Entropy in the Present and Early Universe: New Small Parameters and Dark Energy Problem

Alexander Shalyt-Margolin

doi:10.3390/e12040932

Abstract

It is demonstrated that entropy and its density play a significant role in solving the problem of the vacuum energy density (cosmological constant) of the Universe and hence the dark energy problem. Taking this in mind, two most popular models for dark energy—Holographic Dark Energy Model and Agegraphic Dark Energy Model—are analysed. It is shown that the fundamental quantities in the first of these models may be expressed in terms of a new small dimensionless parameter that is naturally occurring in High Energy Gravitational Thermodynamics and Gravitational Holography (UV-limit). On this basis, the possibility of a new approach to the problem of Quantum Gravity is discussed. Besides, the results obtained on the uncertainty relation of the pair “cosmological constant–volume of space-time”, where the cosmological constant is a dynamic quantity, are reconsidered and generalized up to the Generalized Uncertainty Relation.

Highlights

The Dark Energy Problem is one of the key problems in modern theoretical physics [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
In [24] it has been stated that any contribution into the vacuum energy acts exactly as the cosmological constant Λ and the Vacuum Energy Density is proportional to Λ
Note that one of the first studies of the cosmological constant within the scope of the Heisenberg Uncertainty Principle has been presented in several works [114,115,116] demonstrating the inference: “vacuum fluctuation of the energy density can lead to the observed cosmological constant” [114]

Summary

Introduction

The Dark Energy Problem is one of the key problems in modern theoretical physics [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]. On the assumption that the vacuum energy density ρvac is involved in ρ as a term ρ = ρM + ρvac where ρM is the average matter density, in case of ρvac we can arrive at the same upper limit (right-hand side of the formula (18)) as for ρ.

Results

Conclusion