
Researchers have found that if black holes have certain features, known as "hair," then we could prove it by observing the gravitational ringdown of merging black holes. Future studies could test the no-hair theorem of general relativity.

Researchers have found that if black holes have certain features, known as "hair," then we could prove it by observing the gravitational ringdown of merging black holes. Future studies could test the no-hair theorem of general relativity.