Researchers have developed a technique to analyze how black holes “ring” when they collide and merge: one of the universe’s most dramatic events. When black holes merge, the collision produces a new, larger black hole that “rings” like a plucked guitar string or a bell while it settles into its final, stable shape. But instead of sound waves, the new black hole rings with gravitational waves: ripples in spacetime first predicted by Albert Einstein.

The new black hole vibrates at a specific set of frequencies, depending on its mass and spin, which help scientists learn about the object formed in the collision.

These vibrations, known as quasinormal modes, are the fingerprint of a black hole. Detecting them is central to testing Einstein’s general theory of relativity in the most extreme gravitational environments in the universe.