Two Rules. 9,977 Steps of Chaos. Then This.

Langton's ant lives on a grid and follows two rules. On a dark cell it turns right and lights the cell. On a lit cell it turns left and puts it out. Then it steps forward. For the first few hundred steps it draws neat, symmetric shapes. Then the picture turns into a growing blob of noise, and after 9,977 steps the ant suddenly starts building a diagonal road, the highway: the same 104 steps, over and over, and it never stops. (The classic version calls the two kinds of cell white and black.) The video walks through the first steps one at a time, shows how a small Rust program with no crates finds where the highway starts and how long a lap is by writing down every turn, puts a wall across the road, and tries 1,000 random starting grids. Every one of them ends in a highway, and nobody has proved that it always happens. Every picture in the video is drawn by the tutorial program itself. The channel runs a falling-sand world live 24/7:    / @alchemicalabyss   Chapters 0:00 Two rules, then a mess 0:13 The whole ant in one function 0:34 The first steps, one at a time 0:51 Tidy, symmetric shapes 1:04 Thousands of steps of noise 1:16 Step 9,977: the highway 1:33 How the program finds it 1:52 A wall across the road 2:08 1,000 random grids, and no proof #langtonsant #cellularautomaton #rustlang