# Selected Lectures around the World

## What’s inside a black hole?

Zoom talk at KIAS, Seoul, Korea

November 20th, 2023

The talk is about the frozen star model. A star that looks exactly like a static or rotating black hole to an external observer and is sourced by a “string fluid”. The star is stable and has an interesting spectrum of non-relativistic modes.

Updated information about KIAS string seminars can be found here.

**Black hole Love story**

NYU seminar, 15 Sep., 2022

The response of a gravitating object to an external tidal field is encoded in its Love numbers, which identically vanish for classical black holes in 4 spacetime dimensions. I will explain why for quantum black holes, generically, the Love numbers should be nonvanishing and negative, and show that their magnitude depends on the lowest lying collective excited levels of the quantum spectrum of the black hole.

**Black hole entropy sourced by string winding condensate: outside and inside views**

4’th Black-Hole Microstucture Conference – 26’th Rencontres Itzykson, Jun 6 – 17, 2022, IPhT, CEA Saclay

**The quantum state of the black hole**

### XXXV Max Born Symposium, Wroclaw, Poland, 7 – 12 September 2015

If a black hole (BH) is initially in an approximately pure state and it evaporates by a unitary process, then the emitted radiation will be in a highly quantum state. As the purifier of this radiation, the state of the BH interior must also be in some highly quantum state. So that, within the interior region, the mean-field approximation cannot be valid and the state of the BH cannot be described by some semiclassical metric. On this basis, I will present a model in which the state of the BH interior is described as a collection of a large number of excitations that are packed into closely spaced but single-occupancy energy levels; a sort-of “Fermi sea” of all light-enough particles.

**Black hole paradoxes: The clash of quantum mechanics and gravity**

**Given at: Arnold Sommerfeld Center, August 2014**

Part 1

Part 3

Part 2

Part 4