The Nuclear bomb is believe it or not one of the main weapons in Fallout 4, but ironically is also the cause of the game. The Physics behind Nuclear bombs is extremely complicated, but in this blog I will try to explain it as best as I can. The immense energy behind a nuclear explosion can be attributed to nuclear fission, which is the splitting of atoms. In a nukes case, it is most likely Uranium - 235. Two masses of highly pure Uranium 235 are positioned perfectly so that when they collide they start a chain reaction unleashing massive amount of energy in the form of an explosion. The masses collide extremely fast in order to keep the time of fission short, so that the explosion is as powerful as possible. This was the type of nuke dropped on Hiroshima in 1945 which killed so many people and caused destruction never before seen by man. The initial explosion wasn't the only terrible thing to happen however, because after the explosion massive amounts of radiation remained which made the area and its surroundings uninhabitable. Fallout 4 does a great job of recreating a barren wasteland which the player can easily tell has been ravaged by a nuclear bomb.
<--------- Nuclear Fission of Uranium-235