How long is a piece of string? The knots in it could be a clue.
Dorian Raymer, a biophysicist at the University of California, San Diego, often found himself with unwanted tangles. “Headphones in my backpack would inevitably come out knotted,” he says, and he wanted to know why. Though there is a branch of mathematics called knot theory, it doesn’t explain the probability that a particular piece of string will knot when it is tumbled about, so Raymer and colleague Douglas Smith devised a series of experiments to find out.
They dropped pieces of string of various lengths into…
