How did John von Neumann’s cellular automaton model explain self-reproducing machines?

John von Neumann utilized an abstract model known as a cellular automaton to demonstrate how a machine could achieve self-reproduction from simple components.12

His model explained this process through a two-phase mechanism involving the machine's "genetic" code:

• Construction: The machine interprets its code as instructions to build a replica of itself, excluding the code itself.1
• Data Copying: The machine interprets the same code as data, copying it to ensure the new machine is fully functional and "fertile".1

By separating the instructions for physical construction from the data required for replication, von Neumann provided a theoretical framework for self-reproduction that conceptually anticipated later discoveries in genetics. This work, developed alongside Stanislaw Ulam, remains a foundational concept in the study of complex systems and simulations.12