IAS Fundamental Physics Seminar Series - De Sitter Quantum Gravity and the Emergence of Local Algebras

Abstract
Quantum gravity is expected to be fundamentally non-local, yet our understanding of the early universe—especially during inflation—relies heavily on local quantum field theory in curved spacetime, often modeled by de Sitter space. This raises a key question: how does local physics emerge from a quantum gravity theory where true observables must be gauge-invariant and thus non-local? In this talk, the speaker will explore how relational observables in perturbative quantum gravity around de Sitter space can approximate local field operators under the right conditions. We will see that such approximations break down near certain “minimal” spatial slices after a short time, but remain valid over much larger regions—particularly deep in the future or past, or within a static patch—offering insight into how local physics might arise in a cosmological context.