The merger of two black holes is one of the most sought-after observations of modern astronomy. The first observatories capable of directly detecting gravitational waves — ripples in the fabric of spacetime predicted by Albert Einstein — will begin observing the universe later this year. When these waves rolling in from space are detected on Earth for the first time, astrophysicists predict astronomers will ‘hear,’ through these waves, five times more colliding black holes than previously expected.