  This work is about Bohmian mechanics, a non-relativistic quantum theory about
the motion of particles and their trajectories, named after its inventor David
Bohm (Bohm,1952). This mechanics resolves all paradoxes associated with the
measurement problem in nonrelativistic quantum mechanics. It accounts for
quantum randomness, absolute uncertainty, the meaning of the wave function of a
system, collapse of the wave function, and familiar (macroscopic) reality. We
review the purpose for which Bohmian trajectories were invented: to serve as
the foundation of quantum mechanics, i.e., to explain quantum mechanics in
terms of a theory that is free of paradoxes and allows an understanding that is
as clear as that of classical mechanics. To achieve this we analyse an optical
interferometry experiment devised and carried out 2005 by Shahriar Afshar
(Afshar,2005). The radical claim of Afshar implies in his own words the
'observation of physical reality in the classical sense' for both 'which path
(particle-like)' and 'interference (wave-like)' properties of photons in the
same experimental setup through the violation of the Englert-Greenberger
duality relation (Englert,1996) that according to Englert can be regarded as
quantifying of the 'principle of complementarity'.
