# 7.15. Glossary¶

**Cellular Automaton (CA):** Is a model of a world with very simple physics. “Cellular” means that the world is divided into discrete chunks, called cells. An “automaton” is a machine that performs computations — it could be a real machine, but more often the “machine” is a mathematical abstraction or a computer simulation.

**Church-Turing Thesis:** The claim that these definitions of computability capture something essential that is independent of any particular model of computation

**Cross-Correlation:** Selecting elements from an array and adding them up

**Falsifiability:** A hypothesis is this if there is an experiment, at least in the realm of practicality, that would contradict the hypothesis if it were false.

**Pseudo-Random Number Generators (PRNGs):** Programs that produce random-seeming numbers.

**Turing Complete (Universality):** Means that they can compute any computable function. Universality

**Unfalsifiable:** A hypothesis is this if there is no way to have an experiment, at least in the realm of practicality, that would contradict the hypothesis.