Arrival & check-in

Talk 1: Jan de Boer (University of Amsterdam)

Thoughts on statistics vs. gravity

Lunch

Talk 2: Marine De Clerck (University of Cambridge)

Mixmaster chaos in an AdS black hole interior

Abstract: Amongst the most fascinating behaviours to arise from Einstein's equations is the onset of chaotic dynamics in the approach to certain cosmological singularities. This was analysed in detail in seminal work by Belinskii, Khalatnikov, Lifshitz (BKL) and others some fifty years ago. A consequence of these results is that the Schwarzschild interior solution near the singularity appears very fine-tuned and should give way for BKL-like dynamics in more generic black holes. In arxiv:2312.11622, we construct a setup that realises the so-called 'mixmaster' chaotic dynamics in the interior of an AdS black hole. After a brief review of the BKL work, I will describe our holographic setup and discuss the peculiar symmetries appearing in this problem.

Talk 3: Ioanna Kourkoulou (University of Cambridge)

S-matrix positivity without Lorentz invariance

Abstract: In the last years the analytic S-matrix program has made big advances in elucidating what constraints low-energy effective theories have to satisfy in order to admit consistent UV completions. The extension of these considerations to theories with broken Lorentz invariance is an interesting open problem, with potential applications ranging from condensed matter physics to early universe cosmology, and more. In this work we attempt a step in this direction. To this end, we use as an example a UV complete model for relativistic superfluids – a complex scalar theory with quartic interactions at finite density. With a focus on 2 → 2 processes in center-of-mass configurations we find a few interesting properties, including a new branch cut as a result of the theory’s non-analytic dispersion relations. While our results are model-dependent, we hope to understand which of our findings are related to basic physical properties, and how they may be relevant to other Lorentz-breaking systems.

Coffee

Talk 4: Vijay Balasubramanian (UPenn & Oxford)

Detecting black hole microstates

Discussion with speakers of day 1

Talk 1: Victor Gorbenko (EPFL)

de Sitter bra-ket wormholes

Abstract: I will discuss bra-ket wormhole contribution to the initial state of the universe in de Sitter JT gravity. If time permits, I will also mention preliminary results on analogous contributions in higher dimensions.

Talk 2: Diksha Jain (University of Cambridge)

Supersymmetric Grey Galaxies, Dual Dressed Black Holes and the Superconformal Index

Abstract: Motivated by the recent construction of grey galaxy and Dual Dressed Black Hole solutions in AdS5 × S5, we present two conjectures relating to the large N entropy of supersymmetric states in N=4 Yang-Mills theory. Our first conjecture asserts the existence of a large number of supersymmetric states which can be thought of as a non-interacting mix of supersymmetric black holes and supersymmetric `gravitons'. It predicts a microcanonical phase diagram of supersymmetric states and makes a sharp prediction for the supersymmetric entropy (as a function of 5 charges) in each phase. We also predict a large N formula for the superconformal index as a function of indicial charges and predict a microcanonical indicial phase diagram with nine distinct phases. It predicts agreement between the superconformal index and black hole entropy in one phase (so over one range of charges), but disagreement in other phases (and so at other values of charges).

Talk 3: Victor Godet (LPTHE Paris)

Quantum cosmology as automorphic dynamics

Abstract: I will discuss the canonical quantization of quantum cosmology on toroidal universes. The wavefunctions are automorphic forms, and the Wheeler-DeWitt equation reduces to a dynamical equation on moduli space, so quantum cosmology can be viewed as “automorphic dynamics”. This perspective offers new insights into the Hartle-Hawking state and hints at intriguing connections to number theory.

Lunch

Discussion with speakers of day 2