The interface of cosmology with string and M(illennium) theory (Q2783454)

The purpose of this article is to introduce some of the most promising work and themes under investigation in string cosmology. A brief, qualitative introduction to \(M\) theory is given in Section 2. In Section 3 the work of Brandenberger and Vafa is reviewed in which the 1980s version of string theory is used to solve the initial singularity problem and in an attempt to explain why we live in four macroscopic dimensions despite the fact that string theory seems to predict the wrong number of dimensions. Then this scenario has been updated in order to include the effects of \(p\)-branes. Section 4 provides a brief introduction to the Pre-Big-Bang scenario. Another promising attempt to combine \(M\) theory with cosmology, that of Lukas, Ovrut and Waldram, is presented in Section 5. Section 6 reviews some models involving large extra dimensions. This section begins with a short introduction to the hierarchy problem of standard model particle physics and explains how it may be solved using large extra dimensions. ``Brane World'' scenarios are then discussed focusing primarily on the models of Randall and Sundrum.