Whenever we proceed from the known into the unknown we may hope to understand, but we may have to learn at the same time a new meaning of the word “understanding.”
This violent reaction on the recent development of modern physics can only be understood when one realizes that here the foundations of physics have started moving; and that this motion has caused the feeling that the ground would be cut from science.
The problems of language here are really serious. We wish to speak in some way about the structure of the atoms and not only about the ‘facts’ — the latter being, for instance, the black spots on a photographic plate or the water droplets in a cloud chamber. But we cannot speak about the atoms in ordinary language.
The existing scientific concepts cover always only a very limited part of reality, and the other part that has not yet been understood is infinite.
The equation of motion holds at all times, it is in this sense eternal, whereas the geometrical forms, like the orbits, are changing. Therefore, the mathematical forms that represent the elementary particles will be solutions of some eternal law of motion for matter. This is a problem which has not yet been solved.
Natural science does not simply describe and explain nature; it is a part of the interplay between nature and ourselves.
Even for the physicist the description in plain language will be the criterion of the degree of understanding that has been reached.
Any concepts or words which have been formed in the past through the interplay between the world and ourselves are not really sharply defined with respect to their meaning: that is to say, we do not know exactly how far they will help us in finding our way in the world.