Richard Feynman Lecture -- "Los Alamos From Below"

I spent a fair amount of time during the film playing 'Spot Jack Quaid' in anticipation of Feynman being called out at some point. He is spotted early during the montage when Oppenheimer goes recruiting, and then during various scenes in the background, twice playing bongos (!), but only once is he called by name- Teller calls his name right before the Trinity test for not having goggles or a welding glass to look through, and he notes he is in a truck with a thick windshield that blocks the UV. I smiled so much when that little tidbit happens, as it is a story he prominently tells in his book 'Surely You're Joking Mr Feynman...' He gives an incredible account of his time there in the lecture (and almost stand-up-comedy act) 'Los Alamos from Below' - [this video] So highly entertaining.

If the fissile core is anything like the original Trinity test one, it relies on a solid ball of plutonium metal being compacted to reach criticality (modern ones may be hollow). This means the explosion wavefront needs to arrive simultaneously all around the ball. This is hard! A ton of the computational effort legendarily described by Feynman with his IBM tabulator/multiple coloured cards story was, I believe, just to make this work. Link to the relevant part (the whole lecture is a hoot). [this video] Anyway the original bomb had a lot of detonators all around that needed to be fired right. Modern ones have only two, from the little I've seen in published imagery. [link] One hopes this is arranged so simultaneous firing of both detonators results in a fizzle, and a precise stagger is needed. Either way though, an external explosive force will just disassemble the thing, not cause it to go off.