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As an alternative to dark energy it has been suggested that we may be at the center of an inhomogeneous isotropic universe described by a Lemaitre-Tolman-Bondi (LTB) solution of Einstein's field equations. In order to test this hypothesis…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Antonio Enea Romano

An overview of some recent developments in inhomogeneous models is presented. As the volume and precision of cosmological data improves, it will become more and more essential to understand the non-linear behaviour of the Einstein field…

General Relativity and Quantum Cosmology · Physics 2010-01-06 Charles Hellaby

A local void in the globally Friedmann-Robertson-Walker cosmological model with the critical density ($\Omega_{0}=1$) is studied. The inhomogeneity is described using a Lema\^{\i}tre-Tolman-Bondi solution for a spherically symmetric…

Astrophysics · Physics 2008-02-03 J. W. Moffat , D. C. Tatarski

As an alternative to dark energy that explains the observed acceleration of the universe, it has been suggested that we may be at the center of an inhomogeneous isotropic universe described by a Lemaitre-Tolman-Bondi (LTB) solution of…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-04 Antonio Enea Romano , Misao Sasaki

This paper is devoted to study the cosmological behavior of homogeneous and isotropic universe model in the context of $f(R,T^{\varphi})$ gravity where $\varphi$ is the scalar field. For this purpose, we follow the first order formalism…

General Relativity and Quantum Cosmology · Physics 2018-07-30 M. Sharif , Aisha Siddiqa

We present a regular cubic lattice solution to Einstein field equations that is exact at second order in a small parameter. We show that this solution is kinematically equivalent to the Friedmann-Lema\^itre-Robertson-Walker (FLRW) solution…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-09 J. Larena

We explore observables in a lattice Universe described by a recently found solution to Einstein field equations. This solution models a regular lattice of evenly distributed objects of equal masses. This inhomogeneous solution is…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Jean-Philippe Bruneton , Julien Larena

This article reviews an approach for constructing a simple relativistic fractal cosmology whose main aim is to model the observed inhomogeneities of the distribution of galaxies by means of the Lemaitre-Tolman solution of Einstein's field…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-27 Marcelo B. Ribeiro

The approximate homogeneity of spatial sections of the Universe is well supported observationally, but the inhomogeneity of the spatial sections is even better supported. Here, we consider the implications of inhomogeneity in dust models…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 Boudewijn F. Roukema , Vincent Blanloeil , Jan J. Ostrowski

It is often stated that homogeneity and isotropy of the Universe are assumptions of the almost Friedmann-Lema^itre (FL) model (the hot big bang model), inspired from the Copernican Principle. However, only local homogeneity and isotropy are…

Astrophysics · Physics 2009-11-06 Boudewijn F. Roukema

The possibility that we live in a special place in the universe, close to the centre of a large void, seems an appealing alternative to the prevailing interpretation of the acceleration of the universe in terms of a LCDM model with a…

Astrophysics · Physics 2009-06-23 Juan Garcia-Bellido , Troels Haugboelle

There has been much debate over whether or not one could explain the observed acceleration of the Universe with inhomogeneous cosmological models, such as the spherically-symmetric Lemaitre-Tolman-Bondi (LTB) models. It has been claimed…

Astrophysics · Physics 2009-11-11 R. Ali Vanderveld , Eanna E. Flanagan , Ira Wasserman

We analyze two different algorithms for constructing weakly inhomogeneous models for the low-redshift Universe, in order to provide a tool for testing the geodesic dynamics, within the sphere of validity for the Universe acceleration. We…

General Relativity and Quantum Cosmology · Physics 2020-07-14 P. Marcoccia , G. Montani

The paradigm of \Lambda CDM cosmology works impressively well and with the concept of inflation it explains the universe after the time of decoupling. However there are still a few concerns; after much effort there is no detection of dark…

General Physics · Physics 2017-03-22 B. Vlahovic

Observational tests for the homogeneity of the Universe on large scales are reviewed. Assuming the Cosmological Principle we then estimate cosmological parameters by joint analysis of the Cosmic Microwave Background, Supernovae Ia, peculiar…

Astrophysics · Physics 2017-08-23 Ofer Lahav

In this manuscript, we show that three fundamental building blocks are supporting the Cosmological Principle. The first of them states that there is a special frame in the universe where the spatial geometry is intrinsically homogeneous and…

General Relativity and Quantum Cosmology · Physics 2024-01-05 Leandro G. Gomes

Based upon the intrinsic symmetries approach to inhomogeneous cosmologies, we propose an exact solution to Einstein's field equations where the spatial sections are flat and the source is a non-perfect fluid such that the dissipative terms…

General Relativity and Quantum Cosmology · Physics 2021-03-11 E. Bittencourt , L. G. Gomes , G. B. Santos

Recently, we constructed the specific solution to the second-order cosmological perturbation theory, around any Friedmann-Lemaitre-Robertson-Walker (FLRW) background filled with dust matter and a positive cosmological constant. In this…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-16 Szymon Sikora , Jan J. Ostrowski

The present matter density of the Universe, while highly inhomogeneous on small scales, displays approximate homogeneity on large scales. We propose that whereas it is justified to use the Friedmann-Lemaitre-Robertson-Walker (FLRW) line…

Astrophysics · Physics 2008-11-26 Aseem Paranjape , T. P. Singh

This paper presents numerical solutions of particular Lemaitre-Tolman models approximating a fractal behaviour along the past light cone, as discussed in paper I (0807.0866) of this series. The initial conditions of the numerical problem…

Astrophysics · Physics 2011-02-11 Marcelo B. Ribeiro