I've always been under the impression that the Fallout universe was the same as ours, or at least up until the 1950s where it diverged into the realms of science-fiction as portrayed in movies at the time. However, I was reading the Wiki and noticed that it said about divergence as early as the 1600s. So, when does divergence actually happen?

. I wish I could of helped you more but I'm sure someone will come along that knows more than I do about this stuff and help you. But this is an extremely dead area of the forums.