I previously speculated on why economic growth in the 21st century will be spectacular..My calculations then were based on sales of personal computers and the expected power of each personal computer. It wasn't a very sophisticated analysis, so I was happy to recently learn of this great paper that estimates the total power of graphical processing units (and central processing units) in the world.
That paper calculated the total processing power of all GPUs in 2007 to be 6.4 x 10^18 instructions per second, and that the rate was increasing by 86 percent per year. I translated that into human brain equivalents (HBEs) by assuming that one HBE was equal to 20 quadrillion instructions per second (20 petaflops, or 20,000 teraflops) or 100 trillion instructions per second (0.1 petaflops, or 100 teraflops). The value of 20 petaflops comes from Ray Kurzweil's work, will the value of 100 teraflops was proposed by Hans Moravec.
Anyway, the graph below has two straight lines for those two cases, and one curved line, which represents the results of my earlier calculations. The bottom line is that the curved line representing my earlier calculation is very, very close to the result from the paper, assuming that one HBE is equal to 20 petaflops (20 quadrillion instructions per second). Another bottom line is that we're talking about some pretty stunning numbers very soon. For example, by 2025, the number of HBEs from computers (even using the 20 petaflops value) is approximately 1 billion. And