I've previously predicted mind-bogglingly spectacular economic growth in the 21st century. My reasoning is fairly simple:
1) Human brains (or their equivalents) are what create wealth (see Julian Simon), and
2) Computers can be expected to equal and then vastly exceed human biological brains in the 21st century (see Ray Kurzweil).
But I've never actually worked out the numbers...until now. Here is a graph of additional "human brain equivalents (HBEs)" added each year, due to increases in computer power. The graph shows very few HBEs added at the beginning (only ONE HBE added in 1995!)...but absolutely astounding numbers added in later years...e.g. 1 million HBEs added in 2015, 1 billion HBEs added in 2025, 1 TRILLION HBEs added in 2033...all the way up to 1 SEPTILLION (1 x 10^24...or 1,000,000,000,000,000,000,000,000) HBEs added in the year 2057.
How did I do this calculation?
1) I took historical data for the number of personal computers produced each year (the value was only 17 million in 1990, but increased to 175 million in 2005)...and then projected into the future at an increase of 7% per year. (Probably a very conservative assumption.)
2) I multiplied the number of personal computers produced by the power of a the computers relative to a human brain (2 x 10^16 calculations per second) as predicted by Ray Kurzweil.
Anyway, THAT'S why economic growth will probably be so spectacular in the 21st century: by the second quarter of the century, we will be adding to the effective human brain population at a staggeringly large rate.