In the late 1940s, a number of never-before-seen subatomic particles were discovered which seemed to behave in a most peculiar manner. As was first noticed by physicist Abraham Pais, the new particles, which were unstable, were produced, always in pairs, via the strong interaction (the force that holds the atomic nucleus together against the mutual electrostatic repulsion of the constituent protons), but that the strong force was not responsible for their decay. There is a Heisenberg uncertainty relation between the interaction timescale and the interaction strength; the stronger the interaction, the shorter the timescale. The particles were produced in about 10-23 s, consistent with the strong interaction. They decayed, though, in about 10-10 s and thus indicated that a weaker interaction (aptly named the weak interaction) was responsible for their decay. In 1953 Murray Gell-Mann and Kazuhiko Nishijima put forth a classification scheme that explained the new...