Gravitational waves, ripples in the fabric of space-time produced by catastrophic astrophysical events, are arguably the most elusive prediction of Einstein’s theory of General Relativity, so feeble that Einstein himself thought their detection would be impossible. One hundred years later, the Laser Interferometer Gravitational-wave Observatory (LIGO) and its sister project Virgo have observed multiple gravitational wave signals from the collision of pairs of black holes, a groundbreaking discovery that opened a new observational window on the Universe. An equally momentous discovery took place on August 17, 2017, with the first detection of gravitational waves from the collision of two neutron stars in coincidence with a gamma ray burst and followed by the identification of an optical transient and the multi-wavelength observation of a kilonova by the worldwide astronomy community. We are now in a new era of multi-messenger astrophysics, where gravitational waves are a new important probe in the universe. This talk will present the current status of the LIGO and Virgo detectors, our most recent results, the implications for gravitational wave astronomy and the outlook for future generations of gravitational wave detectors.

Argonne Physics Division Colloquium Schedule