Travess Speculating in Precious Computronium by Ivan Amato

Speculating in Precious Computronium
By Ivan Amato
August 1991

     IT TAKES AN OFFBEAT PERSPECTIVE TO THINK of the evanescent electronic fuss going on inside a computer as a sort of primordial stuff from which almost anything can take shape, from crystals to stars. But that's how physicists and computer builders Norman Margolus and Tommaso Toffoli of the Massachusetts Institute of Technology view their computer child, CAM-8 (for Cellular Automaton Machine 8), a prototype of which is due to get its first breaths of electronic life next month.

     Then again, CAM-8 is an offbeat computer. Its specialty will be running so-called cellular automata models-computer simulations that portray the world as consisting of lots of discrete, locally interacting pieces-molecules of air in a gaseous slam dance, grains in a windblown sand pile, or species of animals sharing an ecosystem. While simulation programs on conventional computers are generally based on equations or algorithms describing the collective behavior of those pieces, cellular automata focus on the pieces themselves and the simple rules by which they interact: how one air molecule or sand grain nudges the next, for example, or how individual predators and their prey play their game of cat and mouse. As the computer traces these local interactions over time, the collective behavior of the system emerges.

     That's a more direct and potentially much more powerful way to simulate many physical systems, Margolus and Toffoli say. What's more, while general-purpose computing Schwarzeneggers such as the Cray XMP and the Connection Machine 2 can run cellular automata models, computers tailormade for them might be able to do so millions of times faster. CAM-8 is meant as a modest step toward that goal.

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