An analysis of the principle of minimal electromagnetic interaction

The meaning and contents of the principle of minimal electromagnetic interactions are analyzed in the framework of the classical electrodynamics of a point charged particle. The essence of this analysis consists in expressing the free electromagnetic field as a difference of retarded and advanced fields and in observing the effect of switching on the minimal coupling on the retarded field. A new equivalent formulation of this principle is given and the possibility of its generalization is suggested.Dedicated to Professor V. Votruba on his sixtieth birthday.