Record-Breaking Gravitational Wave Detection Suggests These Black Holes Merged Before IFLScienceScientists hear 2 newborn black holes 'crying' through ripples in spacetime — and one had a birth unlike anything seen before SpaceGravitational wave events hint at 'second-generation' black holes Phys.orgColliding black holes might have formed from earlier cosmic smashups CaltechWhen Black Holes Eat Their Own Universe Today