Session X01: Einstein Prize Session

Live

In the spring of 1969, a naïve first-year graduate student from Canada was told by his Caltech advisor “Kip” to find out everything that was known at that time about the experimental tests of general relativity. Joseph Weber had just claimed the first detection of gravitational waves, contrary to all conventional wisdom, and Kip worried that general relativity might be wrong. At the time, the experimental evidence supporting the theory was thin, but change was in the air. Thus began a 50-year quest to answer the question: Was Einstein Right? That quest took the student from the Earth and the solar system to binary neutron stars; from the massive black hole in our own galaxy to merging black holes billions of light years away. We will give a broad overview of the themes and questions that drove this quest, drawing attention to some of the remarkable individuals encountered along the way.   

Live

One of the key results of general relativity is that an astrophysical black hole in equilibrium is uniquely described by just two parameters, its mass and spin. This is called the No-Hair Theorem, a result that is not true in alternative theories of gravity. For many years, people have speculated about testing the theorem using gravitational waves from merging black holes. The merger forms a single black hole, which rings down emitting gravitational waves as quasi-normal modes, just like a struck bell. The theorem predicts that the measured mode frequencies and damping times should depend only on the mass and spin of the remnant black hole. For a long time, the consensus has been that this test will require the sensitivity of next-generation detectors. I will show that this consensus is wrong for a surprising reason, and report a test with data from GW150914, the first LIGO gravitational wave detection. An extension of the test confirms Hawking's Area Theorem at the 97\% limit.   

Live

We will argue that gravitational-wave astronomy has the potential to provide information on quantum aspects of black holes. Black hole area quantization, as predicted by Bekenstein, could impart observable imprints on the gravitational-wave signal originated in a binary black hole merger by affecting its absorption properties. These imprints include gravitational-wave echoes after the ringdown and suppressed tidal heating during inspiral phase. This phenomenology is within reach of future gravitatinal-wave detectors, and could be used to measure the fundamental quantum of black hole area, thereby opening experimental avenues to test the predictions of quantum gravity theories.