A couple of weeks ago, the New York Times Magazine published its 2007 “Year in Ideas” issue — their annual compendium of the year’s most interesting and offbeat research. I wrote up five of their scientific and technological entries. The entire issue is online here for free, but I’m also archiving my pieces here for posterity’s sake.

This one is about a pair of scientists that investigated the mystery of how laptop cords get tangled up so quickly when you leave them loose in your bag. Heh.

Knot Physics

When Doug Smith pulls the power cord for his laptop out of his bag, he inevitably finds that — whoops! — it has somehow tangled itself into a dense knot. This is, of course, a common complaint of the high-tech age (and before, with other types of cord). Most of us simply shrug. But Smith is a physics professor at the University of California, San Diego, and he wanted to know precisely why the knots form in the first place.

So he devised a clever experiment. Working with his research assistant Dorian Raymer, he took some string — about the thickness of a computer-mouse cord — and dropped it into a small square plastic box. They spun the box around for 10 seconds, then opened it up. Sure enough, they found “this really monster, complex knot,” Smith says. Then they repeated the experiment a dizzying 3,415 more times, using strings of different lengths and boxes of larger sizes, to see whether there were any rules that governed how badly the string knotted.