Scientific study on why knots happen

Danny says: Tangled telephone cords and electronic cables that come to resemble bird nests can frazzle even the most stoic person. Now researchers have unraveled the mystery behind how such knots form."
200710041236 [Douglas Smith of the University of California, San Diego] and UCSD colleague Dorian Raymer ran a series of homespun experiments in which they dropped a string into a box and tumbled it for 10 seconds (one revolution per second). They repeated the string-dropping more than 3,000 times varying the length and stiffness of the string, box size and tumbling speed.

Digital photos and video of the tumbling strings revealed: Strings shorter than 1.5 feet (.46 meters) didn't form knots; the likelihood of knotting sharply increased as string length went from 1.5 feet to 5 feet (.46 meters to 1.5 meters); and beyond this length, knotting probability leveled off.

Their conclusion?
While there is no magical knot buster, Smith advised what all sailors, cowboys, electricians, sewers and knitters know: to avoid tangles, keep a cord or string tied in a coil so it can't move.