The patterns of Barricelli
I've been obsessed recently with the work of Nils Aall Barricelli who pioneered cellular automata 15 years before John Conway, artificial life 20 years before Christopher Langton and chaos theory 15 years before Benoit Mandelbrot. Barricelli called his creation "symbioorganisms", but it's interesting to try to demystify them without any analogies with living organisms.
The playing field is a finite, circular 1D space of discrete squares. Squares can be occupied by one of many different kinds of elements. Each kind of element has a propensity to move through the space with a constant step. To this space of elements striding around, Barricelli adds 3 rules. (Well, he experimented with many different tweaks in his papers, but this is one concrete, elegant formulation.)
Destruction: When two objects collide, delete both. (This isn't quite what Barricelli says. But it suffices!) Creation: When an object A moves to where a second object B used to be, make a new copy of it, somewhere nearby that depends on B. Mutation: This rule is slightly more difficult to explain, and I found the rules plenty interesting without using it in this post. In brief, empty squares sometimes create new kinds of elements.
