Speed of light (cellular automaton)

In Conway's Game of Life (and related cellular automata), the speed of light is a propagation rate across the grid of exactly one step (either horizontally, vertically or diagonally) per generation. In a single generation, a cell can only influence its nearest neighbours, and so the speed of light (by analogy with the speed of light in physics) is the maximum rate at which information can propagate. It is therefore an upper bound to the speed at which any pattern can move.

As in physics, the speed of light is represented with the letter ${\displaystyle c}$. This in turn is used as a reference for describing the average propagation speed of any given type of spaceship. For example, a glider is said to have a speed of ${\displaystyle c/4}$, as it takes four generations for a given state to be translated by one cell. Similarly, the "lightweight spaceship" is said to have a speed of ${\displaystyle c/2}$, as it takes four generations for a given state to be translated by two cells.

...
Wikipedia