ABSTRACT
Strong interaction physics first began with Rutherford’s discovery of the nucleus in 1910. The solar-system model of the atom that emerged from this discovery soon gave way to Bohr’s theory of the atom, and then to quantum mechanics. Rapid progress was made in understanding atomic physics during this period. Shortly after Chadwick’s discovery, Wigner realized that nuclear forces must have a very short range and must be very strong. The energy per bond is not roughly the same, and so something else is needed to explain the large increase in binding energy. Wigner reasoned that a short-range force can explain this, because as the number of bonds increases the nucleons pull closer together, and thereby experience a deeper potential well. The assignment of strangeness to a given particle follows from isospin assignments plus some conventions.
