ABSTRACT
In accordance with the outline concerning the interrelation of physical theories, it is essential to establish that a theory of a given level contain the corresponding lower-level theories in suitable approximation and that it be itself an approximation of the corresponding higher-level theories. This interrelationship will be studied for the charged point-particle theory of the preceding chapters. From the point of view of symmetry properties, the nonrelativistic approximation of charged-particle theory is therefore inconsistent: the theory is neither Galilean nor Lorentz invariant. The classical theory of charged particles gives no indication of a quantization of charge. There is no smallest amount of charge and the theory carries through for any arbitrary choice of charge on a particle. Sir Isaac Newton's theory of gravitation is inconsistent with the special theory of relativity. In the attempt at constructing a theory of gravitation consistent with special relativity, it became necessary to go beyond special relativity in an essential way.
