| No, it's never been done.* While factories are built all the time, they have never been built entirely from their own products and without human labor as an essential ingredient (a "closed" manufacturing process). There's an economic reason for this: the constraints that make a factory "self-replicating" mostly make things more difficult/expensive; they're only beneficial when operating in a human-hostile area disconnected from existing supply chains, so it's always been better to use open-loop factories + human labor to make products quicker, cheaper, and of higher quality than a self-replicator would. Space industrialization is where self-replicators will be exceptionally useful. These are the key functions of a truly closed-loop self-replicating factory: 1. collect energy 2. use energy to collect matter. 3. use energy and matter to create parts. 4. use energy to assemble parts. For example, consider a water-powered saw mill, made of wood with some metal "vitamins": 1. Wooden water wheels collect energy from flowing rivers. 2. Humans use wood/metal saws to cut trees, and wooden rollers/sleds and transport them to the mill. 3. The mill's saws, drills, and lathes turn the tree trunks into useful wooden parts. 4. Humans move wood parts from station to station in the mill and can assemble another mill from the boards, dowels, and a few metal saw blade/drill bit "vitamins." Could you replace the humans with logging robots, and use robot arms to move things inside the mill? Sure, but humans are so much better suited for these tasks, and now your humble saw mill has to be able to create, power, and control these robots in order to be closed-loop. *Yes clever HN, you can get all pedantic about biological self-replicators, self-assemblers, and nano-bots, but you're just muddying the waters. We haven't ever managed a von Neumann-style "clanking automaton" self-replicator. P.S. don't worry about rampancy—there are physical limits that make sci-fi's Grey Goo floods impossible. |