  We re-examine Peres' statement ``opposite momenta lead to opposite
directions''. It will be shown that Peres' statement is only valid in the large
distance or large time limit. In the short distance or short time limit an
additional deviation from perfect alignment occurs due to the uncertainty of
the location of the source. This error contribution plays a major role in
Popper's orginal experimental proposal. Peres' statement applies rather to the
phenomenon of optical imaging, which was regarded by him as a verification of
his statement. This is because this experiment can in a certain sense be seen
as occurring in the large distance limit. We will also reconsider both
experiments from the viewpoint of Bohmian mechanics. In Bohmian mechanics
particles with exactly opposite momenta will move in opposite directions. In
addition it will prove particularly usefull to use Bohmian mechanics because
the Bohmian trajectories coincide with the conceptual trajectories drawn by
Pittman et al. In this way Bohmian mechanics provides a theoretical basis for
these conceptual trajectories.
