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We examine the evolution of the Friedmann Universe within our recent model of space-time identified with an elastic continuous medium whose deformations are described by a vector field constrained to obey a generalized four-dimensional…

General Relativity and Quantum Cosmology · Physics 2015-12-22 Fayçal Hammad

Understanding the evolution of entropy in the universe is a fundamental aspect of cosmology. This paper investigates the evolution of entropy in a spatially flat $K=0$ universe, focusing on the contributions of matter, radiation, and dark…

General Relativity and Quantum Cosmology · Physics 2025-07-16 Tanisha Joshi , S. D Pathak

After a brief introduction to the sixteenth and seventeenth century views of the Universe and the nineteenth century paradox of Olbers, we start the history of the cosmic expansion with Hubble's epochal discovery of the recession velocities…

Astrophysics · Physics 2008-02-15 Matts Roos

The description of the cosmological expansion and its possible local manifestations via treating the proper conformal transformations as a coordinate transformation from a comoving Lorentz reference frame (RF) to an uniformly accelerated RF…

General Relativity and Quantum Cosmology · Physics 2007-10-23 L. M. Tomilchik

A gravitational theory with derivative matter coupling is proposed which adopt de Sitter expansion at late times with ordinary baryonic matter. Matter components are conserved separately in the cosmological background and the Newtonian…

General Relativity and Quantum Cosmology · Physics 2021-04-19 Zahra Haghani , Shahab Shahidi

We investigate quintessence cosmologies with a matter component consisting of particles with an increasing mass. While negligible in early cosmology, the appearance of a growing matter component has stopped the evolution of the cosmon field…

Astrophysics · Physics 2008-11-26 Luca Amendola , Marco Baldi , Christof Wetterich

Based on the cosmological principle only, the method of describing the evolution of the Universe, called cosmography, is in fact a kinematics of cosmological expansion. The effectiveness of cosmography lies in the fact that it allows, based…

General Relativity and Quantum Cosmology · Physics 2018-12-07 Yu. L. Bolotin , V. A. Cherkaskiy , O. Yu. Ivashtenko , M. I. Konchatnyi , L. G. Zazunov

The general world model for homogeneous and isotropic universe has been roposed. For this purpose, we introduce a global and fiducial system of reference (world reference frame) constructed on a 5-dimensional space-time that is embedding…

Astrophysics · Physics 2008-03-04 Chan-Gyung Park

Recent observations of high-redshift supernovae seem to suggest that the global geometry of the Universe may be affected by a `cosmological constant', which acts to accelerate the expansion rate with time. But these data by themselves still…

Astrophysics · Physics 2009-10-31 Idit Zehavi , Avishai Dekel

We derive a unified expansion law for our universe from the first law of thermodynamics on the apparent horizon, where entropic evolution depicts the emergence of cosmic space. The derivation advances a general form for degrees of freedom…

General Relativity and Quantum Cosmology · Physics 2023-02-22 Hassan Basari V. T. , P. B. Krishna , Titus K. Mathew

In the standard cosmological paradigm cosmic acceleration is to only be a very recent (viz. $z \leq 1$) phenomenon, with the universe being required to be decelerating at all higher redshifts. We suggest that this particular expectation of…

Astrophysics · Physics 2009-11-07 Philip D. Mannheim

It has been argued that a Universe governed by Eddington-Born-Infeld gravity can be compatible with current cosmological constraints. The extra fields introduced in this theory can behave both as dark matter and dark energy, unifying the…

Astrophysics · Physics 2009-04-02 Máximo Bañados , Pedro G. Ferreira , Constantinos Skordis

An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary…

General Relativity and Quantum Cosmology · Physics 2015-03-19 Joan Sola

We present a space-velocity theory of gravitation in a 4-dimensional curved space. The solutions of the field equations yield 3 possibilities for the universe expansion but only the accelerating one is possible. Although the theory has no…

Astrophysics · Physics 2007-05-23 Moshe Carmeli

We present a model of the expanding Universe that begins in a zero energy vacuum state. The Universe results from the spontaneous breaking of the electroweak symmetry, wherein the vacuum with positive expectation energy produces the dark…

General Physics · Physics 2021-04-29 R. N. Henriksen

In [arXiv:2204.13980], we proposed and motivated a modification of the Einstein equation as a function of the topology of the Universe in the form of a bi-connection theory. The new equation features an additional "topological term" related…

General Relativity and Quantum Cosmology · Physics 2023-11-01 Quentin Vigneron , Vivian Poulin

We propose that the size of the universe and its rate of expansion cannot be simultaneously specified with arbitrary precision, a quantum mechanical statement encoded in a deformed commutation relation for the scale factor. The deformation…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-15 Savvas M. Koushiappas

In 1998 astronomers discovered that the expansion of the universe is accelerating. Somehow, something must have made gravity repulsive on cosmological scales. This something was called dark energy; it is described by Einstein's cosmological…

General Relativity and Quantum Cosmology · Physics 2022-10-05 Ulf Leonhardt

We consider the proposition that multiple universes exist by reviewing the various manifestations. In recent years, this idea has been elevated from science fiction and introduced in separate guises as an explanation for coincidence…

General Physics · Physics 2007-05-23 Alasdair Macleod

The geometry of the Universe may be probed using the Alcock-Paczynski (AP) effect, in which the observed redshift size of a spherical distribution of sources relative to its angular size varies according to the assumed cosmological model.…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-10 Fulvio Melia , Jin Qin , Tong-Jie Zhang
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