Stephen Johnson wrote:
‘In May 2019, a ripple of gravitational waves passed through Earth after traveling across the cosmos for 7 billion years. The ripple came in four waves, each lasting just a fraction of a second. Although the ancient signal was faint, its source was cataclysmic: the biggest merger of two black holes ever observed.
It occurred when two mid-sized black holes — 66 and 85 times the mass of our Sun — drifted close together, began spinning around each other and merged into one black hole roughly 142 times the mass of our Sun.
“It’s the biggest bang since the Big Bang observed by humanity,” Caltech physicist Alan Weinstein, who was part of the discovery team, told The Associated Press….’
— via Big Think