Illustration of the American experimental physicist Barry Barish (born 1936). Barish received his PhD in experimental particle physics from The University of California, Berkeley in 1962. In 1963 he moved to the California Institute of Technology where he has spent the rest of his career. Barish is best known for his work on gravitational waves. In 1994 he became the principal investigator of the LIGO (Laser Interferometer Gravitational-Wave Observatory) experiment, and in 1997 its director. Along with colleagues Rainer Weiss and Kip Thorne, Barish won the 2017 Nobel Prize in Physics for his work on the LIGO experiment and the observation of gravitational waves. Gravitational waves are ripples in the curvature of spacetime that travel outward from a central source. They were predicted by Einstein in 1916, and remained undetected until observed by LIGO on the 14th September 2015. The detected waves were a result of two black holes colliding and had taken 1.3 billion years to arrive at Earth.