AN ALTERNATIVE WAY TO INFLATION AND THE POSSIBILITY OF ANTI-INFLATION

Instead of the standard approach to inflation based upon the sufficiently flat potential of a scalar field, theories with flat or almost flat dependence of energy on the field gradients or on the field generalised momenta are considered as an alternative dynamical basis for inflation. As a toy model, the class of non-linear electrodynamics, which also includes the Born-Infeld theory, is explored. An attempt is made to derive the equation of state of radiation governed by this non-linear dynamics. Contrary to the 'false vacuum' of conventional inflation which possesses zero entropy, the 'vacuum-like' state of matter in the theories under investigation may contain an arbitrary amount of entropy thus permitting anti-inflation (inflation reversed in time) without violating the second law of thermodynamics.