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After 45 years since the discovery of quantum-gravitational birth of the cosmological density perturbations we can try to answer the main question of cosmology what is the origin of the Universe. This has become possible because the…

General Relativity and Quantum Cosmology · Physics 2025-05-09 Vladimir N. Lukash , Elena V. Mikheeva

This thesis deals with the averaging problem in cosmology, which has gained considerable interest in recent years, and is concerned with correction terms (after averaging inhomogeneities) that appear in the Einstein equations when working…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-06 Aseem Paranjape

The Universe could be spatially flat, positively curved or negatively curved. Each option has been popular at various times, partly affected by an understanding that models tend to evolve away from flatness. The curvature of the Universe is…

Astrophysics · Physics 2009-08-18 Elena Pierpaoli , Douglas Scott , Martin White

The time variation of fundamental mass scales can have profound cosmological implications. We investigate a particular model of crossover quintessence which is compatible with all present cosmological observations. This model can also…

High Energy Physics - Phenomenology · Physics 2017-08-23 C. Wetterich

Despite its great successes in accounting for the current observations, the so called `standard' model of cosmology faces a number of fundamental unresolved questions. Paramount among these are those relating to the nature of the origin of…

General Relativity and Quantum Cosmology · Physics 2008-02-29 Martin Bojowald , Reza Tavakol

Solutions of the system of evolutionary equations in the short-wavelength approximation are found and studied. A connection is established between the problem of the evolution of short-wavelength gravitational-scalar perturbations and the…

General Physics · Physics 2023-02-22 Yu. G. Ignat'ev

A general-relativistic theory of cosmology, the dynamical variables of which are those of Hubble's, namely distances and redshifts, is presented. The theory describes the universe as having a three-phase evolution with a decelerating…

Astrophysics · Physics 2007-05-23 S. Behar , M. Carmeli

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

A geometric spacetime map of the universe is presented, addressing problems inherent in deep space observations and cosmology. Implications for the observer's perspective, the cosmological "horizon" and "flatness" problem, "inflation", and…

General Relativity and Quantum Cosmology · Physics 2011-11-22 John A. Gowan

The standard method for observationally confirming the existence of a predicted finite topology of the universe involves searching for the repetition of the same finite or extended source in different directions. However, serious problems…

Astrophysics · Physics 2007-05-23 Reuven Opher

These notes are intended as an introductory course for experimental particle physicists interested in the recent developments in astrophysics and cosmology. I will describe the standard Big Bang theory of the evolution of the universe, with…

High Energy Physics - Phenomenology · Physics 2007-05-23 Juan Garcia-Bellido

The origin of the large scale structure in the universe - galaxies, quasars, clusters, voids, sheets - is one of the most important questions in cosmology. One can show that some non-thermal energy density fluctuations must have been…

Astrophysics · Physics 2007-05-23 Mairi Sakellariadou

The rather wide-spread belief that cosmological expansion of a flat 3D--space (with spatial curvature k=0) cannot be observationally distinguished from a kinematics of galaxies moving in a flat and non-expanding space is erroneous. We…

Astrophysics · Physics 2007-05-23 Marek A. Abramowicz , Stanislaw Bajtlik , Jean-Pierre Lasota , Audrey Moudens

It has been known for some time that the usual inference drawn from the observed near-flatness of the large-scale Universe - namely the existence of a cosmological "flatness problem", which is then taken as a partial, but key motivation for…

General Relativity and Quantum Cosmology · Physics 2022-04-18 Marc Holman

The variation of the expansion rate of the Universe with time produces an evolution in the cosmological redshift of distant sources (for example quasar Lyman-$\alpha$ absorption lines), that might be directly observed by future ultra…

Astrophysics · Physics 2009-11-13 A. Balbi , C. Quercellini

We point out that the horizon problem encountered in standard text-books or review papers on cosmology is, in general, derived for world models based on Robertson-Walker line element where homogeneity and isotropy of the universe -- \`a la…

General Relativity and Quantum Cosmology · Physics 2024-04-18 Ashok K. Singal

We explore the morphological and dynamical evolution of galaxy clusters in simulations using scalar and vector-valued Minkowski valuations and the concept of fundamental plane relations. In this context, three questions are of fundamental…

Astrophysics · Physics 2009-07-07 C. Beisbart , R. Valdarnini , T. Buchert

It is traced out a parallel between the cosmological constant problem and the polymer physics. The time evolution of the universe world line is compared with the growing of a polymer chain. An equivalent Flory free energy and a modification…

General Relativity and Quantum Cosmology · Physics 2011-08-31 Paulo Roberto Silva

This manuscript deals with a model of the evolution of an event space represented by the fundamental solution of a N-dimensional generalized Schrodinger equation for free matter. Specifically this solution can be applied to describe the 3D…

General Physics · Physics 2011-04-18 Vladlen G. Shvedov

The present work deals with evolution of the fractal model of the Universe in the background of homogeneous and isotropic FLRW space--time geometry. The cosmic substrum is taken as perfect fluid with barotropic equation of state. A general…

General Physics · Physics 2018-11-27 Dipanjana Das , Sourav Dutta , Abdulla Al Mamon , Subenoy Chakraborty