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Register a new userCosmological scenario based on the particle creation and holographic equipartition
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We propose a cosmological scenario which describes the evolution history of the universe based on the particle creation and holographic equipartition. The model attempts to solve the inflation of the early universe and the accelerated expansion of the present universe without introducing the dark energy from the perspective of thermodynamics. Throughout the evolution of the universe, we assume that the universe always creates particles in some way and holographic equipartition is always satisfied. Further, we choose that the creation rate of particles is proportional to $H^{2}$ in the early universe and to $H$ in the present and late universe, where $H$ is the Hubble parameter. Then we obtain the solutions $a(t)propto e^{alpha t/3}$ and $a(t)propto t^{1/2}$ for the early universe and the solutions $a(t)propto t^{delta}$ and $a(t)propto e^{Ht}$ for the present and late universe, where $alpha$ and $delta$ are the parameters. Finally, we obtain and analyze two important thermodynamic properties for the present model.
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One of the most striking examples for the production of particles out of the quantum vacuum due to external conditions is cosmological particle creation, which is caused by the expansion or contraction of the Universe. Already in 1939, Schrodinger understood that the cosmic evolution could lead to a mixing of positive and negative frequencies and that this would mean production or annihilation of matter, merely by the expansion. Later this phenomenon was derived via more modern techniques of quantum field theory in curved space-times by Parker (who apparently was not aware of Schrodingers work) and subsequently has been studied in numerous publications. Even though cosmological particle creation typically occurs on extremely large length scales, it is one of the very few examples for such fundamental effects where we actually may have observational evidence: According to the inflationary model of cosmology, the seeds for the anisotropies in the cosmic microwave background (CMB) and basically all large scale structures stem from this effect. In this Chapter, we shall provide a brief discussion of this phenomenon and sketch a possibility for an experimental realization via an analogue in the laboratory.
The matter creation model of Prigogine--Geheniau--Gunzig--Nardone is revisited in terms of a redefined creation pressure which does not lead to irreversible adiabatic evolution at constant specific entropy. With the resulting freedom to choose a particular gas process, a flat FRWL cosmological model is proposed based on three input characteristics: (i) a perfect fluid comprising of an ideal gas, (ii) a quasi-adiabatic polytropic process, and (iii) a particular rate of particle creation. Such model leads to the description of the late-time acceleration of the expanding Universe with a natural transition from decelerating to accelerating regime. Only the Friedmann equations and the laws of thermodynamics are used and no assumptions of dark energy component is made. The model also allows the explicit determination as functions of time of all variables, including the entropy, the non-conserved specific entropy and the time the accelerating phase begins. A form of correspondence with the dark energy models (quintessence, in particular) is established via the $Om$ diagnostics. Parallels with the concordance cosmological $Lambda$CDM model for the matter-dominated epoch and the present epoch of accelerated expansion are also established via slight modifications of both models.
In this article we have studied a closed universe which a holographic energy on the brane whose energy density is described by $rho (H) =3c^{2}H^{2}$ and we obtain an equation for the Hubble parameter, this equation gave us different physical behavior depending if $c^2>1$ or $c^2<1$ against of the sign of the brane tension.
In this paper, by using Verlindes formalism and a modified Padmanabhans prescription, we have obtained the lowest order quantum correction to the gravitational acceleration and MOND-type theory by considering a nonzero difference between the number of bits of the holographic screen and number of bits of the holographic screen that satisfy the equipartition theorem. We will also carry out a phase transition and critical phenomena analysis in MOND-type theory where critical exponents are obtained.
We rediscuss the main Cosmological Problems as illusions originated from our ignorance of the hidden information holographically stored in {it vacuo}. The Cosmological vacuum state is full of a large number of dynamical quantum hairs, dubbed {it hairons}, which dominate the Cosmological Entropy. We elaborate on the Cosmological Constant (CC) problem, in both the dynamical and time-constant possibilities. We show that all dangerous quantum mixings between the CC and the Planck energy scales are exponentially suppressed as an entropic collective effect of the hairon environment. As a consequence, the dark energy scale is UV insensitive to any planckian corrections. On the other hand, the inflation scale is similarly stabilized from any radiative effects. In the case of the Dark energy, we show the presence of a holographic entropic attractor, favoring a time variation of $Lambdarightarrow 0$ in future rather than a static CC case; i.e. $w>-1$ Dynamical DE is favored over a CC or a $w<-1$ phantom cosmology. In both the inflation and dark energy sectors, we elaborate on the Trans-Planckian problem, in relation with the recently proposed Trans-Planckian Censorship Conjecture (TCC). We show that the probability for any sub-planckian wavelength modes to survive after inflation is completely negligible as a holographic wash-out mechanism. In other words, the hairons provide for a holographic decoherence of the transplanckian modes in a holographic scrambling time. This avoids the TCC strong bounds on the Inflaton and DE potentials.
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