Title: "Observing and simulating gravitational waves with LIGO, Cosmic Explorer, and SpECTRE"

Abstract: The Laser Interferometer Gravitational-Wave Observatory (LIGO) has ignited the era of gravitational-wave astronomy, observing dozens of gravitational waves from merging black holes and neutron stars. Yet LIGO is only sensitive enough to measure the loudest gravitational waves waves. Cosmic Explorer is a proposed successor to LIGO that will achieve an order-of-magnitude increase in sensitivity beyond LIGO by scaling up proven LIGO technology to a facility ten times larger. Cosmic Explorer will push the reach of our gravitational-wave sensitivity to the edge of the observable universe, enabling us to observe black holes and neutron stars throughout cosmic time, study the nature of dense matter, and address open questions on the nature of gravity and fundamental physics. I will introduce Cosmic Explorer and its scientific potential and will highlight current efforts to identify potential locations for Cosmic Explorer. I will also describe how the the exquisite sensitivity of Cosmic Explorer and other future gravitational-wave observatories is driving efforts to achieve the tremendous accuracies these observatories will require, such as developing SpECTRE, an open-source, next-generation numerical relativity code.