Black holes may look like the simplest objects in the universe, defined only by their mass and spin. But scientists are now exploring whether something more complicated could be hiding around them — and gravitational waves may provide a way to find out.
When two black holes spiral into one another and eventually merge, they produce powerful ripples in spacetime known as gravitational waves. After the collision, the newly formed black hole settles down by emitting a short-lived signal that gradually fades away.
