منابع مشابه
Cosmic Growth History and Expansion History
The cosmic expansion history tests the dynamics of the global evolution of the universe and its energy density contents, while the cosmic growth history tests the evolution of the inhomogeneous part of the energy density. Precision comparison of the two histories can distinguish the nature of the physics responsible for the accelerating cosmic expansion: an additional smooth component – dark en...
متن کاملHubble's diagram and cosmic expansion.
Edwin Hubble's classic article on the expanding universe appeared in PNAS in 1929 [Hubble, E. P. (1929) Proc. Natl. Acad. Sci. USA 15, 168-173]. The chief result, that a galaxy's distance is proportional to its redshift, is so well known and so deeply embedded into the language of astronomy through the Hubble diagram, the Hubble constant, Hubble's Law, and the Hubble time, that the article itse...
متن کاملmodified gravity explain accelerated cosmic expansion ?
We show that the recently suggested explanations of cosmic acceleration by the modification of gravity at small curvature suffer violent instabilities and strongly disagree with the known properties of gravitational interactions. It seems established that at the present epoch the universe expands with acceleration. It follows directly from the observation of high red-shift supernovae [1] and in...
متن کاملEffects of Inhomogeneities on Cosmic Expansion
We evaluate the effect of inhomogeneity energy on the expansion rate of the universe. Our method is to expand to Newtonian order in potential and velocity but to take into account fully nonlinear density inhomogeneities. To linear order in density, kinetic and gravitational potential energy contribute to the total energy of the universe with the same scaling with expansion factor as spatial cur...
متن کاملGravity-driven acceleration of the cosmic expansion.
It is shown here that a dynamical Planck mass can drive the scale factor of the universe to accelerate. The negative pressure which drives the cosmic acceleration is identified with the unusual kinetic energy density of the Planck field. No potential nor cosmological constant is required. This suggests a purely gravity driven, kinetic inflation. Although the possibility is not ruled out, the bu...
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ژورنال
عنوان ژورنال: Astroparticle Physics
سال: 2017
ISSN: 0927-6505
DOI: 10.1016/j.astropartphys.2016.11.002