Physicist Richard Feynman returned over and over to an idea that drove his groundbreaking discoveries. His approach was documented by his Caltech colleague David Goodstein in the book Feynman's Lost Lecture about physics classes Feynman taught in the 1960s: Once, I said to him, "Dick, explain to me, so that I can understand it, why spin one-half particles obey Fermi-Dirac statistics."...