Where do you start? I start with a very crude global index of the value of the stock of human technology—useful ideas about manipulating nature and productively organizing humans—that have been discovered, developed, and then deployed-and-diffused throughout the world economy. How do you construct this index? I calculate it as the average worldwide level of income per capita, times the square root of population. Why “square root”? The square-root recognizes that there is resource scarcity—hence generating income for more people is burdensome, and so the technology level is not simply average output per capita—but also that each mouth comes with two eyes, two arms, and a brain, so that labor is productive—hence total world product is not the technology level either. “Square-root” is a balance. Would you die on the hill that it is square-root, rather than some other power between 0 (which gives average income per capita) or 1 (which gives total world product) multiplying population? No. What do your guesses—I won’t call them numbers—then show, in terms of the annual average proportional growth rates of technology deployed-and-diffused, worldwide? Roughly: growth very slow for millennia—visible only in la longue durée—then growth visible over a human lifetime, barely, after 1500; growth substantial over a human lifetime after 1770; and then growth so that humanity’s technological prowess doubles every generation after 1870.:
