Regular Bouncing Solutions, Energy Conditions, and the Brans—Dicke Theory

Galkina, Olesya; Fabris, J. C.; Falciano, F. T.; Pinto-Neto, Nelson

doi:10.1134/s0021364019200013

Cited by 13 publications

(9 citation statements)

References 23 publications

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“…On the other hand, to obtain a bouncing solution in classical General Relativity, violation of the energy conditions is required. In this section, after briefly reviewing the bouncing scenarios, we present a non-singular model with radiative fluid in BD theory that obeys the energy conditions and does not contain ghosts [29]. To do so, we first briefly analyze the solutions determined by Gurevich et al [30] for the cosmological isotropic and homogeneous flat universe with a perfect fluid with an equation of state p = nρ, where the parameter n is given by 0 ≤ n ≤ 1.…”

Section: Bouncing Solutions and The Energy Conditionsmentioning

confidence: 99%

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Quantum and Classical Cosmology in the Brans–Dicke Theory

2021

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In this paper, we discuss classical and quantum aspects of cosmological models in the Brans–Dicke theory. First, we review cosmological bounce solutions in the Brans–Dicke theory that obeys energy conditions (without ghost) for a universe filled with radiative fluid. Then, we quantize this classical model in a canonical way, establishing the corresponding Wheeler–DeWitt equation in the minisuperspace, and analyze the quantum solutions. When the energy conditions are violated, corresponding to the case ω<−32, the energy is bounded from below and singularity-free solutions are found. However, in the case ω>−32, we cannot compute the evolution of the scale factor by evaluating the expectation values because the wave function is not finite (energy spectrum is not bounded from below). However, we can analyze this case using Bohmian mechanics and the de Broglie–Bohm interpretation of quantum mechanics. Using this approach, the classical and quantum results can be compared for any value of ω.

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Section: Bouncing Solutions and The Energy Conditionsmentioning

confidence: 99%

“…For more details, see Ref. [29]. 33) and ( 34), taking into account the effects of the non-minimal coupling.…”

Section: Bouncing Solutions and The Energy Conditionsmentioning

confidence: 99%

Quantum and Classical Cosmology in the Brans–Dicke Theory

2021

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“…Models with a bounce join a contracting phase, in which the universe was very large and almost flat initially, and move to a subsequent expanding phase. The bounce can be either generated classically (Galkina et al 2019; Ijjas & Steinhardt 2016; Wands 2009) or by quantum effects (Almeida et al 2018; Bacalhau et al 2018; Frion & Almeida 2019; Peter & Pinto‐Neto 2008). In this work, we explore the effects of an asymmetric bounce on the McVittie solution.…”

Section: Scalar Factor For An Asymmetric Bouncing Cosmological Modelmentioning

confidence: 99%

Black hole in asymmetric cosmological bounce

2021

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We determine the causal structure of the McVittie spacetime for a cosmological model with an asymmetric bounce. The analysis includes the computation of trapping horizons; regular, trapped, and antitrapped regions; and the integration of the trajectories of radial null geodesics before, during, and after the bounce. We find a trapped region since the beginning of the contracting phase up to shortly before the bounce, thus showing the existence of a black hole. When the universe reaches a certain minimum scale in the contracting phase, the trapping horizons disappear, and the central singularity becomes naked. These results suggest that neither a contracting nor an expanding universe can accommodate a black hole at all times.

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“…On the other hand, to obtain a bouncing solution in classical General Relativity, violation of the energy conditions is required. In this section, we present a non-singular model with radiative fluid in Brans-Dicke theory that obeys the energy conditions and does not contain ghosts [17]. To do so, we first briefly analyze the solutions determined by Gurevich et al [18] for the cosmological isotropic and homogeneous flat universe with a perfect fluid with an equation of state p = nρ, where the parameter n is given by 0 ≤ n ≤ 1.…”

Section: Bouncing Solutions and The Energy Conditionsmentioning

confidence: 99%

“…For more details, see Ref. [17]. It is important to observe that only in the case of radiative fluid it is possible to obtain a model without singularity preserving the energy conditions, at least in the Brans-Dicke theory.…”

Section: Bouncing Solutions and The Energy Conditionsmentioning

confidence: 99%

Quantum and classical cosmology in the Brans-Dicke theory

Almeida,

Galkina,

Fabris

2021

Preprint

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In this paper we discuss classical and quantum aspects of cosmological models in Brans-Dicke theory. First, we review cosmological bounce solutions in Brans-Dicke theory that obeys energy conditions (without ghost) for a universe filled with radiative fluid. Then we quantize this classical model in a canonical way, establishing the corresponding Wheeler-DeWitt equation in the minisuperspace, and analyze the quantum solutions. When the energy conditions are violated, corresponding to the case ω < − 3 2 , the energy is bounded from below and singularity-free solutions are found. However, in the case ω > − 3 2 we cannot compute the evolution of the scale factor by evaluating the expectation values because the wave function is not finite (energy spectrum is not bounded from below). But we can analyze this case using Bohmian mechanics and the de Broglie-Bohm interpretation of quantum mechanics. Using this approach, the classical and quantum results can be compared for any value of ω.

show abstract

Regular Bouncing Solutions, Energy Conditions, and the Brans—Dicke Theory

Cited by 13 publications

References 23 publications

Quantum and Classical Cosmology in the Brans–Dicke Theory

Quantum and Classical Cosmology in the Brans–Dicke Theory

Black hole in asymmetric cosmological bounce

Quantum and classical cosmology in the Brans-Dicke theory

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