Based on two detectors separated by about 3,000 km and using ultra-stable lasers, a new observatory known as the Advanced LIGO has detected gravitational waves generated by the coalescence of two black holes, that turned into a new black hole with the release of about five solar masses of energy in a few milliseconds at a distance of over a billion light years, thus confirming one of the last untested predictions of the General Theory of Relativity.
