“But what is the material? Plutonium?”
I’m not sure, it depends on what kind of bomb they were building.
“why does a certain amount more cause critical mass?”
It’s just the nature of radioactive material. Nuclear radiation is actually the particles giving off mass and energy, as they are decaying into a different kind of atom. A radioactive element is inherently unstable, and the way they achieve stability is to shed off little bits of themselves until they are a different element that is stable.
Now, normally that radiation just shoots off in all directions and is gone. When you put enough radioactive material together in just the right configuration though, some of that radiation will be absorbed by the other nearby radioactive atoms. When that happens, they can’t simply hold on to that additional mass an energy, because they are too unstable. So they have to “re-emit” the radiation that struck them, along with the radiation that they would be already be emitting.
In the right configuration, that creates a chain reaction, one ray hits an atom, that atom emits two more rays that hit two more atoms, which then emit four rays, that hit four atoms, etc, and it just continues until all the material that can keep the reaction going is used up.
that makes sense. How scary!! I read about that Tsar Bomba. It damaged windows I think thousands of miles away. 40 megatons I think. Probably wrong.
I DO KNOW that the Russian scientist said there is a point where adding more material wont make the explosion bigger, but I forget why.
Very interesting read.
Thank again.