Why does the natural world in Fallout look so damaged 200 years after the nuclear war?

Because Bethesda didn’t care to know how nuclear bombs work. In real life, 200 years after a nuclear bomb detonation, it would look more like this: or and…

If a planet about 10 light years away from Earth had an all-out nuclear war (10 years ago), would we be able to detect it?

No. I’m not sure if this is still true or not, but a number of years ago, I heard from one astronomer who said “If there is an…