There has existed a phenomenological theory for the weak force since 1958. That is to say, there existed formulae that correctly described the effects of the weak force for all particles, under all circumstances, that could be realized in the experiments of that time, with margins of error within a small percentage. The theory could never be a fundamental theory, because it was understood that the theory would break down in more violent collision experiments. But it was also known that it would take at least a decade for the experimentalists to reach such energies in a laboratory, and so it seemed that for the time being this ‘temporary’ theory would have to be sufficient.

For the strong force there were a hotchpotch of phenomenological theories. None of these were very accurate, and this situation was obviously very unsatisfactory. The only features of the strong interactions that were well understood were its various symmetry properties and the ensuing conservation laws. Strangeness, isospin and a few other quantities were very strictly conserved for this force.

This was in striking contrast to the situation with the electromagnetic force. This has the peculiarity that it can propagate over long distances, and so this force is also experienced in the everyday world. The British physicist James Clerk Maxwell had given the mathematical formulation of electrodynamics as early as 1873 (see Figure 6).