  During the last decades there has been a relatively extensive attempt to
develop the theory of stochastic electrodynamics (SED) with a view to
establishing it as the foundation for quantum mechanics. The theory had several
important successes, but failed when applied to the study of particles subject
to nonlinear forces. An analysis of the failure showed that its reasons are not
to be ascribed to the principles of SED, but to the methods used to construct
the theory, particularly the use of a Fokker-Planck approximation and
perturbation theory. A new, non perturbative approach has been developed,
called linear stochastic electrodynamics (LSED), of which a clean form is
presented here. After introducing the fundamentals of SED, we discuss in detail
the principles on which LSED is constructed. We pay attention to the
fundamental issue of the mechanism that leads to the quantum behaviour of field
and matter, and demonstrate that indeed LSED is a natural way to the quantum
formalism by demanding its solutions to comply with a limited number of
principles, each one with a clear physical meaning. As a further application of
the principles of LSED we derive also the Planck distribution. In a final
section we revisit some of the most tantalizing quandaries of quantum mechanics
from the point of view offered by the present theory, and show that it offers a
clear physical answer to them.
