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The inverse scale factor, which in classical cosmological models diverges at the singularity, is quantized in isotropic models of loop quantum cosmology by using techniques which have been developed in quantum geometry for a quantization of…

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

A well-motivated extension of higher order holonomy corrections in loop quantum cosmology (LQC) for the $k=0$ Friedmann-Robertson-Walker model is investigated at the level of heuristic effective dynamics. It reveals that the quantum bounce…

General Relativity and Quantum Cosmology · Physics 2009-03-24 Dah-Wei Chiou , Li-Fang Li

We discuss the asymmetry of cosmic background evolution in time with respect to the quantum bounce in the Loop Quantum Cosmology (LQC), employing the value of scalar field at the bounce $\phi_{\rm B}$. We use the Chaotic and the $R^2$…

General Relativity and Quantum Cosmology · Physics 2019-07-03 Wen-Hsuan Lucky Chang , Jiun-Huei Proty Wu

The existence of a quantum bounce in isotropic spacetimes is a key result in loop quantum cosmology (LQC), which has been demonstrated to arise in all the models studied so far. In most of the models, the bounce has been studied using…

General Relativity and Quantum Cosmology · Physics 2017-06-20 Peter Diener , Brajesh Gupt , Parampreet Singh

One of the most remarkable phenomena in Loop Quantum Cosmology is that, at least for homogeneous cosmological models, the Big Bang is replaced with a Big Bounce that connects our universe with a previous branch without passing through a…

General Relativity and Quantum Cosmology · Physics 2013-11-07 Paula Tarrío , Mikel Fernández-Méndez , Guillermo A. Mena Marugán

Anisotropies generically dominate the earliest stages of expansion of a homogeneous universe. They are particularly relevant in bouncing models, since shears grow in the contracting phase of the cosmos, making the isotropic situation…

General Relativity and Quantum Cosmology · Physics 2020-09-04 Ivan Agullo , Javier Olmedo , V. Sreenath

In this contribution we consider the issue of singularity resolution within loop quantum cosmology (LQC) for different homogeneous models. We present results of numerical evolutions of effective equations for both isotropic as well as…

General Relativity and Quantum Cosmology · Physics 2012-12-04 Alejandro Corichi , Asieh Karami , Edison Montoya

Analyzing quantum cosmological scenarios containing one scalar field with exponential potential, we have obtained a universe model which realizes a classical dust contraction from very large scales, the initial repeller of the model, and…

General Relativity and Quantum Cosmology · Physics 2017-09-13 Samuel Colin , Nelson Pinto-Neto

We investigate the convergence behaviors of the scalar and the vector perturbations for a big bounce phase in loop quantum cosmology. Two models are discussed: one is the universe filled by a massless scalar field; the other is a toy model…

General Relativity and Quantum Cosmology · Physics 2011-04-12 Yu Li , Jian-Yang Zhu

In loop quantum cosmology (LQC), the initial singularity is replaced by a quantum bounce, leading to a universal post-bounce evolution characterized by three distinct epochs: bouncing, transition, and slow-roll inflation, before the hot…

General Relativity and Quantum Cosmology · Physics 2025-12-03 Yogesh , Bao-Fei Li , Mayukh R. Gangopadhyay , Anzhong Wang

We study in detail the power spectra of scalar and tensor perturbations generated during inflation in loop quantum cosmology (LQC). After clarifying in a novel quantitative way how inverse-volume corrections arise in inhomogeneous settings,…

General Relativity and Quantum Cosmology · Physics 2015-03-19 Martin Bojowald , Gianluca Calcagni , Shinji Tsujikawa

In this paper, we systematically study the evolution of the Universe in the framework of a modified loop quantum cosmological model (mLQC-I) with various inflationary potentials, including chaotic, Starobinsky, generalized Starobinsky,…

General Relativity and Quantum Cosmology · Physics 2024-10-22 Jamal Saeed , Rui Pan , Christian Brown , Gerald Clevear , Anzhong Wang

We discuss cosmological effects of the quantum loops of massless particles, which lead to temporal non-localities in the equations of motion governing the scale factor a(t). For the effects discussed here, loops cause the evolution of a(t)…

General Relativity and Quantum Cosmology · Physics 2014-06-11 John F. Donoghue , Basem Kamal El-Menoufi

We consider the introduction of anisotropy in a class of bouncing models of cosmology. The presence of anisotropy often spells doom on bouncing models, since the energy density due to the anisotropic stress outweighs that of other matter…

General Relativity and Quantum Cosmology · Physics 2022-01-27 Karthik Rajeev , Vikramaditya Mondal , Sumanta Chakraborty

We numerically investigate the solutions to the effective equations of the Bianchi II model within the "improved" Loop Quantum Cosmology (LQC) dynamics. The matter source is a massless scalar field. We perform a systematic study of the…

General Relativity and Quantum Cosmology · Physics 2012-10-08 Alejandro Corichi , Edison Montoya

Recent work in quantum loop cosmology suggests the universe undergoes a bounce when evolving from a previous collapsing phase. However, with non-inflationary matter sources, the scenario appears to strongly violate the holography bound…

General Relativity and Quantum Cosmology · Physics 2012-12-19 D. H. Coule

We derive the cosmological Big Bounce scenario from the dipole approximation of Loop Quantum Gravity. We show that a non-singular evolution takes place for any matter field and that, by considering a massless scalar field as a relational…

General Relativity and Quantum Cosmology · Physics 2011-01-24 Marco Valerio Battisti , Antonino Marciano

Cosmological models where the standard big bang is replaced by a bounce have been studied for decades. The situation has, however, dramatically changed in the past years for two reasons: first, because new ways to probe the early Universe…

Cosmology and Nongalactic Astrophysics · Physics 2011-01-17 J. Grain , A. Barrau , T. Cailleteau , J. Mielczarek

We consider the k=1 Friedman-Lemaitre-Robertson-Walker (FLRW) model within loop quantum cosmology (LQC), from the perspective of the two available quantization prescriptions. We focus our attention on the existence of the so called `inverse…

General Relativity and Quantum Cosmology · Physics 2016-04-28 Alejandro Corichi , Asieh Karami

General Relativity is an extremely successful theory, at least for weak gravitational fields, however, it breaks down at very high energies, such as in correspondence of the initial singularity. Quantum Gravity is expected to provide more…

General Relativity and Quantum Cosmology · Physics 2023-04-20 Ana Rita Ribeiro , Daniele Vernieri , Francisco S. N. Lobo