High Energy Theory Seminar

One central puzzle in quantum gravity is to understand how and why predictions from semiclassical gravity can sometimes break down in a regime where we naively expect the semiclassical approximation to be valid. In particular, overlaps among states that are orthonormal in the semiclassical approximation can receive large corrections from quantum fluctuations of the geometry. I will examine such overlaps among states of fixed length in the theory of pure JT gravity, which is dual to the random matrix ensemble of Saad-Shenker-Stanford. Previously, it has been discussed that the discreteness of the boundary spectrum must cause a breakdown of the bulk length basis for lengths proportional to the boundary inverse level spacing, e^{S_0}.  I will discuss how the sum over quantum fluctuations at all orders in the bulk genus expansion indicates a more dramatic breakdown than previously expected, at shorter lengths of O(e^{S_0/3}). From the perspective of the boundary spectrum, these corrections arise from the presence of negative energies in rare members of the random matrix ensemble. Work in progress with John Preskill and Mykhaylo Usatyuk.

The talk is in 469 Lauritsen.

Contact [email protected] for Zoom information.