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The effect of curvature on the results of fractal analyses of the galaxy distribution is investigated. We show that, if the universe satisfies the criteria of a wide class of parabolic homogeneous models, the observers measuring the fractal…

Astrophysics · Physics 2009-10-31 Marie-Noëlle Célérier , Reuben Thieberger

Statistical analyses of the measurements of the Hubble-Lema\^itre constant $H_0$ (163 measurements between 1976 and 2019) show that the statistical error bars associated with the observed parameter measurements have been underestimated --…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-18 Martin Lopez-Corredoira

We revisit how super-Hubble cosmological fluctuations induce, at any time in the cosmic history, a non-vanishing spatial curvature of the local background metric. The random nature of these fluctuations promotes the curvature density…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-06 Baptiste Blachier , Pierre Auclair , Christophe Ringeval , Vincent Vennin

A generalisation to electrodynamics and Yang-Mills theory is presented that permits computation of the speed of light. The model presented herewithin indicates that the speed of light in vacuo is not a universal constant. This may be…

High Energy Physics - Theory · Physics 2007-05-23 M. Temple-Raston

The cosmological scale factor $a(t)$ of the flat-space Robertson-Walker geometry is examined from a Hamiltonian perspective wherein $a(t)$ is interpreted as an independent dynamical coordinate and the curvature density $\sqrt {- g(a)}…

General Physics · Physics 2008-10-04 M. Ibison

Toy models for the Hubble rate or the scalar field potential have been used to analyze the amplification of scalar perturbations through a smooth transition from inflation to the radiation era. We use a Hubble rate that arises consistently…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Roy Maartens , Daniel Tilley

We establish a cosmological-model-independent method to determine the Hubble constant $H_0$ from the localized fast radio bursts (FRBs) and the Hubble parameter measurements from cosmic chronometers and obtain a first such determination…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-12 Yang Liu , Hongwei Yu , Puxun Wu

This paper presents a general averaging procedure for a set of observers which are tilted with respect to the cosmological matter fluid. After giving the full set of equations describing the local dynamics, we define the averaging procedure…

General Relativity and Quantum Cosmology · Physics 2009-04-22 J. Larena

We investigate the gravitational property of the quantum vacuum by treating its large energy density predicted by quantum field theory seriously and assuming that it does gravitate to obey the equivalence principle of general relativity. We…

General Relativity and Quantum Cosmology · Physics 2019-04-22 Qingdi Wang , Zhen Zhu , William G. Unruh

The observed power spectrum of the cosmic microwave background (CMB) is consistent with inflationary cosmology, which predicts a nearly scale-invariant power spectrum of quantum fluctuations of the inflaton field as they exit the Hubble…

High Energy Physics - Theory · Physics 2007-05-23 Leonard Parker

The Universe may feature large-scale inhomogeneities beyond the standard paradigm, implying that statistical homogeneity and isotropy may be reached only on much larger scales than the usually assumed $\sim$100 Mpc. This means that we are…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-05 David Camarena , Valerio Marra , Ziad Sakr , Chris Clarkson

A novel function for modified gravity is proposed, $f(R, T)=R+\lambda R^2+2\beta\ln(T)$, with constants $\lambda$ and $\beta$, scalar curvature $R$, and the trace of stress energy tensor $T$, satisfying $T=\rho-3p>0$. Subsequently, two…

General Physics · Physics 2020-06-16 Emilio Elizalde , Nisha Godani , Gauranga C. Samanta

Recent surveys seem to support bulk peculiar velocities well in excess of those anticipated by the standard cosmological model. In view of these results, we consider here some of the theoretical implications of large-scale drift motions. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Christos G Tsagas

The Hubble constant Ho describes not only the expansion of local space at redshift z ~ 0, but is also a fundamental parameter determining the evolution of the universe. Recent measurements of Ho anchored on Cepheid observations have reached…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 C. Henkel , J. A. Braatz , M. J. Reid , J. J. Condon , K. Y. Lo , C. M. V. Impellizzeri , C. Y. Kuo

Processing the data of lunar laser ranging (LLR), whose accuracy now reaches a few millimeters, points to the effect of anomalous increase in the lunar semimajor axis (with an excessive rate 1.3 cm/yr), which cannot be attributed to the…

Astrophysics · Physics 2007-05-23 Yu. V. Dumin

Using sedimentary and eclipse-based measurements of the lunar recession velocity, we derive a new local-Universe measurement of the Hubble constant ($H_0$) from the recession rate of Earth's Moon. Taking into account the effects of tides,…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-01 Gagandeep S. Anand , Zachary R. Claytor , Ryan Dungee

Astrophysical observations indicate that the ``Local Universe" has a relatively lower matter density ($\Omega_0$) than the predictions of the standard inflation cosmology and the large-scale motions of galaxies which provide a mean mass…

Astrophysics · Physics 2016-08-30 Xiang-Ping Wu , Zugan Deng , Zhenlong Zou , Li-Zhi Fang , Bo Qin

The Hubble-Lemaitre tension is currently one of the most important questions in cosmology. Most of the focus so far has been on reconciling the Hubble constant value inferred from detailed cosmic microwave background measurement with that…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-29 Kylar L. Greene , Francis-Yan Cyr-Racine

We introduce a weighed scalar average formalism ("q-average") for the study of the theoretical properties and the dynamics of spherically symmetric Lemaitre-Tolman-Bondi (LTB) dust models models. The "q-scalars" that emerge by applying the…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Roberto A. Sussman

We propose a modification of Einstein-Cartan gravity equations. The modified cosmology departs from the standard model of cosmology for small Hubble parameter. A characteristic Hubble scale h0, which is intrinsically related to cosmological…

General Relativity and Quantum Cosmology · Physics 2015-07-21 Wei Lu
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