As black holes spiral around each other in the distant universe, Einstein's theory of general relativity predicts gravitational waves – ripples in the fabric of space-time itself. We have now detected such ripples from stellar-mass black holes, as well as directly imaging a supermassive black hole.

Shami Chatterjee, an astronomer at the Cornell Center for Astrophysics and Planetary Science and a member of the NANOGrav collaboration, talks about ongoing efforts to build a Galaxy-scale detector to observe low-frequency gravitational waves from the mergers of supermassive black holes in the distant universe, as well as some of the unexpected discoveries along the way. The unexpected discoveries include enigmatic "fast radio bursts", bright millisecond flashes of radio waves that pop off thousands of times every day, all over the sky, with astonishing energy output.

Dr. Chatterjee searches for and studies neutron stars, and how to use their lighthouse beams as clocks to build a long-wavelength gravitational wave detector. He has done foundational work on fast radio bursts that has been featured twice on the cover of Nature, and plays a small role in the Event Horizon Telescope team that won the 2020 Breakthrough Prize in Fundamental Physics for imaging a black hole.

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