41 
1920-21.] iEther and the Quantum Theory. 
International Congress of Mathematicians at Strasbourg on September 23, 
1920, Larmor said: “The vortex theory and the elastic solid aether theory 
had had their day, but there was no reason at present why we should 
not admit the existence of an aether — a new aether the properties of which 
were so different from those of ordinary matter that they could be 
expressed only in terms of non-Euclidean space. The alternative was 
complete abstraction, the absence of a basis on which to found our 
theories.” * 
The difficulties to be faced on the older view of the aether in connection 
with the principle of relativity have been clearly explained by N. R. 
Campbell in his books on Modern Electrical Theory .*(■ “ Our original idea 
of the aether was ‘ the body in which radiant energy is localised ’ ; if, in 
that statement, we put ‘ bodies ’ for ‘ body/ all our difficulties vanish ; if the 
energy from different sources is localised in different bodies, then it is 
obvious that the velocity of an observer relative to the body in which the 
energy of one source is localised may be different from that relative to the 
body in which the energy from another source is localised. If we speak of 
‘ aethers ’ and not ‘ the aether,’ all our experiments prove is that the 
particular aether with which we are concerned in any case is that which is 
at rest relatively to the source and may be regarded as forming part of it.” 
One way of visualising such a conception is by employing the electrostatic 
tubes of Faraday in the manner sketched by J. J. Thomson. The results 
of the present paper suggest that the magnetic tubes have at least an equal 
claim to be considered as constituting “ the sethers.” 
§ 9. Assuming the existence of discrete magnetic tubes in accordance 
with the hypothesis of Faraday and the indications of the quantum theory, 
we have to consider the possible nature of the tubes. The method by 
which the magnitude of the unit tube has been arrived at suggests un- 
mistakably that the distinguishing feature of the tube is spin about an 
axis in the direction of its length. This is essentially the view developed 
by Maxwell in his theory of molecular vortices, but it is not necessary to 
adopt the particular mechanism by means of which neighbouring vortices 
were enabled to rotate in the same direction. A classical electron moving 
round the periphery of the spinning tube is, however, not unlike one of the 
“idle wheels” imagined by Maxwell. This mode of representation re- 
sembles that suggested by Larmor in the Physical Society Discussion on 
the Ring Electron (1918) — “ One or more electrons constrained to move 
round a channel would be like an amperean current. It is not unlikely 
* Nature, vol. cvi, p. 196 (1920). 
t Modern Electrical Theory , First Edition, ch. xiv ; Second Edition, Appendix I. 
