For The First Time Ever, Scientists Hear Ringing of A Newborn Black Hole

Albert Einstein, in his theory of general relativity, hypothesized that a black hole, formed from two cosmically quaking collisions of two massive black holes, would ring in the aftermath. This ring would produce gravitational waves that, like a struck bell, would reverberate sound waves. Einstein predicted that this particular pitch and decay of these gravitational waves would indicate the mass and the spin of the newly formed black hole.

Now, physicists from MIT and elsewhere have "heard" the ringing of an infant black hole for the first time, and found that the pattern of this ringing does, in fact, predict the black hole's mass and spin -- more evidence that Einstein was right all along.

The findings, published today in Physical Review Letters, also favor the idea that black holes lack any sort of "hair" -- a metaphor referring to the idea that black holes, according to Einstein's theory, should exhibit just three observable properties: mass, spin, and electric charge. All other characteristics, which the physicist John Wheeler termed "hair," should be swallowed up by the black hole itself, and would therefore be unobservable.