ages play make-believe versions of what adults do and get in some actual practice at tasks such as toolmaking. Youngsters generally become proficient food collectors and novice toolmakers between ages 8 and 12, the researchers conclude. Adults, but not necessarily parents, begin teaching hunting and complex toolmaking skills to teens. For the report, Lew-Levy’s group reviewed 58 papers on childhood learning among hunter-gatherers, most published since 2000.

“There’s a blurred line between work and play in foraging societies because children are constantly rehearsing for adult roles by playing,” Boyette says.

Children in Western societies can profitably mix fantasy with playful rehearsals for adult tasks, observes George Mason’s Goldstein, who was a professional stage actor before opting for steadier academic work. “My 5-year-old son is never happier than when he’s helping to check us out at the grocery store,” she says. “But he also likes to pretend to be a robot, and sometimes a robot who checks us out at the grocery store.”

Not too far in the future, preschoolers pretending to be robots may encounter real robots running grocery-store checkouts. Playtime will never be the same.

The first 117 elements on the periodic table were relatively normal. Then along came element 118.

Oganesson, named for Russian physicist Yuri Oganessian (SN: 1/21/17, p. 16), is the heaviest element currently on the periodic table, weighing in with a huge atomic mass of about 300. Only a few atoms of the synthetic element have ever been created, each of which survived for less than a millisecond. So to investigate oganesson’s properties, scientists have to rely largely on theoretical predictions.
Recent papers by physicists, including one published in the Feb. 2 Physical Review Letters, detail some of the strange predicted properties of the weighty element.

1. Relatively weird
   According to calculations using classical physics, oganesson’s electrons should be arranged in shells around the nucleus, similar to those of xenon and radon, two other heavy noble gases. But calculations factoring in Einstein’s special theory of relativity, which take into account the high speeds of electrons in superheavy elements, show how strange the element may be. Instead of residing in discrete shells — as in just about every other element — oganesson’s electrons appear to be a nebulous blob.
2. Getting a reaction
   On the periodic table, oganesson is grouped with the noble gases, which tend not to react with other elements. But because of how its electrons are configured, oganesson is the only noble gas that’s happy to both give away its electrons and receive electrons. As a result, the element could be chemically reactive.
3. Solid as a rock?
   Oganesson’s electron configuration could also let atoms of the element stick together, instead of just bouncing off one another as gas atoms typically do. At room temperature, scientists expect that these oganesson atoms could clump together in a solid, unlike any other noble gases.
4. Bubbling up
   Protons inside an atom’s nucleus repel one another due to their like charges, but typically remain bound together by the strong nuclear force. But the sheer number of oganesson’s protons — 118 — may help the particles overcome this force, creating a bubble with few protons at the nucleus’s center, researchers say. Experimental evidence for a “bubble nucleus” has been found for an unstable form of silicon (SN: 11/26/16, p. 11).
5. Neutral territory
   Unlike oganesson’s protons, which are predicted to be in distinct shells in the nucleus, the element’s neutrons are expected to mingle. This is at odds with some other heavy elements, in which the neutron rings are well-defined.

For Oganessian, these theoretical predictions about the element have come as a surprise. “Now it’s up to experiment,” he says. Predictions about the bizarre element could be put to the test once a facility for creating superheavy elements, under construction at Oganessian’s lab in Dubna, Russia, is up and running later this year.

AUSTIN, Texas — If alien microbes crash-land on Earth, they may get a warm welcome.

When people were asked how they would react to the discovery of extraterrestrial microbial life, they give generally positive responses, researchers reported at a news conference February 16 at the annual meeting of the American Association for the Advancement of Science.

This suggests that if microbial life is found on Mars, Saturn’s icy moon Enceladus (SN: 5/13/17, p. 6) or elsewhere in the solar system, “we’ll take the news rather well,” said Michael Varnum, a social psychologist at Arizona State University in Tempe. What’s more, the tone of news reports announcing potential evidence for intelligent aliens suggests people would welcome that news, too.
Varnum and colleagues asked about 500 online volunteers — all in the United States — to describe how they would react if they learned scientists had discovered alien microbes. Varnum’s team analyzed each response using software that determined the fraction of words indicating positive emotion, such as “nice,” and negative emotion, like “worried.” The program also scanned for reward- and risk-focused words, such as “benefit” and “danger.”
People generally used more positive and reward-oriented words than negative and risk-oriented ones to describe their anticipated reactions. The same held true when participants were asked how they expected everyone else to take the news.
In another study, Varnum’s team asked about 500 U.S.-based volunteers to read one of two newspaper articles. One from 1996 reported the discovery of evidence for fossilized Martian microbes in a meteorite (SN: 8/10/96, p. 84). In the second, researchers announced in 2010 that they had created a synthetic bacterial cell in the lab (SN: 6/19/10, p. 5).
Both groups responded favorably to the articles, but the people who read about Martian microbes had a more positive reaction. This suggests that while people feel good about discoveries of any previously unknown life-forms, they are particularly keen on finding aliens, Varnum says.

But “any finding that comes from one population — like Americans — you have to take with a grain of salt,” Varnum says. He and his colleagues now hope to gather responses from participants of different cultures, to compare how people across the globe would take the news of alien microbes.

Psychologist and SETI researcher Douglas Vakoch, who heads the nonprofit organization Messaging Extraterrestrial Intelligence in San Francisco, suggests researchers also gauge reactions to different scenarios of alien microbial discovery. The Martian meteorite described in the 1996 article “has been on Earth for a long time and nothing bad has happened,” says Vakoch, who wasn’t involved in the work. “That’s a really safe scenario.” But, he wonders, are people as gung-ho about the prospect of finding live microbes on other planets or aboard meteorites?

And what if the aliens were intelligent? “If you find intelligent life elsewhere, [you] know that you’re not the only kid on the block,” says Seth Shostak, an astronomer at the SETI Institute in Mountain View, Calif. Knowing that human intelligence isn’t so special after all could provoke a much different emotional response than finding mere microbes “like pond scum in space,” Shostak says.

To get a sense of how people would feel about finding intelligent aliens, Varnum analyzed reports that the interstellar asteroid ‘Oumuamua could be an alien spaceship (SN Online: 12/18/17). The news articles took a largely positive angle. So the broader public might also take kindly to the discovery of little green men, Varnum says.

Tap — gently — the plump rear of a young Nessus sphinx hawk moth, and you may hear the closest sound yet discovered to a caterpillar voice.

Caterpillars don’t breathe through their mouths. Yet a Nessus sphinx hawk moth, if disturbed, will emit from its open mouth a sustained hiss followed by a string of scratchy burplike sounds. “Hard to describe,” says animal behaviorist Jayne Yack of Carleton University in Ottawa, who urges people just to listen to it for themselves.
This newfound noise from young Amphion floridensis may startle birds or other would-be predators not expecting something as generally quiet as most caterpillars to erupt in sound.

The discovery marks the fourth sound-producing mechanism in caterpillars that Yack and colleagues have found. Some caterpillars use their spiracles, respiratory pores along the flanks, to toot sounds. Caterpillars take in oxygen and release waste carbon dioxide through these pores. These gases, which don’t depend on the caterpillar version of blood to travel throughout the body, move through a branching air duct system of increasingly tiny pipes. Two other kinds of caterpillar noises involve mouthparts rubbing against each other. But none of those noisemakers are involved here, researchers report online February 26 in Journal of Experimental Biology.

Instead, the new anatomical studies and computer modeling suggest that these caterpillars speak by pulling air in through their mouths and into their guts and then releasing it. The rush of air inward could create the first hissing part, and outrushes could make the string of scratchy burps. There’s no sign of a special sound-making flap in the gut, but air whooshing through a constriction could make noisy turbulence. That could give a caterpillar voice its own version of teakettle squeals. In miniature, of course.

A complex coral reef full of nooks and crannies is a coastline’s best defense against large ocean waves. But coral die-offs over the next century could allow taller waves to penetrate the corals’ defenses, simulations suggest. A new study finds that at some Pacific Island sites, waves reaching the shore could be more than twice as high as today’s by 2100.

The rough, complex structures of coral reefs dissipate wave energy through friction, calming waves before they reach the shore. As corals die due to warming oceans (SN: 2/3/18, p. 16), the overall complexity of the reef also diminishes, leaving a coast potentially more exposed. At the same time, rising sea levels due to climate change increasingly threaten low-lying coastal communities with inundation and beach erosion — and stressed corals may not be able to grow vertically fast enough to match the pace of sea level rise. That could also make them a less effective barrier.

Researchers compared simulations of current and future sea level and reef conditions at four sites with differing wave energy near the French Polynesian islands of Moorea and Tahiti. The team then simulated the height of a wave after it has passed the reef, known as the back-reef wave height, under several scenarios. The most likely scenario studied was based on the Intergovernmental Panel on Climate Change’s projections of sea level height by 2100 and corresponding changes in reef structure.

Under those conditions, the average back-reef wave heights at the four sites would be 2.4 times as high in 2100 as today, the team reports February 28 in Science Advances. That change would be largely due to the decrease in coral reef complexity rather than rising sea levels, the simulations suggest. Coastal communities around the world will likely see similar wave height increases, dependent on local reef structures and extent of sea level rise. The finding, the researchers say, shows that conserving reefs is crucial to protecting coastal communities in a changing climate.

As a physics reporter and lover of mathematics, I won’t be celebrating Pi Day this year. That’s because pi is wrong.

I don’t mean that the value is incorrect. Pi, known by the symbol π, is the number you get when you divide a circle’s circumference by its diameter: 3.14159… and so on without end. But, as some mathematicians have argued, the mathematical constant was poorly chosen, and students worldwide continue to suffer as a result.

A longtime fixture of high school math classes, pi has inspired books, art (SN Online: 5/4/06) and enthusiasts who memorize it to tens of thousands of decimal places (SN: 4/7/12, p. 12). But some contend that replacing pi with a different mathematical constant could make trigonometry and other math subjects easier to learn. These critics — including myself — advocate for an arguably more elegant number equal to 2π: 6.28318…. Sometimes known as tau, or the symbol τ, the quantity is equal to a circle’s circumference divided by its radius, not its diameter.

This idea is not new. In 2001, mathematician Bob Palais of the University of Utah in Salt Lake City published an article in the Mathematical Intelligencer titled “ π is wrong!” The topic gained more attention in 2010 with The Tau Manifesto, posted online by author and educator Michael Hartl. But the debate tends to reignite every year on March 14, which is celebrated as Pi Day for its digits: 3/14.
The simplest way to see the failure of pi is to consider angles, which in mathematics are typically measured in radians. Pi is the number of radians in half a circle, not a whole circle. That makes things confusing: For example, the angle at the tip of a slice of pizza — an eighth of a pie — isn’t π/8, but π/4. In contrast, using tau, the pizza-slice angle is simply τ/8. Put another way, tau is the number of radians in a full circle.

That factor of two is a big deal. Trigonometry — the study of the angles and lines found in shapes such as triangles — can be a confusing whirlwind for students, full of blindly plugging numbers into calculators. That’s especially true when it comes to sine and cosine, two important functions in trigonometry. Many trigonometry problems involve calculating the sine or cosine of an angle. When graphed, the two functions look like a series of wiggles, shaped a bit like an “S” on its side, that repeat the same values every 2π. That means pi covers only half of an S. Tau, on the other hand, covers the full wiggle, a more intuitive measure.

Pi has become so embedded in mathematics that it could be hard to excise. A more practical approach may be to introduce tau as a teaching tool alongside pi, rather than a replacement. Education is where tau’s impact is most likely to be felt: Professional scientists and mathematicians can comfortably handle the factors of two that crop up with pi in equations.

You might argue that multiplying by two isn’t that hard, even for students. But it isn’t the arithmetic that concerns me. Trigonometry is notorious for creating a divide between the math-fluent and math-phobic. But helping more people understand and enjoy mathematics isn’t some pie-in-the-sky fantasy. Everyone is capable of doing math. We just need to work smarter, and speak more clearly, to help those who struggle.

So here’s to June 28 — Tau Day.

We’re going to need a bigger trash can.

A pooling of plastic waste floating in the ocean between California and Hawaii contains at least 79,000 tons of material spread over 1.6 million square kilometers, researchers report March 22 in Scientific Reports. That’s the equivalent to the mass of more than 6,500 school buses. Known as the great Pacific garbage patch, the hoard is four to 16 times as heavy as past estimates.

About 1.8 trillion plastic pieces make up the garbage patch, the scientists estimate. Particles smaller than half a centimeter, called microplastics, account for 94 percent of the pieces, but only 8 percent of the overall mass. In contrast, large (5 to 50 centimeters) and extra-large (bigger than 50 centimeters) pieces made up 25 percent and 53 percent of the estimated patch mass.
Much of the plastic in the patch comes from humans’ ocean activities, such as fishing and shipping, the researchers found. Almost half of the total mass, for example, is from discarded fishing nets. A lot of that litter contains especially durable plastics, such as polyethylene and polypropylene, which are designed to survive in marine environments.
To get the new size and mass estimates, Laurent Lebreton of the Ocean Cleanup, a nonprofit foundation in Delft, the Netherlands, and his colleagues trawled samples from the ocean surface, took aerial images and simulated particle pathways based on plastic sources and ocean circulation.
Aerial images provided more accurate tallies and measurements of the larger plastic pieces, the researchers write. That could account for the increase in mass over past estimates, which relied on trawling data and images taken from boats, in addition to computer simulations. Another possible explanation: The patch grew — perhaps driven by an influx of debris from the 2011 tsunami that hit Japan and washed trash out to sea (SN: 10/28/17, p. 32).

BOSTON — The bond between parent and child is powerful enough to override fear. New research shows that if a parent sits with a young child during a potentially scary situation, the child isn’t as afraid of it later.

The study is in line with research suggesting that during particular stages of development, a strong connection with a caregiver tamps down activity in the amygdala, the brain structure that helps process fear and spurs the fight-or-flight response.
“Fight or flight is pointless if you are tiny,” said developmental neuroscientist Nim Tottenham of Columbia University, who presented the work March 26 at a Cognitive Neuroscience Society meeting. For young kids, the bond with a caregiver not only helps ensure survival but also makes kids feel safe, enabling them to approach the world with confidence, Tottenham said. “Attachment is a strategy that has worked very well; it trumps everything.”

Kids from ages 3 to 5 were shown two shapes — a green triangle and a blue square. Just the square was accompanied by a loud, fingers-on-the-chalkboard kind of noise. Some kids had a parent sitting next to them while they saw the shapes; others sat with a researcher. After the parents left, kids chose which door to go through to get a present: one with the scary blue square on it, the other with the innocuous green triangle.

Kids paired with the experimenter avoided the door with the blue square. But kids who had sat next to a parent showed a slight preference for that door, even though they knew they would collect the same present from behind either door.

Stephen Hawking, a black hole whisperer who divined the secrets of the universe’s most inscrutable objects, left a legacy of cosmological puzzles sparked by his work, and inspired a generation of scientists who grew up reading his books.

Upon Hawking’s death on March 14 at age 76, his most famous discovery — that black holes aren’t entirely black, but emit faint radiation — was still fueling debate.

Hawking “really, really cared about the truth, and trying to find it,” says physicist Andrew Strominger of Harvard University, who collaborated with the famed scientist. Hawking “was deeply committed, his whole life, to this quest of understanding more about the physical universe around us.”

After earning his Ph.D. in 1965 at the University of Cambridge, Hawking continued studying cosmology there for the rest of his life. Due to a degenerative illness, amyotrophic lateral sclerosis, or ALS, Hawking gradually lost control of his body, requiring a wheelchair and eventually a voice synthesizer to speak. Yet his desire to uncover nature’s secrets remained boundless.
In one of the most significant realizations of his career, Hawking reported in 1974 that black holes emit a faint glow of particles. This effect arises from quantum mechanics, which states that a sea of transient particles and antiparticles pervades all of space. These “virtual” particles usually annihilate in an instant, but if one of those particles is lost inside a black hole’s boundary, or event horizon, its partner can escape, producing what’s now known as Hawking radiation (SN: 5/31/14, p. 16).

As a result, black holes can gradually evaporate and disappear. This led to a still unresolved paradox: Throw an encyclopedia into a black hole and the information will eventually be lost. But according to quantum mechanics, information can never be destroyed.

Many solutions have been proposed for this problem, but none has stuck. In 2016, Hawking and colleagues proposed a path toward a solution: Black holes might have “soft hair,” low-energy particles that would retain information about what fell inside (SN: 2/06/16, p. 16). Hawking’s collaborators, including Strominger, are still working on the research. Standing at the interface between two seemingly incompatible theories — quantum mechanics, which describes the very small, and the general theory of relativity, which describes gravity — the quandary and its resolution may eventually help reveal a unified theory of quantum gravity.

Hawking made many other contributions, including studies of spacetime curvature during the Big Bang and the possibility that mini black holes might have formed in the universe’s infancy. Despite their groundbreaking nature, Hawking’s ideas remained largely theoretical, says Harvard theoretical astrophysicist Avi Loeb. Hawking radiation, for example, has never been directly detected. “That’s, unfortunately, why he didn’t get the Nobel Prize,” Loeb says.
Yet Hawking achieved a level of fame uncommon among scientists. He excelled at making abstruse science digestible to the public. With his books, most notably the best-selling A Brief History of Time, first published in 1988, Hawking inspired countless future scientists and science lovers (including the author of this article). Theoretical cosmologist Katie Mack of North Carolina State University in Raleigh first opened the book when she was about 10 years old. “I found it so fascinating at the time,” she says. “I found out that Stephen Hawking was called a cosmologist and so I said I wanted to be a cosmologist.” Hawking similarly motivated dozens of her colleagues, Mack says.

Hawking remained active in research even in the last months of his life. A paper on which he is a coauthor, which was updated in the weeks before his death, considered the physics of multiverses, the possibility that a slew of other universes exist in addition to our own.

A funeral was held for Hawking on March 31. Later this year, his ashes will be interred in Westminster Abbey in London, where they will rest alongside the remains of other famous British scientists, including Isaac Newton and Charles Darwin.

While the data was amassing, suddenly there came a tapping,
As of something gently rapping, rapping at LIGO’s door.

The source of a mysterious glitch in data from a gravitational wave detector has been unmasked: rap-tap-tapping ravens with a thirst for shaved ice. At the Advanced Laser Interferometer Gravitational-Wave Observatory, or LIGO, in the desert of Hanford, Wash., scientists noticed a signal that didn’t look like gravitational waves, physicist Beverly Berger said on April 16 at a meeting of the American Physical Society.

A microphone sensor that monitors LIGO’s surroundings caught the sounds of pecking birds on tape in July 2017, Berger, of the LIGO Laboratory at Caltech, said. So the crew went out to the end of one of the detector’s 4-kilometer-long arms to check for evidence of the ebony birds at the scene.

Sure enough, frost covering a pipe connected to the cooling system was covered in telltale peck marks from the thirsty birds. One raven, presumably seeking relief from the desert heat, was caught in the act. Altering the setup to prevent ice buildup now keeps the ravens from tapping, evermore.