The Thing with Feathers by Noah Strycker Read Free Book Online Page B

birds behaved more like those close to them than they did like those farther away. When Cavagna compared these correlation lengths between flocks of different sizes, though, he discovered that they scaled perfectly with the size of the group—birds behaved similarly across longer distances in bigger flocks. He called this a scale-free correlation, and pointed out that this was a feature of critical systems, poised at a tipping point.
    Water becomes a critical system when it freezes, and also when it boils. Avalanches are said to reach a critical point at the moment when they break free. Magnets become critical when they spontaneously align from disorder. Perhaps, Cavagna thought, starlings represent a system that forms flocks at a critical point.
    Then the team analyzed flight directions within a starling flock. They found a model that correctly predicted order within the flock, and proceeded to demonstrate, in a dense, eighteen-page paper, that it was mathematically equivalent to a well-known model of magnetic systems at critical points called the Heisenberg model, which uses quantum mechanics to describe magnetic orientations. When iron, say, is cooled below a certaintemperature, it spontaneously magnetizes. Electrons within the material align their spins below that critical point. Spontaneous magnetism, Cavagna and other physicists argued, was happening in the alignment of flight directions within a flock of starlings. Equations of magnets, it turns out, can describe a starling flock better than biology can.
    —
    CAN EQUATIONS REALLY EXPLAIN how starlings perform coordinated flight? Does physics underlie even the most spontaneous, beautiful displays of life on earth? The answer depends, in a sense, on whether you believe math is discovered or invented; whether it’s a pervasive force, guiding every action in this universe, or whether logic is imposed by the human brain. History’s most ardent philosophers have agonized over the issue, and they are still arguing.
    I like to think that life defies physics, and that the beauty of a cartwheeling flock of starlings originates with the birds themselves rather than in a universal law—in the same way that a Renaissance masterpiece may follow specific rules but still takes a real master to produce. As emergence writer Peter Corning pointed out, knowing the rules doesn’t always bring a solution any closer.
    Andrea Cavagna believes that physics can help us make sense of the natural world, even in ways that may not seem obvious, and his team certainly documented some fascinating observations about flocking behavior in birds. But millions of online viewers reached the same conclusion by instinct and genuine fascination. However you look at it, a murmuration of starlings is absolutely magnetic.

the buzzard’s nostril
    SNIFFING OUT A TURKEY VULTURE’S TALENTS

    O ne day in high school, I told my parents I wanted to photograph vultures.
    “Great,” they said. “But how will you get close enough?”
    “By putting a dead deer in our yard.”
    I’d been inspired by an episode of David Attenborough’s The Life of Birds documentary, the one where the British filmmaker ventures into a Trinidad rainforest carrying a fist-sized hunk of rotting beef. With great flourish, Attenborough hides the meat under a layer of wet leaves on the dark jungle floor and then backs away, muttering lilting phrases such as: “Their beaks are quite adequate for tearing off strips of flesh.” Within forty-five minutes, a turkey vulture appears out of nowhere and uncovers the delicacy—quite a trick, for filmmaker and scavenger alike.
    If Sir David could lure a vulture with a funky old steak, then how many vultures might a whole deer carcass attract? Just imagine how smelly that would be.
    My parents were used to this sort of scheme. They weren’t sure how or why their son had become so obsessed with birds, but, considering the various other possible vices, had resigned to embrace this one. Their