Cillian Murphy's portrayal of J. Robert Oppenheimer, the «father of the atomic bomb,» in Christopher Nolan's upcoming epic,, was an intense undertaking.The actor's traditionally intense visage is only made more dramatic by the sunken cheekbones and dour expression he wears as the theoretical physicist who led the Manhattan Project during World War II, who seemed to carry the literal weight of the world as he conducted experiments that could lead to the end of humanity.«When Oppenheimer was running the Manhattan Project and they were doing their calculations, early on they saw the possibility that when they triggered the first atomic device, to test it, they might start a chain reaction that set fire to the atmosphere and destroyed the whole world,» Nolan explained to ET ahead of the film's premiere.«A small possibility, [but they] couldn't eliminate it completely through theory, and yet they went ahead and they pushed that button,» he continued.