Inflationary cosmology in the central region of string and M-theory moduli space

The "central" region of moduli space of M and string theories is where the string coupling is about unity and the volume of compact dimensions is about the string volume. Here we argue that in this region the nonperturbative potential which is suggested by membrane instanton effects has the correct scaling and shape to allow for enough slow-roll inflation and produce the correct amplitude of CMB anisotropies. A limited knowledge of some generic properties of the induced potential is sufficient to determine the simplest type of consistent inflationary model and its predictions about the spectrum of cosmic microwave background anisotropies: a red spectrum of scalar perturbations, and a negligible amount of tensor perturbations.