Puzzles
A one-line rule for a tiny ant produces chaos, then order, out of nowhere
Place an ant on an infinite grid of white squares. On a white square, it turns right, flips the square to black, and steps forward; on a black square, it turns left, flips the square back to white, and steps forward. Starting on a totally blank grid, what happens to the ant's path after a few thousand steps?
Reveal the answer
For roughly the first 10,000 steps the ant's trail looks like scribbled chaos, then, without warning, it locks into building a repeating diagonal stripe called a 'highway' that extends outward forever. Mathematicians later proved that every version of this rule eventually builds an unbounded path, though nobody predicted the abrupt switch when Chris Langton devised the rule in 1986.