What is the longest nuclear weapons can be delayed, with any POD after 1900 and not causing butterflies so that everything up until mid1945 proceeds more or less as OTL.
If you just got rid of the World Wars, I guess that would get rid of an instant need for nuclear weapons by a couple decades. Or cause some massive geological disaster or plague that kills off a large number of people, that could also be an effective way.
Arthur Jeffrey Dempster is killed by Spanish flu, so he doesn't discover U-235, which possibly delays the discovery until say 1938-39, or even 1940, which means there's no chance of getting a bomb until after the war at the very least.
The other issue is that you don't need relativity to realise that nuclear fission gives off a hell of a lot of energy - that was measured experimentally, and even without the theory to explain it they'd have figured out what was going on over much the same timescale. Once you've measured it, the theory will follow quickly.@nixonshead: The General Theory of Relativity, perhaps, but the Special theory probably would have been found within 5 years. Other people had developed a version of it (admittedly, not as complete as Einstein's), so there's no reason to assume others couldn't.
Didn't Einstein himself say that Poincare was getting there, and that he might have discovered Relativity if Einstein couldn't?@nixonshead: The General Theory of Relativity, perhaps, but the Special theory probably would have been found within 5 years. Other people had developed a version of it (admittedly, not as complete as Einstein's), so there's no reason to assume others couldn't.
Not really, someone's going to stumble across it sooner or later. The only reason I didn't go all-out and suggest killing both him and Francis William Aston in 1918/19 is because I didn't know how important mass spectrometry was in other fields.Is there a way to prevent it from being discovered to the present day given the constraints in the OP, or is it ASB?
Didn't Einstein himself say that Poincare was getting there, and that he might have discovered Relativity if Einstein couldn't?