## If Black Holes Have Hair, We Will See It in the Ringdown of Their Mergers In theory, the structure of a black hole is amazingly simple. It depends on only three things: mass, rotation, and electric charge. All you've got to do is compress objects down tightly enough for the black hole to form. Radioactive waste, old tax returns, a massive cloud of helium, you name it. Compress it into a black hole, and all the information and atomic structure become irrelevant. A black hole is just that simple. At least according to the no-hair theorem. Now a new study finds that if real black holes…