WI Seminar with Abhay Ashtekar

Abstract: The close similarities of the three laws of black hole mechanics, discovered by Bardeen, Carter and Hawking, with the laws of thermodynamics led to the identification of a multiple of the area of the event horizon with entropy. However, developments over the past two decades have shown that this paradigm is not viable for dynamical black holes, especially because of the teleological nature of event horizons. After a brief review of these limitations, I will show that they can be overcome by replacing event horizons with quasi-local horizons. The new  first and second laws hold for black holes arbitrarily far from equilibrium and lead one to identify entropy with marginally trapped surfaces in these horizons.

Brief Bio: Abhay Ashtekar is Atherton Professor at The Pennsylvania State University. He is a member of the National Academy of Sciences and was awarded the Einstein Prize by the American Society, and the Senior Forschungspreis by the Alexander von Humboldt Foundation of Germany. He is a past President of the International Society for General Relativity and Gravitation and in 2015 he served as Editor in Chief of the General Relativity Centennial volume, commissioned by the Society.  An Oral History Interview conducted by the American Institute of Physics can be found at their Niels Bohr Archives  https://www.aip.org/history-programs/niels-bohr-library/oral-histories/45807.