Isotopic Spin and Mass Quantization

In the sessions devoted to quantum electrodynamics it has become clear that the theory of the electron and its electromagnetic interaction is at the moment in good shape, in the sense that there is hardly any direct experimental indication for the need of improvement, let alone for the direction in which modification of the theory should be sought for. It is true that the divergent character of the formalism leads many of us to believe that the last word in quantum electrodynamics has by no means yet been spoken, but there is at the present no conflict between theory and experiment which stimulates attempts to add to the body of our understanding. It is quite a different story in mesodynamics. With certainty we know that there are charged and neutral x-mesons, that these are pseudoscalar and that they are strongly coupled to nucleons. We have also increasing evidence to the effect that this interaction is charge independent, a feature which will presently be discussed in more detail. But no solutions to the coupled nucleon n-meson equations having a well defined range of validity are known to us. And in fact we may have doubts whether these equations themselves are at all worth solving beyond the most trivial stages. As you see, I am raising two points. First, there is one of method: how to define and obtain approximations in the case of large coupling constants. I shall not discuss this problem here but rather make some comments on the second question: to what extent may the conventional set of equations describing coupled nucleons, n-mesons and photons be considered as a reasonable basis for mesodynamics ? To begin with I list a number of questions in meson physics that seem of outstanding interest. Thereupon a program will be outlined aiming at answering those questions from a more unified point of