I just read that 68 years ago Little Boy was dropped on Hiroshima, which made me wonder about some rather historical facts about the development of the first nuclear bombs; they seem to be several questions, but they boil down to the same thing: the theoretical aspects of the development of the bombs.

As far as I know, nuclear fission was already understood at the time, so was all the competition between the american team and the german team to develop the bomb first, a mere matter of engineering? Or what was the role of theoretical physicists such as Richard Feynman? Also, I've heard things like that the team led by Werner Heisenberg had misconceptions about nuclear fission, so that his team could not develop the bomb first.

Can anyone put in perspective the theoretical aspects of the development of the bombs taking care of this historical issues?

I've just read that 68 years ago Little Boy was dropped on Hiroshima, which made me wonder about some rather historical facts about the development of the first nuclear bombs; they seem to be several questions, but they boil down to the same thing: the theoretical aspects of the development of the bombs.

As far as I know, nuclear fission was already understood at the time, so was all the competition between the american team and the german team to develop the bomb first, a mere matter of engineering? Or what was the role of theoretical physicists such as Richard Feynman? Also, I've heard things like that the team led by Werner Heisenberg had misconceptions about nuclear fission, so that his team could not develop the bomb first.

Can anyone put in perspective the theoretical aspects of the development of the bombs taking care of this historical issues?