  In this lecture first I present a brief genesis of the ideas on the
electroweak baryogenesis and then I focus on a mechanism in which the source of
$CP$ violation is a $CP$-violating field condensate which could occur, for
example, in multi-higgs extensions of the Standard Model. In the limit of a
thick bubble wall one finds a classical force acting on particles proportional
to the mass squared and the $CP$ violating phase. One can study this force in
the fluid approximation in which the effects of transport and particle decays
can be taken into account. A novelty in this talk is generalization of the
problem to the relativistic velocity. There is a regime in which the final
formula for the baryon asymmetry has a rather simple form.
