Astronomers have found a background din of exceptionally long-wavelength gravitational waves pervading the cosmos. The cause? Probably supermassive black hole collisions, but more exotic options can’t be ruled out.
Albert Einstein in 1916 proposed the existence of gravitational waves as an outgrowth of his ground-breaking general theory of relativity. Scientists described the universe s gravitational wave background as the equivalent of hearing the hum of a large group of people talking at a party, without being able to distinguish any individual voice.