A Smooth Horizon without a Smooth Horizon

Fuente: arXiv
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Main Authors: Burman, Vaibhav, Das, Suchetan, Krishnan, Chethan
Format: Preprint
Published: 2023
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author Burman, Vaibhav
Das, Suchetan
Krishnan, Chethan
author_facet Burman, Vaibhav
Das, Suchetan
Krishnan, Chethan
contents Recent observations on type III algebras in AdS/CFT raise the possibility that smoothness of the black hole horizon is an emergent feature of the large-$N$ limit. In this paper, we present a $bulk$ model for the finite-$N$ mechanism underlying this transition. We quantize a free scalar field on a BTZ black hole with a Planckian stretched horizon placed as a Dirichlet boundary for the field. This is a tractable model for the stretched horizon that does not ignore the angular directions, and it defines a black hole vacuum which has similarities to (but is distinct from) the Boulware state. Using analytic approximations for the normal modes, we first improve upon 't Hooft's brick wall calculation: we are able to match $both$ the entropy and the temperature, $exactly$. Emboldened by this, we compute the boundary Wightman function of the scalar field in a typical pure state built on our stretched horizon vacuum, at an energy sliver at the mass of the black hole. A key result is that despite the manifest lack of smoothness, this single-sided pure state calculation yields precisely the Hartle-Hawking thermal correlator associated to the smooth horizon, in the small-$G_N$ limit. At finite $G_N$, there are variance corrections that are suppressed as $\mathcal{O}(e^{-S_{BH}/2})$. They become important at late times and resolve Maldacena's information paradox. Highly excited typical pure states on the stretched horizon vacuum are therefore models for black hole microstates, while the smooth horizon describes the thermal state. We note that heavy excited states on the stretched horizon are better defined than the vacuum itself. These results suggest that complementarity in the bulk EFT could arise from a UV complete bulk description in which the black hole interior is not manifest.
format Preprint
id arxiv_https___arxiv_org_abs_2312_14108
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle A Smooth Horizon without a Smooth Horizon
Burman, Vaibhav
Das, Suchetan
Krishnan, Chethan
High Energy Physics - Theory
Recent observations on type III algebras in AdS/CFT raise the possibility that smoothness of the black hole horizon is an emergent feature of the large-$N$ limit. In this paper, we present a $bulk$ model for the finite-$N$ mechanism underlying this transition. We quantize a free scalar field on a BTZ black hole with a Planckian stretched horizon placed as a Dirichlet boundary for the field. This is a tractable model for the stretched horizon that does not ignore the angular directions, and it defines a black hole vacuum which has similarities to (but is distinct from) the Boulware state. Using analytic approximations for the normal modes, we first improve upon 't Hooft's brick wall calculation: we are able to match $both$ the entropy and the temperature, $exactly$. Emboldened by this, we compute the boundary Wightman function of the scalar field in a typical pure state built on our stretched horizon vacuum, at an energy sliver at the mass of the black hole. A key result is that despite the manifest lack of smoothness, this single-sided pure state calculation yields precisely the Hartle-Hawking thermal correlator associated to the smooth horizon, in the small-$G_N$ limit. At finite $G_N$, there are variance corrections that are suppressed as $\mathcal{O}(e^{-S_{BH}/2})$. They become important at late times and resolve Maldacena's information paradox. Highly excited typical pure states on the stretched horizon vacuum are therefore models for black hole microstates, while the smooth horizon describes the thermal state. We note that heavy excited states on the stretched horizon are better defined than the vacuum itself. These results suggest that complementarity in the bulk EFT could arise from a UV complete bulk description in which the black hole interior is not manifest.
title A Smooth Horizon without a Smooth Horizon
topic High Energy Physics - Theory
url https://arxiv.org/abs/2312.14108