INFLATION, DEFLATION, AND FRAME-INDEPENDENCE IN STRING COSMOLOGY

Abstract

The inflationary scenarios suggested by the duality properties of string cosmology in the Brans-Dicke (or string) frame are shown to correspond to accelerated contraction (deflation) when Weyl transformed to the Einstein frame. We point out that the basic virtues of inflation (solving the flatness and horizon problems, amplifying vacuum fluctuations, etc.) have physically equivalent counterparts in the deflationary (Einstein-frame) picture. This could be the answer to some objections recently raised to superstring cosmology.