Algebras and Entropies

Online conference on Zoom.

The experience of an observer interacting with a black hole or in de Sitter space can be described by a Type II von Neumann algebra.

This gives a slightly abstract explanation of why entropy is better defined in gravity than in ordinary quantum field theory. Based on arXiv:2112.12828 and work to appear with V. Chandrasekharan and G. Penington.