From: Rudy Rucker (rucker@sjsumcs.SJSU.EDU)
Date: Thu Apr 15 1993 - 23:26:03 UTC
Carter Bays's standard life was based on a 27-cell neighborhood, meaning that each cell sees a 3x3x3 cube of cells around itself. Bays's favorite rule was what he called 5/5/4/5, meaning that a dead cell is turned of --- I mean turned ON --- iff it has 5 neighbors on. A cell already on stays on if it has 4 or 5 neighbors on. This rule was invented in close analogy with Conway's Life, which is 3/3/2/3. John Walker implemented a slow-running version of Bays's Life, and we included a "movie" of it on the CA LAB disks (Autodesk , 1989). We showed a glider, a "rotor", and a "bucking bronco". As Mcintosh says in his very interesting comments, we do not have enough experience with 3D rules to know if any of them is really as rich as Conway's Life --- although one expects that there will be such rules. As regards the difficulty of looking at 3D CAs, note that Margolus and Toffoli's new CA accelerator, the CAM 6, can run 3D rules quite rapidly. A few months ago Margolus showed me a film of the CAM 6 running a 3D Vote rule. The way in which the program showed the congealing Vote globs was to *render* the image with *virtual light*! This is done in a CA way: a plane of "photons" enters the space at some angle, and at each generation the photons move one step deeper. If a photon hits an object, it stays there and waits. Meanwhile the photon plane moves to the back of the space and then starts marching forward again. Whenever the returning photon plane finds a waiting photon, it sends it back towards the starting plane, reflected at an appropriate angle.
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