[roc]

I read it to mean they were factoring in the computing power as well.

i.e. they estimated that it would take 72,000 Watts-worth of 1990s computers to match the processing power of a Macbook Air.

Though that does add further caveats to an already less-than-ideal comparison (as an MBA is not going to last seven hours at 100% CPU load).

[davidw]

Sounds like they ought to mention how long that is in football fields.

[laconian]

If you placed all the iPhones in the world end to end on a line, some of them would be in the ocean.

There, I wrote about iPhones. Now give me my ad revenue.

[qq66]

How many iPhones in the world? If I guessed about 100 million that would be about 8000 miles, which wouldn't necessarily be in the ocean if you started the line in Europe and cut across Russia/Eurasia.

[beej71]

I'd chuck mine in the ocean just to make it true.

[jurjenh]

Or even better, compare it to a butterfly flapping its wings (http://en.wikipedia.org/wiki/Butterfly_effect) as this kind of comparison is sensitive to so many different factors you can't take any conclusions too seriously.

Still, not a bad yardstick to see how far we've come with respect to computing power per watt - maybe this is why the rate of change is increasing more than exponentially - you have multiple exponential rates converging in a positive feedback system...

[VladRussian]

>maybe this is why the rate of change is increasing more than exponentially

Doesn't seem so. Classic Moore : 7h (25200s) / 2.5s ~= 2^14 that places us in - 1.5 years for a power of 2 - 1990.

>more than exponentially - you have multiple exponential rates converging in a positive feedback system...

not really. The system as whole improves with the same exponential rate precisely because all and each of its components improves with the same exponential rate. Exponential rate of CPU and exponential rate of RAM produce the same one exponential rate of the improvement of the whole system comprised of the CPU and the RAM. Exponential rate of the CPU only, for example, would result in much less than the exponential rate for the whole system.

[bane]

I wonder how many library congresses a modern iPad holds.

[hristov]

Or in Libraries of Congress.

[hmottestad]

Yes, it must be. And from 1990 to 2011 number of transistors per cm2 has doubled 14 or so times.

If they are going to compare it with computational power, they should also factor in battery development since 1990.

[mortenjorck]

What is missing is how many 603ev chips would be needed to approximate the Sandy Bridge Core i5's performance. And of course, how many feet thick that would make the 2.5-second-battery 1997 MacBook Air.