I’ve been interested in cellular automata for a very long time, dating back to when I was a kid. One of the first BASIC programs I remember writing was a version of Conway’s Life that would run on my Atari 400 computer (very slowly I might add). But I’ve also been intrigued by a very simple cellular automata called “wireworld”. Unlike Conway’s Life, each cell in wireworld can be in one of four states:
- insulator: cells in this state are always insulators
- electron head: heads always become tails in the next time step
- electron tails: electron tails always become copper in the next state
- copper: copper will remain copper unless there are precisely one or two heads adjacent to the cell, then it will become a head.
If you play with this, you might see why it would be called wireworld. I’ve known for sometime that you can create all kinds of logic gates with this automata as a basic technology, but today I found this very cool website which implements The Wireworld computer, a complete computer that computes primes, simulated in a Java applet. Very, very cool.
Addendum: I left the java applet running overnight on my machine at work. It computed primes up until 31, pictured at right (click on the image for a full resolution image of the computer state).