Cillian Murphy as J. Robert Oppenheimer in "Oppenheimer."Universal Pictures Atomic bombs work via a process called nuclear fission that involves atom splitting. Shortly after scientists discovered nuclear fission, the possibility of a bomb was quickly realized. Albert Einstein didn't make the first atomic bombs, but his famous equation explains how they work. With its depiction of the first atomic bomb explosion, "Oppenheimer" highlights the massive destructive power of these early nuclear weapons.While you might want to brush up on your physics before seeing the film — Cillian Murphy certainly did to play the role of J.