Event Category: String Seminar

String Seminar:
Tuesdays at 3:40pm on campus

–

Abstract: Reproducing the integer count of black hole microstates from the gravitational path integral is an important problem in quantum gravity. We will show that, by using supersymmetric localization, the gravitational path integral for 1/8-BPS black holes in N=8 supergravity reproduces the index obtained in the string theory construction of such black holes.

–

Recent progress in AdS/CFT has provided a good understanding of how the bulk spacetime is encoded in the entanglement structure of the boundary CFT. However, little is known about how spacetime emerges directly from the bulk quantum theory. We address this question in an effective 3d quantum theory of pure gravity, which describes the high temperature regime of a holographic … Read More

–

Abstract: It has long been conjectured that global symmetries can only be approximate in a theory of quantum gravity. In this talk, I discuss two pieces of work to quantify this statement, putting lower bounds on the amount of violation. In the first calculation, I discuss the global symmetry violation in a black hole evaporation process. The degree to which … Read More

–

Abstract: Topological twists of 3d N=4 gauge theories admit boundary conditions that support vertex operator algebras, initially constructed by Costello and Gaiotto. I will review this construction, then discuss current work (with A. Ballin, T. Creutzig, and W. Niu) proving equivalences of these vertex algebras under abelian 3d mirror symmetry, and relating their module categories (a.k.a. bulk Wilson lines and … Read More

–

Abstract: In recent years, a new holographic paradigm has emerged in which simple theories of gravity in low dimensions are dual to statistical ensembles of quantum mechanical systems rather than particular quantum systems. However, more realistic holographic dualities in higher dimensions are not expected to fundamentally involve microscopic averaging. Nevertheless, there are apparently contributions to the semiclassical gravitational path integral that are … Read More

–

Abstract: I will discuss a certain (1+1)-dimensional model of de Sitter space with an interesting bulk emergence property. I will also touch on the conjectured holographic duality of this model with the infinite-temperature double-scaled SYK model as well as open issues in probing behind-the-horizon physics within these models.

–

Abstract: Quantum Focusing is a powerful conjecture, which plays a key role in the current proofs of manywell-known quantum gravity theorems, including various consistency conditions, and causality constraints in AdS/CFT. I conjecture a (weaker) restricted quantum focusing, which I argue is sufficientto derive all known essential implications of quantum focusing. Subject to a technical assumption,I prove this conjecture, to all … Read More

–

Abstract: I will describe the universal aspect of unitary conformal field theories in the high-temperature limit with a global symmetry group G, where G can be a discrete group or a compact Lie group. I will describe the geometric setup to apply the spurion analysis and explain how we can capture this universal aspect up to a constant factor that … Read More

–

Abstract: We show that if a massive (or charged) body is put in a quantum superposition of spatially separated states in the vicinity of any (Killing) horizon, the mere presence of the horizon will eventually destroy the coherence of the superposition. This occurs because, in effects, the long-range fields sourced by the superposition register on the horizon which forces the … Read More

–

Do the postulates of quantum mechanics survive in quantum gravity?  The probabilistic interpretation of amplitudes, enforced by the unitarity of time evolution, is not guaranteed within the path integral formulation and has to be checked.  Leveraging the gravitational path integral, we find a non-perturbative mechanism whereby a sum over smooth geometries leads to isometric rather than unitary evolution, which we demonstrate … Read More