One can distinguish between two main procedures for a theoretical physicist. One of them is to work from the experimental basis. For this, one must keep in close touch with the experimental physicists. One reads about all the results they obtain and tries to fit them into a comprehensive and satisfying scheme.
The other procedure is to work from the mathematical basis. One examines and criticizes the existing theory. One tries to pinpoint the faults in it and then tries to remove them. The difficulty here is to remove the faults without destroying the very great successes of the existing theory METHODS IN THEORETICAL PHYSICS.
There are these two general procedures, but of course the distinction between them is not hard-and-fast. There are all grades of procedure between the extremes1.
Which procedure one follows depends largely on the subject of study. For a subject about which very little is known, where one is breaking quite new ground, one is pretty well forced to follow the procedure based on experiment. One must keep to the experimental basis if one is not to indulge in wild speculation that is almost certain to be wrong. One should not condemn speculation altogether. It can be entertaining METHODS IN THEORETICAL PHYSICS and may be indirectly useful even if it does turn out to be wrong. One should always keep an open mind receptive to new ideas, so one should not completely oppose speculation, but one must take care not to get too involved in it.
With increasing knowledge of a subject when one has a great deal of support to work from, one can go over more and more towards the mathematical procedure.
1. extremes – крайности