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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

We discuss predictions for cosmology which result from the scaling solution of functional flow equations for a quantum field theory of gravity. A scaling solution is necessary to render quantum gravity renormalizable. Our scaling solution…

General Relativity and Quantum Cosmology · Physics 2023-01-13 C. Wetterich

I discuss a model for quantized gravitation based on the simplicial lattice discretization. It has been studied in some detail using a comprehensive finite size scaling analysis combined with renormalization group methods. The results are…

High Energy Physics - Theory · Physics 2017-08-23 H. W. Hamber

An one-parameter regularization freedom of the Hamiltonian constraint for loop quantum gravity is analyzed. The corresponding spatially flat, homogenous and isotropic model includes the two well-known models of loop quantum cosmology as…

General Relativity and Quantum Cosmology · Physics 2021-11-12 Xiangdong Zhang , Gaoping Long , Yongge Ma

Bridging between descriptions involving few large and many small quantum numbers is the main open problem in loop quantum gravity. In other words, one would like to be able to represent the same physical system in terms of a few "coarse"'…

General Relativity and Quantum Cosmology · Physics 2017-06-26 Norbert Bodendorfer

Cosmological perturbation equations are derived systematically in a canonical scheme based on Ashtekar variables. A comparison with the covariant derivation and various subtleties in the calculation and choice of gauges are pointed out.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Hector H. Hernández , Mikhail Kagan , Parampreet Singh , Aureliano Skirzewski

Quantum cosmology has traditionally been studied at the level of symmetry-reduced minisuperspace models, analyzing the behavior of wave functions. However, in the absence of a complete full setting of quantum gravity and detailed knowledge…

General Relativity and Quantum Cosmology · Physics 2012-09-18 Martin Bojowald

In the quasistatic regime, generic modifications to gravity can give rise to novel scale-dependence of the gravitational field equations. Crucially, the detectability of the new scale-dependent terms hinges upon the existence of an…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-17 Tessa Baker , Pedro G. Ferreira , C. Danielle Leonard , Mariele Motta

Canonical quantum gravity provides insights into the quantum dynamics as well as quantum geometry of space-time by its implications for constraints. Loop quantum gravity in particular requires specific corrections due to its quantization…

General Relativity and Quantum Cosmology · Physics 2015-05-14 Martin Bojowald

We show how Loop Quantum Cosmology can be derived as an effective semiclassical description of Loop Quantum Gravity. Using the tools of QRLG, a gauge fixed version of LQG, we take the coherent states of the fundamental microscopic theory…

General Relativity and Quantum Cosmology · Physics 2014-10-20 Emanuele Alesci , Francesco Cianfrani

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

We study the scalar modes of linear perturbations in loop quantum cosmology. This is done on a lattice where each cell is taken to be homogeneous and isotropic and can be quantized via standard homogeneous loop quantum cosmology techniques.…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Edward Wilson-Ewing

Recent results have shown how quantum cosmology models can be derived from the effective dynamics of condensate states in group field theory (GFT), where 'cosmology is the hydrodynamics of quantum gravity': the classical Friedmann dynamics…

General Relativity and Quantum Cosmology · Physics 2016-10-27 Steffen Gielen

Quantum cosmology implies corrections to the classical equations of motion which may lead to significant departures from the classical trajectory, especially at high curvature near the big-bang singularity. Corrections could in principle be…

General Relativity and Quantum Cosmology · Physics 2014-09-09 Martin Bojowald , David Simpson

Physics in the vicinity of an ultraviolet stable fixed point of a quantum field theory is parametrized by a renormalization group invariant macroscopic length scale, the correlation length $\xi,$ with the quantum effective action a function…

Astrophysics · Physics 2007-05-23 Vipul Periwal

Loop quantum cosmology in (b, v) variables, which is governed by a unit step size difference equation, is embedded into a full theory context based on similar variables. A full theory context here means a theory of quantum gravity arrived…

General Relativity and Quantum Cosmology · Physics 2016-05-20 Norbert Bodendorfer

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…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Hector Hernandez , Mikhail Kagan , Aureliano Skirzewski

In the path integral formulation of the reduced phase space Loop Quantum Gravity (LQG), we propose a new approach to allow the spatial cubic lattice (graph) to change dynamically in the physical time evolution. The equations of motion of…

General Relativity and Quantum Cosmology · Physics 2021-07-14 Muxin Han , Hongguang Liu

A major challenge at the interface of quantum gravity and cosmology is to explain the emergence of the large-scale structure of the Universe from Planck scale physics. In this letter, we extract the dynamics of scalar isotropic cosmological…

General Relativity and Quantum Cosmology · Physics 2024-08-23 Alexander F. Jercher , Luca Marchetti , Andreas G. A. Pithis

We consider the application of the consistent lattice quantum gravity approach we introduced recently to the situation of a Friedmann cosmology and also to Bianchi cosmological models. This allows us to work out in detail the computations…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Rodolfo Gambini , Jorge Pullin