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Several examples are known where quantum gravity effects resolve the classical big bang singularity by a bounce. The most detailed analysis has probably occurred for loop quantum cosmology of isotropic models sourced by a free, massless…

General Relativity and Quantum Cosmology · Physics 2008-12-18 Martin Bojowald

Within loop quantum gravity we construct a coarse-grained approximation for the Einstein-Maxwell theory that yields effective Maxwell equations in flat spacetime comprising Planck scale corrections. The corresponding Hamiltonian is defined…

High Energy Physics - Theory · Physics 2009-11-07 Jorge Alfaro , Hugo A. Morales-Técotl , Luis F. Urrutia

In a previous work we derived an effective Hamiltonian constraint for the Schwarzschild geometry starting from the full loop quantum gravity Hamiltonian constraint and computing its expectation value on coherent states sharply peaked around…

General Relativity and Quantum Cosmology · Physics 2019-09-13 Emanuele Alesci , Sina Bahrami , Daniele Pranzetti

The thermodynamic properties of loop quantum cosmology (LQC) without considering the Lorentz term were established in \cite{Zhu09}. In this paper, we extend this result to the recent proposed new model of LQC with the Lorentz term. We…

General Relativity and Quantum Cosmology · Physics 2021-11-11 Xiangdong Zhang

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

Loop quantum cosmology is an application of recent developments for a non-perturbative and background independent quantization of gravity to a cosmological setting. Characteristic properties of the quantization such as discreteness of…

Astrophysics · Physics 2009-11-13 Martin Bojowald

An improved Hamiltonian constraint operator is introduced in loop quantum cosmology. Quantum dynamics of the spatially flat, isotropic model with a massless scalar field is then studied in detail using analytical and numerical methods. The…

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

Long-range effective methods are ubiquitous in physics and in quantum theory, in particular. Furthermore, the reliability of such methods is higher when the nature of short-ranged interactions need not be modeled explicitly. This may be…

Quantum Physics · Physics 2022-06-07 David M. Jacobs

Since there are quantization ambiguities in constructing the Hamiltonian constraint operator in isotropic loop quantum cosmology, it is crucial to check whether the key features of loop quantum cosmology are robust against the ambiguities.…

General Relativity and Quantum Cosmology · Physics 2010-04-14 Jinsong Yang , You Ding , Yongge Ma

Loop Quantum Cosmology strongly modifies the high-energy dynamics of Friedman-Robertson-Walker models and removes the big-bang singularity. We investigate how LQC corrections affect the stability properties of the Einstein static universe.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Luca Parisi , Marco Bruni , Roy Maartens , Kevin Vandersloot

For a class of solutions of the fundamental difference equation of isotropic loop quantum cosmology, the difference equation can be replaced by a differential equation valid for {\em all} values of the triad variable. The differential…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ghanashyam Date , Golam Mortuza Hossain

In this paper, we address a foundational challenge in quantum field theory on curved spacetime by developing a consistent framework within loop quantum gravity. We introduce a methodology for defining meaningful superpositions of quantum…

General Relativity and Quantum Cosmology · Physics 2026-02-17 Gaoping Long , Cong Zhang

Quantum Hamiltonian complexity studies computational complexity aspects of local Hamiltonians and ground states; these questions can be viewed as generalizations of classical computational complexity problems related to local constraint…

Quantum Physics · Physics 2015-03-17 Dorit Aharonov , Itai Arad , Zeph Landau , Umesh Vazirani

The loop quantum cosmological model from ADM Hamiltonian is studied in this paper. We consider the spatially flat homogeneous FRW model. It turns out that the modified Friedmann equation keeps the same form as the APS LQC model. However,…

General Relativity and Quantum Cosmology · Physics 2022-12-27 You Ding , Xiangdong Zhang

A fundamental issue for any quantum cosmological theory is to specify how probabilities can be assigned to various quantum events or sequences of events such as the occurrence of singularities or bounces. In previous work, we have…

General Relativity and Quantum Cosmology · Physics 2013-10-02 David A. Craig , Parampreet Singh

The loop quantum cosmology "improved dynamics" of the Bianchi type IX model are studied. The action of the Hamiltonian constraint operator is obtained via techniques developed for the Bianchi type I and type II models, no new input is…

General Relativity and Quantum Cosmology · Physics 2014-11-21 Edward Wilson-Ewing

A unified treatment of all known types of singularities for flat, isotropic and homogeneous spacetimes in the framework of loop quantum cosmology (LQC) is presented. These include bangs, crunches and all future singularities. Using…

General Relativity and Quantum Cosmology · Physics 2009-07-18 Parampreet Singh

We construct and study a simple noncommutative scheme (theta-deformation) for the effective Loop Quantum Cosmology of the flat Friedmann-Lema\^itre-Robertson-Walker model in the presence of a homogeneous scalar field $\phi$ with a potential…

General Relativity and Quantum Cosmology · Physics 2021-07-14 Luis Rey Díaz-Barrón , Abraham Espinoza-García , S. Pérez-Payán , J. Socorro

A new mathematical framework is formulated to derive the effective equations of motion for the constrained quantum system which possesses an internal clock. In the realm close to classical behavior, the quantum evolution is approximated by…

General Relativity and Quantum Cosmology · Physics 2008-12-05 Dah-Wei Chiou

In this paper we address the meaning of states in loop quantum cosmology (LQC), in the context of loop quantum gravity. First, we introduce a rigorous formulation of an embedding proposed by Bojowald and Kastrup, of LQC states into loop…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Jonathan Engle
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