I don't think that's the OP meant. But perhaps you're aware of the mother of all demos. That was in 1968, and we've been effectively just figuring out how to e

I don't think that's the OP meant. But perhaps you're aware of the mother of all demos. That was in 1968, and we've been effectively just figuring out how to economically deploy the ideas from that demo, and figure out how to actually use these innovations to affect the rest of our lives for the last 50 years. Another thing to consider is just how systemic and total the innovations in the first half of the 20th century were. We discovered blood types, antibiotics, deployed widespread industrial refrigeration, made air conditioning viable, got widespread automobile adoption, the birth of heavier than air flight, birth of commercial aviation, invention of the jet engine. We harnessed nuclear power for the first time. The first medical x-ray just barely misses the time cut. I don't know if it's fair to characterize the last 50 years as "stagnation", since maybe 1900 to 1950 is an unfair comparison. But it is fair to say that the rate of change as obviously changed.