Oppenheimer once warned Jawaharlal Nehru about US making weapon stronger than Atom Bomb

With his latest film, Oppenheimer, director Christopher Nolan has once again brought attention to one of history's most divisive figures—and, in Nolan's own words, "the most important person who ever lived." The Manhattan Project, an American initiative that produced the first atomic weapons, was overseen by Oppenheimer in the 1940s.

After dropping two bombs on the Japanese cities of Hiroshima and Nagasaki, Oppenheimer frequently discussed the shame he felt and devoted the remainder of his life to promoting nuclear power regulation. 

He advised his administration to use extreme caution and declined to take part in the development of the hydrogen bomb. In Nolan's film, these topics are extensively addressed, and the movie finishes with a vision of the end of the world that a guilty Oppenheimer has.

Additionally, according to author Nayantara Sahgal, Oppenheimer tried to contact then-prime minister Jawaharlal Nehru about the US government's plans to develop a weapon "far more lethal than the atomic bomb" and pleaded with him not to exchange crucial thorium for the wheat that India was in need of at the time with the Americans. 

Sahgal, who is Nehru's niece, reprinted a letter she got from her mother and Vijaya Lakshmi Pandit, who was working as India's envoy in Moscow, Washington, and London at the time, in her book Nehru: Civilising A Savage World.

In the letter, she described a conversation she'd had with Oppenheimer, who'd driven her up from Princeton and informed her that he had "something very urgent to communicate" and was sending Amiya Chakravarti as an emissary. Amiya brought the chilling news that the US was working on a weapon that was "far more deadly than the atom bomb." The US was ready to trade wheat for access to India's "inexhaustible supply" of thorium for this reason. Oppenheimer pleaded with India not to give the US any thorium, either freely or under duress, but Sahgal said that Nehru would not have complied since he "abhorred nuclear weapons and strove passionately to seek their total elimination".

The theoretical physicist was given the opportunity to become an Indian citizen by Nehru in 1954, according to Oppenheimer's co-biographer Kai Bird, but he probably didn't take it seriously because he was a fervent nationalist. Oppenheimer, which features Cillian Murphy in the lead character, carefully examines the witch hunt that his own government conducted against him when he refused to submit to its demands. In India, where it has earned over Rs 50 crore, the movie has been quite successful.