Quantum cosmological perturbations of multiple fluids

We present and expand the simplest possible quantum cosmological bouncing model already discussed in previous works: the trajectory formulation of quantum mechanics applied to cosmology (through the Wheeler-De Witt equation) in the FLRW minisuper- space without spatial curvature. The initial conditions that were previously assumed were such that the wave function would not change its functional form but instead provide a dynamics to its parameters. Here, we consider a more general situation, in practice con- sisting of modified Gaussian wave functions, aiming at obtaining a non singular bounce from a contracting phase. Whereas previous works consistently obtain very symmetric bounces, we find that it is possible to produce highly non symmetric solutions, and even cases for which multiple bounces naturally occur. We also introduce a means of treating the shear in this category of models by quantizing in the Bianchi I minisuperpace.Comment: 10 pages, proceeding of the workshop "Current challenges in cosmology" held in Cali, Colombia, May 18 to 22, 201

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“…24 As we discuss below, the wave function proposed in Ref. 1 can be generalized to yield new bouncing solutions.…”

Section: Wave Functionmentioning

confidence: 99%

The simplest possible bouncing quantum cosmological model

Peter

Vitenti

2016

Mod. Phys. Lett. A

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“…In fact, the more complete bounce solution (61) also yields an almost scale-invariant spectrum of adiabatic cosmological perturbations. Its amplitude reads [82,86]…”

Section: The Perfect Fluidmentioning

confidence: 99%

“…Phase space for the planar system defined by ( 85) and (86). The critical points are indicated by M ± for a dust-type effective equation of state, and S ± for a stiff-matter equation of state.…”

Section: Canonical Scalar Fieldmentioning

confidence: 99%

The de Broglie–Bohm Quantum Theory and Its Application to Quantum Cosmology

Pinto-Neto

2021

Universe

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We review the de Broglie–Bohm quantum theory. It is an alternative description of quantum phenomena in accordance with all the quantum experiments already performed. Essentially, it is a dynamical theory about objectively real trajectories in the configuration space of the physical system under investigation. Hence, it is not necessarily probabilistic, and it dispenses with the collapse postulate, making it suitable to be applied to cosmology. The emerging cosmological models are usually free of singularities, with a bounce connecting a contracting era with an expanding phase, which we are now observing. A theory of cosmological perturbations can also be constructed under this framework, which can be successfully confronted with current observations, and can complement inflation or even be an alternative to it.

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“…However, the presence of another field yields entropy perturbations, the relative fluctuations between the individual energy densities of the different fields, which are not usually treated correctly (for the correct treatment, see e.g. [71]). Furthermore, in such classical bounce scenarios, primordial gravitational waves are also created, and they are as important as scalar perturbations, i.e., the ratio r = T /S between the amplitude of primordial gravitational waves T and the amplitude of scalar perturbations S is approximately one.…”

Section: Observational Aspects For Matter Bouncesmentioning

confidence: 99%

Bohmian Quantum Gravity and Cosmology

Pinto-Neto¹,

Struyve²

2019

Applied Bohmian Mechanics

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Quantum gravity aims to describe gravity in quantum mechanical terms. How exactly this needs to be done remains an open question. Various proposals have been put on the table, such as canonical quantum gravity, loop quantum gravity, string theory, etc. These proposals often encounter technical and conceptual problems. In this chapter, we focus on canonical quantum gravity and discuss how many conceptual problems, such as the measurement problem and the problem of time, can be overcome by adopting a Bohmian point of view. In a Bohmian theory (also called pilot-wave theory or de Broglie-Bohm theory, after its originators de Broglie and Bohm), a system is described by certain variables in space-time such as particles or fields or something else, whose dynamics depends on the wave function. In the context of quantum gravity, these variables are a space-time metric and suitable variable for the matter fields (e.g., particles or fields). In addition to solving the conceptual problems, the Bohmian approach yields new applications and predictions in quantum cosmology. These include space-time singularity resolution, new types of semi-classical approximations to quantum gravity, and approximations for quantum perturbations moving in a quantum background.

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Quantum cosmological perturbations of multiple fluids

Cited by 19 publications

References 44 publications

The simplest possible bouncing quantum cosmological model

The simplest possible bouncing quantum cosmological model

The de Broglie–Bohm Quantum Theory and Its Application to Quantum Cosmology

Bohmian Quantum Gravity and Cosmology

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