spherical disposition leads to a paradox. Indeed, one point located in
"c" will receive the antagonistic influence of " a' " and " b' ". But
if the points "a" and "b" are included in a spherical disposition, it
appears that the influence will be agonistic.
To resolve this paradox, it is necessary to conclude that the space is
curved by the particle and that virtual photon which goes from "a" to
"c" doesn't take the shortest way in an Euclidian space but the
way in a curved space. The outside photons cannot penetrate
inside the particle. The inside photons can not go out of the particle.
force is described by equations of Maxwell but for very short distances (1 Fermi), these
equations must consider the curvature of the space.