This 1952 Nuclear Physics Video Is Amazing
Even after WWII, in the 50's, nuclear physics was still new. And they were pretty forthcoming about the details they understood at the time. This is really interesting. A 'simple terms' synopsis of how nuclear weapons and energy work. All the way down to materials, and how to refine those materials. It really was a simpler time.
Of course we've come a long way from these early nuclear designs... There have been thousands of new ways to make more firepower since then. Though the testing is more or less computed digitally rather than blowing out White Sands National Monument anymore... which is a good thing.