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Using cosmological relativity theory, we derive the formula for the cosmological redshift written explicitly in terms of 1 - "Omega", where "Omega" = "rho"/"rho"_c is the ratio of the average mass density to the critical "closure" density.…

Astrophysics · Physics 2007-05-23 Moshe Carmeli

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

We have had the chance to live through a fascinating revolution in measuring the fundamental empirical cosmological Hubble law. The key progress is analysed : 1) improvement of observational means (ground-based radio and optical…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-10 Georges Paturel , Pekka Teerikorpi , Yurij Baryshev

An estimate of the maximum observable redshift is obtained using only t_{0} approximately equal to (14+- 3)10^{9}years, H_{0} approximately equal to 65 +- 10Km\sec^{-1}Mpc^{-1}(t_{0}H_{0} approximately equal to 0.91 +- 0.08/0.18) assuming…

Astrophysics · Physics 2007-05-23 J. A. Gonzalo

We test the present expansion of the universe using supernova type Ia data without making any assumptions about the matter and energy content of the universe or about the parameterization of the deceleration parameter. We assume the…

Astrophysics · Physics 2009-06-23 Marina Seikel , Dominik J. Schwarz

In a class of models designed to solve the cosmological constant problem by coupling scalar or tensor classical fields to the space-time curvature, the universal scale factor grows as a power law in the age, $a \propto t^\alpha$, regardless…

Astrophysics · Physics 2016-08-25 M. Kaplinghat , G. Steigman , I. Tkachev , T. P. Walker

Cosmological measurements of both the expansion history and growth history have matured, and the two together provide an important test of general relativity. We consider their joint evolutionary track, showing that this has advantages in…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-07 Eric V. Linder

We discuss the classical cosmological tests for a large class of FRW type models driven by a decaying vacuum energy density. Analytic expressions for the lookback time, age of the universe, luminosity distance, angular diameter, and galaxy…

Astrophysics · Physics 2009-11-07 J. V. Cunha , J. A. S. Lima , N. Pires

The Hubble relation between distance and redshift is a purely cosmographic relation that depends only on the symmetries of a FLRW spacetime, but does not intrinsically make any dynamical assumptions. This suggests that it should be possible…

General Relativity and Quantum Cosmology · Physics 2016-11-15 Matt Visser , Celine Cattoen

There are two redshifts in cosmology: $z_{obs}$, the observed redshift computed via spectral lines, and the model redshift, $z$, defined by the effective FLRW scale factor. In general these do not coincide. We place observational…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-06 Bruce A. Bassett , Yabebal Fantaye , Renée Hložek , Cristiano Sabiu , Mat Smith

The observation that Type Ia supernovae are fainter than expected given their red shifts has led to the conclusion that the expansion of the universe is accelerating. The widely accepted hypothesis is that this acceleration is caused by a…

Cosmology and Nongalactic Astrophysics · Physics 2010-07-09 Rutger Dungan , Harrison B. Prosper

Our knowledge about galaxy evolution comes from transforming observed galaxy properties at different redshifts to co-moving physical scales. This transformation depends on using a cosmological model. Here the effects of unintentional mixing…

Astrophysics of Galaxies · Physics 2019-08-14 Vasanth Balakrishna Subramani , Pavel Kroupa , Hossein Shenavar , Vyoma Muralidhara

Our observations of the Universe are fundamentally anisotropic, with data from galaxies separated transverse to the line of sight coming from the same epoch while that from galaxies separated parallel to the line of sight coming from…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-26 Eric V. Linder , MinJi Oh , Teppei Okumura , Cristiano G. Sabiu , Yong-Seon Song

In this paper we present an alternative explanation to the acceleration of the universe and the dark energy problems in terms of the Friedmann Thermodynamics. This model has the capability of making definite predictions in-line with the…

Astrophysics · Physics 2007-05-23 Selcuk Bayin

If the current energy density of the universe is indeed dominated by a cosmological constant, then high-redshift sources will remain visible to us only until they reach some finite age in their rest-frame. The radiation emitted beyond that…

Astrophysics · Physics 2009-11-07 Abraham Loeb

The discovery that the cosmic expansion is accelerating has been followed by an intense theoretical and experimental response in physics and astronomy. The discovery implies that our most basic notions about how gravity work are violated on…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-15 Robert R. Caldwell , Marc Kamionkowski

A Universe with finite age also has a finite causal scale. Larger scales can not affect our local measurements or modeling, but far away locations could have different cosmological parameters. The size of our causal Universe depends on the…

General Physics · Physics 2020-04-17 Enrique Gaztanaga

Recent observations of high redshift Supernovae at lower than expected value of the Hubble constant, widely interpreted as an evidence for accelerating expansion of the Universe, could alternatively be explained assuming a hyperbolic…

Astrophysics · Physics 2007-05-23 Mikolaj "Mik" Sawicki

A common belief about big-bang cosmology is that the cosmological redshift cannot be properly viewed as a Doppler shift (that is, as evidence for a recession velocity), but must be viewed in terms of the stretching of space. We argue that,…

Popular Physics · Physics 2010-11-02 Emory F. Bunn , David W. Hogg

Cosmology is undergoing an explosive period of activity, fueled both by new, accurate astrophysical data and by innovative theoretical developments. Cosmological parameters such as the total density of the Universe and the rate of…

Astrophysics · Physics 2007-05-23 A. S. Sakharov , H. Hofer
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