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The hypothesis that the speed of light decreases by nearly 2 cm per sec and per year is discussed within the frame of a simple phenomenological model. It is shown that this hypothesis can provide an alternative explanation for the…

Astrophysics · Physics 2007-05-23 Yves-Henri Sanejouand

Discoveries in the last few years have revolutionized our knowledge of the universe and our ideas of its ultimate fate. Measurements of the expansion of the universe show that it is not slowing down under normal gravity but accelerating due…

Astrophysics · Physics 2007-05-23 Eric V. Linder

Current observations of the fraction of dark energy and a lower limit on its tension, coupled with an assumption of the non-convexity of the dark energy potential, are used to derive a lower limit of 26 billion years for the future age of…

High Energy Physics - Theory · Physics 2016-09-06 Don N. Page

Recent measurements of the parameters of the Concordance Cosmology Model ($\Lambda$CDM) done in the low-redshift Universe with Supernovae Ia/Cepheids, and in the distant Universe done with Cosmic Microwave Background (CMB) imply different…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-26 B. Czerny , M. L. Martínez-Aldama , G. Wojtkowska , M. Zajaček , P. Marziani , D. Dultzin , M. H. Naddaf , S. Panda , R. Prince , R. Przyluski , M. Ralowski , M. Śniegowska

The age of the Universe in the $\Lambda$CDM cosmology with $\Omega_{matter}=0.26$ and $\Omega_{\Lambda}=0.74$ is the same as in the Milne cosmology which correspods to an almost empty universe. In both cases it is a reciprocal Hubble…

Astrophysics · Physics 2007-05-23 M. Kutschera , M. Dyrda

The concordance (LambdaCDM) model reproduces the main current cosmological observations assuming the validity of general relativity at all scales and epochs, the presence of cold dark matter, and of a cosmological constant, equivalent to a…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-08 Guido Risaliti , Elisabeta Lusso

The extreme luminosity and their fairly unique temporal behaviour have made supernovae a superb tool to measure distances in the universe. As complex astrophysical events they provide interesting insights into explosion physics, explosive…

Astrophysics · Physics 2009-06-25 Bruno Leibundgut

We show that the Supernovae results, implying evidence for an accelerating Universe, may be closely related to the recent discovery of redshift dependence in the fine structure constant $\alpha$. The link is a class of varying speed of…

Astrophysics · Physics 2009-10-31 John D. Barrow , Joao Magueijo

The redshifts of all cosmologically distant sources are expected to experience a small, systematic drift as a function of time due to the evolution of the Universe's expansion rate. A measurement of this effect would represent a direct and…

The cosmic expansion history, mapped by the Hubble parameter as a function of redshift, offers the most direct probe of the dark energy equation of state. One way to determine the Hubble parameter at different redshifts is essentially…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-11 Youhua Xu , Hu Zhan , Yeuk-Kwan Edna Cheung

The redshift drift is a small, dynamic change in the redshift of objects following the Hubble flow. Its measurement provides a direct, real-time, model-independent mapping of the expansion rate of the Universe. It is fundamentally different…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-10 S. Cristiani , K. Boutsia , G. Calderone , G. Cupani , V. D'Odorico , F. Fontanot , A. Grazian , F. Guarneri , C. Martins , L. Pasquini , M. Porru , E. Vanzella

A new model of the observed universe, using solutions to the full Einstein equations, is developed from the hypothesis that our observable universe is an underdense bubble, with an internally inhomogeneous fractal bubble distribution of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 David L. Wiltshire

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

The distance-redshift relation observed for supernovae has led to the discovery that the expansion of the universe is accelerating. A next generation experiment, the Supernova/Acceleration Probe (SNAP), can investigate the nature of the…

Astrophysics · Physics 2017-08-23 Eric V. Linder

The velocity of the Hubble expansion has been added to General Relativity by Moshe Carmeli and this resulted in new equations of motion for the expanding universe. For the first time the observational magnitude-redshift data derived from…

Astrophysics · Physics 2007-05-23 John G. Hartnett

We use the ages of old astrophysical objects (OAO) in the redshift range $0 \lesssim z \lesssim 8$ as stringent tests of the late-time cosmic expansion history. Since the age of the Universe at any redshift is inversely proportional to…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-05 Sunny Vagnozzi , Fabio Pacucci , Abraham Loeb

We apply the new dynamics of 3-space to cosmology by deriving a Hubble expansion solution. This dynamics involves two constants; G and alpha - the fine structure constant. This solution gives an excellent parameter-free fit to the recent…

General Physics · Physics 2007-06-27 Reginald T Cahill

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 $\Lambda$CDM concordance cosmological model provides a remarkably successful description of the formation and evolution of structure in the Universe. However, a growing discrepancy between measurements of the expansion rate $H_0$ from…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-10 Isaque Dutra , Colin J. Burke , Priyamvada Natarajan , Weixiang Yu

The product of two empirical constants, the dimensionless fine structure constant and the von Klitzing constant (an electrical resistance), turns out to be an exact dimensionless number. Then the accuracy and cosmological time variation (if…

General Physics · Physics 2014-11-20 Antonio Alfonso-Faus
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