Robustness of the quantum BKL scenario

Piechocki, Włodzimierz

doi:10.1140/epjc/s10052-020-7668-5

Cited by 19 publications

(20 citation statements)

References 18 publications

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“…The system we consider to be quantized is the celebrated Schwarzschild spacetime [2]. We ascribe to this gravitational system a quantum system by making use of the affine coherent states (ACS) method that we have recently used for the quantization of the Belinski-Khalatnikov-Lifshitz scenario with generic cosmological singularity [3,4].…”

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confidence: 99%

Ascribing quantum system to Schwarzschild spacetime with naked singularity

Góźdź,

Pȩdrak,

Piechocki

2021

Preprint

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We quantize the Schwarzschild black hole using the affine coherent states quantization method. The novelty of our approach is quantization of both temporal and spatial coordinates. Quantization smears the gravitational singularity indicated by the Kretschmann invariant avoiding its localization in the configuration space. This way we resolve, to some extent, the singularity problem of considered black hole. Our approach relies on using only the metric tensor so that it can be applied to other black holes with the metrics satisfying Einstein's equation.

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confidence: 99%

Ascribing quantum system to Schwarzschild spacetime with naked singularity

Góźdź,

Pȩdrak,

Piechocki

2021

Preprint

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“…It is commonly expected that quantum gravity, to be constructed, would be free from the singularities. The quantization of the BKL scenario carried out recently [19,20] gives support to such expectation. However, this result should be confirmed by quantizing that scenario possibly within completely different approach to verify its robustness.…”

Section: Discussionmentioning

confidence: 67%

Generic instability of the dynamics underlying the Belinski-Khalatnikov-Lifshitz scenario

Goldstein,

Piechocki

2021

Preprint

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An exact solution of the equations underlying the Belinski-Khalatnikov-Lifshitz (BKL) scenario is derived and tested for the stability against small perturbations. The regularity of the dynamics is examined using dynamical systems method. An instability and strong nonlinearity of the dynamics occur in the vicinity of the gravitational singularity. Our results present the properties of spacetime near the generic gravitational singularity and seem to be consistent with the BKL conjecture.

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“…The classical singularity of the BKL scenario is replaced by the quantum bounce that presents a unitary evolution of the considered gravitational system. In a later paper [172] they asked whether their claims may change because the affine coherent states quantization method depends on the choice of the group parametrization. Using the two simplest parameterizations of the affine group, they show that qualitative features of their quantum system do not depend on the choice.…”

Section: Quantum Bkl-mixmaster Scenariosmentioning

confidence: 99%

Weyl Curvature Hypothesis in Light of Quantum Backreaction at Cosmological Singularities or Bounces

2021

Universe

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The Weyl curvature constitutes the radiative sector of the Riemann curvature tensor and gives a measure of the anisotropy and inhomogeneities of spacetime. Penrose’s 1979 Weyl curvature hypothesis (WCH) assumes that the universe began at a very low gravitational entropy state, corresponding to zero Weyl curvature, namely, the Friedmann–Lemaître–Robertson–Walker (FLRW) universe. This is a simple assumption with far-reaching implications. In classical general relativity, Belinsky, Khalatnikov and Lifshitz (BKL) showed in the 70s that the most general cosmological solutions of the Einstein equation are that of the inhomogeneous Kasner types, with intermittent alteration of the one direction of contraction (in the cosmological expansion phase), according to the mixmaster dynamics of Misner (M). How could WCH and BKL-M co-exist? An answer was provided in the 80s with the consideration of quantum field processes such as vacuum particle creation, which was copious at the Planck time (10−43 s), and their backreaction effects were shown to be so powerful as to rapidly damp away the irregularities in the geometry. It was proposed that the vaccum viscosity due to particle creation can act as an efficient transducer of gravitational entropy (large for BKL-M) to matter entropy, keeping the universe at that very early time in a state commensurate with the WCH. In this essay I expand the scope of that inquiry to a broader range, asking how the WCH would fare with various cosmological theories, from classical to semiclassical to quantum, focusing on their predictions near the cosmological singularities (past and future) or avoidance thereof, allowing the Universe to encounter different scenarios, such as undergoing a phase transition or a bounce. WCH is of special importance to cyclic cosmologies, because any slight irregularity toward the end of one cycle will generate greater anisotropy and inhomogeneities in the next cycle. We point out that regardless of what other processes may be present near the beginning and the end states of the universe, the backreaction effects of quantum field processes probably serve as the best guarantor of WCH because these vacuum processes are ubiquitous, powerful and efficient in dissipating the irregularities to effectively nudge the Universe to a near-zero Weyl curvature condition.

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Robustness of the quantum BKL scenario

Cited by 19 publications

References 18 publications

Ascribing quantum system to Schwarzschild spacetime with naked singularity

Ascribing quantum system to Schwarzschild spacetime with naked singularity

Generic instability of the dynamics underlying the Belinski-Khalatnikov-Lifshitz scenario

Weyl Curvature Hypothesis in Light of Quantum Backreaction at Cosmological Singularities or Bounces

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