Pendulum waves are one of those physics experiments that can make the natural world seem almost like magic. In a pendulum wave, many pendulums of different lengths start swinging at the same time. As their different lengths cause them to swing at different rates, they start out synchronized and quickly begin to swing in mesmerizing patterns.

This articular pendulum wave was built by artist and Appalachian State University teacher Jeff Goodman outdoors in North Carolina. It uses 16 bowling balls mounted on a wooden frame.

The pendulums’ lengths are precisely calculated so that they will all stop at precisely the same moment. Or at least that’s what they would do in a controlled environment. In this outdoor setup, environmental factors make them stop at slightly different times. Still, the visual display is kind of mind-blowing and begs to be watched over and over.