This is the first episode in a three-episode series about "Oppenheimer" and the historical debates raised by the blockbuster film.

On November 16, 1945, Robert Oppenheimer delivered an address to the American Philosophical Society about the changed world ushered in by a "most terrible weapon." The father of the atomic bomb cautioned his audience at the University of Pennsylvania that international cooperation was necessary to avoid future use of hundreds if not thousands of bombs in aggressive war. But Oppenheimer did not express regret – neither in 1945 nor for the rest of his life – about leading the A-bomb project to its successful completion. Yet he was haunted by its use against "an essentially defeated enemy." The complicated scientist was brought to life on the big screen by actor Cillian Murphy in director Christopher Nolan's cinematic masterpiece, "Oppenheimer." In this episode, national security analyst and arms control expert Joe Cirincione discusses the enduring consequences of the discovery of nuclear fission in 1939 and of the manufacture of weapons of mass destruction capable of destroying human life. Note: Audio excerpts of the "Oppenheimer" film and of director Christopher Nolan are courtesy Universal Pictures.