Scientists and the atomic bomb?!

I also would have to dispute whether it ended badly, since World War II we've had no global wars despite two superpowers which hated each others guts, without nuclear weapons to make a war so bad as to be unthinkable they probably would've faced each other in all out warfare and made the death toll of World War II look like a trivial matter (it's also worth noting that things look very much like the pre-World War I era these days, without nuclear weapons to scare everyone from going to war it is likely we'd eventually get another world war).