Loop Quantum Cosmology and Quantum Black Holes

A special issue of Universe (ISSN 2218-1997).

Deadline for manuscript submissions: closed (30 November 2016) | Viewed by 16500

Special Issue Editor

Department of mathematics, Polytechnic University of Catalonia, Diagonal 647, 08028 Barcelona, Spain
Interests: quintessential inflation and gravitational particle production
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Special Issue Information

Dear Colleagues,

Loop Quantum Gravity (LQG) is one of the most exciting theories beyond General Relativity. Based in the discrete nature of the spacetime and mixing quantum effects with gravity, it could provide us some signatures of our Universe at very high energies. As a particular case, holonomy corrected Loop Quantum Cosmology (LQC) leads to a simple Big Bounce that replaces the classical Big Bang and/or Big Rip singularity. Moreover, the matter bounce scenario in LQC (where at very early times the Universe starts in a quasi matter domination in the contracting phase and evolves through this phase to the Big Bounce, and after bouncing it enters into the expanding regime where it matches with the standard hot Friedmann model), is the most promising alternative to the inflationary paradigm.

Another important issue, for which interest has increased in recent years, is the study within in LQG of quantum black holes. Specifically, the quantization of spherical symmetric vacuum spacetimes and the black hole entropy in the context of LQG, seem to lead to new and suprising results without a classical analogous. For instance, black hole collapse could reverse turning into expansion in analogy with the bouncing Universe in LQC, or the core of a spherically symmetric black hole might be a region of high curvature rather than a singularity.

Finally, and extension of LQG to other theories, such as modified f(R) or teleparallel gravity, could yield new cosmologies in which bouncing backgrounds could be used to depict our Universe.

Prof. Dr. Jaume Haro
Guest Editor

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Published Papers (4 papers)

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458 KiB  
Article
Quantum Tunneling Radiation from Loop Quantum Black Holes and the Information Loss Paradox
Universe 2017, 3(2), 42; https://doi.org/10.3390/universe3020042 - 08 May 2017
Cited by 2 | Viewed by 4171
Abstract
In this work, we present some results relating to the issue of the Loop Quantum Black Holes (LQBH) thermodynamics by the use of the tunneling radiation formalism. The information loss paradox is also discussed in this context, and we have considered the influence [...] Read more.
In this work, we present some results relating to the issue of the Loop Quantum Black Holes (LQBH) thermodynamics by the use of the tunneling radiation formalism. The information loss paradox is also discussed in this context, and we have considered the influence of back reaction effects. Full article
(This article belongs to the Special Issue Loop Quantum Cosmology and Quantum Black Holes)
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338 KiB  
Article
Bouncing Cosmologies with Dark Matter and Dark Energy
Universe 2017, 3(1), 1; https://doi.org/10.3390/universe3010001 - 23 Dec 2016
Cited by 59 | Viewed by 4352
Abstract
We review matter bounce scenarios where the matter content is dark matter and dark energy. These cosmologies predict a nearly scale-invariant power spectrum with a slightly red tilt for scalar perturbations and a small tensor-to-scalar ratio. Importantly, these models predict a positive running [...] Read more.
We review matter bounce scenarios where the matter content is dark matter and dark energy. These cosmologies predict a nearly scale-invariant power spectrum with a slightly red tilt for scalar perturbations and a small tensor-to-scalar ratio. Importantly, these models predict a positive running of the scalar index, contrary to the predictions of the simplest inflationary and ekpyrotic models, and hence, could potentially be falsified by future observations. We also review how bouncing cosmological space-times can arise in theories where either the Einstein equations are modified or where matter fields that violate the null energy condition are included. Full article
(This article belongs to the Special Issue Loop Quantum Cosmology and Quantum Black Holes)
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Review

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283 KiB  
Review
Loop Quantum Cosmology, Modified Gravity and Extra Dimensions
Universe 2016, 2(3), 15; https://doi.org/10.3390/universe2030015 - 10 Aug 2016
Cited by 38 | Viewed by 3246
Abstract
Loop quantum cosmology (LQC) is a framework of quantum cosmology based on the quantization of symmetry reduced models following the quantization techniques of loop quantum gravity (LQG). This paper is devoted to reviewing LQC as well as its various extensions including modified gravity [...] Read more.
Loop quantum cosmology (LQC) is a framework of quantum cosmology based on the quantization of symmetry reduced models following the quantization techniques of loop quantum gravity (LQG). This paper is devoted to reviewing LQC as well as its various extensions including modified gravity and higher dimensions. For simplicity considerations, we mainly focus on the effective theory, which captures main quantum corrections at the cosmological level. We set up the basic structure of Brans–Dicke (BD) and higher dimensional LQC. The effective dynamical equations of these theories are also obtained, which lay a foundation for the future phenomenological investigations to probe possible quantum gravity effects in cosmology. Some outlooks and future extensions are also discussed. Full article
(This article belongs to the Special Issue Loop Quantum Cosmology and Quantum Black Holes)
377 KiB  
Review
Brief Review on Black Hole Loop Quantization
Universe 2016, 2(2), 12; https://doi.org/10.3390/universe2020012 - 15 Jun 2016
Cited by 19 | Viewed by 4052
Abstract
Here, we present a review about the quantization of spherically-symmetric spacetimes adopting loop quantum gravity techniques. Several models that have been studied so far share similar properties: the resolution of the classical singularity and some of them an intrinsic discretization of the geometry. [...] Read more.
Here, we present a review about the quantization of spherically-symmetric spacetimes adopting loop quantum gravity techniques. Several models that have been studied so far share similar properties: the resolution of the classical singularity and some of them an intrinsic discretization of the geometry. We also explain the extension to Reissner–Nordström black holes. Besides, we review how quantum test fields on these quantum geometries allow us to study phenomena, like the Casimir effect or Hawking radiation. Finally, we briefly describe a recent proposal that incorporates spherically-symmetric matter, discussing its relevance for the understanding of black hole evolution. Full article
(This article belongs to the Special Issue Loop Quantum Cosmology and Quantum Black Holes)
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