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    Why is the coronavirus pandemic so politically polarising?

    Covid-19 continues to split some people along party lines. We are now beginning to work out why, writes Graham Lawton

    Humans | Comment 9 December 2020
    By Graham Lawton

    REUTERS/Mike Blake

    LIKE the majority of people in my local area, I follow the rules on face coverings. It’s an inconvenience, but I consider putting on a mask a small sacrifice to protect my health and that of other people. Every day, I see many people – more than could possibly have a legitimate exemption – flagrantly flouting the rules and it really gets up my nose.
    The refuseniks annoy me on multiple levels. They are selfishly putting me and other people at risk. They think they know better than experts. They often fall for conspiracy theories. And even if they are … More

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    If the multiverse exists, are there infinite copies of me?

    According to the many-worlds interpretation of quantum mechanics, the universe is constantly dividing and taking you with it – so would you recognise your other selves if you met them?

    Humans 9 December 2020
    By Daniel Cossins

    Jonathan Knowles/Getty Images

    Is there more than one of you?
    BIOLOGICALLY speaking, there is definitively only one you (see “How likely are you?”). Physics might give you pause for thought, however. The most bewildering argument against your uniqueness comes from quantum mechanics, the fundamental theory that describes the often counter-intuitive behaviour of subatomic particles. It might imply not only that there are multiple, identical versions of you, but even that there are an infinite number of yous out there.
    The quantum realm is notoriously fuzzy: quantum objects such as particles are described in terms of probabilities, encoded in mathematical widgets called wave functions that give you the odds on any number of different states the object might be in. Only when you observe or measure it does the object take on one of those states, at least from your perspective.
    “Quantum theory might imply there are an infinite number of yous out there”
    The truth of what happens at this point – and indeed what, if anything, the wave function itself is trying to tell us about reality – divides physicists. Many stick with a cop-out known as the Copenhagen interpretation: essentially, that we can never know what is happening in this fuzzy pre-measurement realm. In other words, quantum theory makes predictions about reality, but says nothing about what goes on under the hood.
    That isn’t good enough for some. Physicists who subscribe to the rival “many worlds” interpretation insist that all the possibilities encoded in the wave function are real, and that they continue to exist in different universes that split off from ours every time a quantum … More

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    Physics might create a backdoor to an afterlife – but don't bank on it

    Quantum information can never be destroyed, so some of the essence of you could live on after death – but it’s not going to help the physical you

    Humans 9 December 2020
    By Joshua Howgego
    Is death the end, or does part of us live on?
    Getty Images

    What happens when you die?
    MICHELLE FRANCL-DONNAY will never forget 15 April 1987. Her husband Tom was due to pick her up from an evening meeting, but decided to take a swim first. He had an undiagnosed heart condition, and while in the pool had a catastrophic aneurysm. Michelle rode with him in the ambulance. That was the last time she spoke to him.
    “When I saw Tom’s body the next morning, he clearly wasn’t there anymore,” says Francl-Donnay, a chemist at Bryn Mawr College in Pennsylvania and an adjunct scholar at the Vatican Observatory who writes extensively on both science and spirituality. Over the years, she found herself mulling a question humans have asked for a long time: where had he gone?
    Even those of us who rationally reject the idea of an afterlife have trouble letting go of the idea. That might be down to our theory of mind. Because we habitually put ourselves in other people’s shoes and imagine their thoughts and feelings, it can be hard to believe that those thoughts and feelings can just cease to be when ours still feel so real.
    Yet we have no evidence for anything different. When you die, blood stops flowing, the muscles cool and consciousness, whatever that is, slips away. If your body were simply let be, other organisms would rapidly digest it, from microbes already living inside you to newly arrived blowflies.
    Human burial rites just change the timescale or manner of your physical disappearance: if your remains are cremated, for instance, the … More

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    Why people enjoy alcohol or are teetotal may come down to a hormone

    By Claire Ainsworth

    Matt Cardy/Getty Images

    LARS IGUM RASMUSSEN and his mates were going large. Donning their lederhosen, the three middle-aged men headed into Oktoberfest in Munich, Germany, the world’s biggest folk and beer festival. There, each proceeded to quaff an average of 7.5 litres of beer a day, for three days. It was a spectacular bender.
    Getting hammered wasn’t the main aim of the exercise, however: Rasmussen is health correspondent for Danish magazine Politiken and was writing a story exploring the physiological effects of binge drinking. To understand what was happening to him and his friends, he had enlisted the help of metabolic physiologist Filip Knop at the University of Copenhagen. While Rasmussen was interested in finding out what havoc excessive boozing wreaks on the bodies of middle-aged men, Knop had another motive for getting involved. He and his colleague Matt Gillum had been itching to test a new idea about people’s appetite for alcohol – but couldn’t, in good conscience, solicit anyone to partake in a binge of this magnitude. “It would give the ethics officer a heart attack,” says Gillum. Volunteers, however, were a different matter.
    What Knop and Gillum discovered is helping to build a picture of how our bodies control our boozing habits, from the amount we drink to when we stop. The research is homing in on a hormone that partly explains the huge variation in our social drinking habits: why some people are teetotal or can’t drink much, while others are lushes. It also points to the startling idea that our livers have more say in directing our behaviour than anyone imagined.
    Of course, people choose to … More

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    The Preserve review: The inner struggle to survive in a robot world

    How do humans feel living in a world where robots outperform them, asks The Preserve by Ariel S. Winter. Clare Wilson says it’s a great thought experiment

    Humans 9 December 2020
    By Clare Wilson
    How would we react if machines dominated the world?
    Donald Iain Smith/Getty Images

    The Preserve
    Ariel S. Winter
    Simon & Schuster
    WHEN AI that is truly sentient finally emerges, the big question is how humans will fare. Will machines try to hunt us to extinction, as in the Terminator films, or will their omnipotence mean life for humans can be the kind of extended party of Iain M. Banks’s Culture series?
    In Ariel S. Winter’s The Preserve, the robots have reached a stage somewhere in the middle. The book is set in the not-too-distant future, when human populations have dwindled … More

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    Can you ever know yourself? Whatever the answer, it is worth trying

    Gary Ellis Photography/Alamy
    “KNOW thyself.” The first of three maxims said to have been inscribed in the forecourt of the Temple of Apollo in Delphi sounds grand. What it actually means has been a matter of debate for millennia, and when it comes to knowing ourselves, modern science has made things deliciously more complex, too.
    How the physical substance of our bodies creates our sense of being a consistent entity, and what it means to have that sensation, is a long-standing puzzle. Debates about this relationship between matter and mind were meat and drink to the Ancient Greek philosophers, but … More

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    How nature, nurture and sheer randomness combine to make a unique you

    We’re slowly beginning to unpick the complex interplay of genes, environment and experience that make you who you are – and like no one else who ever existed

    Life 9 December 2020
    By Clare Wilson
    Birth is only a waymarker on the road to becoming you
    Kieferpix/Getty Images

    How likely are you?
    CHILDREN are generally fascinated by tales of how they came to be. Even young ones can often grasp the mind-boggling implication if the events of the story leading up to their existence had been any different: they wouldn’t be there to hear it.
    Your you-ness is a precarious thing. Rerun the experiment of you with a different sperm and egg from the same people, and “you” would be as different from your current self, genetically, as siblings are from one another. If the egg were the same, but through some random fluctuation a different sperm won the race, you would also be distinctly different. For a start, depending on whether the sperm bore an X or a Y chromosome, you could have ended up another sex. “That’s a pretty big difference, right there,” says David Linden, a neuroscientist at Johns Hopkins University in Maryland and author of Unique: The new science of human individuality.
    The potential for being a different you didn’t stop once destiny set your founding sperm and egg on their collision course, either. A lot of what makes you what you are is down to how your brain is connected. But your DNA doesn’t encode a precise wiring diagram: it is more like a rather hand-wavy recipe or set of instructions. Even genetically identical twins don’t end up with the same neuronal network. “A pool of cells in the developing brain might receive instructions that say: ‘About half of you move across the midline of the brain’, ” says Linden. “In one twin, 40 per … More

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    You are stardust: The long view of when your existence really began

    The point when you began depends on the scale you look at and how you define a person – in one sense you’re as old as the universe, in another you’ve hardly begun at all

    Humans 9 December 2020
    By Daniel Cossins
    Arguably, you only become a person when you can reflect on other people’s view of you
    Daisuke Takakura

    When did you begin?
    YOU almost undoubtedly know the date, possibly even the hour, you were born. Whether you are past celebrating rather depends. But reflect on the big picture, and the truth about when you began is too epic, and possibly a little too confusing, to be captured by a terse entry on a birth certificate.
    That story begins in the deep cosmos. As anyone with a passing interest in Joni Mitchell’s back catalogue knows, we are stardust. It’s a nice line, and it also happens to be true, says Karel Schrijver, an astrophysicist at the Lockheed Martin Advanced Technology Center in California.
    Most of your body’s trillions of atoms, from calcium in your bones and carbon in your genes to iron in your blood, were forged by nuclear reactions in ancient stars, either when they were burning or when they ended in fiery supernova explosions. Those atoms were recycled through the births and deaths of more stars until, at some point, they escaped for a while. “Our solar system captured these elements to make Earth and everything on it,” says Schrijver – including you.
    In that sense, we can’t know exactly when we began: it depends how many generations of stars our atoms cycled through. But each of us is at least 4.6 billion years old, the age of the solar system, and perhaps as ancient as the universe’s first stars, which appeared some 13.7 billion years ago, just 100 million years after the big bang. The hydrogen within … More