The Cosmic Code
Does the universe run on a simple computer program?
Perhaps the year's most unusual bestseller is A New Kind of Science, a doorstop of a book by physicist and erstwhile boy wonder Stephen Wolfram. With its publication in May, the author emerged from more than 10 years of near isolation from mainstream research to proclaim he's the first to glimpse how the universe really works. The theme of its 1,200-plus pages: The universe is in essence just a simple computer program. All of its complexity, up to and including ourselves, is the product of just a few, as-yet-unknown instructions--the equivalent of a few lines of code in a digital computer.
More than 150,000 copies of the book, published by Wolfram's own company and dubbed simply "ANKOS" in technophile Internet chat rooms, are in print. Wolfram's bold claims to all-encompassing answers have clearly struck a chord, at least in the public. But among scientists, who have now had time to ponder Wolfram's message, the reception has been more muted. One factor is pique, on the part of those who say Wolfram takes credit for insights that have been in circulation for years. Others are skeptical precisely because the revolution Wolfram is brashly proclaiming has been proclaimed before--yet caused barely a ripple in mainstream science.
If nothing else the book highlights how deeply digital computers, those potent icons of modern times, are embedded in contemporary thought. And as Dennis Danielson, a University of British Columbia English professor who specializes in the literature of cosmology, puts it, "We think with the language we speak."
Like clockwork. Some 2,600 years ago the discovery of the laws of proportion underlying musical tones inspired followers of Pythagoras to imagine a celestial "music of the spheres" governing the paths of planets, seasons, biological cycles, and other natural rhythms. Similarly, medieval European clockmakers so wowed Descartes, Kepler, Boyle, and other thinkers that they deemed the universe a mechanical clockwork. And now, when Wolfram says the universe is a program, he means literally, as in computer software.
Wolfram's track record as a genius guaranteed that his claim would draw attention. He gained a Ph.D. at age 20. A year later, in 1981, he was on the Caltech faculty and won a MacArthur "genius award." While at the University of Illinois he invented and still markets a powerful scientific programming language called Mathematica that has made him rich. And his notion is rooted in solid computer science: a widely studied kind of program called a cellular automaton, or CA for short.
A CA provides simple rules that govern how discrete cells on a fixed grid switch from one state to another--say, white to black--in response to changes in neighboring cells. In the world of cellular automatons, reality is not continuous but is a grainy mesh of local bits and bytes. Even time does not progress smoothly, but by ultratiny ticks of a cosmic clock.
Wolfram's book smacks readers' eyeballs with myriad, detailed images of CA-generated patterns, mostly resembling crazy checkerboards. They have played across his computer screen for more than 20 years. As he pondered them by the thousands, he tells U.S. News, he developed "an intuition" that a simple rule like those that produce the endlessly shifting patterns of some CAs must also have spawned the complexity of the universe, from atoms to galaxies and living organisms. The "new science" of his book's title would rely on such step-by-step programs to understand and mimic nature, rather than on the continuous equations of calculus and other advanced mathematics that scientists now use.
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.
Yet at a deeper level Wolfram, Fredkin, and their acolytes may be on to something. In recent years many researchers have begun thinking of physical interactions as calculations and as flows of information, rather then mere encounters among bits of matter and quanta of radiation. Science writer Tom Siegfried, in a recent book, The Bit and the Pendulum, calls it the "new physics of information."
One physicist, Seth Lloyd at MIT, has estimated how many operations the universe would need to have performed so far were it a computer: a 10 followed by 120 zeroes. Lloyd also specializes in getting the very fabric of reality to act like a computer. He designs hyperadvanced quantum computers, in which single atoms or molecules serve as processors. "I talk to atoms and molecules in their own language, and if we ask them very nicely they will compute for us."
But although Lloyd believes the universe is in some sense a giant information processor, he cautions that it may be nothing like the computers we know. "The universe is what it is and it's been around a long time before we got here and it will be here a long time after we're gone, and it doesn't really care what we think it is."
This story appears in the August 19, 2002 print edition of U.S. News & World Report.