In 1916, Einstein made a bold prediction- that gravity actually travels in waves. These “gravitational waves” would be ripples in the fabric of space a bit like ripples on a pond, and would slightly stretch and squash the distances between things as they passed. “Einstein himself who came up with the theory didn’t think that this would ever really be detected,” Kenyon College professor Leslie Wade said. Anything with mass can make gravitational waves by moving around, but they’re so small, the