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There are now evidences that the cosmological constant $\Lambda$ has a non-zero positive value. Alternative scenarios to a pure cosmological constant model are provided by quintessence, an effective negative pressure fluid permeating the…

天体物理学 · 物理学 2008-11-26 Antonio Vale , Jose' P. S. Lemos

We review the recent progress in the Big-Bang nucleosynthesis which includes the standard and non-standard theory of cosmology, effects of neutrino degeneracy, and inhomogeneous nucleosynthesis within the framework of a Friedmann model. As…

宇宙学与河外天体物理 · 物理学 2017-10-24 Riou Nakamura , Masa-aki Hasahimoto , Ryotaro Ichimasa , Kenzo Arai

The large-scale dynamics of the universe is generally described in terms of the time-dependent scale factor $a(t)$. To make contact with observational data, the $a(t)$ function needs to be related to the observable $z(r)$ function, redshift…

综合物理 · 物理学 2025-06-17 Jan Stenflo

Old and new puzzles of cosmology are reexamined from the point of view of quantum theory of the universe developed here. It is shown that in proposed approach the difficulties of the standard cosmology do not arise. The theory predicts the…

天体物理学 · 物理学 2011-09-13 V. E. Kuzmichev , V. V. Kuzmichev

The mathematical concept of the Newtonian limit of Einstein's field equations in the expanding Friedmann universe is formulated. The geodesic equations of motion of planets and light are derived and compared.

宇宙学与河外天体物理 · 物理学 2012-12-24 Sergei Kopeikin

Using the absolute ages of passively evolving galaxies observed at different redshifts, one can obtain the differential ages, the derivative of redshift $z$ with respect to the cosmic time $t$ (i.e. ${\rm d} z/{\rm d}t$). Thus, the Hubble…

天体物理学 · 物理学 2008-11-26 Ze-Long Yi , Tong-Jie Zhang

The model of the homogenous and isotropic universe is considered in which the coordinate system of reference is not defined by the matter but is a priori specified. The scale factor of the universe changes following the linear law. The…

天体物理学 · 物理学 2007-05-23 D. L. Khokhlov

Homogeneous cosmological solutions are obtained in five dimensional space time assuming equations of state $ p = k\rho $ and $ p_{5}= \gamma\rho$ where p is the isotropic 3 - pressure and $p_{5}$, that for the fifth dimension. Using…

广义相对论与量子宇宙学 · 物理学 2009-11-11 D. Panigrahi , Y. Z. Zhang , S. Chatterjee

We propose that the Universe is filled with a massive vector field, non-minimally coupled to gravitation. The field equations of the model are consistently derived and their application to cosmology is considered. The Friedmann equations…

广义相对论与量子宇宙学 · 物理学 2008-11-26 C. G. Boehmer , T. Harko

Astronomical observations suggest that the Universe may be anisotropic on the largest scales. In order to model this situation, we develop a new approach to cosmology that allows for large-scale anisotropy to emerge from the growth of…

广义相对论与量子宇宙学 · 物理学 2023-06-26 Theodore Anton , Timothy Clifton

Results on particle creation from vacuum by the gravitational field of the expanding Friedmann Universe are presented. Finite results for the density of particles and the energy density for created particles are given for different exact…

广义相对论与量子宇宙学 · 物理学 2016-11-02 A. A. Grib , Yu. V. Pavlov

We consider the Universe deep inside the cell of uniformity. At these scales, the Universe is filled with inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies), which perturb the background Friedmann…

宇宙学与河外天体物理 · 物理学 2014-05-20 Maxim Eingorn , Alexander Zhuk

Detailed observations of the temperature fluctuations in the microwave background radiation indicate that we live in an open universe. From the size of these fluctuations it is concluded that the geometry of the universe is quite close to…

天体物理学 · 物理学 2009-11-07 Selcuk Bayin

We present a brief history of the construction of models of the universe, followed by calculations of quantitative characteristics of basic geometric and kinematic properties of the Standard Cosmological Model ($\Lambda$CDM). Using the…

广义相对论与量子宇宙学 · 物理学 2026-04-23 D. I. Nagirner , S. G. Jorstad , A. V. Dementyev

We examine the dark energy and matter densities allowed by precision measurements of distances out to various redshifts, in the presence of spatial curvature and (near) arbitrary behavior of the dark energy equation of state. Degeneracies…

宇宙学与河外天体物理 · 物理学 2011-09-22 Arman Shafieloo , Eric V. Linder

Observational cosmology provides us with a large number of high precision data which are used to derive models trying to reproduce ``on the mean'' our observable patch of the Universe. Most of these attempts are achieved in the framework of…

天体物理学 · 物理学 2011-11-10 Marie-Noëlle Célérier

The existence of a dark energy component has usually been invoked as the most plausible way to explain the recent observational results. However, it is also well known that effects arising from new physics (e.g., extra dimensions) can mimic…

天体物理学 · 物理学 2009-11-10 J. S. Alcaniz , Abha Dev , Deepak Jain

The universe with adiabatic matter creation is considered. It is thought that the negative pressure caused by matter creation can play the role of a dark energy component, and drive the accelerating expansion of the universe. Using the Type…

天体物理学 · 物理学 2015-06-24 Yuan Qiang , Tong-Jie Zhang , Ze-Long Yi

In the Friedmann equations, an infinite initial density is avoided only when the universe is spatially flat. With such equations being then valid when the scale factor $a=0$, the universe must also be in the state of vacuum when $a$ is…

广义相对论与量子宇宙学 · 物理学 2013-06-26 N. Tsitverblit

There is something unknown in the cosmos. Something big. Which causes the acceleration of the Universe expansion, that is perhaps the most surprising and unexpected discovery of the last decades, and thus represents one of the most pressing…

综合物理 · 物理学 2013-04-18 M. Villata
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