Nonmarginal Lemaitre-Tolman-Bondi-like models with inverse triad corrections from loop quantum gravity

Bojowald, Martin; Reyes, Juan D.; Tibrewala, Rakesh

doi:10.1103/physrevd.80.084002

Cited by 71 publications

(89 citation statements)

References 45 publications

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“…A possible solution to this problem is to implement holonomy modifications in an anomaly-free way which does not break any gauge transformations but may deform the classical structure of hypersurface deformations given in [63,64]. Consistent deformations are possible in spherically symmetric models with holonomy modifications [71,72,73,74,75,76,77], but they imply a non-classical space-time structure which is related to slicing independence only in some cases, and after field redefinitions [78,79]. The latter feature not only resolves the contradiction between holonomy modifications and covariance pointed out in [11], it also shows why singularities can be resolved in loop quantum cosmology even for matter obeying the usual energy conditions: Not only the dynamics but also space-time structure become non-classical as a consequence of holonomy modifications, unhinging the mathematical foundation of singularity theorems.…”

Section: Covariancementioning

confidence: 99%

Critical Evaluation of Common Claims in Loop Quantum Cosmology

Bojowald

2020

Universe

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A large number of models have been analyzed in loop quantum cosmology, using mainly minisuperspace constructions and perturbations. At the same time, general physics principles from effective field theory and covariance have often been ignored. A consistent introduction of these ingredients requires substantial modifications of existing scenarios. As a consequence, none of the broader claims made mainly by the Ashtekar school -such as the genericness of bounces with astonishingly semiclassical dynamics, robustness with respect to quantization ambiguities, the realization of covariance, and the relevance of certain technical results for potential observations -hold up to scrutiny. Several useful lessons for a sustainable version of quantum cosmology can be drawn from this outcome. * e-mail address: bojowald@gravity.psu.edu 1 All quotations from [1] given in this paper refer to the second preprint version.

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Section: Covariancementioning

confidence: 99%

Critical Evaluation of Common Claims in Loop Quantum Cosmology

Bojowald

2020

Universe

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“…Interestingly, it was realized in a series of articles [49][50][51][52][53][54] that under suitable conditions, one can construct regularizations where the deformed algebra of constraints remain closed 3 . The consequences of this deformed covariance was then investigated in depth in the context of spherically symmetric backgrounds [60][61][62] and then extended to more general symmetry reduced models in [63][64][65][66][67][68].…”

Section: Introductionmentioning

confidence: 99%

Deformed General Relativity and Quantum Black Holes Interior

2020

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Effective models of black holes interior have led to several proposals for regular black holes. In the so-called polymer models, based on effective deformations of the phase space of spherically symmetric general relativity in vacuum, one considers a deformed Hamiltonian constraint while keeping a non-deformed vectorial constraint, leading under some conditions to a notion of deformed covariance. In this article, we revisit and study further the question of covariance in these deformed gravity models. In particular, we propose a Lagrangian formulation for these deformed gravity models where polymer-like deformations are introduced at the level of the full theory prior to the symmetry reduction and prior to the Legendre transformation. This enables us to test whether the concept of deformed covariance found in spherically symmetric vacuum gravity can be extended to the full theory, and we show that, in the large class of models we are considering, the deformed covariance can not be realized beyond spherical symmetry in the sense that the only deformed theory which leads to a closed constraints algebra is general relativity. Hence, we focus on the spherically symmetric sector, where there exist non-trivial deformed but closed constraints algebras. We investigate the possibility to deform the vectorial constraint as well and we prove that non-trivial deformations of the vectorial constraint with the condition that the constraints algebra remains closed do not exist. Then, we compute the most general deformed Hamiltonian constraint which admits a closed constraints algebra and thus leads to a well-defined effective theory associated with a notion of deformed covariance. Finally, we study static solutions of these effective theories and, remarkably, we solve explicitly and in full generality the corresponding modified Einstein equations, even for the effective theories which do not satisfy the closeness condition. In particular, we give the expressions of the components of the effective metric (for static and spherically symmetric black holes interior) in terms of the functions that govern the deformations of the theory.

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“…Techniques to handle inhomogeneous systems [17,18] are still under development [26][27][28] (see also Ref. [29]), but they do not easily reveal the physical picture.…”

Section: Gravitational Collapse With a Scalar Fieldmentioning

confidence: 99%

“…Written in advanced EddingtonFinkelstein coordinates (v, r v , θ, φ), it has the form [37][38][39] 18) where M (r v , v) is a generic function of r v and v, which is fixed by matching the Eq. (2.18) with Eq.…”

Section: Gravitational Collapse With a Scalar Fieldmentioning

confidence: 99%

“…Within the context of LQC, the status of the classical singularities that arise at the late time stages of the spherically symmetric gravitational collapse, has been studied in LQG [14][15][16][17][18][19][20]. Therein, different fields, such as the standard scalar [14,15,21] or the tachyon [16,22], have been considered to play the role of the collapsing matter source.…”

Section: Introductionmentioning

confidence: 99%

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Semiclassical dynamics of horizons in spherically symmetric collapse

Tavakoli

Marto

Dapor

2014

Int. J. Mod. Phys. D

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In this work, we consider a semiclassical description of the spherically symmetric gravitational collapse with a massless scalar field. In particular, we employ an effective scenario provided by holonomy corrections from loop quantum gravity, to the homogeneous interior spacetime. The singularity that would arise at the final stage of the corresponding classical collapse, is resolved in this context and is replaced by a bounce. Our main purpose is to investigate the evolution of trapped surfaces during this semiclassical collapse. Within this setting, we obtain a threshold radius for the collapsing shells in order to have horizons formation. In addition, we study the final state of the collapse by employing a suitable matching at the boundary shell from which quantum gravity effects are carried to the exterior geometry.

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Nonmarginal Lemaitre-Tolman-Bondi-like models with inverse triad corrections from loop quantum gravity

Cited by 71 publications

References 45 publications

Critical Evaluation of Common Claims in Loop Quantum Cosmology

Critical Evaluation of Common Claims in Loop Quantum Cosmology

Deformed General Relativity and Quantum Black Holes Interior

Semiclassical dynamics of horizons in spherically symmetric collapse

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