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In Loop Quantum Gravity mathematically rigorous models of full quantum gravity were proposed. In this paper we study a cosmological sector of one of the models describing quantum gravity with positive cosmological constant coupled to…

广义相对论与量子宇宙学 · 物理学 2022-11-09 Marcin Kisielowski

Cosmological tensor perturbations equations are derived for Hamiltonian cosmology based on Ashtekar's formulation of general relativity, including typical quantum gravity effects in the Hamiltonian constraint as they are expected from loop…

广义相对论与量子宇宙学 · 物理学 2008-11-26 Martin Bojowald , Golam Mortuza Hossain

I present a streamlined review of how the separate universe approach to cosmological perturbation theory can be used to study the dynamics of long-wavelength scalar perturbations in loop quantum cosmology, and then use it to calculate how…

广义相对论与量子宇宙学 · 物理学 2016-08-03 Edward Wilson-Ewing

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…

广义相对论与量子宇宙学 · 物理学 2015-05-27 Guillermo A. Mena Marugan

The primordial spectrum of cosmological tensor perturbations is considered as a possible probe of quantum gravity effects. Together with string theory, loop quantum gravity is one of the most promising frameworks to study quantum effects in…

广义相对论与量子宇宙学 · 物理学 2009-04-09 J. Grain , A. Barrau

We apply the full theory of Loop Quantum Gravity (LQG) to cosmology and present a top-down derivation of gauge-invariant cosmological perturbation theory from quantum gravity. The derivation employs the reduced phase space formulation of…

广义相对论与量子宇宙学 · 物理学 2021-01-20 Muxin Han , Haida Li , Hongguang Liu

We have found some analytical cosmological solutions to MOdified Gravity (MOG). These solutions describe different evolutionary epochs of an isotropic and homogeneous universe. During each epoch, the evolution of cosmological perturbation…

广义相对论与量子宇宙学 · 物理学 2017-05-04 Fatimah Shojai , Samira Cheraghchi , Hamed Bouzari Nezhad

Loop Quantum Gravity (L.Q.G.) is one of the two most promising tentative theory for a quantum description of gravity. When applied to the entire universe, the so-called Loop Quantum Cosmology (L.Q.C.) framework offers microscopical models…

广义相对论与量子宇宙学 · 物理学 2014-11-20 J. Grain

Within a perturbative cosmological regime of loop quantum gravity corrections to effective constraints are computed. This takes into account all inhomogeneous degrees of freedom relevant for scalar metric modes around flat space and results…

广义相对论与量子宇宙学 · 物理学 2008-11-26 Martin Bojowald , Hector Hernandez , Mikhail Kagan , Aureliano Skirzewski

In the standard approach to studying cosmological structure formation, the overall expansion of the Universe is assumed to be homogeneous, with the gravitational effect of inhomogeneities encoded entirely in a Newtonian potential. A topic…

宇宙学与河外天体物理 · 物理学 2018-02-20 William E. East , Radosław Wojtak , Tom Abel

This chapter provides a review of the frameworks developed for cosmological perturbation theory in loop quantum cosmology, and applications to various models of the early universe including inflation, ekpyrosis and the matter bounce, with…

广义相对论与量子宇宙学 · 物理学 2024-03-08 Ivan Agullo , Anzhong Wang , Edward Wilson-Ewing

Loop quantum cosmology predicts that quantum gravity effects resolve the big-bang singularity and replace it by a cosmic bounce. Furthermore, loop quantum cosmology can also modify the form of primordial cosmological perturbations, for…

广义相对论与量子宇宙学 · 物理学 2017-06-28 Edward Wilson-Ewing

The cosmological primordial power spectrum is known to be one of the most promising observable to probe quantum gravity effects. In this article, we investigate how the tensor power spectrum is modified by Loop Quantum Gravity corrections.…

广义相对论与量子宇宙学 · 物理学 2010-04-06 J. Grain , T. Cailleteau , A. Barrau , A. Gorecki

We study the dynamics of the scalar modes of linear perturbations around a flat, homogeneous and isotropic background in loop quantum cosmology. The equations of motion include quantum geometry effects and hold at all curvature scales so…

广义相对论与量子宇宙学 · 物理学 2015-05-30 Edward Wilson-Ewing

The inflationary and pre-inflationary evolution of scalar modes of cosmological perturbations in a closed universe is analyzed for a loop quantum cosmology model with an inflationary regime consistent with the constraints on inflation…

广义相对论与量子宇宙学 · 物理学 2024-11-26 Lucas M. V. Montese , Nelson Yokomizo

We review some recent progress in the extraction of inflationary observables in loop quantum cosmology. Inverse-volume quantum corrections induce a growth of power in the large-scale cosmological spectra and are constrained by observations.

广义相对论与量子宇宙学 · 物理学 2012-05-23 Gianluca Calcagni

Homogeneous cosmological models with non-vanishing intrinsic curvature require a special treatment when they are quantized with loop quantum cosmological methods. Guidance from the full theory which is lost in this context can be replaced…

广义相对论与量子宇宙学 · 物理学 2008-11-26 Martin Bojowald , Ghanashyam Date , Kevin Vandersloot

Degenerate geometrical configurations in quantum gravity are important to understand if the fate of classical singularities is to be revealed. However, not all degenerate configurations arise on an equal footing, and one must take into…

广义相对论与量子宇宙学 · 物理学 2007-05-23 Martin Bojowald

We calculate the full spectrum, as observed today, of the cosmological gravitational waves generated within a model based on loop quantum cosmology. It is assumed that the universe, after the transition to the classical regime, undergoes a…

广义相对论与量子宇宙学 · 物理学 2013-05-30 Paulo M. Sá , Alfredo B. Henriques

Quantum gravity, as a fundamental theory of space-time, is expected to reveal how the universe may have started, perhaps during or before an inflationary epoch. It may then leave a potentially observable (but probably minuscule) trace in…

广义相对论与量子宇宙学 · 物理学 2015-12-17 Martin Bojowald