Continual injection of randomness [in cellular automata]

In the main text we discuss what happens when one starts from random initial conditions and then evolves according to a definite cellular automaton rule. As an alternative one can consider starting with very simple initial conditions, such as all cells white, and then at each step randomly changing the color of the center cell. Some examples of what happens are shown at the bottom of the previous column. The results are usually very similar to those obtained with random initial conditions.