Abstract

The development of modern quantum theory has superseded the classical theory of particles. Nevertheless, the imagery and terminology of the classical theory still surivive, both in intuitive understanding and mathematical formulation. This paper shows that although the classical concept of a particle may be useful for some purposes of intuition, it is useless for others, and it is never necessary. In microphysics, particles are usually; assigned a cherge e and a mass m. we discuss the meaning of these quantities in terms of laboratory; experience