Quantum mechanics continues to beguile scholars and the public alike, as does the stirring tale of its discovery: during the interwar period, amid the vibrant milieu of Weimar Germany, a collection of liberal, free-thinking physicists, many of whom were Jewish, developed a theory that changed the world. It is thus all the more curious that one of the major architects of this famous theory remains practically unknown: the brilliant German mathematical physicist Pascual Jordan (1902–1980). But despite his crucial contributions to twentieth century physics, Jordan is largely remembered today, if at all, for his Nazi-era writings that praised Hitler's regime. Yet the omission of Jordan has left a lacuna, for it is historically significant that one of the talented quantum pioneers saw no apparent contradiction in joining the Nazi Party.
In this talk, I analyze Jordan's Nazism along with his relationship with Jewish émigrés by reconstructing a paper coauthored by Jordan in collaboration with two Jewish colleagues, Eugene Wigner and John von Neumann. This "three-man paper," drafted in the fateful year of 1933, introduced a new type of non-associative algebras later termed "Jordan algebras." Amazingly, neither Jordan's decision to join the Nazi Party that spring nor Wigner and von Neumann's emigration from Germany that fall prevented this intensive collaborative effort. Through the remarkable tale of Jordan's eponymous algebra, I draw conclusions from his life relevant for both historians of science and historians of modern Germany.