[In Depth] LIGO detects another black hole crash
The biggest discovery in science this year—the observation of ripples in space-time called gravitational waves—was no fluke. For a second time, physicists working with the two massive detectors in the Laser Interferometer Gravitational-Wave Observatory (LIGO) have detected a pulse of such waves, the LIGO team reported on 15 June at a meeting of the American Astronomical Society in San Diego, California. Once again the waves emanated from the merger of two black holes, the ultraintense gravitational fields left behind when massive stars collapse into infinitesimal points. The new observation suggests that if LIGO's detectors reach their design sensitivity—which physicists hope to achieve by 2019—the observatory will spot dozens or even hundreds of the otherwise undetectable events each year, ushering in a new era of gravitational-wave astronomy. Author: Adrian Cho