  A classical explanation of interference effects in the double slit experiment
is proposed. We claim that for every single "particle" a thermal context can be
defined, which reflects its embedding within boundary conditions as given by
the totality of arrangements in an experimental apparatus. To account for this
context, we introduce a "path excitation field", which derives from the
thermodynamics of the zero-point vacuum and which represents all possible paths
a "particle" can take via thermal path fluctuations. The intensity distribution
on a screen behind a double slit is calculated, as well as the corresponding
trajectories and the probability density current. The trajectories are shown to
obey a "no crossing" rule with respect to the central line, i.e., between the
two slits and orthogonal to their connecting line. This agrees with the Bohmian
interpretation, but appears here without the necessity of invoking the quantum
potential.
