General Physics Colloquium, Professor Tom Hartman, Stanford University

Title:  Quantum Gravity in Flatland:  An Adventure in 2+1 Dimensions

Host:  Liam McAllister

Abstract:  The quantum theory of gravity involves a sum over all possible shapes of the universe. While we are far from a complete solution to this problem in our 3+1 dimensional world, it is much simpler in "Flatland": a toy model where space has only two dimensions. In this colloquium, I will describe how the sum over geometries in 2+1 dimensional quantum gravity can be recast as an average over disorder. This leads to an exact duality that relates the volumes of hyperbolic 3-manifolds to a quantum field theory with random interactions. I will also discuss the implications for a realistic theory of gravity in 3+1 dimensions, and for chaotic quantum systems that might be possible to build in the lab or simulate on a quantum computer. This talk is for a broad physics audience.