Gravitational waves, and what they can tell us about the Universe

Our understanding of gravitational waves has increased dramatically since Eddington wrote in 1922 that some believe they ``propagate with the speed of thought.'' While gravitational waves are yet to be directly detected ---ignoring the orbital decay of the Hulse--Taylor binary pulsar as an {\em indirect} measurement--- an impressive experimental effort to detect them has defied many skeptics when LIGO achieved design sensitivity. At the same time, several numerical relativity groups have succeeded in solving the ``holy grail'' problem: evolve a binary black hole system for a number of orbits, following the system through its merger to its final ring--down and decay to quiescence, thus predicting the gravitational waveforms that LIGO, and other experiments, will detect. In this talk I will briefly describe the breathtaking progress we have witnessed, and what the future may hold for gravitational-wave astronomy.