11:30 - 12:30 – Andrea Ghez (University of California, Los Angeles):
"Our Galactic Center: A Laboratory for Exploring the Physics & Astrophysics of Black Holes"
Abstract: Over the last 20 years, advances in high angular resolution imaging technology has enabled the motions of individual stars to be tracked at the Galactic Center. This has provided the best evidence to date not only for the presence of a supermassive black hole at the center of our Galaxy but for the existence of black holes in general. These high resolution measurements have also revealed an environment surrounding the black hole that is quite unexpected in a number of ways, challenging our understanding of the physical processes between black holes and their surround stars and gas. As the only galatic nucleus in which individual stellar orbits can be measured, the Galatic Center is now offering new insights into the fundamental physics of black holes, with unique tests of Einstein's theory of General Relativity on the horizon, and the astrophysics processes between black holes and their host galaxies that are thought to shape the co-evolution of central black holes and their host galaxies.
15:00 - 16:00 Ingrid Stairs (University of British Columbia, Vancouver):
"Pulsar Tests of General Relativity"
Pulsars are radio-emitting neutron stars, and therefore offer the opportunity to probe relativistic effects near strongly self-gravitating objects. Pulsars orbiting white dwarfs, which are far less dense, allow for tests of various equivalence principles. Pulsars in double-neutron-star binaries often permit the measurement of multiple relativistic corrections to a Keplerian orbit, resulting in self-consistency tests for different gravitational theories. I will review the principles of pulsar timing and the current status of these various tests, including the latest results from the only known double-pulsar system. I will also discuss the prospects for direct detection of gravitational waves via pulsar timing.
16:30 - 17:30 Joseph Polchinski (Kavli Institute for Theoretical Physics, Santa Barbara):
"Quantum Gravity and Strings"
In 1899, sixteen years before Einstein wrote down his field equations, Max Planck calculated the fundamental length scale of quantum gravity and found it to be incredibly small, far beyond the reach of direct experiment. Nevertheless, by means of thought experiments and other theoretical tools we have learned deep things about quantum gravity. I will review the developments in string theory, as well as the black hole information paradox and its latest incarnation, the firewall.
15:00 - 16:00 Reinhard Genzel (Max-Planck-Institut für extraterrestrische Physik, Garching):
"Testing the Massive Black Hole Paradigm in the Center of the Milky Way"
Evidence has been accumulating for several decades that many galaxies harbor central mass concentrations that may be in the form of black holes with masses between a few million to a few billion time the mass of the Sun. I will discussmeasurements over the last two decades, employing adaptive optics imaging and spectroscopy on large ground-based telescopes that prove the existence of such a massive black hole in the Center of our Milky Way, beyond any reasonable doubt. These data also provide key insights into its properties and environment. Most recently, a tidally disrupting cloud of gas has been discovered on an almost radial orbit that reached its peri-distance of ~2000 Schwarzschild radii in 2014, promising to be a valuable tool for exploring the innermost accretion zone. Future interferometric studies of the Galactic Center Black hole promise to be able to test gravity in its strong field limit.