Technique · Simulations
Slime mould
Thousands of agents that follow and leave trails grow a network of glowing veins that keeps reorganising, like Physarum slime mould.
Slime mould is a simulation that evolves step by step. Every piece on Synapse Drip is made from a recipe that layers techniques like this one, and you can change any of it in the Studio.
Good to know
- Physarum polycephalum is a single cell with many nuclei that moves by rhythmic squeezing: it pumps its fluid back and forth through tubes, and tubes that carry more flow grow thicker while the rest shrink away.
- Jeff Jones published this agent model in 2010, and the artist Sage Jenson made it widely known in the late 2010s with large, intricate images of the networks it grows.
- The network a slime mould finds is not the shortest possible, but it is a good compromise between length, cost and the ability to survive a cut, which is why engineers study it for designing networks.
- In 2000 Toshiyuki Nakagaki and colleagues showed that a slime mould placed in a maze finds the shortest path between two food sources; the organism is a single giant cell, with no brain or nerves.
- In 2010 Atsushi Tero and colleagues put oat flakes where the cities around Tokyo lie, and the slime mould grew a network close to the real rail system, with about the same efficiency and robustness.
The mathematics
- Each agent samples the trail at three points 8.00 cells ahead, straight on and 30.00 degrees to each side, and turns toward the largest value; this is a rule about three numbers, with no memory and no plan.
- The trail map changes as T' = (1 - 0.150) x (T + 0.30 x (blur of T - T)) plus what the agents deposit: it fades, spreads a little, and is topped up wherever agents are.
- The feedback is positive: a stronger trail attracts more agents, who strengthen it further, so tracks that start equal soon differ widely; the balance between that and the fading of trails is what leaves a network instead of a single blob.
In art
- Physarum images look like river deltas, lightning, neurons and road maps at once, because networks that move things around economically share a few shapes whatever they are made of.
- Artists have grown real slime moulds as living drawings and sculptures, and the simulation lets one see how such a drawing would grow, far faster.
More ways to use it
Related techniques
Reaction-diffusion · Cellular automata · Sandpile · Grain growth · Flocking boids · Attractor cloud · Elementary automaton · Synchrony