Back around 1977 I remember regaling some fellow Caltech physics grad students with my fearless forecasts of the stock market. At that time, some of you may recollect, interest rates were high, gasoline was in short supply, and there was great chaos in the US economy. The Dow Jones Industrial Average was ~1500 or so, moving rapidly downwards. I nevertheless predicted a Dow of (gasp!) 2000 by the year 1980, 4000 by 1990, and 8000 by 2000. They laughed at me.
It wasn't rocket science. A doubling time of 10 years corresponds to a growth rate of about 7% per annum. That's high for a developed economy as a whole, but if you add in a bit of monetary inflation and international trade then it's not too far out of line for better-managed businesses to achieve.
And as for the next few decades? Polishing my crystal ball and doing a bit of round-off, I foresee a DJIA of ... 20,000 in the year 2010 ... 40,000 in 2020 ... and 80,000 in 2030. Pay no attention to the fluctuations during intermediate years.
(see also BubbleBusters (6 February 2002) and other ZhurnalWiki rants such as TheCancerIdeology (19 May 1999), RailWeb (3 Jan 2001), MoneyWisdom (20 May 2001), PopGoes (19 Jun 2001) & HopefulRejoinders (23 Jun 2001), LoomingDisaster (6 Aug 2001), ...)
Over in my part of the world, I used to figure on an average doubling time of 10 years for apartment rents (and many other daily costs). Over 30-some years, this has proven true despite "regulation" and other govt meddling. (Adjusting for a couple of rounds of devaluation, the formal factor 8 in 30 years in actuality became somewhat over factor 10). -- Bo Leuf