The Promise of String Cosmology *

The interplay between string theory and cosmology is very promising. Since string theory will yield a quantum theory of space-time and unify all forces of nature, it has the potential of addressing many of the conceptual problems of the current models of early Universe cosmology. In turn, cosmology is the most obvious testing ground in the effort to construct non-perturbative string theory, and can provide the crucial connection between theory and experiment/observation . Early Universe cosmology has made spectacular progress over the past two decades, driven both by a wealth of new observational data and by theoretical breakthroughs. In particular, a scenario for the very early Universe, the inflationary Universe scenario [2], has emerged which has led to solutions of some of the deep mysteries of standard big bang cosmology, and which has made some quite specific predictions for the geometry of the Universe and for the spectrum of cosmic microwave background (CMB) anisotropies which have been confirmed by the most recent observations [3, 4]. ∗This article was commissioned in conjunction of the Workshop on String Cosmology held from July 24 Aug. 4 2000 at PIMS, Univ. of British Columbia and is published in APCTP Bulletin # 6, (2001). Brown preprint BROWN-HET-1243. For a more technical overview of the existing approaches to connecting string theory and cosmology, the reader is referred in [1].