I was thinking about this today driving my car to Costco and thinking how much better it is in every respect, but that's progress. As for which 50 year period has been most "shocking", I don't know, of course, I'd probably select 1900 to 1950.
Getting back to weird history, this is one reason that WWI fascinates me much more than WWII.
There was, of course, incredible technological innovation during WWII but I think the incredible technological innovation during WWI was more impressive.
When WWI started aircraft were too few to have any significant impact and the few that did exist were basically bedsheets draped over sticks, they looked a lot like the Wright Flier. At the end of WWI aircraft were a major part of warfare and the most modern planes looked a lot like modern planes today, 100+ years later.
At the beginning of WWI tactics and strategies of warfare were not much different from what they had been when Napoleon roamed European battlefields 100 years earlier, at the end tactics and strategies were not much different than they are today, 100 years later.
A soldier from Napoleon's era would have understood pretty much everything he saw on the battlefield in 1914. The major exception is aircraft but as I stated they were so few in number as to not be terribly relevant. Meanwhile, a soldier from 1918 would be familiar with most everything on a modern battlefield. The tanks, aircraft, and other weapons of today are obviously better but there isn't much that is altogether new.
The other reasons that WWI fascinates me are the changes relative to what had existed before and the fact that there are easily plausible scenarios in which the other side wins.
Changes:
WWII saw the end of the Nazi's in Germany and the Fascists in Italy but they had only been in power for about 12 and about 20 years respectively. That is nothing compared to WWI seeing the end of the Hapsburgs in Austria-Hungary, the Romanovs in Russia, and the Hohenzollerns in Germany. While the Kaisers had only ruled Germany at large four about 50 years at least part of the possessions of those three families had been under their rule for centuries.
Plausible for the other side to win:
When WWI began there were three factions in America. There were a significant number of people, mostly first and second generation immigrants from the Central Powers and Irish who wanted the US to join the Central Powers. There were people who wanted the US to join the Allies, and the majority wanted the US to stay neutral. If Germany had been better at diplomacy (which is an extremely low bar) it is easy to imagine the US remaining neutral and not impossible to imagine the US joining the Central Powers. Unlike the WWII, Russia did collapse in WWI and the Germans were supremely close to knocking out the French in 1914 and again in their Spring Offensive in 1918. There are a multitude of plausible scenarios in which the Central Powers achieve at least a partial victory.