The LIGO Scientific Collaboration and the Virgo collaboration identify a second gravitational wave event in the data from Advanced LIGO detectors. The LIGO Observatories are funded by the National Science Foundation (NSF) and were conceived, built and are operated by Caltech and MIT. Physicists have concluded that gravitational waves were produced during the final moments of the merger of two black holes – 14 and 8 times the mass of the sun – to produce a single, more massive spinning black hole that is 21 times the mass of the sun. Gravitational waves are 'ripples' in the fabric of space-time caused by some of the most violent and energetic processes in the Universe.