  The Multiverse is collection of parallel universes. In this article a formal
theory and a topos-theoretic models of the multiverse are given. For this the
Lawvere-Kock Synthetic Differential Geometry and topos models for smooth
infinitesimal analysis are used. Physical properties of multi-variant and
many-dimensional parallel universes are discussed. The source of multiplicity
of physical objects is set of physical constants.
