On the Production of the Positive Electron

The experimental discovery of the positive electron gives us a striking confirmation of Dirac's theory od the electron, and of his most recent attempts to gice a consistent interpretation of the formalism of that theory. As is well know, and quite apart from the difficulties connected with the existence and stability of the electron itself, the theory in its original form led to very grave difficulties in all problems involving length sof the order of the Compton wavelength, in that it predicted the occurrence of electrons of negative kinetic energy, in gross conflict with experience. Dirac has pointed out that we might obtain a consistent theory by assuming that it is only the absence of electrons of negative kinetic energy that has a physical meaning; in this way one could avoid the occurrence of the critical transitions, and yet understand the validity of many correct predictions of the theory, such as the formula for relativistic fine structure, and the Thomson and Klein-Nishina scattering formulae: only the physical interpretation of the formalism was changed, and involved in many cases the appearance pairs of electrons and "antielectrons" -- particles of electronic mass and of positive charge numerically equal to that of the electron. It was this aspect of the theory which remained dubious; and the discovery of the positive electron appears to settle that doubt.