LIGO

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory designed to detect cosmic gravitational waves. Prior to LIGO, all data about the universe had come in the form of light and other forms of electromagnetic radiation, from limited direct exploration on relatively nearby Solar System objects such as the Moon, Mars, Venus, Jupiter and their moons, asteroids etc., and from high energy cosmic particles. Initially, two large observatories were built in the United States with the aim of detecting gravitational waves by laser interferometry. Two additional, smaller gravitational wave observatories are now operational: one in Japan (KAGRA), and one in Italy (Virgo). The two LIGO observatories use mirrors spaced 4 kilometres (13,000 ft) apart to measure changes in length—over an effective span of 1,120 kilometres (700 mi)—of less than one ten-thousandth the charge diameter of a proton. The initial LIGO observatories were funded by the United States National Science Foundation (NSF). They were conceived, built, and are operated by Caltech and MIT in the 1990s. They started to collect data from 2002 to 2010, but no gravitational waves were detected during that period. The Advanced LIGO Project to enhance the original LIGO detectors began in 2008, and continues to be supported by the NSF, with important contributions from the United Kingdom's Science and Technology Facilities Council, the Max Planck Society of Germany, and the Australian Research Council. The improved detectors began operation in 2015. The detection of gravitational waves was reported in 2016 by the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration with the international participation of scientists from several universities and research institutions. Scientists involved in the project and the analysis of the data for gravitational-wave astronomy are organized by the LSC, which includes more than 1,000 scientists worldwide, as well as 440,000 active...