The Laser Interferometer Gravitational-Wave Observatory (LIGO) operated by Caltech and the Massachusetts Institute of Technology has been awarded the Special Breakthrough Prize in Fundamental Physics. Designed to open the field of gravitational-wave astrophysics through the direct detection of gravitational waves predicted by Einstein’s General Theory of Relativity, LIGO’s multikilometer-scale gravitational wave detectors use laser interferometry to measure the minute ripples in space-time caused by passing gravitational waves from cataclysmic cosmic sources. LIGO consists of two widely separated interferometers in Hanford, Wash., and Livingston, La., which operate in unison. After a major upgrade from 2010 to 2015, LIGO almost immediately observed a gravitational wave distorting the structure of spacetime as it passed through the Earth. The detected distortion was less than a billionth of a billionth of a meter in size at the two 4-km observatories. The wave emanated from two black holes with masses about 30 times that of the sun, spiraling into each other 1.3 billion light years away. "This discovery has huge significance: firstly, as evidence for general relativity and its predictions of black hole interactions, and secondly as the beginning of a new astronomy that will reveal the universe through a different medium,” said 2013 Breakthrough Prize winner and world-renowned theoretical physicist Stephen Hawking. “The LIGO team richly deserves the Special Breakthrough Prize." The award recognizes scientists and engineers contributing to the detection of gravitational waves. Founders Ronald W. P. Drever, professor emeritus of physics at Caltech; Kip S. Thorne, the Feynman Professor Emeritus of Theoretical Physics at Caltech; and Rainer Weiss, professor emeritus of physics at MIT, will each equally share $1 million, with 1,012 other experiment contributors equally sharing $2 million in prize money. "This amazing achievement lets us observe for the first time some of the remarkable workings of Einstein's theory,” said Edward Witten, chair of the Selection Committee. “Theoretical ideas about black holes which were close to being science fiction when I was a student are now reality." LIGO's gravitational wave detectors were conceived and R&D was initiated in the 1960s. LIGO was built between 1994 and 2002 through a partnership with the National Science Foundation of the United States.