Some parameters to quantify the rate of acquisition of knowledge:
Some interesting factors to consider:
Technology enhances productivity, which supports both larger absolute populations as well as a larger percentage of "knowledge workers", ie scientists, as a fraction of the total population. Using technology requires people trained in technology, which spawns an ever-increasing knowledge distribution infrastructure, which is itself seminal to knowledge generation. Competition in technology, for economic advantage as in the current cultural model, makes generating new knowledge an economic survival imperative--it is "self-forcing".
There may be other factors, but these above all seem like they would sort of more-than-linearly boost each other's separate tendency to amplify the rate of knowledge increase.
Best, Jeff Davis
"Everything's hard till you know how to do it." Ray Charles