  After a brief introduction we review the nonperturbative weak noise approach
to the KPZ equation in one dimension. We argue that the strong coupling aspects
of the KPZ equation are related to the existence of localized propagating
domain walls or solitons representing the growth modes; the statistical weight
of the excitations is governed by a dynamical action representing the
generalization of the Boltzmann factor to kinetics. This picture is not limited
to one dimension. We thus attempt a generalization to higher dimensions where
the strong coupling aspects presumably are associated with a cellular network
of domain walls. Based on this picture we present arguments for the Wolf-Kertez
expression z= (2d+1)/(d+1) for the dynamical exponent.
