Usually, black holes inch closer gradually, circling in a tightening spiral. This dance births a long ripple of gravitational waves — a tremor in the very fabric of spacetime. Detectors LIGO and Virgo routinely catch such mergers.
But GW190521 is the exception. Two black holes whipped past each other at enormous speed and, barely noticing one another, flew apart. Instead of a long hum, a sharp “wave.” The signal lasted a tenth of a second, yet carried away more energy than the Sun will radiate in 10 billion years.
This discovery paints a different picture of stellar “megacities”: black holes collide at random, generating brief gravitational bursts, not just long spiral dances.
The GW190521 signal lasted a tenth of a second but carried more energy than the Sun will emit over its entire lifetime — tens of billions of years.
In Interstellar, gravitational waves from a slow inspiral help communicate across time. GW190521 is more of a “gravitational punch”: one black hole effectively did a hyperjump past the other, like in Star Wars.