© 2004 Robert A. Freitas Jr. and Ralph C. Merkle. All Rights Reserved.

Robert A. Freitas Jr., Ralph C. Merkle, Kinematic Self-Replicating Machines, Landes Bioscience, Georgetown, TX, 2004.

3.1 Moore Artificial Living Plants (1956)

Von Neumann’s deductions on the logic of replication in the late 1940s and early 1950s were highly abstract and known only to a few specialists who had heard his lectures,* until Kemeny’s 1955 article [243] in Scientific American brought these concepts to a wider audience. Just one year later, in 1956, mathematician and scientist Edward F. Moore offered the first known suggestion for a real-world application of kinematic self-replicating machines, representing the vanguard in a long line of commentators who would later expound upon the powerful economic potential of exponential growth among populations of such devices.

* A short story by science fiction writer Philip K. Dick, entitled “Autofac,” describes a nationwide system of automated factories that produce food, consumer goods, and “miniature replicas” of more factories, perhaps one of the first descriptions of autonomous machine self-replication to appear in this genre [668], though a few related stories describing replicated robots appeared in the 1920s [657-659] and 1930s [660]. Dick’s story ends with the factory, when it is almost destroyed, shooting out a torrent of metal seeds that germinate into miniature factories – which from today’s more informed perspective we might interpret as self-replicating nanorobots [303]. “Autofac” was published in November 1955, but it has been claimed [668] that Dick completed the story no later than 11 October 1954, which would appear to predate Moore’s article and possibly Kemeny’s article as well, though not, of course, von Neumann’s original 1948 lecture [317]. (Dick wrote about von Neumann’s game theory [655], so he’d probably read von Neumann’s self-replication work as well.) Earlier stories by Dick in 1952 [665] and 1953 [666] had described self-repairing or self-replicating, evolving war machines that inherit an entire planet. (Vulcan’s Hammer (1960) [656], a later novel by Dick, continued his theme of an autonomous computer able to expand and rebuild itself.) “Epilogue,” a science fiction story published by Poul Anderson in 1962 [669], describes self-replicating factory barges using minerals extracted from ocean water as raw materials and is more clearly derived from Moore’s speculations. Contemporary science fiction writers frequently returned to the theme of self-replicating robots in the 1950s [661-663], 1960s [671-674], 1970s [2936], 1980s [693, 694], 1990s [675, 676], and 2000s [2898].

“It is unlikely that the [kinematic] machine von Neumann described will ever actually be built, because it would have no useful purpose except as a demonstration,” noted Moore in his 1956 Scientific American article [677]. But then he continued:

“I would like to propose another type of self-reproducing machine, more complicated and more expensive than Von Neumann’s which could be of considerable economic value. It would make copies of itself not from artificial parts in a stock room but from materials in nature. I call it an artificial living plant (Figure 3.1). Like a botanical plant, the machine would have the ability to extract its own raw materials from the air, water and soil. It would obtain energy from sunlight – probably by a solar battery or a steam engine. It would use this energy to refine and purify the materials and to manufacture them into parts. Then, like Von Neumann’s self-reproducing machine, it would assemble these parts to make a duplicate of itself.

“For the first model of such a machine, a good location would be the seashore, where it could draw on a large variety of available materials. The air would provide nitrogen, oxygen and argon; the sea water would provide hydrogen, chlorine, sodium, magnesium, sulfur…; the beach would provide silicon and possibly aluminum and iron….From these elements the machine would make wires, solenoids, gears, screws, relays, pipes, tanks and other parts, and then assemble them into a machine like itself, which in turn could make more copies….The next step would be to tackle the harder problems of designing artificial living plants for the ocean surface, for desert regions or for any other locality having much sunlight but not now under cultivation. It is easy to see that a plant of this kind could have considerable economic value. It could be harvested for a material it extracted or synthesized, just as cotton, mahogany and sugar cane are now harvested from plants in nature. Thus an artificial plant which used magnesium as its chief structural material could be harvested for its magnesium.

“If the object is to manufacture a specific product, would it not be much simpler to design an automatic factory to make it, rather than to go to all the trouble of creating an artificial living plant? It would indeed be simpler, but obviously the returns would not be as great. Where a factory turns out products at a constant rate, the production of the artificial living plant would grow exponentially. If its net reproduction time were one year, after 30 years there would be more than a billion of these plants! Needless to say, they could not be allowed to reproduce indefinitely, for they would soon fill up the oceans and the continents….It might be worth while to build into these plants a tendency to migrate, like lemmings, to preassigned locations where they could be harvested conveniently (Figure 3.2).”

Commenting on Moore’s plan years later, in 1972, Freeman Dyson [2934] observed that: “It may well happen that on Earth, for aesthetic or ecological reasons, the use of self-reproducing machines will be strictly limited and the methods of biological engineering will be used instead wherever this alternative is feasible. For example, self-reproducing machines could proliferate in the oceans and collect minerals for man’s use, but we might prefer to have the same job done more quietly by corals and oysters. If economic needs were no longer paramount, we could afford a certain loss of efficiency for the sake of a harmonious environment. Self-reproducing machines may therefore play on Earth a subdued and self-effacing role.”

Last updated on 1 August 2005