The Strangest Man : The Hidden Life of Paul Dirac , Mystic of the Atom Reviewed by Brian

In September 1926 Paul Dirac began a five-month visit with Niels Bohr at the Institute for Theoretical Physics in Copenhagen. Dirac, then barely twenty-four years old, had been in possession of his Ph.D. since only May of that year. Bohr was middle aged and already a Nobel laureate, but he was accustomed to working with junior colleagues. Nevertheless, collaboration between the two physicists proved to be impossible. Whereas Dirac was taciturn, Bohr was voluble: his habit of thinking out loud produced a constant stream of sentences in need of revision or retraction. By bouncing half-baked ideas off Dirac, Bohr elicited little more than the response, “At school I was always taught not to start a sentence until I knew how to finish it.” When Bohr bemoaned to Ernest Rutherford, “Dirac never says anything,” Rutherford replied with a story about a shop owner assuaging a dissatisfied customer who had purchased a parrot that would not speak. “Please forgive me. You wanted a parrot that talks, and I gave you the parrot that thinks.” Dirac departed Copenhagen in January 1927 to stay with Max Born in Göttingen. In doing so, he joined the steady flow of promising young physicists who traveled between those two centers of quantum physics in the 1920s. According to Max Delbrück, one of Born’s students and a future Nobelist, these peripatetics were “highly