Results 21 to 30 of about 32,545 (270)

Relative information entropy in cosmology: The problem of information entanglement

Physics Letters B, 2016
The necessary information to distinguish a local inhomogeneous mass density field from its spatial average on a compact domain of the universe can be measured by relative information entropy.
Viktor G. Czinner, Filipe C. Mena
doaj   +1 more source

Inhomogeneity and the post-inflationary universe [PDF]

Second international workshop on particle physics and the early universe (COSMO-98), 1999
We discuss the interaction between perturbations in the inflaton and the background during the preheating phase in simple inflationary models. By numerically solving the Einstein field equations we are able to assess the impact of non-linear gravitational effects on preheating, and to assess the accuracy of perturbative discussions of the preheating ...
Easther, Richard, Parry, Matthew
openaire   +2 more sources

Age problem in Lemaître–Tolman–Bondi void models

Physics Letters B, 2015
As is well known, one can explain the current cosmic acceleration by considering an inhomogeneous and/or anisotropic universe (which violates the cosmological principle), without invoking dark energy or modified gravity.
Xiao-Peng Yan, De-Zi Liu, Hao Wei
doaj   +1 more source

Cyclic Szekeres universes

European Physical Journal C: Particles and Fields, 2019
We consider the Szekeres universe with an inhomogeneous dust fluid and a homogeneous and isotropic ghost matter source with equation of state $$p_{g}=( \gamma -1) \rho _{g},$$ pg=(γ-1)ρg, where $$\gamma $$ γ is a constant.
John D. Barrow, Andronikos Paliathanasis
doaj   +1 more source

Distortions of Robertson–Walker metric in perturbative cosmology and interpretation as dark matter and cosmological constant

European Physical Journal C: Particles and Fields, 2020
In the last years, we saw more and more attempts to explain dark matter as a general relativistic effect, at least for some fraction. Following this philosophy, we considered the gravitational distortions due to the inhomogeneous distribution of matter ...
Federico Re
doaj   +1 more source

COSMOLOGICAL PERTURBATIONS IN PRESENCE OF SCALAR FIELDS

Odessa Astronomical Publications, 2014
We investigate the role of the scalar field assuming its presence at late stages of the Universe evolution together with dust presented by a system of an arbitrary number of gravitating masses (galaxies, groups of galaxies and clusters of galaxies) and ...
A. Yu. Burgazli, M. Eingorn, A. Zhuk
doaj   +1 more source

Large Scale Cosmological Anomalies and Inhomogeneous Dark Energy

Galaxies, 2014
A wide range of large scale observations hint towards possible modifications on the standard cosmological model which is based on a homogeneous and isotropic universe with a small cosmological constant and matter.
Leandros Perivolaropoulos
doaj   +1 more source

Entropy and Holography Constraints for Inhomogeneous Universes [PDF]

Physical Review Letters, 2000
We calculated the entropy of a class of inhomogeneous dust universes. Allowing spherical symmetry, we proposed a holographic principle by reflecting all physical freedoms on the surface of the apparent horizon. In contrast to flat homogeneous counterparts, the principle may break down in some models, though these models are not quite realistic.
Wang, Bin, Abdalla, Elcio, Osada, Takeshi   +2 more
openaire   +3 more sources

Cosmic Microwave Background, Accelerating Universe and Inhomogeneous Cosmology [PDF]

, 2005
We consider a cosmology in which a spherically symmetric large scale inhomogeneous enhancement or a void are described by an inhomogeneous metric and Einstein's gravitational equations.
Barausse E Matarrese S Riotto A, Bondi H, Bonnor W B, Coles P, Contaldi C R, Copi C J Huterer D Starkman G D, Cruz M, Dennis M R, Dennis M R, Donoghue E P Donoghue J F, Dyer C C, Eriksen H K, Eriksen H K, Flanagan E E, Geshnizjani G Chung D J H, Giovannini M, Glück M Pisano C, Górski K M Hivon E Wandelt B, Hajian A Souradeep T, Hajian A Souradeep T Cornish N J, Hansen F K, Hansen F K Banday A J Górski K M, Hirata C M Seljak U, J W Moffat, Katz G Weeks J, Kolb E W Matarrese S Notari A Riotto A, Kolb E W Matarrese S Notari A Riotto A, Komatsu E Spergel D N Wandelt B D, Krasiński A, Land K Magueijo J, Land K Magueijo J, Land K Magueijo J, Land K Magueijo J, Land K Magueijo J, Larson D L Wandelt B D, Lemaître G, Lemaître G, Moffat J W, Mukherjee P Wang Y, Notari A, Raine D J, Rees M J, Riess A G, Räsänen S, Räsänen S, Siegel E R Fry J N, Straumann N, Tolman R C, Vielva P, Weeks J R, Wiltshire D L   +50 more
core   +1 more source

Singularity-free and non-chaotic inhomogeneous Mixmaster in polymer representation for the volume of the universe

Physics Letters B, 2019
We analyze the semiclassical polymer dynamics of the inhomogeneous Mixmaster model by choosing the cubed scale factor as the discretized configurational variable, while the anisotropies remain pure Einsteinian variables. Such a modified theory of gravity
Stefano Antonini, Giovanni Montani
doaj   +1 more source