Physics of critical mass for uranium, mostly the work of Rudolf Peierls on nuclear fission and how a simple question from Otto Frisch led to the realization that an atomic bomb was possible.

Followup video: How to calculate an atomic bomb's critical mass    • How to calculate an atomic bomb's cri...  

Playlist Physics of Nuclear Weapons:    • Physics of Nuclear Weapons  
"Critical Assembly Simulator" by Alex Wellerstein https://blog.nuclearsecrecy.com/misc/...

00:00 Introduction
01:01 Nuclear Fission
02:20 Critical mass: Bohr
03:25 Critical mass: Perrin
04:27 Critical mass: Peierls
08:29 Cross section & mean free path
09:59 Critical mass: FrischPeierls