When Information Hits a Wall: Barriers in Cellular Automata

TL;DR: Add one frozen cell to a cellular automaton and watch the entire pattern reshape itself. This post explores what happens when you introduce a single barrier into elementary CAs — and why it matters for both theory and real-world modeling. What happens when a single cell in a cellular automaton refuses to change? In elementary cellular automata (ECAs), every cell updates each generation based on its neighbors and a deterministic rule. Patterns emerge, spread, and evolve across the grid in