On September 14, 2015, LIGO made the first-ever observation of ripples in the fabric of space and time—or gravitational waves—arriving at the earth from the collision of two black holes in the distant universe. The discovery confirmed a major prediction of Albert Einstein’s 1915 general theory of relativity and provides a new way to observe the cosmos. The observatory has since made several more binary black hole merger detections, and more recently detected a binary neutron star merger with a large number of electromagnetic follow-up observations confirming consistent with the kilonova picture. In recognition for his work with LIGO, Dr. Barish was awarded the Nobel Prize in Physics in 2017, along with Kip S. Thorne and Rainer Weiss, “for decisive contributions to the LIGO detector and the observation of gravitational waves.”