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Article

Vacuum Semiclassical Gravity Does Not Leave Space for Safe Singularities

1
Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía, 18008 Granada, Spain
2
Departamento de Física Teórica and IPARCOS, Universidad Complutense de Madrid, 28040 Madrid, Spain
3
Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid, Spain
*
Author to whom correspondence should be addressed.
Academic Editor: Włodzimierz Piechocki
Universe 2021, 7(8), 281; https://doi.org/10.3390/universe7080281
Received: 14 July 2021 / Accepted: 22 July 2021 / Published: 1 August 2021
(This article belongs to the Special Issue Gravitational Singularities and Their Quantum Fates)
General relativity predicts its own demise at singularities but also appears to conveniently shield itself from the catastrophic consequences of such singularities, making them safe. For instance, if strong cosmic censorship were ultimately satisfied, spacetime singularities, although present, would not pose any practical problems to predictability. Here, we argue that under semiclassical effects, the situation should be rather different: the potential singularities which could appear in the theory will generically affect predictability, and so one will be forced to analyse whether there is a way to regularise them. For these possible regularisations, the presence and behaviour of matter during gravitational collapse and stabilisation into new structures will play a key role. First, we show that the static semiclassical counterparts to the Schwarzschild and Reissner–Nordström geometries have singularities which are no longer hidden behind horizons. Then, we argue that in dynamical scenarios of formation and evaporation of black holes, we are left with only three possible outcomes which could avoid singularities and eventual predictability issues. We briefly analyse the viability of each one of them within semiclassical gravity and discuss the expected characteristic timescales of their evolution. View Full-Text
Keywords: quantum fields in curved spacetime; black holes; gravitational collapse; Hawking evaporation; ultracompact stars; semiclassical gravity quantum fields in curved spacetime; black holes; gravitational collapse; Hawking evaporation; ultracompact stars; semiclassical gravity
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MDPI and ACS Style

Arrechea, J.; Barceló, C.; Boyanov, V.; Garay, L.J. Vacuum Semiclassical Gravity Does Not Leave Space for Safe Singularities. Universe 2021, 7, 281. https://doi.org/10.3390/universe7080281

AMA Style

Arrechea J, Barceló C, Boyanov V, Garay LJ. Vacuum Semiclassical Gravity Does Not Leave Space for Safe Singularities. Universe. 2021; 7(8):281. https://doi.org/10.3390/universe7080281

Chicago/Turabian Style

Arrechea, Julio, Carlos Barceló, Valentin Boyanov, and Luis J. Garay. 2021. "Vacuum Semiclassical Gravity Does Not Leave Space for Safe Singularities" Universe 7, no. 8: 281. https://doi.org/10.3390/universe7080281

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