Dynamical Vacuum in Quantum Cosmology

Alvarenga, F. G.; Lemos̀, Nivaldo A.

doi:10.1023/a:1018896900336

Cited by 58 publications

(90 citation statements)

References 14 publications

(22 reference statements)

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“…Of course, we have studied a very specific model. But, this model is somehow similar, from the point of view of the behaviour of the scale factor, to those exposed in [2,11,12]; hence, we can argue that the cosmic repulsion coming from the conformal gravity may also be unstable, in the sense employed here, even if the study of this question for the conformal gravity theory is much more involved due to the complexity of field content. On the other hand, the model presented in [1] indicates a changing of the sign of the cosmological constant, and it has already been shown in other situations that such transition from anti-gravity to gravity phase leads to instabilities [20,21].…”

Section: Final Commentssupporting

confidence: 68%

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On the consistency of a repulsive gravity phase in the early Universe

Batista

Fabris

Gonçalves

2001

Class. Quantum Grav.

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We exploit the possibility of existence of a repulsive gravity phase in the evolution of the Universe. A toy model with a free scalar field minimally coupled to gravity, but with the "wrong sign" for the energy and negative curvature for the spatial section, is studied in detail. The background solutions display a bouncing, non-singular Universe. The model is well-behaved with respect to tensor perturbations. But, it exhibits growing models with respect to scalar perturbations whose maximum occurs in the bouncing. Hence, large inhomogeneties are produced. At least for this case, a repulsive phase may destroy homogeneity, and in this sense it may be unstable. A newtonian analogous model is worked out; it displays qualitatively the same behaviour. The generality of this result is discussed. In particular, it is shown that the addition of an attractive radiative fluid does not change essentially the results. We discuss also a quantum version of the classical repulsive phase, through the Wheeler-de Witt equation in mini-superspace, and we show that it displays essentially the same scenario as the corresponding attractive phase. PACS number(s): 04

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Section: Final Commentssupporting

confidence: 68%

“…Indeed, quantum models in mini-superspace where there is, besides gravity, a perfect fluid are examples of non-singular models obtained through such effects. A carefull analysis of this problem, performed in [11,12], indicates that a kind of repulsive gravity effect appears as the Universe approaches the singularity.…”

Section: Introductionmentioning

confidence: 99%

On the consistency of a repulsive gravity phase in the early Universe

Batista

Fabris

Gonçalves

2001

Class. Quantum Grav.

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“…The variable is a global time since it does not involve the canonical momenta (Alvarenga & Lemos, 1998;Hajicek, 1986;Beluardi & Ferraro, 1995). A similar analysis can be carried out for the model based on leading to the following super-Hamiltonian…”

Section: )mentioning

confidence: 92%

“…Of particular interest are the investigations in which matter is described as a perfect fluid and quantization is performed using both the ADM method (Arnowitt, Deser, & Misner, 1962) and the method of superspace quantization (Wheeler, 1968). Detailed analyses were undertaken by Lapchinsky and Rubakov (1977) and others (Lemos, 1996;Alvarenga & Lemos, 1998;Alvarenga, Fabris, Lemos, & Monaret, 2002) in this regard. These analyses were conducted using the canonical formulation of the generally relativistic hydrodynamics of a perfect fluid due to Schutz (1970Schutz ( , 1971).…”

Section: Introductionmentioning

confidence: 99%

On Quantum Cosmology of the <em>R</em><sup>2</sup> Gravity Theory

Ahmed¹

2014

APR

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We study the minisuperspace quantization of the theory of gravity where an R 2 term is included in the Einstein Hilbert action. Matter is described by a perfect fluid and we employ the generally relativistic hydrodynamic formulation of Schutz. We set up the Wheeler-DeWitt equation and obtain its solutions. A finite norm wave packet solution is constructed and used to calculate asymptotic values for the expectation values of the scale factor and the Ricci scalar

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“…(187) Solutions of the zeroth order equation (186) are known [1,2,4] and presented in the previous sections. In the next sub-section we will show how the second order part of this equation can be very simplified using the de Broglie-Bohm quantum theory.…”

Section: Theory Of Cosmological Perturbations In a Quantum Cosmologicmentioning

confidence: 99%

Quantum cosmology from the de Broglie–Bohm perspective

Pinto-Neto¹,

Fabris²

2013

Class. Quantum Grav.

123

138

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We review the main results that have been obtained in quantum cosmology from the perspective of the de Broglie-Bohm quantum theory. As it is a dynamical theory of assumed objectively real trajectories in the configuration space of the physical system under investigation, this quantum theory is not essentially probabilistic and dispenses the collapse postulate, turning it suitable to be applied to cosmology. In the framework of minisuperspace models, we show how quantum cosmological effects in the deBroglie-Bohm's approach can avoid the initial singularity, and isotropize the Universe. We then extend minisuperspace in order to include linear cosmological perturbations. We present the main equations which govern the dynamics of quantum cosmological perturbations evolving in non-singular quantum cosmological backgrounds, and calculate some of their observational consequences. These results are not known how to be obtained in other approaches to quantum theory. In the general case of full superspace, we enumerate the possible structures of quantum space and time that emerge from the de Broglie-Bohm picture. Finally, we compare some of the results coming from the de Broglie-Bohm theory with other approaches, and discuss the physical reasons for some discrepancies that occur.

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Dynamical Vacuum in Quantum Cosmology

Cited by 58 publications

References 14 publications

On the consistency of a repulsive gravity phase in the early Universe

On the consistency of a repulsive gravity phase in the early Universe

On Quantum Cosmology of the <em>R</em><sup>2</sup> Gravity Theory

Quantum cosmology from the de Broglie–Bohm perspective

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