Gravitational wave background

Gravitational waves are ripples in space-time, which is the fabric of the universe. Just like when you drop a stone in a pond and it makes ripples on the surface of the water, when big events like explosions or collisions happen in the universe, they can make gravitational waves.

The gravitational wave background is like the background noise in the universe. It is the combined sound of all of the gravitational waves that are happening all around us, all the time. Even though we can't see it, it's there, and scientists are trying to tune in and listen to it so they can learn more about how the universe works.