Exteriors to bouncing collapse models

Schmitz, Tim

doi:10.48550/arxiv.2012.04383

Cited by 5 publications

(7 citation statements)

References 51 publications

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“…From an observer inside the collapsing matter, the surface would travel along a time-like path, which gives no contradictions due to the discontinuity of the spacetime across the matter surface in the re-expanding branch. This is consistent with earlier work [38][39][40][41]51], which all conclude that a bounce has to happen outside of a causal horizon of the eternal metric or it will leave in a parallel universe if one insists on a continuous and time-like collapse. Both these assumptions are violated in [1], which gives rise to this shock wave solution.…”

Section: Discussionsupporting

confidence: 92%

“…As observer and matter meet each other after finite time, this is different to most other proposals for loop quantum gravity inspired black hole models where a causal horizon is present [1, 2, 12-25, 27, 51]. A generalisation to a collapse model as in [38][39][40][41]51] would always lead to the result that the observer and matter do never meet again as the matter bounces out of a parallel universe -at least if black hole evaporation is neglected. Here instead, the matter is crossing the outer horizon, then the inner one, bouncing out again at x min , crossing first the same inner horizon and then the same outer horizon to arrive in the same exterior again.…”

Section: Matter Regionmentioning

confidence: 82%

“…As argued, this might be possible as L(t) becomes again arbitrarily large after a bounce. Usually, this happens in a parallel universe [38][39][40][41]51].…”

Section: Matter Regionmentioning

confidence: 99%

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Causal Structure of a recent Loop Quantum Gravity Black Hole Collapse Model

Münch

2021

Preprint

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The causal structure of the recent loop quantum gravity black hole collapse model [1] is analysed. As the spacetime is only approximately diffeomorphism invariant up to powers of , it is not straight forwardly possible to find global conformally compactified coordinates and to construct the Penrose diagram. Therefore, radial in-and outgoing light rays are studied to extract the causal features and sketch a causal diagram. It was found that the eternal metric [2], which is the vacuum solution of the collapse model, has a causal horizon. However, in the collapsing case light rays travel through matter to causally connect the regions in-and outside the horizon -the causal horizon is not present in the collapsing scenario. It is worked out that this is related to the shock wave and spacetime discontinuity, which allows matter travelling super-luminal along a space-like trajectory from the vacuum point of view, but remaining time-like from the matter perspective. The final causal diagram is a nice compact patch of a Reissner-Nordström causal diagram. Further, possibilities of a continuous matter collapse with only time-like evolution are studied. It was found that the time-reversed vacuum metric is also a solution of the dynamical equations and a once continuously differentiable matching of the vacuum spacetime across the minimal radius is possible. This allows an everywhere continuous and time-like collapse process at the cost of an infinite extended causal diagram. This solution is part of an infinitely extended eternal black hole solution with a bounce, whose global extension is constructed. Due to the analysis of radial light rays, it is possible to sketch causal diagrams of these spacetimes.

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Section: Discussionsupporting

confidence: 92%

Section: Matter Regionmentioning

confidence: 82%

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Causal Structure of a recent Loop Quantum Gravity Black Hole Collapse Model

Münch

2021

Preprint

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“…A quantum theory of gravity is expected to eliminate the singularities predicted by general relativity, in particular, those associated with incomplete geodesics at the final stage of the collapse of regular matter into a black hole [1]. Several methods for removing the singularity in approaches to quantum gravity have been proposed [2][3][4][5][6][7] and the appearance of a bounce at a minimum radius is generically obtained in semiclassical models [8,9]. These results suggest that the role of matter in the description of black hole formation (and subsequent evolution [10]) is crucial.…”

Section: Introductionmentioning

confidence: 99%

Configurational entropy of black hole quantum cores

Casadio¹,

Rocha²,

Meert³

et al. 2022

Preprint

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Two types of information entropy are studied for the quantum states of a model for the matter core inside a black hole geometry. A detailed description is first given of the quantum mechanical picture leading to a spectrum of bound states for a collapsing ball of dust in general relativity with a non-trivial ground state. Information entropies are then computed, shedding new light on the stability of the ground state and the spectrum of higher excited states.

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“…A generic feature of these works is that, as in cosmology, the singularity is resolved and matter bounces when space-time curvature reaches the Planck scale. This is seen in LQG [52][53][54][55][56][57] and in other approaches [68][69][70][71][72][73]; a model-independent view is studied in [74], and a recent review is [75].…”

Section: Introductionmentioning

confidence: 99%

On the fate of quantum black holes

Husain,

Kelly,

Santacruz

et al. 2022

Preprint

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We study the quantum dynamics of the Lemaître-Tolman-Bondi space-times using a polymer quantization prescription based on loop quantum cosmology that incorporates fundamental discreteness. By solving an effective equation derived from this quantization, we find analytical solutions for the Oppenheimer-Snyder and thinshell collapse models, and numerical solutions for a variety of asymptotically flat collapsing dust profiles. Our study (i) tracks the formation, evolution and disappearance of dynamical horizons, (ii) shows that matter undergoes a non-singular bounce that results in an outgoing shock wave, (iii) determines black hole lifetime to be proportional to the square its mass, and (iv) provides a conformal diagram that substantially modifies the standard "information loss" picture by resolving the singularity and replacing the event horizon by transient apparent horizons.

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Exteriors to bouncing collapse models

Cited by 5 publications

References 51 publications

Causal Structure of a recent Loop Quantum Gravity Black Hole Collapse Model

Causal Structure of a recent Loop Quantum Gravity Black Hole Collapse Model

Configurational entropy of black hole quantum cores

On the fate of quantum black holes

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