How Non-local is Quantum Gravity?

by Alexandre Belin (Milano Bicocca)

Wednesday 29 Nov 2023, 14:30 → 15:30 Europe/Rome

P1D (Dipartimento di Fisica e Astronomia - Edificio Paolotti)

Locality is a powerful property of quantum field theory and implies that information can be strictly localized in regions of space, and is completely inaccessible from far away. On the other hand, the holographic nature of quantum gravity suggests that the theory is ultimately non-local and that information can never be localized deep inside some spacetime region, but rather is always accessible from the boundary. This is meant to hold as a fully non-perturbative statement, but the fate of locality in G_N perturbation theory is unclear. To investigate locality in quantum gravity, an important first step is to define candidate local operators. The challenge is that to be diffeomorphism-invariant, i.e. to respect the gravitational Gauss law, such operators must be gravitationally dressed which usually makes them non-local. In this talk, I will discuss the incarnation of this problem in the context of AdS/CFT and propose a set of operators which appear to be local to all orders in G_N perturbation theory. Such operators can only be defined around sufficiently complicated CFT states, for reasons that I will explain. I will also comment on the connection of this framework to the introduction of an observer in de Sitter space.