The background featured on the front page is the result of running a certain 2D cellular automaton.

Here is the recipe:

  1. Start with a 2n×2n empty board.
  2. Awaken the four central cells.
  3. A cell is born if it has one or two neighbors.
  4. A cell dies if it has seven or eight neighbors.
  5. Iterate until a stable state is reached.

Some examples: