As the newly-formed black hole settles into a new state, it produces reverberations that are also visible as a faint "ringing." With these new signals, the team was provided with a complete picture of a binary black hole merger, from the moment they collided to the final reverberations. We’ve found some of the strongest evidence yet that astrophysical black holes are the black holes predicted from Albert Einstein’s theory of general relativity. In 2021, he and his colleagues demonstrated a cutting-edge method for isolating certain frequencies using data from the first black hole merger. Along with proposed ground-based observatories, these improved detectors will mean astronomers can listen more closely to the tones emitted by black hole mergers and test the characteristics of black holes more rigorously.