Squirrels remember problem-solving techniques two years on

​​Squirrels remember problem-solving techniques two years on

Squirrels, with their nut-burying habits and uncanny knack of finding them later, are known for their ability to recall important details. But scientists have discovered a new squirrel trait they see as a different kind of memory skill, an ability to remember problem-solving techniques from almost two years earlier.

“This is not just remembering where things have been left, it shows they can recall techniques which they have not used for a long time,” said Dr. Théo Robert from the University of Exeter, co-author of the new study. “It’s also different from what we see in the wild because they’re remembering things for longer than the few months of memory needed to find hidden food.”

The new discovery came by way of an experiment conducted by Robert and his colleagues at the University of Exeter. Working with five grey squirrels, the team tasked the animals with pressing levers in order to get their mitts on some tasty hazelnuts. The first time around, the squirrels took an average of eight seconds to complete the task. With practice, they eventually reduced their hazelnut retrieval time to just two seconds.

Then, 22 months later, the team presented the same squirrels with a modified version of this same task. The puzzle appeared differently, but actually required the same technique to obtain the hazelnuts and at first this threw the squirrels off. They hesitated for an average of 20 seconds before even beginning the task, something the researchers attribute to a neophobic response, or a fear of new things.

But once the squirrels got going, they were able to retrieve the hazelnuts in just three seconds on their first try, and then finally in an average of two seconds. This, the researchers say, is evidence of the squirrels’ long-term memory skills as they recalled and applied the same technique used in the earlier challenge.

“This might be why grey squirrels can survive very well in towns and cities,” says Dr. Pizza Ka Yee Chow, of Exeter’s Centre for Research in Animal Behaviour. “For example, they’re very good at getting food from bird feeders. People may try different types of bird feeders to keep the squirrels away, but this research shows grey squirrels can not only remember tricks for getting food but can apply those skills in new situations.”

[Squirrels don’t remember where they put the nuts.  They know the types of places they use for nut storage.  They are just as likely to hit some other squirrel’s nuts as their own. As long as there are enough stored nuts in aggregate then it works.

The real test is how to apply this work to human primary and secondary students to minimize the knowledge loss over the summer months.]


Redefining the kilogram in terms of Planck’s constant

Redefining the kilogram in terms of Planck’s constant

The kilogram has the dubious distinction of being the only SI unit still based on a physical object; specifically, a metal cylinder kept in a vault in France. Plans are well underway to redefine the kilogram in mathematical terms instead, and to that end a team at the National Institute of Standards and Technology (NIST) has submitted a precise new calculation of a key formula.

Since 1879, the kilogram has been defined as the exact mass of the International Prototype of the Kilogram (IPK), a small cylinder made of platinum and iridium. But there are a few problems with defining a base unit in terms of a physical artefact: the IPK gathers contaminants that make it slightly heavier over time, so it needs to be regularly treated. To complicate matters, there are 40 copies around the world and they’re all getting “dirty” at different rates, meaning their masses are slowly drifting out of sync.

That’s obviously not something you want in a base unit that’s supposed to be universal. And the discrepancies don’t just affect the kilogram itself: other units such as the pound, ton or milligram are defined in terms of their relationship to the kilo, as are non-mass units like the ampere (for electric current) or the candela (luminous intensity).

A better option is to develop a new definition based on a mathematical foundation that can be calculated anywhere, and the Planck constant fits the bill. This formula allows researchers to find mass in relation to electromagnetic energy, so by finding as precise a value for it as possible, the kilogram can be redefined in terms of the official definition of the meter and the second.

NIST’s new value for the Planck constant is 6.626069934 x 10-34 kg∙m2/s, with an uncertainty of 13 parts per billion. If that number makes your eyes glaze over, the important part is the end: 13 parts per billion is incredibly precise.

To measure the Planck constant, the researchers used a Kibble balance, a device that suspends a 1-kg weight with electromagnetic forces. They can calculate the constant according to the amount of electromagnetic energy it takes to balance the mass.

The team says the more precise figure comes courtesy of having 16 months’ worth of measurements to draw from, as well as adjustments they’d made in how the electromagnetic field was created and measured.

These experiments join several other projects that were attempting to find the most precise value of the Planck constant, and while everyone’s answers were different, they have low enough levels of uncertainty to make a case for redefining the kilogram in terms of the Planck constant.

“There needed to be three experiments with uncertainties below 50 parts per billion, and one below 20 parts per billion,” says Stephan Schlamminger, lead researcher on the project. “But we have three below 20 parts per billion.”

All of these measurements have been submitted for consideration by an international body, which will review them to determine the official value of Planck’s constant. The official definition of a kilogram – along with the other units that depend on it – is set to be changed in November next year.


Why Do We See More Species in Tropical Forests? The Mystery May Finally Be Solved | Science | Smithsonian

Why Do We See More Species in Tropical Forests? The Mystery May Finally Be Solved | Science | Smithsonian

When Charles Darwin first sailed into the tropics aboard the HMS Beagle in 1835, he was stunned. The 26-year-old naturalist had expected to find the same level of diversity of plants and animals as he had left behind in the higher latitudes of Plymouth, England. Instead, on the balmy Galapagos Islands, he found a multitude of strange and diverse creatures thriving together.

Rowing ashore to explore, Darwin jotted in his notes that the number of different “vegetable and animal” inhabitants on tiny tropical islands was strikingly higher than at other sites along his voyage. He wondered: How was it possible that the tropics seemed to hold so much more diversity than the more northerly forests of Europe? Shouldn’t these tightly packed creatures have battled it out to extinction long ago?

Darwin never found out the answer to that particular mystery (after all, he had a lot on his mind), and so the question persisted for another century. Finally, in the early 1970s, two ecologists independently came up with the same hypothesis to explain the mysterious phenomenon—at least with trees.

Daniel Janzen and Joseph Connell put forth a seemingly counterintuitive explanation. Perhaps, they posited, the astonishing plant diversity we find in tropical forests is enabled by two factors: the presence of “natural enemies” that target specific species and keep population size in check, and the tendency of youngsters of one species to settle far away from their parents, beyond those predators’ reach.

Until recently, researchers have only been able to prove that the Janzen-Connell hypothesis holds true in localized studies. The problem was, they lacked access to the kind of global datasets necessary to explain the broader planetary pattern of decreasing diversity from equator to poles. Now, in a new study published last week in the journal Science, researchers show that this hypothesized mechanism is indeed responsible for global trends in forest biodiversity.

Last year, forest ecologists Jonathan Myers and Joe LaManna traveled to a workshop in Hainan, China focused on analysis of data generated by the Smithsonian’s Forest Global Earth Observatory (ForestGEO), a network of 60 forests across the planet that are exhaustively monitored. Myers and LaManna, both of Washington University in Saint Louis, Missouri, knew that ForestGEO could provide the global dataset they needed to answer the question that has been vexing them and other ecologists since Darwin’s voyage.

“One of the striking differences between temperate and tropics is that all of those ‘extra’ species are very rare,” says LaManna, a post-doctoral researcher and first author of the new study. Consider that temperate forests can be packed wall to wall with redwood trees, whereas the tropics are dotted with a bevy of unique trees that often exist in isolation from others in their species. “How can those rare species persist in the face of extinction?” asks Myers, a professor of biology and co-author on the study.

Answering that question required a massive undertaking. The dataset tallied 2.4 million trees from 3,000 species in an exacting fashion to ensure comparability across each forest. More than 50 co-authors from 41 institutions including the Smithsonian then analyzed the data, which spanned 24 ForestGEO plots around the planet. “It was a lot,” says LaManna. “Every stem down to one centimeter in diameter is mapped, measured, tagged and identified.”

The herculean effort paid off. After analyzing the data, they found a surprising trend: In areas with higher numbers of adult trees, there were fewer young saplings of the same species. This pattern was strikingly more pronounced in the tropics than in the temperate regions they sampled.

This means that, unlike in higher latitude ecosystems, near the equator trees are less likely to coexist around neighbors in the same family. It’s as if, at some point, the tree parents and their sapling kids unanimously agreed that was time to move out of the basement. Except in a forest, living farther apart doesn’t just allow the parent trees to luxuriate in their empty nest. It’s a matter life and death for the species.

“With trees it’s less a direct effect of the parent tree on the offspring,” Myers says. “It’s an indirect effect where the natural enemies that attack the adults also attack the offspring.” These enemies could be pathogens, seed predators or herbivores that target one species. Just as dense human populations in cities enable the rapid spread of communicable diseases, these enemies can rapidly devastate a dense forest of the same species.

If your saplings settle down farther away, however, it’s less likely that any one enemy will wipe them all out. “You think of enemies as being bad influences on trees, especially ones of low abundance,” LaManna says. “But they can be a strong stabilizing force—[enemies] can actually buffer them and keep them from going extinct.” You might say: With enemies like this, who needs friends?

“It’s changed the way I think about ecology,” Myers says. “The enemy can actually have a beneficial effect in maintaining the rare species in these communities, especially in the tropics.”

The data provides compelling explanation for why we see the global biodiversity patterns we do, says Gary Mittelbach, a forest ecologist and professor of integrative biology at Michigan State University who was not involved in the study. “The fact that they were able to show it on a worldwide basis with standardized methods helps solidify the idea,” says Mittelbach.

One weakness of the study is that, while it implies a global trend, there are no samples from north of Central Europe or south of Papua New Guinea. “I kind of wish they had more [forests] in Asia and Europe so not all the high latitude ones are in North America,” says Mittelbach. Even with the dearth of samples from high latitudes, however, “I’m still pretty convinced of the pattern,” he says.

Though the researchers succesfully showed that the trend put forth by Janzen and Connell holds true, the question of what exactly is causing the tropics to be so diverse still remains.

Myers speculates that the stability of the tropical climate may contribute to its rich biodiversity, compared to the drastic changes that have taken place over geologic time in the higher latitudes. “There’s been a lot more disturbance in the temperate zone” over the past thousands of years, he says. By “disturbance,” Myers means ice sheets that repeatedly bulldozed across North America in Earth’s past.

The tropics have not endured such disturbances. Researchers attribute the high reproduction and low extinction rates in tropical species of plants and animals to the relatively comfy climate. That’s worked out well for them until now, but forests around the world are changing as a result of more volatile climate patterns. For instance, as higher latitudes become warmer, temperate trees are migrating slowly north.

“There might be a direct or indirect influence of climate in mediating the strength of the biotic interactions between enemies and trees,” Myers says. “Where it’s warmer or wetter you might expect pathogens to have a stronger influence.”

The global trend these researchers have uncovered illustrates just how much the diversity of biological life on Earth can hinge on small-scale interactions. “This mechanism is a global scale process, and we’re talking about interactions between adults, young and their specialized enemies at the scale of 10 meters,” LaManna says. “That very local-scale interaction is contributing to a pattern of biodiversity across the entire globe.”


Laser as bright as a billion Suns alters fundamental physics of light and matter

Laser as bright as a billion Suns alters fundamental physics of light and matter

Physicists from the University of Nebraska-Lincoln have created the brightest light ever produced on Earth, and it could be the first step towards more powerful X-ray technology. The researchers focused their Diocles Laser to a brightness a billion times that of the surface of the Sun, and found that at that extreme level, the fundamental physics of how light enables vision begin to change.

Normally, when light from the Sun, a lightbulb or any other source strikes the surface of an object, the electrons in the object cause the photons in the light to scatter. Our eyes pick that up to allow us to see the object, but brighter light won’t change the object’s appearance beyond making it look brighter. When the Diocles Laser is cranked up, however, things start to get a little weird.

The team blasted the laser at electrons suspended in helium, and then measured how single electrons scattered the photons of light that hit them. Electrons are known to scatter just one photon at a time under normal circumstances, but in this experiment almost 1,000 were scattered simultaneously.

“When we have this unimaginably bright light, it turns out that the scattering – this fundamental thing that makes everything visible – fundamentally changes in nature,” says Donald Umstadter, lead researcher on the study. “It’s as if things appear differently as you turn up the brightness of the light, which is not something you normally would experience. (An object) normally becomes brighter, but otherwise, it looks just like it did with a lower light level. But here, the light is changing (the object’s) appearance. The light’s coming off at different angles, with different colors, depending on how bright it is.”

This diagram shows how the motion of an electron (bottom) affects the color signature of the scattered light (top) (Credit: Donald Umstadter and Wenchao Yan)

The difference is that the brightness of the Diocles Laser seems to have surpassed a previously-unknown threshold. Changing the brightness of a light source doesn’t usually change the angle or energy of a photon after it’s scattered, but in this case, the light bounces back at a different angle, shape and wavelength, which affects how the object would look to the human eye.

The effect seems to be caused by the fact that the laser light changes the motion of the electrons in the object’s atoms: instead of their usual up-and-down motion, the affected electrons zip around in a figure-eight path. Electrons ejecting photons in response to being struck by incoming photons is standard practice, but in this case, the ejected photon absorbs extra energy and becomes an X-ray.

The researchers say this development could improve current X-ray technology. The energized photons could help create high-resolution, 3D images of objects and people at a lower dose, spotting tiny details that current techniques may miss. On a more theoretical level, the powerful laser can help scientists solve some long-standing problems in the lab.


Indecisive water can exist as two different liquids

Indecisive water can exist as two different liquids

Water is way weirder than you might think. We know it can exist as a solid, liquid and gas, but put it under extreme pressure and it converts into a freaky fourth state called tunneling, and it may even freeze at temperatures it would normally boil. But now, researchers have found that water actually has two different liquid forms, and its weirdness may come from the relationship between those forms.

The finding started with the understanding that ice exists in different forms. When we freeze water at home, its molecules line up in a crystalline structure that’s fairly ordered and symmetrical. But out in space, ice tends to take on a less structured, amorphous form, and even then, there are two different types with low and high densities. It’s long been thought that this could apply to its liquid form, but it’s never been directly observed – until now.

Using two X-ray methods to watch how the molecules move around, researchers at Stockholm University observed high-density amorphous ice as it relaxed into the low-density form. One X-ray technique gave the team a window into the atomic structure of the transition, while another let researchers study its dynamics and motion. Showing clear signs of liquid behavior, the team realized both phases were technically liquids.

“I have studied amorphous ices for a long time with the goal to determine whether they can be considered a glassy state representing a frozen liquid,” says Katrin Amann-Winkel, co-author of the study. “It is a dream come true to follow in such detail how a glassy state of water transforms into a viscous liquid which almost immediately transforms to a different, even more viscous, liquid of much lower density.”

The conclusion the researchers reached is that water gets its weirdness mostly from the interplay between these different liquid forms. Understanding them could help paint a wider picture of how water is affected by changes in temperature, pressure, and the addition of other chemicals.

“The new results give very strong support to a picture where water at room temperature can’t decide in which of the two forms it should be, high or low density, which results in local fluctuations between the two,” says Lars G.M. Pettersson, co-author of the study. “In a nutshell: Water is not a complicated liquid, but two simple liquids with a complicated relationship.”


Explaining the “Mountain or Valley?” Illusion


Explaining the “Mountain or Valley?” Illusion

Our brains are wired to believe that light generally comes from above. This makes sense–here on Earth, light from the sun pretty much always is coming from either directly above us, or above us at an angle. This is such a persistent phenomenon that we use it to determine the shape of objects. If an object has a shadow beneath it, we assume it is convex, whereas if it has a shadow above it, we assume it is concave. This, as explained in this MinutePhysics video, is why we struggle to discern whether a formation is a mountain or a valley when a photo is taken from far away, like space. Cartographers who make relief maps even orient their drawing’s light in a place it would never naturally occur, just so we can understand what’s sticking up and what’s hollowed out. It’s pretty nuts to consider how much of our perception is based on our very specific experiences living on this particular rock in space, and how different our experience would be otherwise.


All the Animals That Love Touchscreens – Atlas Obscura

All the Animals That Love Touchscreens – Atlas Obscura

AS AN AVICULTURIST AT THE Aquarium of the Pacific in Long Beach, California, Sara Mandel is always looking for ways to make her penguins’ lives more interesting. She and her fellow staffers blow bubbles for their charges. They’ve thrown them penguin parties, complete with confetti and a disco ball.

So one day in 2013, when Mandel happened to have her iPad at work, she asked her boss whether it might be ok to show it to the penguins. She had already downloaded a game, “Game for Cats“—in which mice, lasers and butterflies scurry across the screen, and react to touch—for her pets at home. “I bet they’ll ignore it,” her boss said, but he told her to go ahead and give it a try anyway.

So she booted it up. One penguin, a one-year-old named Newsom, “immediately put his bill on it,” remembers Mandel. “It made a sound. And all of a sudden he was in hunting mode. He just kept doing it over and over again.”

Sitting in one place and tapping on a screen may seem like a fundamentally human pursuit. But over the past few years, more and more animals have begun to use computers—for scientific studies, for rehabilitation efforts, or, like Newsom the penguin, just to have something to do. And a whole lot of those species, from pigeons to wolves to black bears to tortoises, seem to actively enjoy it.

“Our animals appear to really like the work,” says Lina Oberliessen, a researcher at the Wolf Science Center in Ernstbrunn, Austria. “Some of them are kind of workaholics.” The WSC’s stated mission is “to investigate the common characteristics shared by wolf, dog, and man,” which they accomplish through behavioral and cognitive research. Oberliessen, for instance, is studying whether or not wolves have a sense of fairness by asking them to choose how food rewards are distributed between themselves and other wolves.

To make studies like this easier, the wolves and dogs that live at the Center are trained early on, with food rewards and clicker reinforcement, to be comfortable using touchscreens. “They learn that they have to touch it, and that it’s good,” says Oberliessen. Depending on the study, they’re then taught to associate particular symbols with corresponding outcomes—say, one versus two treats being dispensed—and to choose between them by bumping the screen with their noses. (Some particularly excitable wolves also use their paws.)

This system makes things much simpler for the researchers, who take advantage of the flexibility the screen offers to design a variety of tests. “It’s really simple—if the animal knows how to use a screen, you can modify the symbols and change the tasks,” she says. It also makes for eager study subjects, some of whom have truly internalized their training.

“Some animals love the touchscreen so much that it seems they don’t really care what happens,” says Oberliessen. “Sometimes they don’t even take the reward.” They wait eagerly for their turns with the machines, and if a certain wolf or dog isn’t scheduled to use one on a particular day, “they seem disappointed,” she says. “They look like [they’re asking], ‘I’m not being tested? Why!?’”

And when faced with the wolf-touchscreen equivalent of the spinning pinwheel of death, she says, they react just like humans: “If they do it wrong and the screen turns white again, they get frustrated. They press again right away, and don’t wait until the next symbol comes.”

“It’s really cute,” she adds.

Other researchers have similar stories. Dr. Jennifer Vonk, a cognitive scientist who, over the course of various projects, has trained black bears, orangutans, and silverback gorillas to use touchscreens, posits that her study subjects enjoy the intellectual stimulation the computers provide (although the food rewards, and the opportunity to interact with humans, certainly don’t hurt). “They voluntarily participate in an environment where there are other things to do,” she writes in an email. “The bears would run indoors from the outdoor habitat when they saw us coming. The orangutans used to spit and poke at me until it was their turn to ‘play.’”

It’s not just mammals, either. In 2014, a team of researchers from the University of Lincoln and the University of Vienna trained tortoises to use a touchscreen in order to test their spatial awareness. Not only did the tortoises quickly figure out what they were being asked to do—faster than dogs given the same task—there’s no reason to think they weren’t having a good time, writes Dr. Anna Wilkinson, the study’s lead author, in an email.

“They readily worked on it, which suggests that they did not dislike it,” she writes. (“One way to tell if a tortoise is comfortable in a situation is to examine its neck length,” she adds. “As you can see from the video [below], Esme looks comfortable in there.”)

Onboarding these new users isn’t always easy. Sarah Ritvo, a doctoral student at York University who specializes in animal-computer interaction, told a story about a colleague who ran into a problem while using touchscreens to test whether orangutans prefer pictures of their own species to those of other apes. “There was a big male orangutan, and he didn’t want to physically touch pictures of other male orangutans—it was basically a dominance thing,” she says. “He started picking up a stick and touching the screen instead.” The hack caught on: “All of a sudden, all the other orangutans refused to touch the touchscreen,” she says. “We ended up having to buy everyone wooden dowels.”

Such investments are generally worth it. For scientists, it’s a win-win when animals dig computers. It makes a day’s work easier, both for them and for their research subjects. For others like Mandel, who are focused on making the lives of captive animals better, the fun itself is the point. After Newsom took so strongly to Mandel’s iPad, a volunteer donated an old tablet to the aquarium. It’s now a regular part of the penguins’ enrichment rotation, along with more traditional playthings such as soap bubbles or floating toys. “When I bring it out, they get really excited,” says Mandel.

By this point, Newsom the penguin, who is now four years old, has largely outgrown the screen. But the younger penguins, who might otherwise be a bit bored during breeding season, tend to really take to it. “Every summer we get new penguins, and every summer they have to figure out what life is like for a penguin,” says Mandel. “For some reason, they’re all interested in the iPad.”

Zoos, aquariums, and rescue centers across the world have picked up on the trend. Game for Cats is popular—besides its permanent place at the penguin exhibit, it has helped rehab an injured pigeon, and made an appearance at a big cat sanctuary in North Carolina. Orangutans at the Melbourne Zoo are playing XBox Kinect. One researcher working with a great ape sanctuary in Des Moines has even designed what he calls the “RoboBonobo”—a squirt-gun-wielding robot ape that the primates on display can control with an iPad, in order to squirt the less hairy primates watching them.

Some experts think games are only the tip of the iceberg. Orangutans at the Miami Zoo are already using tablets to give their keepers dinner suggestions—someday, animals might use touchscreens to control many things about their own environments, from temperature to light levels to whether or not they are visible to guests. “Here’s an interface that’s programmable, and it can be big or small, it can provides light, sound, smells, even tactile information,” says Ritvo. “It’s such a spectacular way to broaden their worlds.”

In the meantime, there are ways in which we can learn from them, too: “I would be very surprised to see an orangutan sitting in front of a screen all day,” says Ritvo. “They prefer to wrestle and play.”


A Video That Finally Explains the 4th Dimension in a Way We Can Understand – Core77

A Video That Finally Explains the 4th Dimension in a Way We Can Understand – Core77

Geometry was my best math subject, and it served me well during my CAD jockey years. But one thing I could never wrap my head around was the notion of a 4th dimension. People smarter than me would try explaining it to me at a bar, and while I could comprehend the individual words coming out of their mouths, I could never put the concept together in my head.

Finally, after seeing this video by the folks behind a game called Miegakure, I can start to wrap my head around it:

Miegakure is an interactive puzzle game that lets you mess around with different shapes while toggling back and forth between the 3D and 4D world.

The fourth dimension in this game is not time, it works just like the first three: it is a mathematical generalization. [The game] plays like a regular 3D platformer, but at the press of a button one of the dimensions is exchanged with the fourth dimension, allowing for four-dimensional movement.

Your ability to move in the fourth dimensions in addition to the usual three allows you to perform miraculous feats like seeing inside closed buildings, walking through walls, stealing objects from closed containers, binding two separate rings without breaking them, etc…

These actual consequences of the mathematical formulation of 4D space have been thought about for more than a century (in the 1884 novella Flatland for example) but it is the first time anyone can actually perform them, thanks to the video game medium.

Here’s what the game looks like:


New evidence that all stars are born in pairs | Berkeley News

New evidence that all stars are born in pairs | Berkeley News

Did our sun have a twin when it was born 4.5 billion years ago?

Almost certainly yes — though not an identical twin. And so did every other sunlike star in the universe, according to a new analysis by a theoretical physicist from UC Berkeley and a radio astronomer from the Smithsonian Astrophysical Observatory at Harvard University.

Many stars have companions, including our nearest neighbor, Alpha Centauri, a triplet system. Astronomers have long sought an explanation. Are binary and triplet star systems born that way? Did one star capture another? Do binary stars sometimes split up and become single stars?

Astronomers have even searched for a companion to our sun, a star dubbed Nemesis because it was supposed to have kicked an asteroid into Earth’s orbit that collided with our planet and exterminated the dinosaurs. It has never been found.

The new assertion is based on a radio survey of a giant molecular cloud filled with recently formed stars in the constellation Perseus, and a mathematical model that can explain the Perseus observations only if all sunlike stars are born with a companion.

“We are saying, yes, there probably was a Nemesis, a long time ago,” said co-author Steven Stahler, a UC Berkeley research astronomer.

“We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years.”

In this study, “wide” means that the two stars are separated by more than 500 astronomical units, or AU, where one astronomical unit is the average distance between the sun and Earth (93 million miles). A wide binary companion to our sun would have been 17 times farther from the sun than its most distant planet today, Neptune.

Based on this model, the sun’s sibling most likely escaped and mixed with all the other stars in our region of the Milky Way galaxy, never to be seen again.

“The idea that many stars form with a companion has been suggested before, but the question is: how many?” said first author Sarah Sadavoy, a NASA Hubble fellow at the Smithsonian Astrophysical Observatory. “Based on our simple model, we say that nearly all stars form with a companion. The Perseus cloud is generally considered a typical low-mass star-forming region, but our model needs to be checked in other clouds.”

The idea that all stars are born in a litter has implications beyond star formation, including the very origins of galaxies, Stahler said.

Stahler and Sadavoy posted their findings in April on the arXiv server. Their paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.

Stars birthed in ‘dense cores’

Astronomers have speculated about the origins of binary and multiple star systems for hundreds of years, and in recent years have created computer simulations of collapsing masses of gas to understand how they condense under gravity into stars. They have also simulated the interaction of many young stars recently freed from their gas clouds. Several years ago, one such computer simulation by Pavel Kroupa of the University of Bonn led him to conclude that all stars are born as binaries.

Yet direct evidence from observations has been scarce. As astronomers look at younger and younger stars, they find a greater proportion of binaries, but why is still a mystery.

“The key here is that no one looked before in a systematic way at the relation of real young stars to the clouds that spawn them,” Stahler said. “Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution. We now believe that most stars, which are quite similar to our own sun, form as binaries. I think we have the strongest evidence to date for such an assertion.”

According to Stahler, astronomers have known for several decades that stars are born inside egg-shaped cocoons called dense cores, which are sprinkled throughout immense clouds of cold, molecular hydrogen that are the nurseries for young stars. Through an optical telescope, these clouds look like holes in the starry sky, because the dust accompanying the gas blocks light from both the stars forming inside and the stars behind. The clouds can, however, be probed by radio telescopes, since the cold dust grains in them emit at these radio wavelengths, and radio waves are not blocked by the dust.

The Perseus molecular cloud is one such stellar nursery, about 600 light-years from Earth and about 50 light-years long. Last year, a team of astronomers completed a survey that used the Very Large Array, a collection of radio dishes in New Mexico, to look at star formation inside the cloud. Called VANDAM, it was the first complete survey of all young stars in a molecular cloud, that is, stars less than about 4 million years old, including both single and mulitple stars down to separations of about 15 astronomical units. This captured all multiple stars with a separation of more than about the radius of Uranus’ orbit — 19 AU — in our solar system.

Stahler heard about the survey after approaching Sadavoy, a member of the VANDAM team, and asking for her help in observing young stars inside dense cores. The VANDAM survey produced a census of all Class 0 stars – those less than about 500,000 years old – and Class I stars – those between about 500,000 and 1 million years old. Both types of stars are so young that they are not yet burning hydrogen to produce energy.

Sadavoy took the results from VANDAM and combined them with additional observations that reveal the egg-shaped cocoons around the young stars. These additional observations come from the Gould Belt Survey with SCUBA-2 on the James Clerk Maxwell Telescope in Hawaii. By combining these two data sets, Sadavoy was able to produce a robust census of the binary and single-star populations in Perseus, turning up 55 young stars in 24 multiple-star systems, all but five of them binary, and 45 single-star systems.

Using these data, Sadavoy and Stahler discovered that all of the widely separated binary systems — those with stars separated by more than 500 AU — were very young systems, containing two Class 0 stars. These systems also tended to be aligned with the long axis of the egg-shaped dense core. The slightly older Class I binary stars were closer together, many separated by about 200 AU, and showed no tendency to align along the egg’s axis.

“This has not been seen before or tested, and is super interesting,” Sadavoy said. “We don’t yet know quite what it means, but it isn’t random and must say something about the way wide binaries form.”

Egg-shaped cores collapse into two centers

Stahler and Sadavoy mathematically modeled various scenarios to explain this distribution of stars, assuming typical formation, breakup and orbital shrinking times. They concluded that the only way to explain the observations is to assume that all stars of masses around that of the sun start off as wide Class 0 binaries in egg-shaped dense cores, after which some 60 percent split up over time. The rest shrink to form tight binaries.

“As the egg contracts, the densest part of the egg will be toward the middle, and that forms two concentrations of density along the middle axis,” he said. “These centers of higher density at some point collapse in on themselves because of their self-gravity to form Class 0 stars.”

“Within our picture, single low-mass, sunlike stars are not primordial,” Stahler added. “They are the result of the breakup of binaries. ”

Their theory implies that each dense core, which typically comprises a few solar masses, converts twice as much material into stars as was previously thought.

Stahler said that he has been asking radio astronomers to compare dense cores with their embedded young stars for more than 20 years, in order to test theories of binary star formation. The new data and model are a start, he says, but more work needs to be done to understand the physics behind the rule.

Such studies may come along soon, because the capabilities of a now-upgraded VLA and the ALMA telescope in Chile, plus the SCUBA-2 survey in Hawaii, “are finally giving us the data and statistics we need. This is going to change our understanding of dense cores and the embedded stars within them,” Sadavoy said.


Brain Architecture: Scientists Discover 11 Dimensional Structures That Could Help Us Understand How the Brain Works

Brain Architecture: Scientists Discover 11 Dimensional Structures That Could Help Us Understand How the Brain Works

Scientists studying the brain have discovered that the organ operates on up to 11 different dimensions, creating multiverse-like structures that are “a world we had never imagined.”

By using an advanced mathematical system, researchers were able to uncover architectural structures that appears when the brain has to process information, before they disintegrate into nothing.

Their findings, published in the journal Frontiers in Computational Neuroscience, reveals the hugely complicated processes involved in the creation of neural structures, potentially helping explain why the brain is so difficult to understand and tying together its structure with its function.

The team, led by scientists at the EPFL, Switzerland, were carrying out research as part of the Blue Brain Project—an initiative to create a biologically detailed reconstruction of the human brain. Working initially on rodent brains, the team used supercomputer simulations to study the complex interactions within different regions.

In the latest study, researchers honed in on the neural network structures within the brain using algebraic topology—a system used to describe networks with constantly changing spaces and structures. This is the first time this branch of math has been applied to neuroscience.

“Algebraic topology is like a telescope and microscope at the same time. It can zoom into networks to find hidden structures—the trees in the forest—and see the empty spaces—the clearings—all at the same time,” study author Kathryn Hess said in a statement.

In the study, researchers carried out multiple tests on virtual brain tissue to find brain structures that would never appear just by chance. They then carried out the same experiments on real brain tissue to confirm their virtual findings.

They discovered that when they presented the virtual tissue with stimulus, groups of neurons form a clique. Each neuron connects to every other neuron in a very specific way to produce a precise geometric object. The more neurons in a clique, the higher the dimensions.

In some cases, researchers discovered cliques with up to 11 different dimensions.

The structures assembled formed enclosures for high-dimensional holes that the team have dubbed cavities. Once the brain has processed the information, the clique and cavity disappears.

“The appearance of high-dimensional cavities when the brain is processing information means that the neurons in the network react to stimuli in an extremely organized manner,” said one of the researchers, Ran Levi.

“It is as if the brain reacts to a stimulus by building then razing a tower of multi-dimensional blocks, starting with rods (1D), then planks (2D), then cubes (3D), and then more complex geometries with 4D, 5D, etc. The progression of activity through the brain resembles a multi-dimensional sandcastle that materializes out of the sand and then disintegrates,” he said.

Henry Markram, director of Blue Brain Project, said the findings could help explain why the brain is so hard to understand. “The mathematics usually applied to study networks cannot detect the high-dimensional structures and spaces that we now see clearly,” he said.

“We found a world that we had never imagined. There are tens of millions of these objects even in a small speck of the brain, up through seven dimensions. In some networks, we even found structures with up to eleven dimensions.”

The findings indicate the brain processes stimuli by creating these complex cliques and cavities, so the next step will be to find out whether or not our ability to perform complicated tasks requires the creation of these multi-dimensional structures.

In an email interview with Newsweek , Hess says the discovery brings us closer to understanding “one of the fundamental mysteries of neuroscience: the link between the structure of the brain and how it processes information.”

By using algebraic topology, she says, the team was able to discover “the highly organized structure hidden in the seemingly chaotic firing patterns of neurons, a structure which was invisible until we looked through this particular mathematical filter.”

Hess says the findings suggest that when we examine brain activity with low-dimensional representations, we only get a shadow of the real activity taking place. This means we can see some information, but not the full picture. “So, in a sense our discoveries may explain why it has been so hard to understand the relation between brain structure and function,” she explains.

“The stereotypical response pattern that we discovered indicates that the circuit always responds to stimuli by constructing a sequence of geometrical representations starting in low dimensions and adding progressively higher dimensions, until the build-up suddenly stops and then collapses: a mathematical signature for reactions to stimuli.

“In future work we intend to study the role of plasticity—the strengthening and weakening of connections in response to stimuli—with the tools of algebraic topology. Plasticity is fundamental to the mysterious process of learning, and we hope that we will be able to provide new insight into this phenomenon,” she added.