Stochastic Inflation: New Results

This is an old article which has never been posted for public use and which only appeard in a relatively hard-to-get Proceedings of the Sakharov Conference in Moscow (May, 1991). The subject of this article has received a lot of attention in last two years. Although we acknowledge that there has been a very big progress in the field of relating the spectrum of fluctuations to scalar field potentials of inflation models, which have outdated some of our results (particularly because we never took into account the tensor fluctuations which have been shown to be crucial for reconstructing the inflaton potential) we think that some of the other ideas and approaches which we presented in this article maybe still of interest. We did not rewrite the article to include any of the newer approaches and we did not add any of the newer references. The reader is advised to refer to recent papers (for example, see the paper astro-ph/9403001 by Edward Kolb and Sharon Vadas) for state of the art review and up-to-date references. ==The original abstract of the article==: We prove that, in stochastic approach, there exists an equivalence relation between different inflationary models under some redefinition of field and time variables. The postinflationary physics is insensitive to it and one can say that related theories are in fact indistinguishable from the viewpoint