The origin of spacetime dimensionality

Abstract

I address the issue of spacetime dimensionality within Kaluza-Klein theories and theories with large extra dimensions. I review the arguments explaining the dimensionality of the universe, within the framework of string gas cosmology and braneworld cosmology, respectively.

Comments: Talk presented in the Conference ``Challenges in Particle Astrophysics'' - 6th Rencontres du Vietnam, Hanoi (Vietnam) 6-12 Aug. 2006