In Oppenheimer (2023), Oppenheimer let Serber demonstrate the size of the nuclear bomb to his team:
Serber: Using U-235, the bomb will need a...
Oppenheimer: Uh-uh.
Serber: Sorry. Gadget will need a 33-pound sphere about this size. Or using plutonium, the ten-pound sphere.
In this scene, Oppenheimer clearly instructed Serber not to use the word ‘bomb’; instead, Serber used the word ‘Gadget’.”
Why doesn't Oppenheimer like the word "bomb" being used to describe the bomb?
It was a security measure so that word of what the device actually was could be concealed from those who should not know when discussed.
At the April 1943 Los Alamos Primer Conference, physicist Robert Serber used the word “bomb” as he began his now-famous lectures. According to Serber, this prompted Oppenheimer to take action:
I started lecturing. I started talking about the “bomb.” After a couple of minutes Oppie sent John Manley up to tell me not to use that word. Too many workmen around, Manley said. They were worried about security. I should use “gadget” instead. In the Primer Condon wrote it down both ways. But around Los Alamos after that we called the bomb we were building the “gadget.”
Source — The Los Alamos Primer: The First Lectures on How To Build an Atomic Bomb, p. 4, by Robert Serber & Richard Rhodes (ed.)
