With a few exceptions, like Oppenheimer and Bohr, the physicists at Los Alamos are fictitious versions of their real-life counterparts. For example, Frank Winter apparently represents Seth Neddermeyer, who was in charge of the implosion project, and Charlie Isaacs is given some of the same tasks as Richard Feynman, like showing Bohr around the site and visiting the X-10 reactor at Oak Ridge.