[QUAST Seminar] Mykhaylo Usatyuk: Closed universes in two dimensional gravity

Quantum gravity in spacetimes without asymptotic boundaries is poorly understood. In this talk we will study simple two dimensional models of closed universes using the gravitational path integral. We will construct a Hilbert space of closed universe states and show that wormhole effects are important when computing observables. The inclusion of wormholes reduces the dimension of the non-perturbative Hilbert space to one, giving a single closed universe state. We will comment on some properties of this unique state in holographic theories, and give a separate argument based on factorization.