The first direct detections of gravitational waves in late 2015 were made possible by a dedicated forty year quest to design, build, and operate LIGO, the Laser Interferometer Gravitational-wave Observatory. Why so long?? Dr. Reitze will discuss what makes gravitational waves so difficult to detect and at the same time such powerful and unique probes of the universe. Using fantastically sensitive interferometers, the first detections of colliding black holes have now been made — three times! These detections have profound implications for how we will view the universe in coming decades.