Jonathan Gair

Two black holes spiral faster and faster until they merge into one. This dance shakes space itself: waves ripple outward from the collision site, like ripples from a stone thrown into a pond. Sometimes the merger also produces a flash of light.

A huge pond, with ripples spreading from two heavy stones circling each other. The stones draw closer, the ripples become more frequent and stronger, and soon the stones will collide. Gravitational waves are like those ripples, but not on water — in the very fabric of spacetime.

Pairs of black holes dance in three different styles before merging. The first is a neat waltz: the objects swirl in the same direction, like partners facing the same way. Such pairs are born from binary stars and often have unequal masses. The second is chaotic disco: spins are scattered, masses nearly equal.