Black Holes Don't Stop at a Star's Death — Evidence for 'Second-Generation' Mergers
July 12, 2026GWTC-5.0, the gravitational-wave catalog released in 2026, shows signs that some merged black holes went on to collide again, producing a 'second generation.' SORABUMI breaks down what happened 700 million and 2.4 billion light-years away, and how spin patterns exposed a hierarchy of mergers.