Physics Colloquium

The past five years have witnessed the beginning of a new era in astrophysics, beginning with the 2015 discovery of gravitational waves from the collision of two black holes. Since then, 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, and the 2017 detection of gravitational waves from the collision of two neutron stars, in coincidence with a gamma ray burst and a kilonova, has elevated multi-messenger astrophysics from concept to tool for discovery and exploration. Gravitational waves are a new, important probe for understanding the universe, with a rich science potential ranging from astronomy to cosmology to nuclear physics. This talk will present the current status of the LIGO and Virgo detectors, review what we have learned about black holes, neutron stars and the Universe, discuss the implications for gravitational wave astrophysics and give an outlook for future generations of gravitational wave detectors.