# Quantum black holes without strings

### APA

't Hooft, G. (2020). Quantum black holes without strings. Perimeter Institute. https://pirsa.org/20120008

### MLA

't Hooft, Gerard. Quantum black holes without strings. Perimeter Institute, Dec. 03, 2020, https://pirsa.org/20120008

### BibTex

@misc{ pirsa_PIRSA:20120008, doi = {10.48660/20120008}, url = {https://pirsa.org/20120008}, author = {{\textquoteright}t Hooft, Gerard}, keywords = {Quantum Gravity}, language = {en}, title = {Quantum black holes without strings}, publisher = {Perimeter Institute}, year = {2020}, month = {dec}, note = {PIRSA:20120008 see, \url{https://pirsa.org}} }

Gerard 't Hooft Utrecht University

## Abstract

The quantum states of matter in the immediate vicinity of a black hole can be studied using no other information than Standard Model physics combined with perturbative gravity. The point is that the relevant energy scale of the most important fields involved is low compared to the Planck scale, provided the black hole is big compared to the Planck scale. Usually this problem is investigated by using the metric that includes the effects of matter that formed the black hole in the distant past and sometimes also matter that is radiated away in the distant future. Arguments are presented however to justify that one should ignore those effects. The metric then becomes invariant under time translation, and this is what we need to get the energy eigen states. It is this scheme that forces us to impose the antipodal identification as a new boundary condition, giving us a beautiful picture of black hole quantum evolution. The logic of choosing this compulsory topological twist in space-time is explained. There are still many very hard questions and I hope to be able to inspire people to look into these.