The first greatest economic boom came with the mass replacement of animal power with steam power.
The second greatest economic boom started around 1910 with the coming widespread deployment of automobiles, airplanes, indoor plumbing, refrigeration, radio and telephones.
The first was probably the use of language or tools. (Hard to say which came first, since other animals use tools too after a fashion.) After that the control of fire, the domestication of animals, agriculture, the city...
Fortunately they seem to occur at increasingly small intervals.
He has an interesting plot where he takes a number of opinions about the most important events ever (e.g. fire, farming, etc.), and plots them all on a logarithmic time plot. The line fit to the 20 or so opinions is very apparent.
I'm still inclined to give the position to steam. Coaxing a lump of coal to do more work than a team of horses was an exponential shift (while staying within the realm of widespread application, unlike fission.)
If they occur at increasingly small intervals, they are probably also decreasingly important and far-reaching. Probably we see those that are closer to us more important as they are.
I don't think that's the case. Due to exponential population growth, the majority of humans that have ever lived are still alive, so it would seem to be a natural hypothesis that most of the progress that has ever been made has been made in the past century.
You realize what happened after the boom of the 1920s, right? The worst depression this world has ever seen . There are many who say we are close to another.
The second greatest economic boom started around 1910 with the coming widespread deployment of automobiles, airplanes, indoor plumbing, refrigeration, radio and telephones.