It seems appropriate to open this meeting with an attempt at a broad survey of what we think we know about nuclear structure, and of what are the most serious gaps in our knowledge. We may start by listing what are the main points in the theoretical views that are held today: 1 (I) We suppose that the nucleus which has a charge Z and . mass number A consists of Z protons and (A-Z) neutrons, the associated neutral atom containing Z electrons in its extranuclear structure.
(2) We suppose that these particles obey the principles of quantum mechanics as set forth, for example, in Dirac's book. Also, we accept the relativistic principle of equivalence of mass and energy.
(3) We suppose that electrons, protons, and neutrons obey Fermi-Dirac statistics, i.e., that all wave functions involving more than one of any of these kinds of particles is anti-symmetric in the co6rdinates of like particles. Also, that these particles each have a spin angular momentum of ยฝh.
(4) We suppose further that charged particles interact according to the Coulomb law, and interact with the electromagnetic field in the sense implied by Maxwell's equations, both through their charges and through their magnetic moments.
(5) We suppose that protons and protons, and protons and neutrons interact with each other by means of additional specifically nuclear interactions which are negligible at greater distances than xo -12 cm. and at distances of the order Io -is cm. are much greater than the Coulomb interactions.