"I am become death, the destroyer of worlds."
This quote, which originally came from the Hindu scripture Bhagavad Gita but is widely attributed to Oppenheimer, is uttered several times in the film. During a steamy encounter, Oppenheimer's lover Jean Tatlock reads the quote from a book in one of Oppenheimer's books about Hinduism (he had a lifelong interest in the religion and its teachings), foreshadowing his eventually feelings about the role he played in the development and deployment of the atomic bomb.
After the first test of a nuclear weapon, which was later called the "Trinity Test," Oppenheimer said he reflected on this new, powerful weapon, which he and his team thought could potentially cause a chain reaction that could end the world. He was remorseful that he, through his invention, wrought so much death and destruction on the world and changed it forever. For Oppenheimer, he was the embodiment of death; with his invention, he (and those who came after him) could end life as he knew it.
"I don't know if we can be trusted with such a weapon. But I know the Nazis can't."
Oppenheimer says this during his involvement in the Manhattan Project. He expresses frustration that he and his team are being forced to create such a destructive weapon. He knew that Adolf Hitler and his Nazi party couldn't be trusted with such a powerful weapon; however, he also questioned if the U.S. Government or anyone else could be trusted with it as well. In the end, Oppenheimer adhered to the lesser of two evils principle. In other words, the development of an atomic weapon is immoral. But the U.S. developing an atomic weapon is less immoral than the Nazis developing a weapon. This principle in part convinced Oppenheimer to head up the Manhattan Project and create the weapon so that the Nazis couldn't develop it before the U.S.
"You think because you let them tar and feather you that the world will forgive you? They won't."
Here, J. Robert Oppenheimer's wife encourages him to fight against charges that he is a Communist sympathizer. Outside forces, led by Admiral Lewis Strauss, had accused Oppenheimer of being a Communist sympathizer to ride the wave of McCarthyism in the culture and revoke his security clearance. Despite having issues, Kitty and her husband loved each other, and Kitty wanted nothing but the best from him. This quote reflects that dynamic in their relationship.
