  The features of vacuum particle creation in an external classical field are
studied for simplest external field models in $3 + 1$ dimensional QED. The
investigation is based on a kinetic equation that is a nonperturbative
consequence of the fundamental equations of motion of QED. The observed
features of the evolution of the system apply on the qualitative level also for
systems of other nature and therefore are rather general. Examples from
cosmology and condensed matter physics illustrate this statement. The common
basis for the description of these systems are kinetic equations for vacuum
particle creation belonging to the class of integro-differential equations of
non-Markovian type with fastly oscillating kernel. This allows to characterize
processes of this type as belonging to the class of field induced phase
transitions.
