IAS Workshop: Quantum Aspects of Black Holes and Spacetime

This lecture examines the Hartle-Hawking state, focusing on dominant Euclidean sphere topology. It analyzes how including a classical observer resolves problems in holographic theories failing semi-classical physics.

This session delves into the structure and implications of holographic algebras as they manifest at null infinity. It explores their role in understanding quantum information in gravitational theories.

This talk discusses an axiomatic framework for quantum gravity, rigorously establishing theorems with the quantum extremal surface prescription. It clarifies the regime of validity for G→0 while cG remains fixed.

This lecture investigates black hole singularities in AdS/CFT as divergences in two-point functions, smoothed out by stringy effects at finite 't Hooft coupling. It connects these phenomena to classical dynamical systems.

This presentation explores the de Sitter double cone geometry, demonstrating how static patch observers lead to a linear ramp consistent with random matrix behavior. The ramp arises from relative time shifts between clocks.

This talk investigates the late-time behavior of two-point correlation functions in de Sitter space, presenting evidence from Jackiw-Teitelboim gravity for a topologically nontrivial saddle that contributes a constant to the correlator norm, interpreted as an average over microscopic theories.

This lecture examines the Hartle-Hawking no-boundary state, exploring its relevance to de Sitter entropy puzzles and inflationary cosmology. It computes the norm of the state, focusing on spherical spatial slice contributions.

This lecture explores the Hartle-Hawking wavefunction in Schwarzschild-de Sitter spacetime, comparing its semiclassical norm to the Euclidean Nariai geometry action. It clarifies quantum corrections and the path integral phase.

This talk discusses wavefunctions of the universe incorporating timelike boundaries, consistent with Lambda CDM cosmology. It summarizes constraints from CMB and BAO data and examines their holographic implications.

This lecture investigates the complex phase of the de Sitter density of states, proposing its cancellation by including a charged black hole observer. It calculates the one-loop determinant within 2D dilaton gravity.

Sean Hartnoll re-examines the Belinski-Khalatnikov-Lifshitz (BKL) spacetime singularity dynamics through the lens of quantum chaos and holographic duality, proposing a dual 'primon gas' description connected to number theory.

This talk introduces quantum reference frames (QRFs) and their role in quantum gravity, demonstrating how they illuminate quantum effects in superposed spacetimes. It presents a perspective-neutral formulation and applications.

This lecture presents a topological gravity model defined by summing a 3D TQFT over bulk topologies, formulated for holographic duality. It explores explicit examples and their implications for pure 3D quantum gravity.

This talk argues that certain spacetime regions may fail to emerge from holographic theories, drawing conclusions from large N arguments and tensor network models. It comments on methods for restoring spacetime emergence.

This lecture reviews positivity criteria for the gravitational path integral to define a valid Hilbert space for open and closed universes. It describes cases where these highly constraining criteria are satisfied.

This talk explores the fate of quantum states in the semiclassical limit of AdS/CFT, focusing on black holes and 'baby universes.' It discusses how states approach mixed states due to information loss and wormhole effects.

This lecture argues that Euclidean wormholes in AdS/CFT arise from erratic N-dependence in large-N CFTs, proposing a filtering procedure for gravitational duals. It examines both external and internal wormhole configurations.

This talk investigates the evaporation processes of near-extremal black holes, exploring the quantum mechanical implications and information loss paradoxes within this regime of black hole physics.

This second part addresses a puzzle in JT (super)gravity where naive bulk computations yield negative one-sided entropy for two-sided black holes. It demonstrates how semi-quenched entropy restores positivity.