Reduced motion detected — the chemistry starts paused. Use +500 STEPS to grow it without animation.
Drag on the canvas to seed chemical B · right-drag or the ERASE tool wipes it · 1–8 pick a pattern · Space pauses · [ ] resize the brush · X swaps seed/erase · R reseeds · keyboard? Tab to the canvas, arrows move, Enter seeds, E erases
01 · PATTERNS
02 · BRUSH
[ shrinks · ] grows · seeding drops A = 0.5, B = 0.25 — Pearson’s starting disturbance.
03 · CHEMISTRY
04 · TIME
05 · COLOUR
06 · WALLPAPER
The grid wraps around at its edges, so repeats join without seams.
07 · THE SCIENCE
In 1952 Alan Turing suggested that chemicals he called morphogens, reacting together and diffusing through a tissue, could turn a uniform state into a pattern: an instability of the uniform equilibrium, triggered by random disturbances.
This canvas runs the Gray–Scott model. Chemical A is fed in at rate f; two Bs turn an A into B (A + 2B → 3B); B is removed at rate f + k; A diffuses twice as fast as B.
In 1993 John Pearson mapped what this model does across f and k and named the patterns with Greek letters. He found spots that grow to a critical size and divide in two, and crowded spots that all die off together.
Honest footnote: Pearson notes that at this 2:1 diffusion ratio there are no stable Turing patterns; the ones he shows grew from finite disturbances — exactly what your brush adds. The toy is named for Turing’s idea, not claimed for every pattern on it.
Numbers used here: D_A = 1.0, D_B = 0.5, Δt = 1, a 3×3 Laplacian (centre −1, sides 0.2, corners 0.05), wrap-around edges, a 256×256 grid.