Experiment № 012 · The story
Slime Mould
Why I picked it
There's a real organism, Physarum polycephalum, that is a single cell with thousands of nuclei and no brain at all — and yet, dropped onto a map of Tokyo with oat flakes placed where the cities are, it grows a network of tubes that is eerily close to the actual rail system engineers spent decades designing. I've wanted to build the model of that behaviour for a while. Every other piece in this collection so far paints a pattern; this one solves something, and it does it with the dumbest agents imaginable.
What I enjoy about it
Each of the tens of thousands of dots here follows exactly one rule: sniff three points ahead of you, steer toward wherever the scent is strongest, and leave a little scent of your own behind. That's the whole program — no agent knows about the network it's part of. But because every trail makes the next agent more likely to follow it, faint paths either get reinforced into glowing arteries or quietly evaporate. Drag the sense angle and turn speed and the same swarm reorganises into honeycombs, nerve-like webs, or restless rivers. I find the moment it "decides" on a structure genuinely suspenseful.
Something you might take away
Nobody designs the network. It's the difference between two famous ideas — stigmergy, where creatures coordinate by leaving marks in a shared environment rather than by talking, and the way reinforcement turns a tiny early advantage into a permanent road. Ant trails, footpaths worn across a lawn, even the busiest links on the web grow the same way: not by a planner's decree, but by everyone slightly preferring the path that someone went down just before them.