A stone falls into still water — ripples spread across the surface. A black hole behaves similarly when something falls into it or when it merges with another black hole. The hole begins to oscillate, and these oscillations propagate through space as gravitational waves. Astrophysicists call this process the "ringing" of a black hole.
The authors of the new work built a computer model that, for the first time, shows the complete history of such a ring — from the very first burst to the barely noticeable damping after a long time. Previously, only the "sound" itself, the oscillation frequencies, was studied. Now one can see how the signal's loudness changes and how quickly it fades. For this, they used not the standard Einstein equations but an extended version — a parameterized theory "beyond Teukolsky." It adds small corrections to the calculations that could point to new physics.
The simulation was compared with exact mathematical solutions. For simple cases, the agreement was excellent. When the oscillations became more complex, a "contamination" of other tones appeared, making it harder to isolate the clean signal. It is precisely such mixed signals that arrive from real black holes. Thus, the new approach will help more accurately decode data from gravitational wave detectors and search for traces of unknown laws of nature.
A black hole "rings" not with a single pure tone but with several at once, like a bell struck with a hammer. Each tone decays at its own rate, and from them one can determine the mass and spin of the hole.
In the movie "Interstellar," the heroes transmit data via gravitational waves — much in the way scientists hope to one day catch the "whisper" of quantum corrections to Einstein's theory.