Heat may be a limiting factor to Moore’s law. By 2010, scientists predict, a single chip may hold more than a billion transistors, giving off 1,000 watts of thermal energy — far more heat per square inch than a nuclear reactor.

Already, Los Alamos National Laboratory’s 30-teraops Q computer, designed to provide full-scale, three-dimensional simulation of the physics involved in a nuclear explosion, will require 5 megawatts of energy. A coming 100-teraops machine will require even more.

In contrast, the cooling sytem for the lab’s 160 gigaops Green Destiny, using Transmeta chips, consumes only five kilowatts.