> So economists do the same thing, they take some ratio of numbers that seem to be tracking the 'size' of the economy and then run that trend out 50, 100, 500 years.
Very few academic economists do 30+ year extrapolations, let alone 50, 100, 500. The vast majority of long-term growth macro-economic literature are attempts to explain/model the large observed differences in outcomes in GDP/capita between different countries, and hopefully distill some useful policy advise from that. Forecasting beyond even 5 years or so is a very niche activity in academic economics. (Source: PhD economics and former model builder for pension fund and souvereign wealth funds)
Fair point, I withdraw any assertion that in published papers economists over extend their numbers. It has been my experience that in the reporting on those papers I have seen much less restraint. And yes, I'm aware that survivor bias may mislead in this regard.
Very few academic economists do 30+ year extrapolations, let alone 50, 100, 500. The vast majority of long-term growth macro-economic literature are attempts to explain/model the large observed differences in outcomes in GDP/capita between different countries, and hopefully distill some useful policy advise from that. Forecasting beyond even 5 years or so is a very niche activity in academic economics. (Source: PhD economics and former model builder for pension fund and souvereign wealth funds)