Stephen Wolfram's idea is so simple that it sounds like science fiction: The universe, which is constantly generating complex structures like snowflakes and galaxies and life forms, is ultimately reducible to a few simple rules, like the instructions for executing a computer program.
Wolfram, creator of the software program Mathematica and the youngest-ever (at 21) recipient of a MacArthur "genius" grant, has spent the last 10 years developing the idea of modeling the natural world with simple programs. Now he has embarked on a tour of the United States to bring his idea to the scientific community. He stopped at Cornell Oct. 2 to address an overflow audience in Call Auditorium of Kennedy Hall.
Most scientists and mathematicians, although recognizing the originality of Wolfram's work, have been quick to dis-miss his sweeping claims of sparking a scientific revolution. If his reception at Cornell is any indication, however, his idea has hit the scientific community with the force of a missile: there was standing-room-only in the 600-seat auditorium and signed copies of Wolfram's book, A New Kind of Science, were sold out (at $44.95 a copy) even before the lecture began.
Wolfram is well aware of how absurd his theories sound. "It was pointed out to me by some bright journalist that I was 42 when the book came out," he said with a chuckle -- 42 being, as any fan of Douglas Adams' Hitchhiker's Guide to the Galaxy well knows, "the answer to life, the universe and everything."
Wolfram's long-awaited magnum opus, a tome of almost 1,300 pages, was published in May at Wolfram's own expense. In it, he lays out what he sees as the groundwork for a fundamental rethinking of the principles and methods of science, which ultimately will lead to the replacement of the detailed mathematical equations physicists, chemists and biologists use to model the complicated world with simple computer programs called "cellular automata."
In his talk, Wolfram introduced the concept of cellular automata: programs that operate in a space made up of squares on a grid and fill the space with successive lines of black and white squares according to simple rules. A square in a new line on the grid might be black, for example, if it diagonally touches another black square, or if all three squares touching it from above are white.
Cellular automata were invented in the 1950s, and the research on them has not -- until now -- been particularly earth-shattering. Most of them create simple patterns, or die out after a few hundred or a few thousand generations. What Wolfram has done that is so extraordinary is to discover, describe and experiment with cellular automata that create no detectable pattern at all, despite the simplicity of their governing rules.
This flies in the face of both intuition and most accepted theory, which holds that in order to model complex behavior, it is necessary to construct equally complex equations.
"In our everyday experience -- in, say, doing engineering -- what we're used to is that [in order] to make something complicated, we generally have to start off with complicated plans or use complicated rules," said Wolfram. "But what we see here is that even extremely simple rules can produce incredibly complicated behavior."
In fact, Wolfram believes, all "complicated behavior" in nature, from the forms of living organisms to the form of space-time itself, can be modeled using cellular automata.
In one of the most striking visual demonstrations of his theory, Wolfram showed a photograph of a seashell, marked with a seemingly random pattern of dark triangles on a light background, next to a printout of one of his random-pattern-generating cellular automata. They appeared to be exactly the same.
Wolfram's massive body of work is sure to contain something to infuriate everyone. Biologists in particular will take issue with his view that different species are simply the outputs of possible programs, implying that natural selection is of little or no importance in generating complex forms and behaviors.
But Wolfram, once a precocious teenage physicist who dropped out of undergraduate study at the University of Oxford because he found it insufficiently challenging, has never hesitated to question an accepted body of theory, no matter how fundamental. (He did, however, go on to earn his Ph.D. from the California Institute of Technology at age 20.)
"It took me years to come to terms with this phenomenon," he said. "In fact, it has gradually overturned almost everything I thought I knew about many of the foundations of science."
Now, he hopes to have exactly that effect on the rest of the world.
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