## Herman L. Verlinde (Princeton ) “SYK and de Sitter gravity”

## 4D Seminar: Jan Schutte Engel (UC Berkeley)”Exploring our Universe with High-Frequency Gravitational Waves”

The first direct observations of gravitational waves (GWs) by ground-based interferometers have ushered in the era of GW astronomy. While the central focus of such experiments has been on the Hz − kHz frequency range, an exploration across a much wider spectrum is warranted. The Universe is expected to be populated by GWs over many decades in frequency, analogous to … Read More

## Roger Casals (UC Davis) “Spectral Networks and Morse flow trees”

Abstract. I will explain how to associate a spectral network to a Demazure weave via Floer theory. Specifically, the talk will present how spectral networks, as introduced by Gaiotto-Moore-Neitzke, arise when computing J-holomorphic strips associated to augmentations of Lagrangian fillings of Legendrian links. In particular, this provides a Floer-theoretical description of Stokes lines in higher rank and with arbitrary irregular Stokes … Read More

## Shreya Vardhan (Stanford) “Emergence and breakdown of the membrane picture in Brownian models”

It has previously been observed that the evolution of entanglement entropies and OTOCs in systems ranging from random unitary circuits to holographic CFTs can be understood within a common framework known as the “membrane picture.” In this talk, we consider a class of Brownian local evolutions, where the Lorentzian evolution of the system on multiple copies can be equivalently described … Read More

## Edward Mazenc (ETH Zurich) “Strings From Feynman Diagrams”

Abstract: How do bulk strings relate to boundary Feynman diagrams? I will give an overview of my work with Rajesh Gopakumar on deriving the closed string dual to the simplest possible gauge theory, a Hermitian matrix integral. Working in the conventional ‘t Hooft limit, we extract topological string theories which replace the minimal string away from the double-scaling limit. We … Read More

## Lisa Yang (MIT) “Cryptographic Censorship”

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

## Juan Malda (IAS) “Comments on the Hartle Hawking wavefunction and density matrix of the universe”

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.

## Ahsan Khan (IAS) ” Algebra of the Infrared with Twisted Masses”

Abstract: The “Algebra of the Infrared” refers to a collection of homotopical algebra structures (discovered by Gaiotto-Moore-Witten) that one associates to a massive two-dimensional N=(2,2) quantum field theory (subject to certain constraints). This provides a powerful framework for working out the category of boundary conditions of such QFTs. Specializing to the example of massive Landau-Ginzburg models, one is lead to a … Read More

## Vasily Krylov (MIT) “From geometric realization of affine Hecke algebras to character formulas”

Abstract: In the first part of the talk, I will recall Kazhdan-Lusztig’s geometric realization of the affine Hecke algebra H_q as well as Bezrukavnikov’s categorification of the statement. One of the fundamental tools of the theory is the so-called asymptotic affine Hecke algebra introduced by Lusztig (it can be thought of as a “limit” of H_q as “q goes to … Read More

## Martin Sasieta (Brandeis) ” Geometric Surprises in the Python’s Lunch Conjecture”

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