An 8-state cellular automaton where a closed loop of signals copies itself. The loop detects its own boundary and constructs an offspring — the first artificial self-replicating machine (1984).
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Generation: 0
Mode: Langton Loop
Active cells: —
0: quiescent
1: sheath
2: core
3: signal R
4: signal L
5: signal
6: turn
7: extend
Langton 1984: first demonstration of self-replication in a CA. The loop consists of ~150 cells with a 94-step cycle. Offspring loop detaches and replicates exponentially.
8 states, neighborhood of 5 (von Neumann), 219 transition rules.