Gwern pointed me to the quote on his website: https://www.gwern.net/on-really-trying https://www.gwern.net/on-really-trying The quote is: "the one secret conc

Gwern pointed me to the quote on his website: https://www.gwern.net/on-really-trying https://www.gwern.net/on-really-trying The quote is: "the one secret concerning the atomic bomb which might have been kept and which was given to the public and to all potential enemies without the least inhibition, was that of the possibility on its construction". As others had suspected, it's about the atomic bomb, not the H-bomb, which in retrospect makes more sense of course.