Here's why Einstein didn't help build the first nuclear bomb

Einstein urged 'quick action' against the Nazi nuclear threat

In August 1939, Einstein and Szilard sent President Franklin D. Roosevelt a letter warning that the Nazis could develop a nuclear bomb. The letter cited the Hungarian physicist Szilard's work and recommended "quick action" in launching a nuclear program to counter this impending threat.

Despite having urged the US to launch a nuclear program, Einstein never took part in the Manhattan Project and he was even barred from consulting with the physicists picked by Los Alamos Laboratory director J. Robert Oppenheimer – the subject of Christopher Nolan's new movie about the development of the nuclear bomb.

The reason is that US officials believed his left-wing political views posed a security threat. In July 1940, they denied him the security clearance required to work on the project.

The Manhattan Project was formed in August 1942. On July 16, Oppenheimer and his so-called "luminaries" performed the first-ever detonation of a nuclear weapon called the "Gadget", for the Trinity Test. Less than a month later, the Allied forces dropped nuclear weapons on Hiroshima and Nagasaki in Japan.

"Woe is me," Einstein is quoted as saying when he learned of the horrific attacks, according to the Bulletin of the Atomic Scientists. "Had I known that the Germans would not succeed in producing an atomic bomb," he said, "I would have never lifted a finger."

According to The New York Times, Szilard and his fellow Hungarian-born physicist Eugene Wigner both expressed their agreement with Einstein.

Oppenheimer echoed Einstein's regret

Oppenheimer himself also expressed regret later in life, echoing the sentiment expressed by Einstein. Recalling the Trinity test, Oppenheimer is famously quoted as stating that it made him think of a line from the Hindu sacred scripture, the Bhagavad-Gita: "Now I am become Death, the destroyer of worlds."

Amid the paranoia of the Red Scare of the US McCarthy era in the 1950s, Oppenheimer's security clearance was also revoked, despite the fact that he led the team that developed the nuclear bomb.

The "father of the atomic bomb" expressed a keen interest in the humanities, including philosophy and language learning, throughout his life, and he was ostracized by the US government for his left-wing beliefs, which saw him join groups tied to the Communist Party before the Manhattan Project.

Oppenheimer's leadership of the Manhattan Project is the focus of Christopher Nolan's new epic 'Oppenheimer', which releases in cinemas today, July 21. You can watch the trailer below.

The new movie encourages reflection on the existential threats we face today, including climate change, artificial intelligence, and nuclear escalation, all of which are reflected by the Bulletin of the Atomic Scientists' Doomsday Clock, which is currently set to 90 seconds before midnight.