ﻻ يوجد ملخص باللغة العربية
We examine the consequences of a universe with a non-constant cosmological term in Einsteins equations and find that the Bianchi identities reduce to the first law of thermodynamics when cosmological term is identified as being proportional to the entropy density of the universe. This means that gravitating dark energy can be viewed as entropy, but more, the holographic principle along with the known expansion of the universe indicates that the entropy of the universe is growing with time and this leads to a cosmic repulsion that also grows with time. Direct implications of this result are calculated and shown to be in good accord with recent observational data.
In order to apply holography and entropy relations to the whole universe, which is a gravitational and thus nonextensive system, for consistency one should use the generalized definition for the universe horizon entropy, namely Tsallis nonextensive e
Perfect fluids are modeled by using an effective field theory approach which naturally gives a self-consistent and unambiguous description of the intrinsic non-adiabatic contribution to pressure variations. We study the impact of intrinsic entropy pe
We study the emergence of entropy in gravitational production of dark matter particles, ultra light scalars minimally coupled to gravity and heavier fermions, from inflation to radiation domination (RD). Initial conditions correspond to dark matter f
In this work, we analyzed the effect of different prescriptions of the IR cutoffs, namely the Hubble horizon cutoff, particle horizon cutoff, Granda and Oliveros horizon cut off, and the Ricci horizon cutoff on the growth rate of clustering for the T
Multiple scalar fields nonminimally interacting through pure affine gravity are considered to generate primordial perturbations during an inflationary phase. The couplings considered give rise to two distinct sources of entropy perturbations that may