Most people are familiar with pendulum collision balls. Most kids have played with the simple pendulum with four or five balls that if you knock one into the others, the force is distributed to the last ball. But this pendulum wave is much more impressive and mesmerizing. Fifteen balls at different heights are swung, and the reaction is simply amazing. The older video from 2010 has gone viral this summer thanks to NPRHarvard, and Geekologie