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In the standard cosmological framework, the Hubble diagram is interpreted by assuming that the light emitted by standard candles propagates in a spatially homogeneous and isotropic spacetime. However, the light from "point sources"--such as…

Cosmology and Nongalactic Astrophysics · Physics 2013-07-02 Pierre Fleury , Hélène Dupuy , Jean-Philippe Uzan

We present a novel theory of the very early universe which addresses the traditional horizon and flatness problems of big bang cosmology and predicts a scale invariant spectrum of perturbations. Unlike inflation, this scenario requires no…

High Energy Physics - Theory · Physics 2012-04-24 Kurt Hinterbichler , Justin Khoury

From the standpoint of theoretical physics we can treat Newtonian cosmology as a problem in nonlinear dynamics. The attempt to average the density, in search of a method of making contact between theory and observation, is replaced by the…

Astrophysics · Physics 2007-05-23 J. L. McCauley

We point out that the horizon problem encountered in standard text-books or review papers on cosmology is, in general, derived for world models based on Robertson-Walker line element where homogeneity and isotropy of the universe -- \`a la…

General Relativity and Quantum Cosmology · Physics 2024-04-18 Ashok K. Singal

The cosmological principle states that our Universe is statistically homogeneous and isotropic at large scales. However, due to the relative motion of the Solar System, an additional kinematic dipole can be detected in the distribution of…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-31 Yu-Tian Xu , Ji-Ping Dai , Dong Zhao , Jun-Qing Xia

Let $(M, g)$ denote a cosmological spacetime describing the evolution of a universe which is isotropic and homogeneous on large scales, but highly inhomogeneous on smaller scales. We consider two past lightcones, the first,…

General Relativity and Quantum Cosmology · Physics 2021-05-05 Mauro Carfora , Francesca Familiari

The mean power spectrum of galaxies is compared with theoretical models. Possibilities to explain the observed power spectrum are discussed. Superclusters and voids form a quasi-regular lattice of mean cell size 120 Mpc; the main axis of…

Astrophysics · Physics 2018-03-28 J. Einasto

The paper 0705.0332v1 seeks to study the effect of non-trivial spatial curvature in homogeneous and isotropic models. We note that the space considered is not homogeneous, and that the equations of motion used are inconsistent with the…

Astrophysics · Physics 2008-12-18 Syksy Rasanen

We review recent findings that the universe on its largest scales shows hints of the violation of statistical isotropy, in particular alignment with the geometry and direction of motion of the solar system, and missing power at scales…

Astrophysics · Physics 2011-04-11 Dragan Huterer

Cosmological observables are used to construct cosmological models. Since cosmological observations are limited to the light cone, a fixed number of observables (even measured to arbitrary accuracy) may not uniquely determine a cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-20 Edward W. Kolb , Callum R. Lamb

We consider an evolution of anisotropic cosmological model on the example of the Bianchi type I homogeneous universe. It is filled by the mixture of matter and dark energy with an arbitrary barotropic equation of state (EoS). The general…

General Relativity and Quantum Cosmology · Physics 2023-06-14 S L Parnovsky

Using an analytical model, we compute the distribution of image separations resulting from gravitational lensing of distant sources, for 7 COBE-normalized CDM models with various combinations of Omega_0 and lambda_0. Our model assumes that…

Astrophysics · Physics 2009-11-07 Hugo Martel , Premana Premadi , Richard Matzner

The common attribute of all Big Bang cosmologies is that they are based on the assumption that the universe is expanding. However examination of the evidence for this expansion clearly favours a static universe. The major topics considered…

General Physics · Physics 2014-07-10 David F. Crawford

Supernovae observations strongly support the presence of a cosmological constant, but its value, which we will call apparent, is normally determined assuming that the universe can be accurately described by a homogeneous model. Even in the…

General Relativity and Quantum Cosmology · Physics 2012-11-07 Antonio Enea Romano , Pisin chen

Much of the published work regarding the Isotropic Singularity is performed under the assumption that the matter source for the cosmological model is a barotropic perfect fluid, or even a perfect fluid with a $\gamma$-law equation of state.…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Geoffery Ericksson , Susan M. Scott

The evidence for the accelerated expansion of the universe and the time-dependence of the fine-structure constant suggests the existence of at least one scalar field with a mass of order H_0. If such a field exists, then it is generally…

Astrophysics · Physics 2009-11-10 Justin Khoury , Amanda Weltman

An alternative to the postulate of dark energy required to explain the accelerated expansion of the universe is to adopt an inhomogeneous cosmological model to explain the supernovae data without dark energy. We adopt a void cosmology…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-02 J. W. Moffat

In view of new experimental results that strongly suggest a non-zero cosmological constant, it becomes interesting to revisit the Friedman-Lemaitre model of evolution of a universe with cosmological constant and radiation pressure. In this…

Astrophysics · Physics 2007-05-23 Robert Coquereaux , Alex Grossmann

We discuss the two potentially important effects which should be taken into account in the analysis of the cosmological redshift-space distortion especially at high redshifts; the effect of inhomogeneities in the light propagation and the…

Astrophysics · Physics 2007-05-23 Yasushi Suto , Takahiko Matsubara

After reviewing the cosmological constant problem - why is Lambda not huge? - I outline the two basic approaches that had emerged by the late 1980s, and note that each made a clear prediction. Precision cosmological experiments now indicate…

High Energy Physics - Theory · Physics 2007-05-23 Raphael Bousso