In 2017, astronomers witnessed the birth of a black hole for the first time. Gravitational wave detectors picked up the ripples in spacetime caused by two neutron stars colliding to form the black hole, and other telescopes then observed the resulting explosion. But the real nitty-gritty of how the black hole formed, the movements of matter in the instants before it was sealed away inside the black hole’s event horizon, went unobserved. That’s because the gravitational waves thrown off in these final moments had such a high frequency that our current detectors can’t pick them up. If you could observe ordinary matter as it turns into a black hole, you would be seeing something similar to the Big Bang played backwards. The scientists who design gravitational wave detectors have been hard at work to figure out how improve our detectors to make it possible.