Chapter 9: Fundamental Physics

Section 2: The Notion of Reversibility

Properties [of second-order cellular automata]

The initial conditions used here have a single black cell on two successive initial steps. For rule 150R, however, there is no black cell on the first initial step. The pattern generated by rule 150R has fractal dimension Log[2, 3 + Sqrt[17]] - 1 or about 1.83. In rule 154R, each diagonal stripe is followed by at least one 0; otherwise, the positions of the stripes appear to be quite random, with a density around 0.44.

From Stephen Wolfram: A New Kind of Science [citation]