’s or other magnitudes of the same kind. But a number of facts and phenomena render the success of this attitude doubtful.
In the first place, in the case of the electron, the ratio of its charge to its mass is of the order of
.[130] It follows that the electrostatic repulsion which two distant electrons exert upon each other is
times greater than their mutual gravitational attraction. Now the existence of so high a number, constituting one of the characteristics of the electron, seems to preclude the possibility of our deducing the existence of the electron from the field equations. It would appear as though some other controlling influence were active. We might possibly have to seek for this influence in the total number of electrons existing in the universe, a number determined, presumably, by chance.
Field physics, together with the principle of action, encounters further difficulties when we consider the quantum phenomena and the existence of Bohr’s atom. In a number of cases, therefore, there appears to be something deeper behind the field itself. If so, we should have to limit the rôle of the field to a purely passive part, to that of transmitting effects, not of engendering them. If, however, we abandon all attempts at interpreting matter in terms of the field quantities, this does not mean that we must relapse into the discarded idea of substance. In the present state of our knowledge all these problems are so confused that it seems useless to state anything definite about them. All we can say is that we are faced with a something which we do not understand. Weyl expresses these ideas in the following words:
“If Mie’s views are correct, we could recognise the field as objective reality, and physics would no longer be far from the goal of giving so complete a grasp of the nature of the physical world, of matter and of natural forces, that logical necessity would extract from this insight the unique laws that underlie the occurrence of physical events. For the present, however, we must reject these bold hopes. The laws of the metrical field deal less with reality itself than with the shadow-like extended medium that serves as a link between material things, and with the formal constitution of this medium that gives it the power of transmitting effects.” And elsewhere: “We must here state in unmistakable language that physics at its present stage can in no wise be regarded as lending support to the belief that there is a causality of physical nature which is founded on rigorously exact laws.”
All in all, we must realise that the farther we go, the more inextricable our difficulties become. The existence of matter still remains a mystery.