1915 - Albert Einstein publishes general theory of relativity, explains gravity as the warping of spacetime by mass or energy
1916 - Einstein predicts massive objects whirling in certain ways will cause spacetime ripples—gravitational waves
1936 - Einstein has second thoughts and argues in a manuscript that the waves don't exist—until reviewer points out a mistake
1962 - Russian physicists M. E. Gertsenshtein and V. I. Pustovoit publish paper sketch optical method for detecting gravitational
waves—to no notice
1969 - Physicist Joseph Weber claims gravitational wave detection using massive aluminum cylinders—replication efforts fail
1972 - Rainer Weiss of the Massachusetts Institute of Technology (MIT) in Cambridge independently proposes optical method for detecting waves
1974 - Astronomers discover pulsar orbiting a neutron star that appears to be slowing down due to gravitational radiation—work that later earns them a Nobel Prize
1979 - National Science Foundation (NSF) funds California Institute of Technology in Pasadena and MIT to develop design for LIGO
1990 - NSF agrees to fund $250 million LIGO experiment
1992 - Sites in Washington and Louisiana selected for LIGO facilities; construction starts 2 years later
1995 - Construction starts on GEO600 gravitational wave detector in Germany, which partners with LIGO and starts taking data in 2002
1996 - Construction starts on VIRGO gravitational wave detector in Italy, which starts taking data in 2007
2002 - 2010 - Runs of initial LIGO—no detection of gravitational waves
2007 - LIGO and VIRGO teams agree to share data, forming a single global network of gravitational wave detectors
2010 - 2015 - $205 million upgrade of LIGO detectors
2015 - Advanced LIGO begins initial detection runs in September
2016 - On 11 February, NSF and LIGO team announce successful detection of gravitational waves