We assume that our universe originated from highly excited and interacting strings with coupling constant g=O(1). Fluctuations of spacetime geometry are large in such strings and the physics dictating the emergence of a final spacetime configuration is not known. We propose that, nevertheless, it is determined by an entropic principle that the final spacetime configuration must have maximum entropy for a given amount of energy. This principle implies, under some assumptions, that the spacetime configuration that emerges finally is a (3+1)-dimensional FRW universe filled with w=1 perfect fluid and with 6-dimensional compact space of size l; in particular, the number of large spacetime dimensions is d=3+1. Such an universe may evolve subsequently into our universe, perhaps as in Banks Fischler scenario.
Physics Letters B
- Pub Date:
- February 2007
- High Energy Physics - Theory;
- Condensed Matter - Statistical Mechanics;
- General Relativity and Quantum Cosmology
- 11 pages. Latex file. Version 2: References added