I definitely think of the first ~7 decades of the 20th century that way. If you were born in 1900, you would (most likely) have witnessed: the internal combustion engine, human flight (from nothing to faster than the speed of sound), a major world wide economic depression, two world wars, the invention of nuclear power, major social and legal changes in the '60s (in some places at least), and the exploration of space, starting from nothing and most likely including humans walking on the moon.
Or another way to look at it: during the N years I have lived, how much has the the world changed compared to the period of time between 1900 and 1900 + N? Though on reflection, I guess this is probably the sort of thought experiment that becomes more interesting as one gets older..
