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A complete model of the universe needs at least three parts: (1) a complete set of physical variables and dynamical laws for them, (2) the correct solution of the dynamical laws, and (3) the connection with conscious experience. In quantum…

High Energy Physics - Theory · Physics 2007-05-23 Don N. Page

The purpose of this review is to provide a brief overview of some recent conceptual developments about possible criteria to guarantee the uniqueness of the quantization in a variety of situations that are found in cosmological systems.…

General Relativity and Quantum Cosmology · Physics 2021-08-18 Jerónimo Cortez , Guillermo A. Mena Marugán , José M. Velhinho

We study the classical and quantum cosmology of a universe in which the matter content is a perfect fluid and the background geometry is described by a Bianchi type I metric. To write the Hamiltonian of the perfect fluid we use the Schutz…

General Relativity and Quantum Cosmology · Physics 2019-09-23 Fatimah Tavakoli , Babak Vakili

Contrary to the general belief, there has recently been quite a few examples of unitary evolution of quantum cosmological models. The present work gives more examples, namely Bianchi type VI and type II. These examples are important as they…

General Relativity and Quantum Cosmology · Physics 2016-11-03 Sachin Pandey , Narayan Banerjee

Quantum cosmology is usually studied quantizing symmetry-reduced variables. Is it possible, instead, to define quantum cosmology starting from the full quantum gravity theory? In Loop Quantum Gravity (LQG), it is possible to cut the degrees…

General Relativity and Quantum Cosmology · Physics 2011-10-18 Francesca Vidotto

We investigate the canonical quantization in the framework of N=1 simple supergravity for the case of a very simple gravitational midisuperspace described by Gowdy $T^3$ cosmological models. We consider supersymmetric quantum cosmology in…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Alfredo Macias , Abel Camacho , Jutta Kunz , Claus Laemmerzahl

Considerable attention has been paid to the study of the quantum geometry of nonrotating black holes within the framework of Loop Quantum Cosmology. This interest has been reinvigorated since the introduction of a novel effective model by…

General Relativity and Quantum Cosmology · Physics 2023-11-03 Beatriz Elizaga Navascués , Guillermo A. Mena Marugán , Andrés Mínguez Sánchez

Recently, inhomogeneous generalisations of the Friedmann-Lemaitre-Robertson-Walker cosmological models have gained interest in the astrophysical community and are more often employed to study cosmological phenomena. However, in many papers…

Cosmology and Nongalactic Astrophysics · Physics 2011-10-17 Krzysztof Bolejko , Marie-Noëlle Célérier , Andrzej Krasiński

In the recent years the quantization methods of Loop Quantum Gravity have been successfully applied to the homogeneous and isotropic Friedmann-Robertson-Walker space-times. The resulting theory, called Loop Quantum Cosmology (LQC), resolves…

General Relativity and Quantum Cosmology · Physics 2010-11-23 Michal Artymowski , Zygmunt Lalak , Lukasz Szulc

The holonomy-flux algebra $\A$ of loop quantum gravity is known to admit a natural representation that is uniquely singled out by the requirement of covariance under spatial diffeomorphisms. In the cosmological context, the requirement of…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Abhay Ashtekar , Miguel Campiglia

Quantum Reduced Loop Gravity provides a promising framework for a consistent characterization of the early Universe dynamics. Inspired by BKL conjecture, a flat Universe is described as a collection of Bianchi I homogeneous patches. The…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Emanuele Alesci , Francesco Cianfrani

Fluctuation terms and higher moments of a quantum state imply corrections to the classical equations of motion that may have implications in early-universe cosmology, for instance in the state-dependent form of effective potentials. In…

General Relativity and Quantum Cosmology · Physics 2023-07-10 Martin Bojowald , Freddy Hancock

We present a complete quantization of an approximately homogeneous and isotropic universe with small scalar perturbations. We consider the case in which the matter content is a minimally coupled scalar field and the spatial sections are…

General Relativity and Quantum Cosmology · Physics 2013-10-16 Mikel Fernández-Méndez , Guillermo A. Mena Marugán , Javier Olmedo

A free massless scalar field is coupled to homogeneous and isotropic loop quantum cosmology. The coupled model is investigated in the vicinity of the classical singularity, where discreteness is essential and where the quantum model is…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Martin Bojowald , Franz Hinterleitner

Loop quantum cosmology allows for arbitrary superpositions of the triad variable. We show here how these superpositions can become indistinguishable from a classical mixture by the interaction with fermions. We calculate the reduced density…

General Relativity and Quantum Cosmology · Physics 2013-01-23 Claus Kiefer , Christian Schell

Recent developments concerning oscillatory spacelike singularities in general relativity are taking place on two fronts. The first treats generic singularities in spatially homogeneous cosmology, most notably Bianchi types VIII and IX. The…

General Relativity and Quantum Cosmology · Physics 2013-06-28 Claes Uggla

We present a review on basic aspects of quantum cosmology in the presence of cut-off physics. We first analyze how the Wheeler-DeWitt equation in a pure metric approach describes the quantum Universe, showing how the singularity is not…

General Relativity and Quantum Cosmology · Physics 2021-09-20 Gabriele Barca , Eleonora Giovannetti , Giovanni Montani

This brief article sums up results obtained in arXiv:0911.2653, which develops a constrained SU(2) lattice gauge theory in the "dipole" approximation. This is a further step toward the issue of a (inhomogeneous) loop quantum cosmology and…

General Relativity and Quantum Cosmology · Physics 2010-03-02 Antonino Marciano

It has been suggested that the homogeneous black hole interior spacetime, when quantized following the techniques of loop quantum cosmology, has a resolved singularity replaced by a black-to-white hole transition. This result has however…

General Relativity and Quantum Cosmology · Physics 2021-03-23 Francesco Sartini , Marc Geiller

We study cosmological tensor perturbations on a quantized background within the hybrid quantization approach. In particular, we consider a flat, homogeneous and isotropic spacetime and small tensor inhomogeneities on it. We truncate the…

General Relativity and Quantum Cosmology · Physics 2016-06-07 Florencia Benítez Martínez , Javier Olmedo