Who is Dr. Robert Oppenhsimer from The Demon-Haunted World and what is their importance?

Dr. Robert Oppenheimer is the scientific director of the Manhattan Project to develop the first atomic bomb that was later dropped on Hiroshima and Nagasaki, Japan during World War II, Oppenheimer later came to believe that he had sinned and was remorseful for his actions. Sagan mentions him as a scientist who developed a conscience, one of the "good guys" among nucloear phyisicists. After witnessing the devastation caused by the weapons he developed, Oppenheimer became chairman of the general advisory committee to the post-war Atomic Energy Commission (AEC).