Gravitational Waves

"Using gravitational waves, tiny ripples in space-time first predicted by Albert Einstein back in 1915, astronomers have discovered that a "stellar graveyard" is packed with mergers between extreme stellar remnants like black holes and neutron stars, created when massive stars die in supernova explosions."https://www.space.com/astronomy/gravitational-waves-reveal-stellar-graveyard-packed-with-neutron-star-and-black-hole-mergers