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Main Authors: Engelhardt, Netta, Gesteau, Elliott
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2504.14586
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author Engelhardt, Netta
Gesteau, Elliott
author_facet Engelhardt, Netta
Gesteau, Elliott
contents We argue that a large class of asymptotically AdS geometries with a semiclassical baby universe cannot be realized within the AdS/CFT correspondence. This in particular resolves a recent puzzle introduced by Antonini and Rath, in which a single CFT state appeared to simultaneously describe an AdS spacetime with a baby universe and one without. We construct a low-energy (and low complexity) boundary operator whose expectation values in the descriptions with and without the baby universe cannot match if the baby universe is semiclassical. This operator conclusively identifies the actual bulk dual: the spacetime without a semiclassical baby universe. This result assumes only that AdS/CFT admits an extrapolate dictionary and an asymptotically isometric encoding of the causal wedge into the dual CFT, without which the correspondence may well be vacuous.
format Preprint
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institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Further Evidence Against a Semiclassical Baby Universe in AdS/CFT
Engelhardt, Netta
Gesteau, Elliott
High Energy Physics - Theory
We argue that a large class of asymptotically AdS geometries with a semiclassical baby universe cannot be realized within the AdS/CFT correspondence. This in particular resolves a recent puzzle introduced by Antonini and Rath, in which a single CFT state appeared to simultaneously describe an AdS spacetime with a baby universe and one without. We construct a low-energy (and low complexity) boundary operator whose expectation values in the descriptions with and without the baby universe cannot match if the baby universe is semiclassical. This operator conclusively identifies the actual bulk dual: the spacetime without a semiclassical baby universe. This result assumes only that AdS/CFT admits an extrapolate dictionary and an asymptotically isometric encoding of the causal wedge into the dual CFT, without which the correspondence may well be vacuous.
title Further Evidence Against a Semiclassical Baby Universe in AdS/CFT
topic High Energy Physics - Theory
url https://arxiv.org/abs/2504.14586