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While the simple picture of a spatially flat, matter plus cosmological constant universe fits current observation of the accelerated expansion, strong consideration has also been given to models with dynamical vacuum energy. We examine the…

Astrophysics · Physics 2008-11-26 Eric V. Linder

There is a persistent state of confusion regarding the account of the quantum origin of the seeds of cosmological structure during inflation. In fact, a recent article (C. Kiefer & D. Polarski, ArXiv: 0810.0087 [astro-ph]) addresses the…

General Relativity and Quantum Cosmology · Physics 2011-05-09 Daniel Sudarsky

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 basic problem of quantum cosmology is the definition of the quantum state of the universe, with appropriate boundary conditions on Riemannian three-geometries. This paper describes recent progress in the corresponding analysis of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Giampiero Esposito

Given the wealth of increasingly accurate cosmological observations, especially the recent results from the WMAP, and the development of methods and strategies in the search for cosmic topology, it is reasonable to expect that we should be…

Astrophysics · Physics 2008-11-26 M. J. Reboucas , J. S. Alcaniz

I consider the formulation of hybrid cosmological models that consists of a classical gravitational field interacting with a quantized massive scalar field in the formalism of ensembles on configuration space. This is a viable approach that…

General Relativity and Quantum Cosmology · Physics 2013-12-03 Marcel Reginatto

It is shown that an accelerating expansion of the present-day Universe extracted from observed luminosity of the type Ia supernovae can be explained by quantum theory which takes into account feedback coupling between geometry and matter…

Astrophysics · Physics 2009-10-27 V. V. Kuzmichev , V. E. Kuzmichev

We have found that the hierarchial problems appearing in cosmology is a manifestation of the quantum nature of the universe. The universe is still described by the same formulae that once hold at Planck's time. The universe is found to be…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Arbab I. Arbab

We study the quantization of geometry in the presence of a cosmological constant, using a discretiza- tion with constant-curvature simplices. Phase space turns out to be compact and the Hilbert space finite dimensional for each link. Not…

General Relativity and Quantum Cosmology · Physics 2015-04-22 Carlo Rovelli , Francesca Vidotto

Geometrical model for quantum objects is suggested. It is shown that equations for free material Dirac field and for Maxwell electromagnetic field can be considered as relations describing propagation of the space topological defects. This…

General Physics · Physics 2008-02-18 O. A. Olkhov

We consider a universe with an arbitrary number of extra dimensions, $N$. We present a new method for constructing the cosmological equations of motion and find analytic solutions with an explicit dependence on $N$. When we take the…

General Relativity and Quantum Cosmology · Physics 2017-09-06 David Sloan , Pedro Ferreira

This Chapter provides an up to date, pedagogical review of some of the most relevant advances in loop quantum cosmology. We review the quantization of homogeneous cosmological models, their singularity resolution and the formulation of…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Ivan Agullo , Alejandro Corichi

A brief review of the modern state of quantum cosmology is presented as a theory of quantum initial conditions for inflationary scenario. The no-boundary and tunneling states of the Universe are discussed as a possible source of probability…

General Relativity and Quantum Cosmology · Physics 2017-08-23 A. O. Barvinsky

We discuss the way non-perturbative quantization of cosmological spacetimes in loop quantum cosmology provides insights on the physics of Planck scale and the resolution of big bang singularity. In recent years, rigorous examination of…

General Relativity and Quantum Cosmology · Physics 2009-03-27 Parampreet Singh

We calculate the reduced density matrix for the inflaton field in a model of chaotic inflation by tracing out degrees of freedom corresponding to various bosonic fields. We find a qualitatively new contribution to the density matrix given…

General Relativity and Quantum Cosmology · Physics 2009-10-31 A. Barvinsky , A. Kamenshchik , C. Kiefer , I. Mishakov

Quantum Reduced Loop Gravity provides a promising framework for a consistent characterization of the early Universe dynamics. Inspired by BKL conjecture, a flat Universe is described as a collection of Bianchi I homogeneous patches. The…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Emanuele Alesci , Francesco Cianfrani

The distribution of visible matter in the universe, such as galaxies and galaxy clusters, has its origin in the week fluctuations of density that existed at the epoch of recombination. The hierarchical distribution of the universe, with its…

Cosmology and Nongalactic Astrophysics · Physics 2015-01-21 Bruce N. Miller , Jean-Louis Rouet , Yui Shiozawa

An introduction to modern theories for the origin of structure in the Universe is given. After a brief review of the growth of cosmological perturbations in an expanding Universe and a summary of some important observational results, the…

Astrophysics · Physics 2008-02-03 Robert H. Brandenberger

Quantum Hall effects provide intuitive ways of revealing the topology in crystals, i.e., each quantized "step" represents a distinct topological state. Here, we seek a counterpart for "visualizing" quantum geometry, which is a broader…

Quantum Physics · Physics 2025-01-10 B. Q. Song , J. D. H. Smith , T. Jiang , Y. X. Yao , J. Wang

The probability representation, in which cosmological quantum states are described by a standard positive probability distribution, is constructed for minisuperspace models selected by Noether symmetries. In such a case, the tomographic…

General Relativity and Quantum Cosmology · Physics 2008-12-18 S. Capozziello , V. I. Man'ko , G. Marmo , C. Stornaiolo