Seminar of the Group for Gravitation, Particles and Fields (Online)

Organizer: Faculty of Physics, Belgrade

Time: Friday, 19 November 2021, 12:00 Belgrade/CET

Black hole entropy and the information loss paradox

Voja Radovanovic (Faculty of Physics, University of Belgrade)

Link: via the BigBlueButton platform, https://gravityserver.ipb.ac.rs/b/mar-xoo-t1v-vwn

Abstract: The most important unsolved problem in black hole physics is the information loss paradox, i.e. whether the process of formation and evaporation of a black hole is unitary in accordance with quantum mechanics. The unitarity implies that von Neumann entropy of the Hawking radiation should initially increase but subsequently fall back down, following the so-called Page curve.

In the first talk of this series we consider black hole thermodynamics and discuss various concepts of entropy: fine-grained, coarse-grained and entanglement entropy. In addition, we calculate entanglement entropy for Rindler observer and show how to generalize this result to curved space-time, where it is used to define generalized entropy of a black hole.

The upcoming talks will be devoted to the so-called wormhole replica trick and the notion of an island – a kind of a quantum extremal surface recently advocated by Maldacena. We study a particular case of 2D dilaton gravity obtained by dimensional reduction of the Einstein-Hilbert action for Schwarzschild metric. We calculate the von Neumann entropy of the Hawking radiation and reproduce the Page curve.


Time: Friday, 5 November 2021, 11:00 Belgrade/CET

Conformal bootstrap – a non-perturbative approach to conformal field theories

Ilija Buric (Department of Physics, University of Pisa)

Link: via the BigBlueButton platform, https://gravityserver.ipb.ac.rs/b/mar-xoo-t1v-vwn

Abstract: Conformal bootstrap is a collection of methods for the study  of conformal field theories, which are based on minimal assumptions such as unitarity and self-consistency. After reviewing the basic structure of conformal field theories, I will illustrate some of these methods on one numerical and one analytic example.