- As the Java bandwagon picks up steam, Web-based simulations of
cellular automata are popping up on a daily basis. Since we reported on
early Java versions of Conway's Life by Orbital Technologies
and Paul Callahan last January and February, and then
Al Hensel's screaming implementation this past summer,
more than twenty CA applets have appeared in the
Gamelan Java Directory - search on 'Life' and 'Cellular' to find them.
- Our favorite new discovery in this collection comes from
Mitchel Resnick and
Brian Silverman at M.I.T.
Their
Exploring Emergence interactive tutorial gives a charming 10-part introduction
to cellular automata in the spirit of Logo turtle graphics. The culminating
example of their mini-course is Brian's Brain, a well-known CA rule devised
by Silverman and discssed in the book Cellular Automata Machines by
Toffoli and Margolus (M.I.T. Press, 1987).
- This week's soup shows part of a CAM8 simulation of Brain after
100,000 updates, with the same coding as in the CAM book. To quote from
Resnick and Silverman,
- ... there are many more gliders - and many more types of gliders -- than with the
Life rule. In fact, almost everything ends up as a glider. Glider guns are also very common,
and they themselves are gliders. And if you watch carefully, you might even find a
glider-gun gun.
- Whereas Conway's Life evidently relaxes to a final mix of fixed and
periodic local structures starting from generic disordered configurations,
Brian's Brain establishes a dynamic statistical equilibrium of great
complexity. Kellie Evans has since found similar chaotic steady states for
higher range Larger than Life rules near the LtL phase boundary.
Two more Java CA resources are worth mentioning. First, Bruce Christenson's Life has
perhaps the nicest user interface to date. In particular there is a way to control the
speed of simulation. Java compilers have now improved to the point where versions
such as Hensel's desparately need this feature to slow down the movies! Second, for
do-it-yourself folks, the new Java By Example book from Sunsoft includes source code for a more general purpose CA simulator. These examples are also included on several Java CDs distributed by SUN.
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