Is It Live or Is It Cybernetic?

WHAT DOES IT MEAN TO BE ALIVE? THE QUESTION MIGHT SEEM best suited to philosophers and physicians, but thanks to a subspecialty of complexity theory known as artificial life, it has become a hot topic among computer jocks.

Artificial life grew out of a type of computer program called a cellular automaton, invented by the Hungarian mathematician John von Neumann, creator of one of the first digital computers in the 1940s. A cellular automaton creates ever changing onscreen patterns by instructing dots to change color based on the colors of neighboring dots. The result is a lively, self- organizing community of dots. In the 1980s Christopher Langton, a researcher at Los Alamos National Laboratory, discovered a cellular automaton containing a loop-shaped figure that could spontaneously reproduce itself | -- the same thing molecules of DNA do. Says Langton: "That was a watershed."

With self-reproducing "cells" -- and, later, electronic ants, birds and other organisms -- scientists could actually test the notion that the equations of complexity really describe natural systems. Computer life does seem to mimic real life, at least crudely: it eats, reproduces and evolves. So if it looks like a duck, walks like a duck and quacks like a duck, isn't it reasonable to call it a duck? The answer from many complexity theorists: Yes, they've created a silicon-based life-form.