Talk by Dr. Lynn Cominsky (Sonoma State University) Gravitational waves are predicted by Einstein's General Theory of Relativity.  They travel at the speed of light, but are much harder to detect than light waves.  On September 14, 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) received the first direct gravitational wave signals.  The event that produced them was the merger of two distant and massive black holes that were in mutual orbit. Prof. Cominsky presents an introduction to LIGO, to gravitational waves and how they were detected, and to the kinds of black holes that "make waves" in the fabric of space and time.  Originally recorded on Nov. 2, 2016.