Up to this point the motive that has guided us has been the desire to discover unity in nature by reducing all things to some fundamental form of existence. There is, however, another way to approach the problem; and this time our guiding principle will be no longer solely mathematical harmony, but also experimental facts.
We must realise that the tensor
, whose components represent those physical magnitudes which our senses perceive and our instruments measure, can at best be considered to portray effects observed only in a macroscopic way. Phenomena such as radioactive explosions and all we have learnt indirectly from the exploration of the atom go to show that matter in the final analysis is constituted by whirling electrons around which intense electromagnetic fields are present. It follows that a microscopic investigation of matter would yield a very different picture from that which we construct from our crude sense perceptions, and that could we but view the atom in an ultra-microscopic way it would appear to us as a region subjected to intense electromagnetic actions. It would seem, therefore, that our macroscopic tensor
must comprise the electromagnetic one
in its constitution.
But in order to remove the duality between matter and electricity, we should have to prove that