Moore's Second Law

Gordon Moore continued to follow up on the progress of the microchip, when he began to see a new, non-technological reason that the spectacular gains reaped under the first law could be unsustainable. Essentially, the improvements in microprocessor power over the last decade or two have come from the fact that we've been able to improve the manufacturing process of putting more transistors on a single chip.

Shrinking the chip die and other sorts of 'cleverness' has done this, as Moore might say. However, Moore's follow up comes, surprisingly enough, from the field of economics: that the cost of building plants to create continually more powerful processors will continue to grow at such a rate that to depend on the doubling of power every 18-24 months due to process improvements will not be possible indefinitely.