Abstract: Holographic tensor networks model AdS/CFT, but so far they have been limited by involving only systems that are very different from gravity. Unfortunately, we cannot straightforwardly discretize gravity to incorporate it, because that would break diffeomorphism invariance. In this talk I will present a resolution, based on upcoming work with Ronak Soni and Annie Y. Wei. We construct a … Read More
Abstract: I will talk about my recent work (2402.03425) with Netta Engelhardt, Åsmund Folkestad, Adam Levine, and Evita Verheijden. We formulate and take two large strides towards proving a quantum version of the weak cosmic censorship conjecture. We first prove “Cryptographic Censorship”: a theorem showing that when the time evolution operator of a holographic CFT is approximately pseudorandom (or Haar … Read More
We will review the Hartle Hawking wavefunction of the universe in the context of slow roll inflation. We will explain the motivation behind it, as well as a problem with the result. We will also discuss the computation of the density matrix corresponding to the observable region of the universe.
Abstract: In de Sitter (dS), observers cannot be treated as separate from the rest of spacetime, and hence observables are inextricably linked to their observers. In this talk, we emphasize that observers must also be treated using QFT. We then explore how well spaces of states and observables, each defined relative to a QFT observer, approximate standard non-gravitating QFT in a fixed … Read More
Abstract: String theory has its origins based on the so-called dual resonance hypothesis which had only slender experimental support. This led to the discovery of the Veneziano amplitude which sums over poles in one channel or the other, unlike what we do in familiar quantum field theory. I will present a new representation of the Veneziano amplitude, arising from a … Read More
Abstract: A bulge surface, on a time reflection-symmetric Cauchy slice of a holographic spacetime, is a non-minimal extremal surface that occurs between two locally minimal surfaces homologous to a given boundary region. According to the python’s lunch conjecture of Brown et al., the bulge’s area controls the complexity of bulk reconstruction, in the sense of the amount of post-selection that … Read More
Abstract Chern-Simons theory provides an attractive, intrinsically diffeomorphism invariant, framework for 3d quantum gravity. In this talk, I will describe a new method for incorporating matter into CS gravity while retaining its useful features. The key object is the “Wilson spool,” a gauge-invariant, effective description of massive one-loop determinants. I will illustrate its utility for reproducing the physics of massive … Read More
Abstract: In JT gravity coupled to a CFT, I argue without using the path integral that the entanglement wedge of a boundary region is bounded by a quantum extremal surface (QES). For any candidate not bounded by a QES, a unitary in the complement can make reconstruction within the candidate inconsistent with boundary causality. The case without islands is a … Read More
“New ideas for old black holes” The speakers and schedule are: 10:00 am – 11:00 am. Lenny Susskind11:15 am – 12:15 pm Zhenbin Yang 2:30 pm – 3:30 pm Adam Levine 3:45 pm- 4:45 pm Chang-Han Chen Topic: New ideas for old black holesTime: May 8, 2024 09:45 AM Pacific Time (US … Read More
Abstract: All black holes in AdS become unstable at a non-zero critical temperature, except if they are protected by supersymmetry. In the favored ground state, the black hole fragments into a a finite matter halo and a smaller remnant. In the dual CFT description, the instability is realized by two phases with distinct condensates that meet at a critical line … Read More