whatAn ant on a grid, with the entire rulebook in two clauses: on a white cell turn right, on a black cell turn left; either way flip the cell you leave and walk one step. Each seed scatters a little junk near the start. Time is staged: the early scribble runs slow enough to watch, then the world accelerates.

whyThe claim is one of the strangest small facts in mathematics: the ant scribbles apparent chaos for thousands of steps, and then, every time, abruptly begins a highway, a 104-step dance laying a diagonal ribbon to the edge of the world. Measured here it broke into its highway at step 5,720 on one seed, 3,224 on another, 17,368 on a third: always, and nobody has proved why. The page detects the dance in the ant's own footprints and stamps the step where chaos ended. Click to drop a second ant, and the two flip each other's cells, building and unbuilding each other's work until the tidy story dissolves.

howThe grid is the width of your screen; a run that reaches the edge begins again with fresh junk. Highway detection samples the ant every 104 steps and looks for five identical displacements. A third click begins again. One integer seeds the junk, so the same seed finds its highway at the same step.