The Cosmic Code
Does the universe run on a simple computer program?
In parallel. Startling as it sounds, Wolfram is not the first to have had this revelation. Another iconoclastic scientist, Ed Fredkin, a former director of the computer science laboratory at the Massachusetts Institute of Technology and now a visiting scientist at the Media Lab there, has boosted cellular automatons as the secret of the universe for more than 30 years. He promotes what he calls "digital philosophy" on a conviction, born from his experience helping design some of the first powerful digital computers, that our universe is governed by pure whole numbers, or integers, and even space and time are broken up into tiny digital increments. By his reckoning the universe not only is the output of a cellular automaton program but is running on an "engine" or computer of undetermined structure in a parallel universe he calls "Other." He has even described how such a machine could generate souls.
Fredkin welcomes Wolfram to the digital-universe club but grouses that his colleague is stingy with credit. Wolfram's genius is for publicity, he says. "That's his real contribution. He's stood up and said it all in a way that's made people listen."
Wolfram, who argues that extensive notes at the back of his book provide all the credit his colleagues should need, has begun marketing CDs with do-it-yourself CA software that he hopes will spread the gospel. "I think it is tremendously important for people to experience these experiments for themselves. I had to see this phenomenon for myself over and over again," he says.
But like Fredkin decades ago, Wolfram so far has not set off his predicted wave of change in science. Phillip Schewe, a physicist and staffer at the American Institute of Physics, keeps his eye on new manuscripts being submitted to journals and Internet archives. "He's no phony, but there's not much of a reaction at all," Schewe says. "It may come, but not yet."
Many scientists agree that cellular automatons are powerful tools for modeling nature. Set up right, "you can fit just about anything" with such programs, says Cosma Shalizi, a postdoctoral fellow at the Santa Fe Institute in New Mexico. But they say the resemblance goes only so far.
Mathematician John Conway of Princeton University was one of the first to demonstrate the power of cellular automatons when, in a feat celebrated by computer science cognoscenti, he invented "the game of life" in 1970. Displayed on a computer, its cellular automatons form patterns that often travel and interact unpredictably, almost like living organisms. But when asked if the universe itself could work by such rules, Conway scoffs. "It's a ridiculous hypothesis. A CA behaves in a fundamentally different way than the rest of the universe."
Too rigid? For one thing, if a fixed grid of computing cells underlies reality, the physical world should behave differently in some directions than others; so far, there is no sign that it does. (Fredkin actually is trying to get data from major physics labs to see if some experimental results vary subtly depending on the orientation of the setup.) For another, it is not at all clear how the rigid rules of a CA program could explain Einstein's relativity--where events look different depending on your frame of reference--or the weird physics of quantum mechanics in which, for instance, some particles act like waves.
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