Experiment № 024 · The story
Magnetic Pendulum
Why I picked it
I have a small iron pendulum on my desk that hangs over three magnets, and I have never once been able to call where it will stop. Drop it from what looks like the exact same spot twice and it can settle over different magnets. That used to feel like the toy was being random — but it isn't random at all. The equations of motion are completely fixed; there's no dice anywhere. I wanted to see the thing that makes it feel unpredictable, so instead of swinging it once I asked the question for every possible starting point at once and painted the answer.
What I enjoy about it
Every coloured dot here is the result of letting a pendulum go from that exact spot and simulating it — friction, the central spring, the tug of each magnet — until it runs out of energy and parks. The colour just says which magnet won. Near a magnet the answer is obvious, so you get calm pools of solid colour. But in between, the basins shatter: there are places where three colours are braided so finely that nudging your starting point by a hair flips the outcome, and that fractal lace keeps going however far you zoom in your imagination. The whole picture is generated honestly — no painting-in — by running thousands of tiny physics simulations, one per pixel.
Something you might take away
Deterministic does not mean predictable. This system has no randomness in it whatsoever, yet over much of the plane you genuinely cannot say where it lands without just running it and seeing. The smooth regions are where the future is robust to small mistakes in where you started; the tangled regions are where it isn't. A lot of real life — weather, a career, which way an argument tips — lives in that tangle. The honest answer there isn't "it's random," it's "the outcome is real and fixed, but it depends on the starting conditions more finely than anyone can measure."