A simulation of an accretion disk surrounding a supermassive black hole.
(Credit: Scott C. Noble)

When the LIGO collaboration first detected the spacetime ripples of a gravitational wave it came from the merger of two black holes. To date, scientists have detected at least ten pairs of black holes spiraling into and combining with each other.

But there’s still an outstanding mystery about these singularities: why are some of them so big? Some have been far larger than scientists think po