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In the context of the new standard LambdaCDM cosmology we resolve conflicts in the literature regarding fundamental aspects of the expansion of the universe and cosmic horizons and we link these concepts to observational tests. We derive…

Astrophysics · Physics 2007-05-23 Tamara M. Davis

We prove that certain asymptotically flat initial data sets with nontrivial topology and/or differentiable structure collapse to form singularities. The class of such initial data sets is characterized by a new smooth invariant, the maximal…

General Relativity and Quantum Cosmology · Physics 2010-06-16 Kristin Schleich , Donald M. Witt

This paper compares recent approaches appearing in the literature on the singularity problem for space-times with nonvanishing torsion.

General Relativity and Quantum Cosmology · Physics 2008-11-26 Giampiero Esposito

The energy-momentum tensor coming from one-parameter effective Yang- Mills theory is here used to describe the matter-energy content of the homogeneous and isotropic Friedmann cosmology in its early stages. The behavior of all solutions is…

General Relativity and Quantum Cosmology · Physics 2010-02-25 Vitorio A. De Lorenci

We consider a non singular origin for the Universe starting from an Einstein static Universe in the framework of a theory which uses two volume elements $\sqrt{-{g}}d^{4}x$ and $\Phi d^{4}x$, where $\Phi $ is a metric independent density,…

General Relativity and Quantum Cosmology · Physics 2015-05-28 E. I. Guendelman

The Universe is mostly composed of large and relatively empty domains known as cosmic voids, whereas its matter content is predominantly distributed along their boundaries. The remaining material inside them, either dark or luminous matter,…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-02 Nico Hamaus , Alice Pisani , Paul M. Sutter , Guilhem Lavaux , Stéphanie Escoffier , Benjamin D. Wandelt , Jochen Weller

We "explain", using a Classical approach, how the Universe was created out of "nothing", i.e., with no input of initial energy nor mass. The inflationary phase, with exponential expansion, is accounted for, automatically, by our equation of…

General Physics · Physics 2010-12-14 Marcelo Samuel Berman

The principles of General Relativity allow for a non-vanishing cosmological constant, which can possibly be interpreted at least partially in terms of quantum-fluctuations of matter fields. Depending on sign and magnitude it can cause…

Astrophysics · Physics 2007-05-23 Domenico Giulini , Norbert Straumann

We study the effects of inhomogeneities on the evolution of the Universe, by considering a range of cosmological models with discretized matter content. This is done using exact and fully relativistic methods that exploit the symmetries in…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Timothy Clifton , Daniele Gregoris , Kjell Rosquist , Reza Tavakol

In this paper we investigate the fate of the universe with an anisotropic background sourced by anisotropic matter. We see the behaviour of the Raychaudhuri Equation and investigate wheather a congrurence of time like geodesics focus to a…

General Relativity and Quantum Cosmology · Physics 2015-09-23 Manabendra Sharma

We present a general form for the solution of an expanding general-relativistic Friedmann universe that encounters a singularity at finite future time. The singularity occurs in the material pressure and acceleration whilst the scale…

General Relativity and Quantum Cosmology · Physics 2009-11-10 John D. Barrow

The physical models of a successful unified theory about the Universe must operate in different phase of matter evolution and different fields of physics. The attempts to build such wide range theory as a bunch of theories developed for…

General Physics · Physics 2007-05-23 S. Sarg

The averaged term of squared vorticity is attributed to accelerated expansion. Cosmological singularity has been a consequence of excessive symmetry of flow, such as "Hubble's law". More realistic one is suggested. Exact dynamic and…

General Physics · Physics 2012-10-30 I. S. Nurgaliev

We extend the scope of the Raychaudhuri-Komar singularity theorem of General Relativity to affine theories of gravity with and without torsion. We first generalize the existing focusing theorems using time-like and null congruences of…

General Relativity and Quantum Cosmology · Physics 2020-02-19 Paulo Luz , Filipe C. Mena

In the stringy cosmology, we investigate singularities in geodesic surface congruences for the time-like and null strings to yield the Raychaudhuri type equations possessing correction terms associated with the novel features owing to the…

General Relativity and Quantum Cosmology · Physics 2009-02-23 Yong Seung Cho , Soon-Tae Hong

Generalizing earlier results of Joshi and Dwivedi (Commun. Math. Phys. 146, 333 (1992); Lett. Math. Phys. 27, 235 (1993)), we analyze here the spherically symmetric gravitational collapse of a matter cloud with a general form of matter for…

General Relativity and Quantum Cosmology · Physics 2009-10-22 I. H. Dwivedi , P. S. Joshi

Spatially homogeneous but possibly anisotropic cosmologies have two main types of singularities: (1) asymptotically velocity term dominated (AVTD) - (reversing the time direction) the universe evolves to the singularity with fixed…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Beverly K. Berger

The abstract boundary construction of Scott and Szekeres is a general and flexible way to define singularities in General Relativity. The abstract boundary construction also proves of great utility when applied to questions about more…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Michael J. S. L. Ashley , Susan M. Scott

A matter bouncing entropy-corrected cosmological model has been suggested. The model allows only positive curvature with negative pressure and no violation of the null energy condition. The result obtained in this paper is supported by some…

General Relativity and Quantum Cosmology · Physics 2022-10-12 Nasr Ahmed , Tarek M. Kamel , Mohamed I Nouh

The large-scale statistics of observables such as the galaxy density are chiefly determined by their dependence on the local coarse-grained matter density. This dependence can be measured directly and efficiently in N-body simulations by…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Christian Wagner , Fabian Schmidt , Chi-Ting Chiang , Eiichiro Komatsu