**The 2023 Andrew Chamblin Memorial Colloquium**

http://andrewchamblin.org/lecture.html

Speaker: Dr. Vijay Balasubramanian

Professor

University of Pennsylvania

Title: The entropy of black holes

Abstract: One of the most famous results of twentieth-century physics states that black holes carry an entropy proportional to the area of their horizons. This entropy formula is universal in general relativity: it applies to black holes with any mass, charge, or rotation, and in any spacetime dimension. I will describe a recent proposal explaining the microscopic origin and universality of this formula. The proposal exploits new developments in the study of many-body chaos, thermalization, and quantum dynamics, along with concepts of complexity and information from theoretical computer science, communications theory, and cryptography. These developments also suggest that the interior of a black hole is causally accessible to external observers, but only if they can perform egregiously complex measurements that are inaccessible under normal conditions.