We now know why shoes squeak, and it involves miniature lightning bolts

A close up of a man's lower legs, with both feet wearing tall black sneakers and black socks. He wears white basketball shorts and is bouncing a basketball between his hands while standing on a midline on a wooden basketball court.

The ubiquitous squeak of sneakers on a basketball court may be caused by more than just friction, a new study suggests.

Researchers have found that the sharp chirp of rubber on a hard floor happens when tiny areas of slipping between the shoe's sole and the floor move at supersonic speeds — and, in some experiments, the process involved miniature, lightning-like sparks. What's more, the findings could lead to an improved understanding of earthquakes and aid in the design of grippy surfaces.