  In the paper it is shown that, even without a knowledge of the concrete form
of the equations of mathematical physics and field theories, with the help of
skew-symmetric differential forms one can see specific features of the
equations of mathematical physics, the relation between mathematical physics
and field theory, to understand the mechanism of evolutionary processes that
develop in material media and lead to emergency of physical structures forming
physical fields. This discloses a physical meaning of such concepts like
"conservation laws", "postulates" and "causality" and gives answers to many
principal questions of mathematical physics and general field theory.
  In present paper, beside the exterior forms, the skew-symmetric differential
forms, whose basis (in contrast to the exterior forms) are deforming manifolds,
are used. Mathematical apparatus of such differential forms(which were named
evolutionary ones) includes nontraditional elements like nonidentical relations
and degenerate transformations and this enables one to describe discrete
transitions, quantum steps, evolutionary processes, and generation of various
structures.
