The Structure of Quantum Singularities on a Cauchy Horizon

Fuente: arXiv
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Main Author: Shahbazi-Moghaddam, Arvin
Format: Preprint
Published: 2024
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author Shahbazi-Moghaddam, Arvin
author_facet Shahbazi-Moghaddam, Arvin
contents Spacetime singularities pose a long-standing puzzle in quantum gravity. Unlike Schwarzschild, a generic family of black holes gives rise to a Cauchy horizon on which, even in the Hartle-Hawking state, quantum observables such as $\langle T_{μν} \rangle$ -- the expectation value of the stress-energy tensor -- can diverge, causing a breakdown of semiclassical gravity. Because they are diagnosed within quantum field theory (QFT) on a smooth background, these singularities may provide a better-controlled version of the spacetime singularity problem, and merit further study. Here, I highlight a mildness puzzle of Cauchy horizon singularities: the $\langle T_{μν} \rangle$ singularity is significantly milder than expected from symmetry and dimensional analysis. I address the puzzle in a simple spacetime $W_P$, which arises universally near all black hole Cauchy horizons: the past of a codimension-two spacelike plane in flat spacetime. Specifically, I propose an extremely broad QFT construction in which, roughly speaking, Cauchy horizon singularities originate from operator insertions in the causal complement of the spacetime. The construction reproduces well-known outer horizon singularities (e.g., in the Boulware state), and remarkably, when applied to $W_P$, gives rise to a universal mild singularity structure for robust singularities, ones whose leading singular behavior is state-independent. I make non-trivial predictions for all black hole Cauchy horizon singularities using this, and discuss extending the results beyond robust singularities and the strict near Cauchy horizon limit.
format Preprint
id arxiv_https___arxiv_org_abs_2411_11948
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Structure of Quantum Singularities on a Cauchy Horizon
Shahbazi-Moghaddam, Arvin
High Energy Physics - Theory
General Relativity and Quantum Cosmology
Spacetime singularities pose a long-standing puzzle in quantum gravity. Unlike Schwarzschild, a generic family of black holes gives rise to a Cauchy horizon on which, even in the Hartle-Hawking state, quantum observables such as $\langle T_{μν} \rangle$ -- the expectation value of the stress-energy tensor -- can diverge, causing a breakdown of semiclassical gravity. Because they are diagnosed within quantum field theory (QFT) on a smooth background, these singularities may provide a better-controlled version of the spacetime singularity problem, and merit further study. Here, I highlight a mildness puzzle of Cauchy horizon singularities: the $\langle T_{μν} \rangle$ singularity is significantly milder than expected from symmetry and dimensional analysis. I address the puzzle in a simple spacetime $W_P$, which arises universally near all black hole Cauchy horizons: the past of a codimension-two spacelike plane in flat spacetime. Specifically, I propose an extremely broad QFT construction in which, roughly speaking, Cauchy horizon singularities originate from operator insertions in the causal complement of the spacetime. The construction reproduces well-known outer horizon singularities (e.g., in the Boulware state), and remarkably, when applied to $W_P$, gives rise to a universal mild singularity structure for robust singularities, ones whose leading singular behavior is state-independent. I make non-trivial predictions for all black hole Cauchy horizon singularities using this, and discuss extending the results beyond robust singularities and the strict near Cauchy horizon limit.
title The Structure of Quantum Singularities on a Cauchy Horizon
topic High Energy Physics - Theory
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2411.11948