Entropy of Anisotropic Universe and Fractional Branes

Abstract

We obtain the entropy of a homogeneous anisotropic universe applicable, by assumption, to the fractional branes in the universe in the model of Chowdhury and Mathur. The entropy for the 3 or 4 charge fractional branes thus obtained is not of the expected form E^{3/2} or E^2. One way the expected form is realised is if p \to ρfor the transverse directions and if the compact directions remain constant in size. These conditions are likely to be enforced by brane decay and annihilation, and by the S, T, U dualities. T duality is also likely to exclude high entropic cases, found in the examples, which arise due to the compact space contracting to zero size. Then the 4 charge fractional branes may indeed provide a detailed realisation of the maximum entropic principle we proposed recently to determine the number (3 + 1) of large spacetime dimensions.

Version 2: 21 pages. More discussion and references added. To appear in General Relativity and Gravitation

References in corpus (6)

• String Gas Cosmology and Structure Formation
• Why do we live in 3+1 dimensions?
• Fractional Brane State in the Early Universe
• Challenges for String Gas Cosmology
• A Principle to Determine the Number (3 + 1) of Large Spacetime Dimensions
• A Stringy Correspondence Principle in Cosmology

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• An equation of state in the limit of high densities
• Stabilisation of Seven Directions in an Early Universe M -- theory Model
• Variety of $(d+1)$ dimensional Cosmological Evolutions with and without bounce in a class of LQC -- inspired Models
• A Class of LQC--inspired Models for Homogeneous, Anisotropic Cosmology in Higher Dimensional Early Universe
• Non singular M theory Universe in Loop Quantum Cosmology -- inspired Models