Working Knowledge: String Theory; September 2004; Scientific American Magazine; by Mark Fischetti; 2 Page(s)

The yo-yo is just a simple toy, right? Not anymore. Rim weights and axle technologies now exploit the physics of angular momentum to make possible all sorts of tricks and traits.

Yo-yos date back more than 2,000 years to China and Greece. They rolled their way into Europe, and by the 18th century the "émigrette" or "quiz" had become a favored toy of aristocrats.