ABSTRACT
Supergravity is a low-energy limit of a fundamental M/string theory. At present there is no well-established M/string theory cosmology. However, there are some urgent issues in cosmology which require a knowledge of the fundamental theory. Those issues are related to expanding universe, dark matter, inflation, creation of particles after inflation, etc. The basic problem is that general relativity which is required for explanation of the cosmology and an expanding universe is not yet combined with any relativistic quantum theory and particle physics to the extent in which a full description of the early universe would be possible. Superstring theory offers a consistent theory of quantum gravity at least at the level of the string theory perturbation theory in ten-dimensional target space. The non-perturbative string theory which includes the D-branes is much less understood, since these objects are charged under so-called RamondRamond charges which can be incorporated only at the non-perturbative level. The main attempts during the last few years have been focused on understanding the M-theory, which represents a string theory at strong coupling, when an additional dimension is decompactified. M-theory has as a low-energy limit the 11-dimensional supergravity and has two types of extended objects: two-branes and five-branes.
