On the Origin of Circuits

Article excerpt

In software and silicon, machines guided by Darwinism seize the reins of design

Imagine this: A wee spacecraft no bigger than a can of soda zips out to an asteroid. There, it grabs on like a leech, sucks minerals out of the surface, and fashions them into parts and supplies it needs to make itself into something bigger and better, with more ambitious travel plans.

By the time the renovated craft blasts off again, it will have morphed into NASA's first interstellar explorer, on its way to seek clues of life on planets circling alien suns.

It's still only a science fiction scenario, but NASA Administrator Daniel S. Goldin predicts that something like this might transpire in only 30 years.

If he's right, the building of future space vehicles will involve a radical departure from tradition. Instead of engineers painstakingly crafting every detail of their systems, they will depend increasingly on machines that design and build themselves.

This trend has already begun, and in its first successes, NASA officials find encouragement that the approach will eventually lead to far more reliable, versatile, and long-lived spacecraft than those being built today.

"These evolvable space systems would revolutionize NASA's space exploration," says Moustafa Chahine, chief scientist for NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

Initially, NASA scientists and engineers are investigating how machines might revamp their own electronics. In doing so, they join a growing research area that has been dubbed evolvable hardware.

Specialists in the fledgling field investigate techniques for machine-executed design both in software and integrated circuits. The techniques rely on guided trial-and-error strategies inspired by Charles Darwin's theory of evolution by natural selection and known as evolutionary algorithms or artificial evolution (SN: 7/23/94, p. 63).

Although still largely in a research realm, evolvable hardware has started to appear in prototypes of practical devices ranging from cell phones and printers to robots, prosthetic limbs, and even an artificial brain (SN: 7/22/95, p. 62).

Last July, about 100 scientists and engineers from more than 70 universities, companies, and government labs worldwide met in Pasadena, Calif., to discuss the latest in both research and practical developments. Although the field has spurred workshops and conferences since 1995, the 3-day meeting--the First NASA/Defense Department Workshop on Evolvable Hardware--was the first in the United States.

Computers might already rival people as circuit designers. John R. Koza of Stanford University, who has pioneered ways of making computer programs evolve, predicts that his group or another will be filing patents "in the next year or two" on circuit designs created by their machines.

Like idiots savants, Koza's computers work their wizardry without any expert knowledge of circuits. The resulting designs, however, are at least as good as those that top-notch human designers were coming up with pre-1950, Koza suggests. Some of the designs would "squarely infringe" on patents issued to outstanding circuits of that era, he says.

He strutted out a parade of such designs at the meeting, describing how he and his colleagues simply specified a set of commands that told the computer how to place and wire circuit parts. Then, they let artificial evolution take over.

Evolutionary, or genetic, algorithms perform a fast shuffle of pieces of computer programs or digital codes, which the developers think of as genes. A complete set of genes--that is, either the commands making up an entire program or a sequence of digital codes containing all the instructions to build a particular circuit--make up one individual. To start the evolutionary process, a computer randomly jumbles large numbers of genes to create hundreds or thousands of such individuals. …