Does the cosmos play by these rules?
Stephen Wolfram's theory that the universe can be summed up in computer code traces its roots to a computer game created by Princeton University mathematician John Conway more than 30 years ago. The game, called simply Life, became a cult classic after it was reviewed in Scientific American magazine.
Players begin by using their cursors to blacken selected squares on a grid. Then they click on the "go" button and the game unfolds according to three rules. Any blackened square with two or three blackened neighbors "lives." Any square with four neighbors "dies" — that is, disappears from the screen. An empty square bordered by three blackened squares gives birth to a new blackened square.
The ensuing patterns, basic at first, soon develop mesmerizing complexity as the game's logic plays itself out. As successive generations of blackened squares breed and die, the computer screen becomes a roiling stew of activity that looks like a petri dish of bacteria blooming at high speed.
Each game varies according to how many squares were darkened at the beginning and in what pattern. Most starting points end up as static patterns after bubbling through many generations. But others cause unending growth and perpetual motion.
Initially, Wolfram had dismissed Life as a toy. Then he began to experiment with his own simple computer programs, called "cellular automata" for their property of automatically generating cells, or squares. By 1981, he came to see Life as a validation of his budding theory.
The programs with which Wolfram was tinkering are slightly more complex than Life, governed by eight rules, rather than Life's three, for determining whether squares "live" or "die." These programs come in 256 variations. Wolfram began testing all 256 of them.
He discovered that some — such as Rule 30, on which many of his conclusions are based — build infinitely varying patterns. He gradually came to believe that the frenetic disorder generated by Rule 30 was as complex as anything in the universe.