Philippa Kaur

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    in Space & Astronomy

    Dust and a cold spell on Betelgeuse could explain why the giant star dimmed

    Astronomers around the world were startled in late 2019 when Betelgeuse, one of the brightest stars in the sky, grew dark for several months. Rumors swirled that the star was about to go supernova. It didn’t. But debate over what was going on exploded. Now, newly released images taken before and during the “Great Dimming” suggest what happened: The star’s surface cooled and triggered a cloud of dust that temporarily blocked its light.

    “This is the best interpretation we can get with the data that we have … without flying our spaceship to Betelgeuse and seeing what’s going on there,” says astrophysicist Emily Cannon of KU Leuven in Belgium.

    Cannon and colleagues used the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in Chile to take snapshots of Betelgeuse for more than a year. Serendipitously, the team had captured an image of the star in January 2019, months before the dimming began, and could compare that image with others taken in December 2019 and January and March 2020.

    The dimming wasn’t spread uniformly across Betelgeuse’s surface, the team reports June 16 in Nature. A dark splotch was concentrated over the star’s southern hemisphere. The researchers then ran computer simulations of the star, which included incorporating how dynamic gas bubbles constantly churn beneath its surface, to figure out the likeliest explanation for the way that the dimming played out.

    Earlier observations of the star had split astronomers into two camps (SN: 11/29/20). One group thought that a cloud of dust had blocked Betelgeuse’s light (SN: 3/12/20). Another thought that there wasn’t enough evidence of dust, and the dimming was due to temporary cooling at Betelgeuse’s surface.

    Betelgeuse, one of the brightest stars in the sky, marks the shoulder (circled in red) of the constellation Orion.Nick Risinger/skysurvey.org, ESO

    Astrophysicist Miguel Montargès says that now that he’s seen his team’s data, he’s in both camps. “The most natural conclusion is that both events happened,” says Montargès, of the Paris Observatory.

    The team’s hypothesis is that in late 2019, a temporary cold patch formed in Betelgeuse’s southern hemisphere due to the normal churning of surface plasma, and that cooling caused the star’s light to dim. The cold patch then allowed gas that had been released from the star’s surface to cool enough to form dust particles, which further blocked the star’s light.

    “You start getting a runaway effect,” which makes it easier for more dust to form, says astrophysicist Emily Levesque of the University of Washington in Seattle, who was not involved in the research but wrote a commentary in the same issue of Nature. As the dust spread out, the starlight shone through again.

    Some astronomers are still unconvinced that dust is part of the answer. The images plus simulations don’t prove dust was there, says astrophysicist Thavisha Dharmawardena of the Max Planck Institute for Astronomy in Heidelberg, Germany. “This discussion will continue till we obtain direct evidence for dust,” says Dharmawardena, who has looked for — and failed to find — signs of dust during the Great Dimming.

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    Montargès thinks the dust was just hard to see using other techniques. “When people say they are not seeing new dust, I think they are wrong,” he says. “It’s that their data does not allow them to see it.”

    Both researchers agree that the Atacama Large Millimeter Array in Chile could break the stalemate. That telescope was out of commission last summer due to the COVID-19 pandemic, when its observations would have been most useful. More observations are scheduled for this summer, and if dust is still there, ALMA should see it.

    Still, “if we cannot identify it, it’s not because it’s not there,” Montargès says. “It’s because we are too late.”

    The Betelgeuse observations may help astronomers recognize similar dimming events in other stars, Levesque says. Betelgeuse is Earth’s closest red supergiant star, a late phase of the stellar life cycle that comes before a supernova explosion. While dust does not predict an explosion, it can be part of how these stars lose mass before they die.

    So when will Betelgeuse go out with a bang? “Not today,” Montargès says. “Every day, we are closer to the explosion, that’s for sure. I think it’s not tomorrow, or even in our lifetime, for Betelgeuse.” More

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    in Humans

    The biggest flaw in human decision-making – and how to fix it

    Behavioural scientists Daniel Kahneman and Olivier Sibony explain why “noise” in professional judgements harms everything from criminal justice to medical treatments

    Humans

    16 June 2021

    By Graham Lawton

    Siegfried Layda/Getty Images
    If you have ever jumped to the wrong conclusion, made a terrible mistake thanks to your inbuilt biases or been subtly nudged back to your senses, then you are (a) human and (b) already on personal terms with the work of Daniel Kahneman, Olivier Sibony and Cass Sunstein. Thanks to their academic and popular writing, the world is now very familiar with what are collectively called “cognitive biases” – systematic errors in human thinking – and ways to correct them.
    Sunstein co-wrote the highly influential book Nudge: Improving decisions about health, wealth and happiness with Richard Thaler, while Kahneman popularised the work that won him the Nobel prize in economics in 2002 with his book Thinking, Fast and Slow. Sibony is the author of You’re About to Make a Terrible Mistake: How biases distort decision-making and what you can do to fight them.
    You may think that, in no small part thanks to their efforts, the swamp of human fallibility has been well and truly drained by now. But that would be yet another mistake. Kahneman, Sibony and Sunstein say there is an even more important source of warped decision-making. The three have banded together in a behavioural science supergroup to draw attention to what they call “noise” – persistent inconsistencies in professional judgements that lead to bad outcomes in all walks of life.
    Kahneman and Sibony spoke to New Scientist about the group’s new book Noise: A flaw in human judgment (Little, Brown Spark in the UK; William Collins in the US). Sunstein was due to join the conversation, but was called away at the last minute by his … More

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    in Space & Astronomy

    Gravitational waves confirm a black hole law predicted by Stephen Hawking

    Despite their mysterious nature, black holes are thought to follow certain simple rules. Now, one of the most famous black hole laws, predicted by physicist Stephen Hawking, has been confirmed with gravitational waves.

    According to the black hole area theorem, developed by Hawking in the early 1970s, black holes can’t decrease in surface area over time. The area theorem fascinates physicists because it mirrors a well-known physics rule that disorder, or entropy, can’t decrease over time. Instead, entropy consistently increases (SN: 7/10/15).

    That’s “an exciting hint that black hole areas are something fundamental and important,” says astrophysicist Will Farr of Stony Brook University in New York and the Flatiron Institute in New York City.

    The surface area of a lone black hole won’t change — after all, nothing can escape from within. However, if you throw something into a black hole, it will gain more mass, increasing its surface area. But the incoming object could also make the black hole spin, which decreases the surface area. The area law says that the increase in surface area due to additional mass will always outweigh the decrease in surface area due to added spin.

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    To test this area rule, MIT astrophysicist Maximiliano Isi, Farr and others used ripples in spacetime stirred up by two black holes that spiraled inward and merged into one bigger black hole. A black hole’s surface area is defined by its event horizon — the boundary from within which it’s impossible to escape. According to the area theorem, the area of the newly formed black hole’s event horizon should be at least as big as the areas of the event horizons of the two original black holes combined.

    The team analyzed data from the first gravitational waves ever spotted, which were detected by the Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO, in 2015 (SN: 2/11/16). The researchers split the gravitational wave data into two time segments, before and after the merger, and calculated the surface areas of the black holes in each period. The surface area of the newly formed black hole was greater than that of the two initial black holes combined, upholding the area law with a 95 percent confidence level, the team reports in a paper to appear in Physical Review Letters.

    “It’s the first time that we can put a number on this,” Isi says.

    The area theorem is a result of the general theory of relativity, which describes the physics of black holes and gravitational waves. Previous analyses of gravitational waves have agreed with predictions of general relativity, and thus already hinted that the area law can’t be wildly off. But the new study “is a more explicit confirmation,” of the area law, says physicist Cecilia Chirenti of the University of Maryland in College Park, who was not involved with the research.

    So far, general relativity describes black holes well. But scientists don’t fully understand what happens where general relativity — which typically applies to large objects like black holes — meets quantum mechanics, which describes small stuff like atoms and subatomic particles. In that quantum realm, strange things can happen.

    For example, black holes can release a faint mist of particles called Hawking radiation, another idea developed by Hawking in the 1970s. That effect could allow black holes to shrink, violating the area law, but only over extremely long periods of time, so it wouldn’t have affected the relatively quick merger of black holes that LIGO saw.

    Physicists are looking for an improved theory that will combine the two disciplines into one new, improved theory of quantum gravity. Any failure of black holes to abide by the rules of general relativity could point physicists in the right direction to find that new theory.

    So physicists tend to be grumpy about the enduring success of general relativity, Farr says. “We’re like, ‘aw, it was right again.’” More

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    in Space & Astronomy

    Most planets on tilted orbits pass over the poles of their suns

    Earth is on an orderly path around the sun, orbiting in nearly the same plane as our star’s equator. In 2008, however, astronomers began finding worlds in other solar systems that sail far above and below their star’s equatorial plane.

    Now a surprising discovery about these wrong-way worlds may eventually reveal their origin: Most of them follow polar orbits (SN: 6/17/16). If Earth had such an orbit, every year we’d pass over the sun’s north pole, dive through its equatorial plane, then pass below the sun’s south pole before coming back up again.

    Astronomers Simon Albrecht and Marcus Marcussen at Aarhus University in Denmark and colleagues analyzed 57 planets in other solar systems for which the researchers could determine the true tilt between a planet’s orbit and its star’s equatorial plane. Two-thirds of the planets have normal orbits, tilted no more than 40 degrees, the team found. The other 19 planets are misaligned.

    But the orbits of those misaligned planets don’t make just any old angle with their star’s equator. Instead, they pile up around 90 degrees. In fact, all but one of the misaligned planets are on polar orbits, having tilts from 80 to 125 degrees, the astronomers report online May 20 at arXiv.org.

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    “It’s very, very strange,” says Amaury Triaud, an astronomer at the University of Birmingham in England who has found a number of misaligned planets but was not involved with the new study. “It’s a beautifully executed idea, and the result is most intriguing,” he says. “It’s so new and so weird.”

    The result may lend insight into the biggest mystery about these planets: how they arose (SN: 10/18/13). Such worlds were a shock to astronomers, because planets form inside pancake-shaped disks of gas and dust orbiting in their stars’ equatorial planes. Thus, planets should lie near the plane of their sun’s equator, too. In our solar system, for example, Earth’s orbit tilts only 7 degrees from the solar equatorial plane, and even Pluto — which many astronomers no longer call a planet — has an orbit tilted only 12 degrees from that plane (and 17 degrees from the Earth’s orbital plane).

    “At the moment, we are not sure what is the underlying mechanism” or mechanisms for creating misaligned planets, Albrecht admits. Whatever it is, though, it should account for the newly discovered plethora of perpendicular planets, he says.

    A possible clue, Albrecht says, comes from the single exception to the rule: the one misaligned planet in the sample that is not on a polar orbit. This planet also happens to be the most massive in the sample, packing the mass of between five and eight Jupiters. Albrecht says that may be just a coincidence — or it may reveal something about how the other planets became misaligned.

    In the future, the astronomers hope to understand how these wayward worlds acquired their odd orbits. All known misaligned planets orbit close to their stars, but are these worlds more likely than normal, close-in planets to have giant planets near them? The scientists don’t yet know, but if they find such a correlation, those companions may have somehow flung these bizarre worlds onto their peculiar planetary paths. More

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    in Humans

    Awake review: What would happen if nobody could sleep?

    By Gregory Wakeman

    (L-R) Lucius Hoyos as Noah, Gina Rodriguez as Jill, Ariana Greenblatt as MatildaPeter H. Stranks/NETFLIX
    In the dystopian sci-fi movie Awake, everyone on Earth suddenly loses the ability to sleep, plunging the world into hysteria.
    As scientists race to find a cure, ex-soldier Jill Adams (Gina Rodriguez) discovers that her young daughter Matilda (Ariana Greenblatt) might just possess the means to save mankind.
     Awake’s compelling premise is enough to make the opening of the film enjoyable. Director Mark Raso slowly cranks up the tension – there are some unsettling set pieces, and the film doesn’t waste time trying to explain the phenomenon. Instead, the slow reveal of information does enough to keep you hooked.Advertisement
    Unfortunately, though, Awake soon goes off the rails. Raso is constantly trying to create the same mindset of those who are unable to sleep in the viewers, but it just makes things increasingly confusing.
    It also doesn’t help that, by only following Jill’s relationship with Matilda and her son Noah (Lucius Hoyos), Awake is too contained. We learn very little about what’s going on across the world, so when symptoms suddenly escalate and humanity descends into anarchy, it has very little impact.
    But what would actually happen if you suddenly couldn’t sleep?

    Alastair McLean at Queen’s University in Kingston, Ontario, who specialises in sleep deprivation, says its biggest impact is on interpersonal interactions, as people quickly become quite irritable.
    “In terms of performance, one of the most obvious things that happens are microsleeps,” says McLean, in which people fall asleep for up to 30 seconds and can’t remember what happened. “They can occur after 24 hours.”
    [embedded content]
    There is also cognitive slowing, which sees people taking longer to make decisions, and cognitive rigidity, in which individuals can only think about things in one fixed way. Loss of motivation, paranoia, memory and balance issues, mood changes and visual problems can also occur, while some people experience hallucinations and even speech difficulties.
    In 1963, 17-year-old Randy Gardner set the record for the longest time a human had gone without sleep, staying awake for 11 days and 25 minutes. Finland’s Toimi Soini and the UK’s Maureen Weston and Tony Wright have allegedly beaten this time, but none of them were studied as closely as Gardner.
    Studies of sleep deprivation on animals have also proven to be revealing. “In 1989, Allan Rechtschaffen and his Chicago group studied rats that were sleep deprived. After two to three weeks, they started to die,” says McLean. “You saw the same pattern in all of them. They began to eat more and more as the sleep loss went on. Despite that, they had a fall in body weight.”

    A 2020 study by researchers at Harvard Medical School on sleep deprivation in fruit flies also provided the same outcome. The more they didn’t sleep, the greater the increase in a molecule in the gut known as reactive oxidative species.
    “If they gave the fruit flies materials to offset the effects of this, they didn’t die,” says McLean. “We’ve been looking for the effects of sleep deprivation in the brain. It looks, though, that it’s the gut that may be critical when it comes to survival.”
    Based on the trailer for Awake, McLean agrees that it looks accurate in its use of disorientation and even hallucinations, but says it appears to exaggerate the problems and even speed up the timeframe in which they occur.
    By doing just, that Awake strains to repeat the success of thrillers like A Quiet Place and Bird Box. But not only does it lack the ingenuity, tension and star power of these films, it is too aimless, meandering and lacking in heart to come close.
    Awake is now available on Netflix .

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    in Space & Astronomy

    An arc of galaxies 3 billion light-years long may challenge cosmology

    A giant arc of galaxies appears to stretch across more than 3 billion light-years in the distant universe. If the arc turns out to be real, it would challenge a bedrock assumption of cosmology: that on large scales, matter in the universe is evenly distributed no matter where you look.

    “It would overturn cosmology as we know it,” said cosmologist Alexia Lopez at a June 7 news conference at the virtual American Astronomical Society meeting. “Our standard model, not to put it too heavily, kind of falls through.”

    Lopez, of the University of Central Lancashire in Preston, England, and colleagues discovered the purported structure, which they call simply the Giant Arc, by studying the light of about 40,000 quasars captured by the Sloan Digital Sky Survey. Quasars are the luminous cores of giant galaxies so distant that they appear as points of light. While en route to Earth, some of that light gets absorbed by atoms in and around foreground galaxies, leaving specific signatures in the light that eventually reaches astronomers’ telescopes (SN: 7/12/18).

    The Giant Arc’s signature is in magnesium atoms that have lost one electron, in the halos of galaxies about 9.2 billion light-years away. The quasar light absorbed by those atoms traces out a nearly symmetrical curve of dozens of galaxies spanning about one-fifteenth the radius of the observable universe, Lopez reported. The structure itself is invisible on the sky to human eyes, but if you could see it, the arc would span about 20 times the width of the full moon.

    Astronomers discovered what they say is a giant arc of galaxies (smile-shaped curve in the middle of this image) by using the light from distant quasars (blue dots) to map out where in the sky that light got absorbed by magnesium atoms in the halos (dark spots) that surround foreground galaxies.A. Lopez

    “This is a very fundamental test of the hypothesis that the universe is homogeneous on large scales,” says astrophysicist Subir Sarkar of the University of Oxford, who studies large-scale structures in the universe but was not involved in the new work. If the Giant Arc is real, “this is a very big deal.”

    But Sarkar isn’t convinced it is real yet. “Our eye has a tendency to pick up patterns,” Sarkar says, noting that some people have claimed to see cosmologist Stephen Hawking’s initials written in fluctuations in the cosmic microwave background, the oldest light in the universe.

    Lopez ran three statistical tests to figure out the odds that galaxies would line up in a giant arc by chance. All three suggest that the structure is real, with one test surpassing physicists’ gold standard that the odds of it being a statistical fluke are less than 0.00003 percent.

    That sounds pretty good, but it’s not enough, Sarkar says. “Right now, I would say they still don’t have compelling evidence,” he says. More observations, from Lopez’s group and others, could confirm or refute the Giant Arc.

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    If it is real, the Giant Arc would join a growing group of large-scale structures in the universe that, taken together, would break the standard model of cosmology. This model assumes that when you look at large enough volumes of space — above about 1 billion light-years — matter is distributed evenly. The Giant Arc appears about three times as long as that theoretical threshold. It joins other structures with similarly superlative names, like the Sloan Great Wall, the Giant Gamma-Ray Burst Ring and the Huge Large Quasar Group.

    “We can have one large-scale structure that could just be a statistical fluke,” Lopez said. “That’s not the problem. All of them combined is what makes the problem even bigger.” More

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    in Humans

    We Are Satellites review: What brain implants could do to family life

    By Robyn Chowdhury

    A brain implant promises to boost multitasking in We Are Satellitesmetamorworks/Getty Images
    We Are Satellites
    Sarah Pinsker
    Head of ZeusAdvertisement

    CAN we really trust a company seeking to put wires in our brains? And is it worth suspending any mistrust for the sake of our children’s futures? These are the deep, real-life questions posed by award-winning author Sarah Pinsker in her second sci-fi novel, We Are Satellites.
    The story follows a family of four as they become increasingly entangled in the debate on a brain-boosting implant called the Pilot. Pinsker skilfully takes us on a journey that is about far more than mere technology as the Pilot becomes part of everyday life, from schools to government offices.
    The novel excels at integrating questions about the medical technology industry with genuine representations of queer love and family life. Every twist and turn of the novel has family at its heart. The differing opinions of the parents, mothers Val and Julie, on the Pilot sets up a tense family dynamic, fraught with arguments and difficult conversations.
    Unlike Elon Musk’s Neuralink or other brain stimulation devices that are designed to help people with disabilities, the Pilot has one core function: multitasking. It also claims to enhance the attention span of its users. Val and Julie have to consider whether they want their children Sophie and David to opt for this little-understood procedure.
    The first part of the novel revolves around the anxieties of deciding whether or not you want your child to have an invasive procedure for the sake of keeping up with classmates. It touches on the theme of accessibility as Sophie has epilepsy, leaving her unable to have a Pilot implanted. The discussion of discrimination throughout the novel does well to address concerns that technology which could give some people an advantage might leave others behind.
    The pace of the novel lends itself to character-building, with the first two parts spending time helping us understand each character’s motivations. Pinsker gives us a glimpse inside the minds of the characters, showing us how little they communicate their innermost thoughts and how this affects their family.
    The technology in We Are Satellites is similar to an existing brain implant meant to enhance memory. Instead of enhancing memory, the Pilot works by stimulating the right temporoparietal junction in the brain, which is responsible for reorienting attention.
    The focus of the novel isn’t how the technology works, however, but the implications it has for society. The Pilot’s popularity leaves those who don’t have it – because they can’t afford it, they object to having wires in their brain or they have a disability – at a disadvantage. No Pilot means less by way of job opportunities.
    “We can never really be sure about the full ramifications of having wires and electrodes in the brain”
    Far from being a doomy, dystopian novel about terrifying technology, We Are Satellites takes a balanced look at the pros and cons while maintaining healthy scepticism towards the medical technology sector. Through David, we are shown we can never really be sure about the ramifications of having wires and electrodes stuck in the brain – and how hard it can be to communicate exactly what is going on in your own head.
    Sophie’s involvement in the anti-Pilot movement becomes another source of turmoil for the family as she embarks on a mission to discover the truth about the technology – no matter what the cost.
    The story increases in pace during its third part, with several incredibly captivating chapters packed with action and tension as we begin to understand Sophie’s mistrust of the Pilot.
    We Are Satellites is a story about technology with family at its heart. It’s not just about whether we trust scientists to stick things in our brain, or even what happens when technology goes wrong. It’s about what brain-enhancing could do for us, who it would exclude and what happens when a family becomes tangled up within the debate.

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    in Humans

    The summer triangle is now visible in the sky – here's how to spot it

    By Abigail Beall

    John Chumack/SCIENCE PHOTO LIBRARY
    IN THE northern hemisphere, summer nights are marked by an asterism (a pattern of stars that isn’t an official constellation) called the summer triangle. Despite the name, the three stars that make it up aren’t just visible in this season: many stargazers in the southern hemisphere also get a glimpse of them in their winter months too.
    The summer triangle is a vivid asterism, made up of the brightest stars from the constellations Aquila, Lyra and Cygnus. Altair, a star from Aquila, is the twelfth brightest in the night sky. Lyra’s Vega is only 25 light years away from us, … More