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In a previous paper, some of us studied general relativistic homogeneous gravitational collapses for dust and radiation, in which the density profile was replaced by an effective density justified by some quantum gravity models. It was…

General Relativity and Quantum Cosmology · Physics 2014-08-19 Yue Liu , Daniele Malafarina , Leonardo Modesto , Cosimo Bambi

A new model is studied which describes the quantum behavior of transitions through an isotropic quantum cosmological bounce in loop quantum cosmology sourced by a free and massless scalar field. As an exactly solvable model even at the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald

Singularities in general relativity such as the big bang and big crunch, and exotic singularities such as the big rip are the boundaries of the classical spacetimes. These events are marked by a divergence in the curvature invariants and…

General Relativity and Quantum Cosmology · Physics 2015-10-01 Parampreet Singh

If we imagine rewinding the universe to early times, the scale factor shrinks and the existence of a finite spatial volume may play a role in quantum tunnelling effects in a closed universe. It has recently been shown that such finite…

General Relativity and Quantum Cosmology · Physics 2023-11-15 Jean Alexandre , Katy Clough , Silvia Pla

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

Loop Quantum Gravity is a background independent, nonperturbative approach to the quantization of General Relativity. Its application to models of interest in cosmology and astrophysics, known as Loop Quantum Cosmology, has led to new and…

General Relativity and Quantum Cosmology · Physics 2015-05-27 Guillermo A. Mena Marugan

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

Lemaitre-Tolman-Bondi models as specific spherically symmetric solutions of general relativity simplify in their reduced form some of the mathematical ingredients of black hole or cosmological applications. The conditions imposed in…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Tomohiro Harada , Rakesh Tibrewala

In this paper we investigate dynamics of the modified loop quantum cosmology models using dynamical systems methods. Modifications considered come from the choice of the different field strength operator $\hat{F}$ and result in different…

General Relativity and Quantum Cosmology · Physics 2014-11-18 Orest Hrycyna , Jakub Mielczarek , Marek Szydlowski

The effective quantum dynamics of Bianchi I spacetime is addressed within the statistical regularization scheme in Quantum Reduced Loop Gravity. The case of a minimally coupled massless scalar field is studied and compared with the…

General Relativity and Quantum Cosmology · Physics 2019-05-29 Emanuele Alesci , Gioele Botta , Giovanni Luzi , Gabriele V. Stagno

In this paper, a new Hamiltonian constraint operator for loop quantum cosmology is constructed by using the Chern-Simons action. The quantum dynamics of the $k=0$ cosmological model with respect to a massless scalar field as an emergent…

General Relativity and Quantum Cosmology · Physics 2019-09-23 Jinsong Yang , Cong Zhang , Yongge Ma

Some long standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the resolution of the big bang singularity in loop…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Abhay Ashtekar , Tomasz Pawlowski , Parampreet Singh

After a brief introduction, basic ideas of the quantum Riemannian geometry underlying loop quantum gravity are summarized. To illustrate physical ramifications of quantum geometry, the framework is then applied to homogeneous isotropic…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Abhay Ashtekar

We show that the effective dynamics of the recently proposed isotropic condensate state of group field theory with Laplacian kinetic operator can be equivalent to that of homogeneous and isotropic loop quantum cosmology in the improved…

General Relativity and Quantum Cosmology · Physics 2014-09-30 Gianluca Calcagni

We study a contracting universe composed of cold dark matter and radiation, and with a positive cosmological constant. As is well known from standard cosmological perturbation theory, under the assumption of initial quantum vacuum…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Yi-Fu Cai , Edward Wilson-Ewing

We show that the quantization ambiguities of loop quantum cosmology, when considered in wider generality, can be used to produce discretionary dynamical behavior. There is an infinite dimensional space of ambiguities which parallels the…

General Relativity and Quantum Cosmology · Physics 2023-05-03 Lautaro Amadei , Alejandro Perez , Salvatore Ribisi

The concept of effective dynamics has proven successful in LQC, a loop-inspired quantization of cosmological spacetimes. We apply the same idea of its derivation in LQC to the full theory, by computing the expectation value of the scalar…

General Relativity and Quantum Cosmology · Physics 2018-09-17 Andrea Dapor , Klaus Liegener

General relativity predicts a singularity in the beginning of the universe being called big bang. Recent developments in loop quantum cosmology avoid the singularity and the big bang is replaced by a big bounce. A classical theory of…

General Physics · Physics 2011-02-08 Walter Petry

We study the dynamics of states perturbatively expanded about a harmonic system of loop quantum cosmology, exhibiting a bounce. In particular, the evolution equations for the first and second order moments of the system are analyzed. These…

General Relativity and Quantum Cosmology · Physics 2011-01-20 Martin Bojowald , David Mulryne , William Nelson , Reza Tavakol

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