Resisting collapse: How matter inside a black hole can withstand gravity

Brustein, Ram; Medved, A. J. M.

doi:10.1103/physrevd.99.064019

Cited by 29 publications

(30 citation statements)

References 67 publications

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“…However, it is reasonable to assume that, once that quantum gravity effect are taken into account, singularities will be regularized. The structure and properties of the corresponding non-singular black holes is largely unknown, in part due to our lack of knowledge about the dynamics in quantum gravity, although there have been many and diverse attempts at constructing geometries or toy models that aim at capturing the leading effects beyond general relativity [5][6][7][8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Geodesically complete black holes

et al. 2020

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The 1965 Penrose singularity theorem demonstrates the utterly inevitable and unavoidable formation of spacetime singularities under physically reasonable assumptions, and it remains one of the main results in our understanding of black holes. It is standard lore that quantum gravitational effects will always tame these singularities in black hole interiors. However, the Penrose's theorem provides no clue as to the possible (non-singular) geometries that may be realized in theories beyond general relativity as the result of singularity regularization. In this paper we analyze this problem in spherically symmetric situations, being completely general otherwise, in particular regarding the dynamics of the gravitational and matter fields. Our main result is that, contrary to what one might expect, the set of regular geometries that arises is remarkably limited. We rederive geometries that have been analyzed before, but also uncover some new possibilities. Moreover, the complete catalogue of possibilities that we obtain allows us to draw the novel conclusion that there is a clear tradeoff between internal and external consistency: One has to choose between models that display internal inconsistencies, or models that include significant deviations with respect to general relativity, which should therefore be amenable to observational tests via multi-messenger astrophysics. CONTENTS

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Section: Introductionmentioning

confidence: 99%

Geodesically complete black holes

et al. 2020

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“…Our own proposal — the collapsed‐polymer model — similarly has a maximally negative pressure, but only from the perspective of a skeptic. This subtle point regarding observer dependence was touched upon in [] and will be elaborated on later when we discuss the same model from a postmodern perspective. Meanwhile, as far as the skeptic is concerned,

p_{r} = - ρ = - \frac{1}{8 π G r^{2}}

along with a vanishing transverse pressure …”

Section: Introductionmentioning

confidence: 85%

“…This subtle point regarding observer dependence was touched upon in [] and will be elaborated on later when we discuss the same model from a postmodern perspective. Meanwhile, as far as the skeptic is concerned,

p_{r} = - ρ = - \frac{1}{8 π G r^{2}}

along with a vanishing transverse pressure A model that features

p_{r} = - ρ \propto - \frac{1}{r^{2}}

was discussed in another context in which the negative pressure was sourced by a spherically symmetric “hedgehog” configuration of cosmic strings.…”

Section: Introductionmentioning

confidence: 85%

“…The Penrose diagram corresponding to this geometry is illustrated in Figure . Other models of this ilk — exploiting the idea of negative pressure for the purpose of regularizing the interior — are the gravastar, the black star, a back‐reaction‐corrected geometry and our own model, the collapsed polymer BH, as well as . See [] for extensive reviews of models of regular BHs.…”

Section: Introductionmentioning

confidence: 99%

“…What is then needed is an object whose interior metric never approaches the Schwarzschild solution until it is parametrically close to the horizon; that is,

R_{Q G} \sim R_{S}

. From this perspective, our own polymer model and the gravastar stand out because, in these two cases, the deviations persist up to a radius that is parametrically close to the outer surface . We will then turn our attention to this pair of models, beginning with the gravastar.…”

Section: Introductionmentioning

confidence: 99%

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Non‐Singular Black Holes Interiors Need Physics Beyond the Standard Model

Brustein

Medved

2019

Fortschritte der Physik

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The composition as well as the very existence of the interior of a Schwarzschild black hole (BH) remains at the forefront of interesting, open problems in fundamental physics. To address this issue, we turn to Hawking's "principle of ignorance", which says that, for an observer with limited information about a physical system, all descriptions that are consistent with known physics are equally valid. We compare three different observers who view the BH from the outside and agree on the external Schwarzschild geometry. First, the modernist, who accepts the classical BH as the final state of gravitational collapse, the singularity theorems that underlie this premise and the central singularity that the theorems predict. The modernist is willing to describe matter in terms of quantum fields in curved space but insists on (semi)classical gravity. Second is the skeptic, who wishes to evade any singular behavior by finding a loophole to the singularity theorems within the realm of classical general relativity (GR). The third is a postmodernist who similarly wants to circumvent the singularity theorems but is willing to invoke exotic quantum physics in the gravitational and/or matter sector to do so. The postmodern view suggests that the uncertainty principle can stabilize a classically singular BH in a similar manner to the stabilization of the classically unstable hydrogen atom: Strong quantum effects in the matter and gravitational sectors resolve the would-be singularity over horizon-sized length scales. The postmodern picture then requires a significant departure from (semi)classical gravity, as well as some exotic matter beyond the standard model of particle physics (SM). We find that only the postmodern framework is consistent with what is known so far about BH physics and conclude that a valid description of the BH interior needs matter beyond the SM and gravitational physics beyond (semi)classical GR.

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Thermodynamic Stability of a New Three Dimensional Regular Black Hole

Hendi

Hajkhalili

Mahmoudi

2023

Fortschritte der Physik

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A new model of the regular black hole in dimensions is introduced by considering an appropriate matter field as the energy‐momentum tensor. First, we propose a novel model of d‐dimensional energy density that in dimensions leads to the existence of an upper bound on the radius of the event horizon and a lower bound on the mass of the black hole which are motivated by the features of astrophysical black holes. According to these bounds, we introduce an admissible domain for the event horizon radius, depending on the metric parameters. After investigation of geometric properties of the obtained solutions, we study the thermal stability of the solution in the canonical ensemble and find that the regular black hole is thermally stable in the mentioned admissible domain. Besides, the free energy is calculated to examine the global stability of the solution.

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Resisting collapse: How matter inside a black hole can withstand gravity

Cited by 29 publications

References 67 publications

Geodesically complete black holes

Geodesically complete black holes

Non‐Singular Black Holes Interiors Need Physics Beyond the Standard Model

Thermodynamic Stability of a New Three Dimensional Regular Black Hole

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