  Effects associated in quantum mechanics with a divisible probability wave are
explained as physically real consequences of the equal but opposite reaction of
the apparatus as a particle is measured. Taking as illustration a Mach-Zehnder
interferometer operating by refraction, it is shown that this reaction must
comprise a fluctuation in the reradiation field of complementary effect to the
changes occurring in the photon as it is projected into one or other path. The
evolution of this fluctuation through the experiment will explain the
alternative states of the particle discerned in self interference, while the
maintenance of equilibrium in the face of such fluctuations becomes the source
of the Born probabilities. In this scheme, the probability wave is a
mathematical artifact, epistemic rather than ontic, and akin in this respect to
the simplifying constructions of geometrical optics.
