School of Natural Sciences

A simple model of topological gravity can be defined by summing a 3d TQFT over all bulk topologies. I will explain how this sum is formulated so as to be holographically dual to a well-defined boundary ensemble. I will then present several explicit...

In holography, an effective spacetime description emerges from the fundamental boundary description. But can all spacetime geometries emerge from a holographic theory? In this talk, I will argue that in some situations, a region of spacetime can...

Does the gravitational path integral define a valid Hilbert space for open and closed universes? In this talk, I will review the positivity criteria that the gravitational path integral has to satisfy in order for all open and closed universe states...

I will discuss the fate of quantum states in the semiclassical limit of the AdS/CFT correspondence, focusing on cases where the gravitational side involves black holes or “baby universes.” Typically, these states do not converge to simple, pure...

We argue that Euclidean wormhole configurations in AdS/CFT--central to the factorization problem--originate from the erratic $N$-dependence that arises in the large-$N$ limit of conformal field theories (CFTs). We propose that constructing the...

It was argued that any fixed holographic theory contains only one closed universe state and hence fails to give semi-classical physics. It was proposed that this problem can be resolved by including a classical observer living inside the universe...

Part 2 of the talk by Pratik Rath. In this talk, I will discuss a puzzle in JT (super)gravity coupled to matter, first observed by Lin-Maldacena-Rozenberg-Shan. The one-sided entropy of a two-sided black hole in the presence of many matter operator...

Part 1: In this talk, I will discuss an entropic puzzle in JT gravity and its resolution, which requires taking into account non-perturbative effects in the gravitational path integral. In JT gravity, which is dual to a random matrix ensemble, the...

Classical random walks have long served as useful intuition for the dynamics of light scalar fields in de Sitter space. This description can be shown to arise from QFT on a fixed dS background, via RG flow. The RG approach also permits corrections...