Illustration of the German-American physicist Rainer Weiss (born 1932). Weiss has made important contributions to the study of the cosmic microwave background (CMB) and the detection of gravitational waves. He measured the spectrum and angular distribution of the CMB and invented the laser interferometer technique used for the LIGO (Laser Interferometer Gravitational-Wave Observatory) experiment. Along with colleagues Kip Thorne and Barry Barish, Weiss were awarded 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.