Cosmology
In the context of cellular automata, cosmology is the study of the ultimate fate of patterns over time.
An early classification that has been established for class two and class four cellular automata groups patterns according to the ash they produce:
- Patterns that eventually die out entirely. Known as sparks or diehards.
- Patterns that eventually stabilize in a constellation of periodic, unmoving objects (still lifes and oscillators).
- Patterns that eventually create a set of periodic, moving objects (spaceships) that escape to infinity. Known as pure glider generators.
- Patterns that eventually create both moving and unmoving ash.
This leaves out as interesting edge cases patterns that do not stabilize into ash and instead show more complex long-term behavior. Examples of such behavior include all infinite growth patterns, such as guns, sawtooths, and spacefillers, but also some patterns with bounded population.
Class three automata additionally show a large (and possibly dominating) residue of chaotic growth patterns, typically appearing to grow infinitely, but whose ultimate fate is not predictable. The existence of such patterns is predicted, though in most cases not proven, for class four automata as well.