Colliding black holes could clock the universe’s expansion rate

Scientists may have found a way of using the collisions of black holes to measure the rate at which the universe is expanding. The violent mergers of black holes launch ripples in space-time called gravitational waves, and a new technique measures changes in these signals that occur as they experience the universe’s expansion.

- Robert Lea

Scientists hope to use cosmic collisions between tight binary black hole pairings as what the team term ‘spectral sirens’ to provide an alternative measurement technique for the Hubble constant. Finally settling this pressing cosmological concern could reveal how the universe has evolved and how it looked in its early years. At the heart of the spectral siren method are gravitational waves.