  We propose a new, transport-theoretic (tt) class of relativistic extensions
of quantum field theories of fundamental interactions. Its concepts are
inspired by Feynman's atomistic idea about the physical world and by the
extension of fluid dynamics to shorter distances through the Boltzmann
transport equation. The extending tt Lagrangians imply the original Lagrangians
as path-integralwise approximations. By constructing a tt Lagrangian that
extends a general gauge-invariant Lagrangian, we show that a tt extension of
the standard model is feasible. We define a tt Lagrangian in terms of tt fields
of the spacetime variable and an additional, four-vector variable. We explain
the fields of quantum field theories as certain covariant, local averages of tt
fields. Only two tt fields may be needed for modeling fundamental interactions:
(i) a four-vector one unifying all fundamental forces, and (ii) a
two-component-spinor one unifying all fundamental matter particles. We comment
on the new physics expected within the tt framework put forward, and point out
some open questions.
