theory of Lorentz was, like those of Weber, Riemann, and Clausius,[1] a theory of electrons; that is to say, all electrodynamical phenomena were ascribed to the agency of moving electric charges, which were supposed in a magnetic field to experience forces proportional to their velocities, and to communicate these forces to the ponderable matter with which they might be associated.[2]
In spite of the fact that the earlier theories of electrons had failed to fulfil the expectations of their authors, the assumption that all electric and magnetic phenomena are due to the presence or motion of individual electric charges was one to which physicists were at this time disposed to give a favourable consideration, for, as we have seen,[3] evidence of the atomic nature of electricity was now contributed by the study of the conduction of electricity through liquids and gases. Moreover, the discoveries of Hertz[4] had shown that a molecule which is emitting light must contain some system resembling a Hertzian vibrator; and the essential process in a Hertzian vibrator is the oscillation of electricity to and fro. Lorentz himself from the outset of his career[5] had supposed the interaction of ponderable matter with the electric field to be effected by the agency of electric charges associated with the material atoms.
The principal difference by which the theory now advanced by Lorentz is distinguished from the theories of Weber,
- ↑ Cf. pp. 226, 231, 262.
- ↑ Some writers have inclined to use the term 'electron-theory' as if it were specially connected with Sir Joseph Thomson's justly celebrated discovery (cf. p. 407, supra) that all negative electrons have equal charges. But Thomson's discovery, though undoubtedly of the greatest importance as a guide to the structure of the universe, has hitherto exercised but little influence on general electromagnetic theory. The reason for this is that in theoretical investigations it is customary to denote the changes of electrons by symbols, e1, e2, …; and the equality or non-equality of these makes no difference to the equations. To take an illustration from Celestial Mechanics, it would clearly make no difference in the general equations of the planetary theory if the masses of the planets happened to be all equal.
- ↑ Cf. chapter xi.
- ↑ Cf. pp. 357-363.
- ↑ Verh. d. Ak. v. Wetenschappen, Amsterdam, Deel xviii (1878).
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