Who was Frank Oppenheimer? J Robert Oppenheimer's brother explained

And one other figure who naturally had a real impact on Oppenheimer was his brother, Frank – who is played in the film by After and You star Dylan Arnold – and who is shown to have ties to the Communist party.

But just who was Frank Oppenheimer? Read on for everything you need to know.

Who was Frank Oppenheimer?

Born in 1912, Frank Friedman Oppenheimer was eight years J Robert's junior. Although he briefly considered a career as a professional flautist, he eventually followed his brother into the field of physics and provided his own contributions to the Manhattan Project.

While studying at Caltech, Frank met his future wife Jacquenette 'Jackie' Quann (played in the film by Emma Dumont) and became interested in the Young Communist League, of which she was a member.

As is shown in the film, Frank and Jackie both went on to join the American Communist Party following their marriage in 1936, a move that had been discouraged by J Robert despite his own left-leaning politics and his academic interest in the ideology. Frank and Jackie left the party in 1939, after about three and a half years as members.

During the early stages of the Manhattan Project, Frank was working at the University of California Radiation Laboratory on the problem of uranium isotope separation and he eventually arrived at the Project's Los Alamos base in 1943.

There he worked under Kenneth Bainbridge (played in the film by Josh Peck) and played a crucial role in a number of tasks including preparing the test site ahead of the Trinity test – at which he was present.

Much like his brother, Frank would go on to have fears about the proliferation of nuclear weapons, and on 30th August 1945 – less than a month after the bomb was dropped on Hiroshima – he became a founding member of the Association of Los Alamos Scientists which promoted peaceful control of nuclear power.

In the years after the war, during the era of McCarthyism, Frank's previous associations with the Communist Party made him a prime target for the House Un-American Activities Committee (HUAC).

As part of an investigation into the possible mishandling of atomic secrets during the war, Frank was called before the HUAC in 1949 and eventually resigned from his post at the University of Minnesota, although he refused to name other members of the Party.

The next ten years or so were understandably very difficult for Frank, who was unable to find employment either at home or abroad – the latter due to being denied a passport – and so he and Jackie instead worked as cattle ranchers.

But in 1957 – with McCarthyism on the wane – he returned to teaching at a local high school, and two years later he was offered a position at the University of Colorado after endorsements from a number of high-profile physicists.

He went on to have a successful career in physics – with his key contribution being the founding of the Exploratorium Museum in San Francisco – before passing away aged 72 in 1985, 18 years after his brother's death.

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Oppenheimer is now showing in UK cinemas. Check out more of our Film coverage or visit our TV Guide to see what's on tonight.

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Oppenheimer is now showing in UK cinemas. Check out more of our Film coverage or visit our TV Guide and Streaming Guide to find out what's on tonight.

Try Radio Times magazine today and get 12 issues for only £1 with delivery to your home – subscribe now. For more from the biggest stars in TV, listen to The Radio Times Podcast.