Von Neumann’s cellular automata
John Von Neumann began considering the idea of self-replicating systems and machines in the 1940/s. Originally, he considered actual robots, who could build other robots that could build other robots. He quickly became bogged down by the complexity of real world machinery, and the expense of providing enough parts for a robot to build a robot. Instead of using real world machinery, he created cellular automata, which was a grid that changed according to a set of rules—each cell changing according to the state of its neighboring cells. Using this abstract model, he was able to construct self-replicating systems, machines that could build copies of themselves.
Here’s a copy of a report put out by NASA in 1980, considering the advantages of using self-replicating machinery to automate the extraction of materials, and the production of useful products. It was my introduction to self-replication and cellular automata.