  Conventionally, one interprets the correlations observed in
Einstein-Podolsky-Rosen experiments by Bell's inequalities and quantum
nonlocality. We show, in this paper, that identical correlations arise, if the
phase relations of electromagnetic fields are considered. In particular, we
proceed from an analysis of a one-photon model. The correlation probability in
this case contains a phase relation cos(b - a) between the two settings. In the
two photon model the phases of the photon's electromagnetic fields are related
at the origin. It is shown that this relation can be translated into a
linearity requirement for electromagnetic fields between the two polarizers.
Along these lines we compute the correlation integral with an expression
conserving linearity. This expression, as shown, correctly describes the
measured values. It seems thus that quantum nonlocality can be seen as a
combination of boundary conditions on possible electromagnetic fields between
the polarizers and a relation of the electromagnetic fields of the two photons
via a phase. We expect the same feature to arise in every experiment, where
joint probabilities of separate polarization measurements are determined.
