When astronomers announced in February that they had detected the ripples in space-time known as gravitational waves from a pair of black holes colliding, the discovery was hailed as the advent of a new window on nature.

It is a way of hearing the universe instead of just looking at it, as well as a long-sought vindication of Einstein’s theory of gravity, general relativity.

At the time, there were rumors that the discovery was not a fluke and that other gravitational-wave cataclysms had been recorded. Now it seems that black hole collisions may be frequent facts of nature, with humanity at least tuned in to the darker, deeper vibrations of nature.