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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

In recent years, Loop Quantum Gravity has emerged as a solid candidate for a nonperturbative quantum theory of General Relativity. It is a background independent theory based on a description of the gravitational field in terms of…

General Relativity and Quantum Cosmology · Physics 2009-10-16 Guillermo A. Mena Marugan

Within the framework of Quantum Reduced Loop Gravity we quantize the Hamiltonian for a gauge vector field. The regularization can be performed using tools analogous to the ones adopted in full Loop Quantum Gravity, while the matrix elements…

General Relativity and Quantum Cosmology · Physics 2017-06-07 Jakub Bilski , Emanuele Alesci , Francesco Cianfrani , Pietro Donà , Antonino Marciano

Inhomogeneities are introduced in loop quantum cosmology using regular lattice states, with a kinematical arena similar to that in homogeneous models considered earlier. The framework is intended to encapsulate crucial features of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Martin Bojowald

This Chapter provides an up to date, pedagogical review of some of the most relevant advances in loop quantum cosmology. We review the quantization of homogeneous cosmological models, their singularity resolution and the formulation of…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Ivan Agullo , Alejandro Corichi

Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e. the fact that the backward evolution…

General Relativity and Quantum Cosmology · Physics 2016-10-19 Martin Bojowald

The Affine Coherent State Quantization procedure is applied to the case of a FRLW universe in the presence of a cosmological constant. The quantum corrections alter the dynamics of the system in the semiclassical regime, providing a…

High Energy Physics - Theory · Physics 2014-09-16 Michaël Fanuel , Simone Zonetti

The effective approach in Loop Quantum Cosmology (LQC) has provided means to obtain predictions for observable quantities in LQC models. While an effective dynamics in LQC has been extensively considered in different scenarios, a robust…

General Relativity and Quantum Cosmology · Physics 2022-08-11 Gustavo S. Vicente , Rudnei O. Ramos , Leila L. Graef

Loop quantum gravity and cosmology are reviewed with an emphasis on evaluating the dynamics, rather than constructing it. The three crucial parts of such an analysis are (i) deriving effective equations, (ii) controlling the theory's…

General Relativity and Quantum Cosmology · Physics 2011-01-31 Martin Bojowald

This introductory review is addressed to beginning researchers. Some of the distinguishing features of loop quantum gravity are illustrated through loop quantum cosmology of FRW models. In particular, these examples illustrate: i) how…

General Relativity and Quantum Cosmology · Physics 2010-11-11 Abhay Ashtekar

This is an introduction to loop quantum cosmology (LQC) reviewing mini- and midisuperspace models as well as homogeneous and inhomogeneous effective dynamics.

General Relativity and Quantum Cosmology · Physics 2012-03-27 Kinjal Banerjee , Gianluca Calcagni , Mercedes Martín-Benito

Introducing a new method, we demonstrate how the action of reduced operators can be derived without resorting to a recoupling theory and how they exactly reproduce the results obtained in the standard approach of Quantum Reduced Loop…

General Relativity and Quantum Cosmology · Physics 2020-07-07 Jakub Bilski , Antonino Marciano

The closed, spatially isotropic FLRW universe (k=+1) is endowed with modifications due to a discrete underlying space-structure. Motivated from Loop Quantum Gravity techniques, a full Thiemann regularisation is performed. The impact of…

General Relativity and Quantum Cosmology · Physics 2021-03-22 Klaus Liegener , Stefan Andreas Weigl

In this paper, we first provide a brief review of the effective dynamics of two recently well-studied models of modified loop quantum cosmologies (mLQCs), which arise from different regularizations of the Hamiltonian constraint and show the…

General Relativity and Quantum Cosmology · Physics 2021-06-25 Bao-Fei Li , Parampreet Singh , Anzhong Wang

Loop Quantum Cosmology (LQC) is a theory which renders the Big Bang initial singularity into a quantum bounce, by means of short range repulsive quantum effects at the Planck scale. In this work, we are interested in reproducing the…

General Relativity and Quantum Cosmology · Physics 2021-11-25 Marcello Miranda , Daniele Vernieri , Salvatore Capozziello , Francisco S. N. Lobo

A cosmology inspired structure for phase space is introduced, which leads to finitization and lattice-like discretization of position and momentum eigenvalues in a preferred, cosmic frame. Lorentz invariance is broken at very high energies,…

High Energy Physics - Theory · Physics 2007-05-23 Helio Fagundes

In this article, we review the use of numerical techniques to obtain solutions for the quantum Hamiltonian constraint in loop quantum cosmology (LQC). First, we summarize the basic features of LQC, and describe features of the constraint…

General Relativity and Quantum Cosmology · Physics 2012-01-04 David Brizuela , Daniel Cartin , Gaurav Khanna

Loop Quantum Gravity (LQG) is a promising approach to quantum gravity, in particular because it is based on a rigorous quantization of the kinematics of gravity. A difficult and still open problem in the LQG program is the construction of…

General Relativity and Quantum Cosmology · Physics 2013-03-01 Tim Koslowski

We propose a new derivation from the full Loop Quantum Gravity (LQG) to the Loop Quantum Cosmology (LQC) improved $\bar{\mu}$-scheme effective dynamics, based on the reduced phase space formulation of LQG and a proposal of effective…

General Relativity and Quantum Cosmology · Physics 2020-09-30 Muxin Han , Hongguang Liu

In the past, the possibility to employ (scalar) material reference systems in order to describe classical and quantum gravity directly in terms of gauge invariant (Dirac) observables has been emphasised frequently. This idea has been picked…

General Relativity and Quantum Cosmology · Physics 2022-12-05 Kristina Giesel , Thomas Thiemann