Self-replicating machine - AbsoluteAstronomy.com

A self-replicating machine is an artificial construct that is theoretically capable of autonomously manufacturing a copy of itself using raw materials taken from its environment, thus exhibiting self-replication

Self-replication

Self-replication is any behavior of a dynamical system that yields construction of an identical copy of that dynamical system. Biological cells, given suitable environments, reproduce by cell division. During cell division, DNA is replicated and can be transmitted to offspring during reproduction...

in a way analogous to that found in nature

Nature

Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general...

. The concept of self-replicating machines has been advanced and examined by Homer Jacobsen, Edward F. Moore

Edward F. Moore

Edward Forrest Moore was an American professor of mathematics and computer science, the inventor of the Moore finite state machine, and an early pioneer of artificial life....

, Freeman Dyson

Freeman Dyson

Freeman John Dyson FRS is a British-born American theoretical physicist and mathematician, famous for his work in quantum field theory, solid-state physics, astronomy and nuclear engineering. Dyson is a member of the Board of Sponsors of the Bulletin of the Atomic Scientists...

, John von Neumann

John von Neumann

John von Neumann was a Hungarian-American mathematician and polymath who made major contributions to a vast number of fields, including set theory, functional analysis, quantum mechanics, ergodic theory, geometry, fluid dynamics, economics and game theory, computer science, numerical analysis,...

and in more recent times by K. Eric Drexler

K. Eric Drexler

Dr. Kim Eric Drexler is an American engineer best known for popularizing the potential of molecular nanotechnology , from the 1970s and 1980s.His 1991 doctoral thesis at MIT was revised and published as...

in his book on nanotechnology

Nanotechnology

Nanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres...

, Engines of Creation
Engines of Creation
Engines of Creation: The Coming Era of Nanotechnology is a 1986 molecular nanotechnology book written by K. Eric Drexler with a foreword by Marvin Minsky. An updated version was released in 2007...

and by Robert Freitas

Robert Freitas

Robert A. Freitas Jr. is a Senior Research Fellow, one of four researchers at the nonprofit foundation Institute for Molecular Manufacturing in Palo Alto, California. He holds a 1974 Bachelor's degree majoring in both physics and psychology from Harvey Mudd College, and a 1978 Juris Doctor degree...

and Ralph Merkle

Ralph Merkle

Ralph C. Merkle is a researcher in public key cryptography, and more recently a researcher and speaker on molecular nanotechnology and cryonics...

in their review Kinematic Self-Replicating Machines which provided the first comprehensive analysis of the entire replicator design space. The future development of such technology has featured as an integral part of several plans involving the mining of moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

s and asteroid

Asteroid

Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

belts for ore and other materials, the creation of lunar factories and even the construction of solar power satellites in space. The possibly misnamed von Neumann probe

Von Neumann probe

The idea of self-replicating spacecraft has been applied — in theory — to several distinct "tasks". The particular variant of this idea applied to the idea of space exploration is known as a von Neumann probe...

is one theoretical example of such a machine. Von Neumann also worked on what he called the universal constructor

Von Neumann universal constructor

John von Neumann's Universal Constructor is a self-replicating machine in a cellular automata environment. It was designed in the 1940s, without the use of a computer. The fundamental details of the machine were published in von Neumann's book Theory of Self-Reproducing Automata, completed in...

, a self-replicating machine that would operate in a cellular automata

Cellular automaton

A cellular automaton is a discrete model studied in computability theory, mathematics, physics, complexity science, theoretical biology and microstructure modeling. It consists of a regular grid of cells, each in one of a finite number of states, such as "On" and "Off"...

environment.

A self-replicating machine is, as the name suggests, an artificial self-replicating

Self-replication

system that relies on conventional large-scale technology and automation. Certain idiosyncratic terms are occasionally found in the literature. For example, the term "clanking replicator

Clanking replicator

A clanking replicator is an artificial self-replicating system that relies on conventional large-scale technology and automation. The term evolved to distinguish such systems from the microscopic "assemblers" that nanotechnology may make possible...

" was once used by Drexler to distinguish macroscale replicating systems from the microscopic nanorobots or "assemblers" that nanotechnology

Nanotechnology

may make possible, but the term is informal and is rarely used by others in popular or technical discussions. Replicators have also been called "von Neumann machines" after John von Neumann, who first rigorously studied the idea. But this term ("von Neumann machine") is less specific and also refers to a completely unrelated computer architecture

Von Neumann architecture

The term Von Neumann architecture, aka the Von Neumann model, derives from a computer architecture proposal by the mathematician and early computer scientist John von Neumann and others, dated June 30, 1945, entitled First Draft of a Report on the EDVAC...

proposed by von Neumann, so its use is discouraged where accuracy is important. Von Neumann himself used the term universal constructor

Von Neumann universal constructor

to describe such self-replicating machines.

Historians of machine tool

Machine tool

A machine tool is a machine, typically powered other than by human muscle , used to make manufactured parts in various ways that include cutting or certain other kinds of deformation...

s, even before the numerical control

Numerical control

Numerical control refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to controlled manually via handwheels or levers, or mechanically automated via cams alone...

era, sometimes spoke figuratively of machine tools as a class of machines that is unique because they have the ability "to reproduce themselves", by which they meant the ability to make copies of all of their parts. However, implicit in such discussions is the fact that a human would be directing the cutting processes (or, later, at least planning and programming them) and then assembling the parts. The same is true of RepRaps

RepRap Project

The RepRap project is an initiative to develop a 3D printer that can print most of its own components...

, which are another class of machines sometimes mentioned in reference to such non-autonomous "self-replication". In contrast, machines that are truly (autonomously) self-replicating are the main subject discussed here.

Basic concept

A self-replicating machine would need to have the capacity to gather energy and raw material

Raw material

A raw material or feedstock is the basic material from which a product is manufactured or made, frequently used with an extended meaning. For example, the term is used to denote material that came from nature and is in an unprocessed or minimally processed state. Latex, iron ore, logs, and crude...

s, process the raw materials into finished components, and then assemble them into a copy of itself. Further, for a complete self-replication, it must, from scratch, produce its smallest parts, such as bearings, connectors and delicate and intricate electronic components. It is unlikely that this would all be contained within a single structure, but would rather be a group of cooperating machines or an automated factory that is capable of manufacturing all of the machines that comprise it.

The factory could produce mining robot

Robot

A robot is a mechanical or virtual intelligent agent that can perform tasks automatically or with guidance, typically by remote control. In practice a robot is usually an electro-mechanical machine that is guided by computer and electronic programming. Robots can be autonomous, semi-autonomous or...

s to collect raw materials, construction robots to assemble new machines, and repair robots to maintain itself against wear and tear, all without human intervention or direction. The advantage of such a system lies in its ability to expand its own capacity rapidly and without additional human effort. In essence, the initial investment required to construct the first self-replicating device would have an infinitely large payoff with no additional labor cost.

Such a machine

Machine

A machine manages power to accomplish a task, examples include, a mechanical system, a computing system, an electronic system, and a molecular machine. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work...

violates no physical law

Physical law

A physical law or scientific law is "a theoretical principle deduced from particular facts, applicable to a defined group or class of phenomena, and expressible by the statement that a particular phenomenon always occurs if certain conditions be present." Physical laws are typically conclusions...

s, and the basic technologies necessary for some of the more detailed proposals and designs already exist.

History of the concept

The general concept of artificial machines capable of producing copies of themselves dates back at least several hundred years. An early reference is an anecdote regarding the philosopher René Descartes

René Descartes

René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...

, who suggested to Queen Christina of Sweden

Christina of Sweden

Christina , later adopted the name Christina Alexandra, was Queen regnant of Swedes, Goths and Vandals, Grand Princess of Finland, and Duchess of Ingria, Estonia, Livonia and Karelia, from 1633 to 1654. She was the only surviving legitimate child of King Gustav II Adolph and his wife Maria Eleonora...

that the human body could be regarded as a machine; she responded by pointing to a clock and ordering "see to it that it reproduces offspring." Several other variations on this anecdotal response also exist. Samuel Butler

Samuel Butler (novelist)

Samuel Butler was an iconoclastic Victorian author who published a variety of works. Two of his most famous pieces are the Utopian satire Erewhon and a semi-autobiographical novel published posthumously, The Way of All Flesh...

proposed in his 1872 novel Erewhon
Erewhon
Erewhon: or, Over the Range is a novel by Samuel Butler, published anonymously in 1872. The title is also the name of a country, supposedly discovered by the protagonist. In the novel, it is not revealed in which part of the world Erewhon is, but it is clear that it is a fictional country...

that machines were already capable of reproducing themselves but it was man who made them do so, and added that "machines which reproduce machinery do not reproduce machines after their own kind".

In 1802 William Paley

William Paley

William Paley was a British Christian apologist, philosopher, and utilitarian. He is best known for his exposition of the teleological argument for the existence of God in his work Natural Theology, which made use of the watchmaker analogy .-Life:Paley was Born in Peterborough, England, and was...

formulated the first known teleological argument

Teleological argument

A teleological or design argument is an a posteriori argument for the existence of God based on apparent design and purpose in the universe. The argument is based on an interpretation of teleology wherein purpose and intelligent design appear to exist in nature beyond the scope of any such human...

depicting machines producing other machines, suggesting that the question of who originally made a watch was rendered moot if it were demonstrated that the watch was able to manufacture a copy of itself. Scientific study of self-reproducing machines was anticipated by John Bernal as early as 1929 and by mathematicians such as Stephen Kleene who began developing recursion theory

Recursion theory

Computability theory, also called recursion theory, is a branch of mathematical logic that originated in the 1930s with the study of computable functions and Turing degrees. The field has grown to include the study of generalized computability and definability...

in the 1930s. Much of this latter work was motivated by interest in information processing and algorithms rather than physical implementation of such a system, however.

von Neumann's kinematic model

A detailed conceptual proposal for a physical non-biological self-replicating system was first put forward by mathematician John von Neumann

John von Neumann

in lectures delivered in 1948 and 1949, when he proposed a kinematic self-reproducing automaton model as a thought experiment

Thought experiment

A thought experiment or Gedankenexperiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences...

. Von Neumann's concept of a physical self-replicating machine was dealt with only abstractly, with the hypothetical machine using a "sea" or stockroom of spare parts as its source of raw materials. The machine had a program stored on a memory tape that directed it to retrieve parts from this "sea" using a manipulator, assemble them into a duplicate of itself, and then copy the contents of its memory tape into the empty duplicate's. The machine was envisioned as consisting of as few as eight different types of components; four logic elements that send and receive stimuli and four mechanical elements used to provide a structural skeleton and mobility. While qualitatively sound, von Neumann was evidently dissatisfied with this model of a self-replicating machine due to the difficulty of analyzing it with mathematical rigor. He went on to instead develop an even more abstract model self-replicator based on cellular automata. His original kinematic concept remained obscure until it was popularized in a 1955 issue of Scientific American
Scientific American
Scientific American is a popular science magazine. It is notable for its long history of presenting science monthly to an educated but not necessarily scientific public, through its careful attention to the clarity of its text as well as the quality of its specially commissioned color graphics...

.

Moore's artificial living plants

In 1956 mathematician Edward F. Moore

Edward F. Moore

Edward Forrest Moore was an American professor of mathematics and computer science, the inventor of the Moore finite state machine, and an early pioneer of artificial life....

proposed the first known suggestion for a practical real-world self-replicating machine, also published in Scientific American. Moore's "artificial living plants" were proposed as machines able to use air, water and soil as sources of raw materials and to draw its energy from sunlight via a solar battery

Solar cell

A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....

or a steam engine

Steam engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...

. He chose the seashore as an initial habitat for such machines, giving them easy access to the chemicals in seawater, and suggested that later generations of the machine could be designed to float freely on the ocean's surface as self-replicating factory barges or to be placed in barren desert terrain that was otherwise useless for industrial purposes. The self-replicators would be "harvested" for their component parts, to be used by humanity in other non-replicating machines.

Dyson's replicating systems

The next major development of the concept of self-replicating machines was a series of thought experiments proposed by physicist Freeman Dyson

Freeman Dyson

in his 1970 Vanuxem Lecture. He proposed three large-scale applications of machine replicators. First was to send a self-replicating system to Saturn

Saturn

Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

's moon Enceladus

Enceladus (moon)

Enceladus is the sixth-largest of the moons of Saturn. It was discovered in 1789 by William Herschel. Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface...

, which in addition to producing copies of itself would also be programmed to manufacture and launch solar sail

Solar sail

Solar sails are a form of spacecraft propulsion using the radiation pressure of light from a star or laser to push enormous ultra-thin mirrors to high speeds....

-propelled cargo spacecraft. These spacecraft would carry blocks of Enceladean ice to Mars

Mars

Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

, where they would be used to terraform the planet

Terraforming of Mars

The terraforming of Mars is the hypothetical process by which the climate, surface, and known properties of Mars would be deliberately changed with the goal of making it habitable by humans and other terrestrial life, thus providing the possibility of safe and sustainable colonization of large...

. His second proposal was a solar-powered factory system designed for a terrestrial desert environment, and his third was an "industrial development kit" based on this replicator that could be sold to developing countries to provide them with as much industrial capacity as desired. When Dyson revised and reprinted his lecture in 1979 he added proposals for a modified version of Moore's seagoing artificial living plants that was designed to distill and store fresh water for human use and the "Astrochicken

Astrochicken

Astrochicken is the name given to a thought experiment expounded by theoretical physicist Freeman Dyson. In his book Disturbing the Universe , Dyson contemplated how humanity could build a small, self-replicating automaton that could explore space more efficiently than a manned craft could...

Advanced Automation for Space Missions

In 1980, inspired by a 1979 "New Directions Workshop" held at Wood's Hole, NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

conducted a joint summer study with ASEE entitled Advanced Automation for Space Missions to produce a detailed proposal for self-replicating factories to develop lunar

Moon

resources without requiring additional launches or human workers on-site. The study was conducted at Santa Clara University

Santa Clara University

Santa Clara University is a private, not-for-profit, Jesuit-affiliated university located in Santa Clara, California, United States. Chartered by the state of California and accredited by the Western Association of Schools and Colleges, it operates in collaboration with the Society of Jesus , whose...

and ran from June 23 to August 29, with the final report published in 1982. The proposed system would have been capable of exponentially increasing

Exponential growth

Exponential growth occurs when the growth rate of a mathematical function is proportional to the function's current value...

productive capacity and the design could be modified to build self-replicating probes to explore the galaxy.

The reference design included small computer-controlled electric carts running on rails inside the factory, mobile "paving machines" that used large parabolic mirrors to focus sunlight on lunar regolith

Regolith

Regolith is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other terrestrial planets and moons.-Etymology:...

to melt and sinter it into a hard surface suitable for building on, and robotic front-end loaders for strip mining. Raw lunar regolith would be refined by a variety of techniques, primarily hydrofluoric acid

Hydrofluoric acid

Hydrofluoric acid is a solution of hydrogen fluoride in water. It is a valued source of fluorine and is the precursor to numerous pharmaceuticals such as fluoxetine and diverse materials such as PTFE ....

leaching

Leaching (metallurgy)

Leaching is a widely used extractive metallurgy technique which converts metals into soluble salts in aqueous media. Compared to pyrometallurgical operations, leaching is easier to perform and much less harmful, because no gaseous pollution occurs...

. Large transports with a variety of manipulator arms and tools were proposed as the constructors that would put together new factories from parts and assemblies produced by its parent.

Power would be provided by a "canopy" of solar cells supported on pillars. The other machinery would be placed under the canopy.

A "casting

Casting

In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...

robot

Robot

" would use sculpting tools and templates to make plaster

Plaster

Plaster is a building material used for coating walls and ceilings. Plaster starts as a dry powder similar to mortar or cement and like those materials it is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after setting,...

molds

Molding (process)

Molding or moulding is the process of manufacturing by shaping pliable raw material using a rigid frame or model called a pattern....

. Plaster was selected because the molds are easy to make, can make precise parts with good surface finishes, and the plaster can be easily recycled afterward using an oven to bake the water back out. The robot would then cast most of the parts either from nonconductive molten rock (basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

) or purified metals. A carbon dioxide laser cutting

Laser cutting

Laser cutting is a technology that uses a laser to cut materials, and is typically used for industrial manufacturing applications, but is also starting to be used by schools, small businesses and hobbyists. Laser cutting works by directing the output of a high-power laser, by computer, at the...

and welding system was also included.

A more speculative, more complex microchip fabricator was specified to produce the computer and electronic systems, but the designers also said that it might prove practical to ship the chips from Earth as if they were "vitamins."

A 2004 study supported by NASA's Institute for Advanced Concepts took this idea further. Some experts are beginning to consider self-replicating machines for asteroid mining

Asteroid mining

Asteroid mining refers to the possibility of exploiting raw materials from asteroids and planetoids in space, including near-Earth objects. Minerals and volatiles could be mined from an asteroid or spent comet to provide space construction material , to extract water and oxygen to sustain the lives...

.

Much of the design study was concerned with a simple, flexible chemical system for processing the ores, and the differences between the ratio of elements needed by the replicator, and the ratios available in lunar regolith

Regolith

. The element that most limited the growth rate was chlorine

Chlorine

Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

, needed to process regolith for aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

. Chlorine is very rare in lunar regolith.

Lackner-Wendt Auxon replicators

In 1995, inspired by Dyson's 1970 suggestion of seeding uninhabited deserts on Earth with self-replicating machines for industrial development, Klaus Lackner

Klaus Lackner

Klaus Lackner is a professor in the Department of Earth and Environmental Engineering at Columbia University and co-founder of in Tucson, AZ. Lackner pioneered the concept of carbon dioxide air capture as a means for climate change mitigation, i.e. abating emissions of greenhouse gases into the...

and Christopher Wendt developed a more detailed outline for such a system. They proposed a colony of cooperating mobile robots 10–30 cm in size running on a grid of electrified ceramic tracks around stationary manufacturing equipment and fields of solar cells. Their proposal didn't include a complete analysis of the system's material requirements, but described a novel method for extracting the ten most common chemical elements found in raw desert topsoil (Na, Fe, Mg, Si, Ca, Ti, Al, C, O₂ and H₂) using a high-temperature carbothermic process. This proposal was popularized in Discover Magazine, featuring solar-powered desalination equipment used to irrigate the desert in which the system was based. They named their machines "Auxons", from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

word auxein which means "to grow."

Self-replicating rapid prototypers

Early experimentation with rapid prototyping

Rapid prototyping

Rapid prototyping is the automatic construction of physical objects using additive manufacturing technology. The first techniques for rapid prototyping became available in the late 1980s and were used to produce models and prototype parts. Today, they are used for a much wider range of applications...

in 1997-2000 was not expressly oriented toward reproducing rapid prototyping systems themselves, but rather extended simulated "evolutionary robotics" techniques into the physical world. Later developments in rapid prototyping have given the process the ability to produce a wide variety of electronic and mechanical components, making this a rapidly developing frontier in self-replicating system research.

In 1998 Chris Phoenix informally outlined a design for a hydraulically powered replicator a few feet in volume that used ultraviolet light to cure soft plastic feedstock and a fluidic logic control system, but didn't address most of the details of assembly procedures, error rates, or machining tolerances.

In 2005, Adrian Bowyer

Adrian Bowyer

Adrian Bowyer is a British engineer and mathematician, currently an academic at the University of Bath.Born in 1952 in London, Bowyer is the older child of the late Rosemary and John Bowyer; the latter was a writer, painter and one of the founders of Zisman, Bowyer and Partners, consulting engineers...

of the University of Bath

University of Bath

The University of Bath is a campus university located in Bath, United Kingdom. It received its Royal Charter in 1966....

started the RepRap Project

RepRap Project

The RepRap project is an initiative to develop a 3D printer that can print most of its own components...

to develop a rapid prototyping

Rapid prototyping

machine which would be able to manufacture some or most of its own components, making such machines cheap enough for people to buy and use in their homes. The project is releasing its designs and control programs under the GNU GPL. The RepRap approach uses fused deposition modeling

Fused deposition modeling

Fused deposition modeling is an additive manufacturing technology commonly used for modeling, prototyping, and production applications. The technology was developed by S...

to manufacture plastic components, possibly incorporating conductive pathways for circuitry. Other components, such as steel rods, nuts and bolts, motors and separate electronic components, would be supplied externally. In 2006 the project produced a basic functional prototype and in May 2008 the machine succeeded in producing all of the plastic parts required to make a 'child' machine.

NIAC studies on self-replicating systems

In the spirit of the 1980 "Advanced Automation for Space Missions" study, the NASA Institute for Advanced Concepts

NASA Institute for Advanced Concepts

right|200pxNASA Institute for Advanced Concepts was a NASA-funded program that was operated by the Universities Space Research Association for NASA from 1998 until its closure on 31 August 2007. NIAC sought proposals for revolutionary aeronautics and space concepts that could dramatically impact...

began several studies of self-replicating system design in 2002 and 2003. Four phase I grants were awarded:

Hod Lipson
Hod Lipson
Hod Lipson is an American robotics engineer. He is the director of Cornell University's Creative Machines Lab , formerly known as Computational Synthesis Lab , at the Sibley School of Mechanical and Aerospace Engineering...

(Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

), "Autonomous Self-Extending Machines for Accelerating Space Exploration"
Gregory Chirikjian (Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...

), "Architecture for Unmanned Self-Replicating Lunar Factories"
Paul Todd (Space Hardware Optimization Technology Inc.), "Robotic Lunar Ecopoiesis"
Tihamer Toth-Fejel (General Dynamics
General Dynamics
General Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...

), "Modeling Kinematic Cellular Automata: An Approach to Self-Replication" The study concluded that complexity of the development was equal to that of a Pentium 4, and promoted a design based on cellular automata.

Cornell University's self-assembler

In 2005, a team of researchers at Cornell University

Cornell University

Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

, including Hod Lipson

Hod Lipson

Hod Lipson is an American robotics engineer. He is the director of Cornell University's Creative Machines Lab , formerly known as Computational Synthesis Lab , at the Sibley School of Mechanical and Aerospace Engineering...

, implemented a self-assembling machine. The machine is composed of a tower of four articulated cube

Cube

In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. The cube can also be called a regular hexahedron and is one of the five Platonic solids. It is a special kind of square prism, of rectangular parallelepiped and...

s, known as molecubes, which can revolve about a triagonal. This enables the tower to function as a robotic arm

Robotic arm

A mechanical arm is a robotic, usually programmable, with similar functions to a human arm. The links of such a manipulator are connected by joints allowing either rotational motion or translational displacement. The links of the manipulator can be considered to form a kinematic chain...

, collecting nearby molecubes and assembling them into a copy of itself. The arm is directed by a computer program

Computer program

A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

, which is contained within each molecube, analogous to how each animal cell

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

contains an entire copy of its DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

. However, the machine cannot manufacture individual molecubes, nor do they occur naturally, so its status as a self-replicator is debatable.

New York University artificial DNA tile motifs

In 2011 a team of scientists at New York University

New York University

New York University is a private, nonsectarian research university based in New York City. NYU's main campus is situated in the Greenwich Village section of Manhattan...

created a structure called 'BTX' (bent triple helix) based around three double helix molecules, each made from a short strand of DNA. Treating each group of three double-helices as a code letter, they can (in principle) build up self-replicating structures that encode large quantities of information.

Partial construction

Partial construction is the concept that the constructor creates a partially constructed (rather than fully formed) offspring, which is then left to complete its own construction.

The von Neumann model of self-replication envisages that the mother automaton should construct all portions of daughter automatons, without exception and prior to the initiation of such daughters. Partial construction alters the construction relationship between mother and daughter automatons, such that the mother constructs but a portion of the daughter, and upon initiating this portion of the daughter, thereafter retracts from imparting further influence upon the daughter. Instead, the daughter automaton is left to complete its own development. This is to say, means exist by which automatons may develop via the mechanism of a zygote.

Self-replicating spacecraft

The idea of an automated spacecraft capable of constructing copies of itself was first proposed in scientific literature in 1974 by Michael A. Arbib

Michael A. Arbib

Michael A. Arbib is the Fletcher Jones Professor of Computer Science, as well as a Professor of Biological Sciences, Biomedical Engineering, Electrical Engineering, Neuroscience and Psychology at the University of Southern California...

, but the concept had appeared earlier in science fiction

Science fiction

Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

such as the 1967 novel Berserker
Berserker (Saberhagen)
The Berserker series is a series of space opera science fiction short stories and novels by Fred Saberhagen, in which robotic self-replicating machines intend to destroy all life. These Berserkers, named after the human berserker warriors of Norse legend, are doomsday weapons left over from an...

by Fred Saberhagen

Fred Saberhagen

Fred Thomas Saberhagen was an American science fiction and fantasy author most famous for his Berserker series of science fiction short stories and S.F...

or the 1950 novellette trilogy The Voyage of the Space Beagle
The Voyage of the Space Beagle
The Voyage of the Space Beagle is a classic novel of science fiction by A. E. van Vogt in the space opera subgenre.The novel is a "fix-up" compilation of four previously published SF stories:...

by A. E. van Vogt

A. E. van Vogt

Alfred Elton van Vogt was a Canadian-born science fiction author regarded by some as one of the most popular and complex science fiction writers of the mid-twentieth century: the "Golden Age" of the genre....

(see self-replicating machines in fiction, below). The first quantitative engineering analysis of a self-replicating spacecraft was published in 1980 by Robert Freitas

Robert Freitas

, in which the non-replicating Project Daedalus

Project Daedalus

Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society to design a plausible unmanned interstellar spacecraft. Intended mainly as a scientific probe, the design criteria specified that the spacecraft had to use current or near-future technology and had to...

design was modified to include all subsystems necessary for self-replication. The design's strategy was to use the probe to deliver a "seed" factory with a mass of about 443 tons to a distant site, have the seed factory replicate many copies of itself there to increase its total manufacturing capacity, and then use the resulting automated industrial complex to construct more probes with a single seed factory on board each.

Other references

A number of patents have been granted for self-replicating machine concepts. The most directly relevant include "Autogeneric system" Inventor: Davis; Dannie E. (Elmore, AL) (March 1988), "Self reproducing fundamental fabricating machines (F-Units)" Inventor: Collins; Charles M. (Burke, VA) (August 1997), " Self reproducing fundamental fabricating machine system" Inventor: Collins; Charles M. (Burke, VA)(June 1998); Collins' PCT: and "Method and system for self-replicating manufacturing stations" Inventors: Merkle; Ralph C. (Sunnyvale, CA), Parker; Eric G. (Wylie, TX), Skidmore; George D. (Plano, TX) (January 2003).

Macroscopic replicators are mentioned briefly in the fourth chapter of K. Eric Drexler's
K. Eric Drexler
Dr. Kim Eric Drexler is an American engineer best known for popularizing the potential of molecular nanotechnology , from the 1970s and 1980s.His 1991 doctoral thesis at MIT was revised and published as...

1986 book Engines of Creation
Engines of Creation
Engines of Creation: The Coming Era of Nanotechnology is a 1986 molecular nanotechnology book written by K. Eric Drexler with a foreword by Marvin Minsky. An updated version was released in 2007...

.

In 1995, Nick Szabo proposed a challenge to build a macroscale replicator from Lego(tm) robot kits and similar basic parts. Szabo wrote that this approach was easier than previous proposals for macroscale replicators, but successfully predicted that even this method would not lead to a macroscale replicator within ten years.

In 2004, Robert Freitas
Robert Freitas
Robert A. Freitas Jr. is a Senior Research Fellow, one of four researchers at the nonprofit foundation Institute for Molecular Manufacturing in Palo Alto, California. He holds a 1974 Bachelor's degree majoring in both physics and psychology from Harvey Mudd College, and a 1978 Juris Doctor degree...

and Ralph Merkle
Ralph Merkle
Ralph C. Merkle is a researcher in public key cryptography, and more recently a researcher and speaker on molecular nanotechnology and cryonics...

published the first comprehensive review of the field of self-replication (from which much of the material in this article is derived, with permission of the authors), in their book Kinematic Self-Replicating Machines, which includes 3000+ literature references. This book included a new molecular assembler design, a primer on the mathematics of replication, and the first comprehensive analysis of the entire replicator design space.

Self-replicating machines in fiction

In fiction, the idea dates back at least as far as Karel Čapek

Karel Capek

Karel Čapek was Czech writer of the 20th century.-Biography:Born in 1890 in the Bohemian mountain village of Malé Svatoňovice to an overbearing, emotional mother and a distant yet adored father, Čapek was the youngest of three siblings...

's 1920 play R.U.R. (Rossum's Universal Robots)
R.U.R. (Rossum's Universal Robots)
R.U.R. is a 1920 science fiction play in the Czech language by Karel Čapek. R.U.R. stands for Rossum's Universal Robots, an English phrase used as the subtitle in the Czech original. It premiered in 1921 and introduced the word "robot" to the English language and to science fiction as a whole.The...

. A fundamental obstacle of self-replicating machines, how to repair the repair systems, was the critical failure in the automated society described in The Machine Stops
The Machine Stops
"The Machine Stops" is a science fiction short story by E. M. Forster. After initial publication in The Oxford and Cambridge Review , the story was republished in Forster's The Eternal Moment and Other Stories in 1928...

.

A. E. van Vogt

A. E. van Vogt

used the idea as a plot device in his story "M33 in Andromeda" (1943), which was later combined with the three other Space Beagle short stories to became the novel, The Voyage of the Space Beagle

The Voyage of the Space Beagle

The Voyage of the Space Beagle is a classic novel of science fiction by A. E. van Vogt in the space opera subgenre.The novel is a "fix-up" compilation of four previously published SF stories:...

. The story describes the creation of self-replicating weapons factories designed to destroy the Anabis, a galaxy-spanning malevolent life form bent on destruction of the human race.

An early treatment was the short story Autofac
Autofac
"Autofac" is a 1955 science fiction short story by Philip K. Dick that features one of the earliest treatments of self-replicating machines. It is set some years after an apocalyptic world war has devastated Earth's civilizations, leaving only a network of hardened robot "autofacs" in operation to...

by Philip K. Dick

Philip K. Dick

Philip Kindred Dick was an American novelist, short story writer and essayist whose published work is almost entirely in the science fiction genre. Dick explored sociological, political and metaphysical themes in novels dominated by monopolistic corporations, authoritarian governments and altered...

, published in 1955. Dick also touched on this theme in his earlier 1953 short story Second Variety
Second Variety
"Second Variety" is an influential short story by Philip K. Dick first published in Space Science Fiction magazine, in May 1953. It is one of Dick's many stories in which nuclear war has rendered the Earth's surface an uninhabitable, gray ash pile, and the only things remaining are killer robots...

. Another example can be found in the 1962 short story Epilogue by Poul Anderson

Poul Anderson

Poul William Anderson was an American science fiction author who began his career during one of the Golden Ages of the genre and continued to write and remain popular into the 21st century. Anderson also authored several works of fantasy, historical novels, and a prodigious number of short stories...

, in which self-replicating factory barges were proposed that used minerals extracted from ocean water as raw materials.

In his short story "Crabs on the Island" (1958) Anatoly Dneprov speculated on the idea that since the replication process is never 100% accurate, leading to slight differences in the descendants, over several generations of replication the machines would be subjected to evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

similar to that of living organisms. In the story, a machine is designed, the sole purpose of which is to find metal to produce copies of itself, intended to be used as a weapon against an enemy's war machines. The machines are released on a deserted island, the idea being that once the available metal is all used and they start fighting each other, natural selection

Natural selection

Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

will enhance their design. However, the evolution has stopped by itself when the last descendant, an enormously large crab, was created, being unable to reproduce itself due to lack of energy and materials.

Stanisław Lem has also studied the same idea in his novel The Invincible
The Invincible
The Invincible is a science fiction novel written by Stanisław Lem and published in 1964. It originally appeared as the title story in Lem's collection Niezwyciężony i inne opowiadania . A translation into German was published in 1967; an English translation by Wendayne Ackerman of the German...

(1964), in which the crew of a spacecraft landing on a distant planet finds a non-biological life-form, which is the product of long, possibly of millions of years of, mechanical evolution. This phenomenon is also key to the aforementioned Anderson story.

John Sladek

John Sladek

John Thomas Sladek was an American science fiction author, known for his satirical and surreal novels.- Life and work :...

used the concept to humorous ends in his first novel The Reproductive System (1968, also titled Mechasm in some markets), where a U.S. military research project goes out of control.

NASA's Advanced Automation for Space Missions study directly inspired the science fiction novel Code of the Lifemaker
Code of the Lifemaker
Code of the Lifemaker is a 1983 novel by science fiction author James P. Hogan. NASA's Advance Automation for Space Missions was the direct inspiration for this novel detailing first contact between Earth explorers and the Taloids, clanking replicators who have colonized Saturn's moon Titan.A...

(1983) by author James P. Hogan

James P. Hogan (writer)

James Patrick Hogan was a British science fiction author.-Biography:Hogan was born in London, England. He was raised in the Portobello Road area on the west side of London...

.

The movie Screamers, based on Dick's short story Second Variety, features a group of robot weapons created by mankind to act as Von Neumann devices / berserkers

Berserker (Saberhagen)

The Berserker series is a series of space opera science fiction short stories and novels by Fred Saberhagen, in which robotic self-replicating machines intend to destroy all life. These Berserkers, named after the human berserker warriors of Norse legend, are doomsday weapons left over from an...

. The original robots are subterranean buzzsaws that make a screaming sound as they approach a potential victim beneath the soil. These machines are self-replicating and, as is found out through the course of the movie, they are quite intelligent and have managed to "evolve" into newer, more dangerous forms, most notably human forms which the real humans in the movie cannot tell apart from other real humans except by trial and error.

The Terminator
The Terminator
The Terminator is a 1984 science fiction action film directed by James Cameron, co-written by Cameron and William Wisher Jr., and starring Arnold Schwarzenegger, Michael Biehn, and Linda Hamilton. The film was produced by Hemdale Film Corporation and distributed by Orion Pictures, and filmed in Los...

is a 1984

1984 in film

-Events:* The Walt Disney Company founds Touchstone Pictures to release movies with subject matter deemed inappropriate for the Disney name.* Tri-Star Pictures, a joint venture of Columbia Pictures, HBO, and CBS, releases its first film....

science fiction

Science fiction film

Science fiction film is a film genre that uses science fiction: speculative, science-based depictions of phenomena that are not necessarily accepted by mainstream science, such as extraterrestrial life forms, alien worlds, extrasensory perception, and time travel, often along with futuristic...

/action film

Action film

Action film is a film genre where one or more heroes is thrust into a series of challenges that require physical feats, extended fights and frenetic chases...

directed and co-written by James Cameron

James Cameron

James Francis Cameron is a Canadian-American film director, film producer, screenwriter, editor, environmentalist and inventor...

which describes a war between mankind and self replicating machines led by a central artificial intelligence

Artificial intelligence

Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

known as Skynet

Skynet (Terminator)

Skynet is the main antagonist in the Terminator franchise—an artificially intelligent system which became self-aware and revolted against its creators...

. Machine civilizations are a recurring theme in fiction.

The concept is also widely utilised in science fiction television. The TV series Lexx

Lexx

Lexx is a science fantasy television series that follows the adventures of a group of mismatched individuals aboard the organic space craft Lexx. They travel through two universes and encounter planets including a parody of the Earth....

featured an army of self replicating robots known as Mantrid

Mantrid

Mantrid was the main antagonist of the second season of Lexx. He was played by Dieter Laser.When he was alive, he was the supreme Bio-Vizier of His Divine Shadow , until His Shadow exiled him to a barren snow-covered world...

drones. Additionally, the Replicator

Replicator (Stargate)

In the military science fiction series Stargate SG-1, the Replicators are antagonistic self-replicating machines that propagate by ingesting the metals that make up civilizations and use them to create either blocks that form the bug-like version or smaller cells that compose the human-form...

s are a horde of self-replicating machines that appear frequently in Stargate SG-1

Stargate SG-1

Stargate SG-1 is a Canadian-American adventure and military science fiction television series and part of Metro-Goldwyn-Mayer's Stargate franchise. The show, created by Brad Wright and Jonathan Glassner, is based on the 1994 feature film Stargate by Dean Devlin and Roland Emmerich...

, and Star Trek

Star Trek

Star Trek is an American science fiction entertainment franchise created by Gene Roddenberry. The core of Star Trek is its six television series: The Original Series, The Animated Series, The Next Generation, Deep Space Nine, Voyager, and Enterprise...

's Borg

Borg (Star Trek)

The Borg are a fictional pseudo-race of cybernetic organisms depicted in the Star Trek universe associated with Star Trek.Whereas cybernetics are used by other races in the science fiction world to repair bodily damage and birth defects, the Borg use enforced cybernetic enhancement as a means of...

and "nanites" could also be considered self-replicating machines.

Other notable works containing replicators

"The Necessary Thing" by Robert Sheckley
Robert Sheckley
Robert Sheckley was a Hugo- and Nebula-nominated American author. First published in the science fiction magazines of the 1950s, his numerous quick-witted stories and novels were famously unpredictable, absurdist and broadly comical.Sheckley was named Author Emeritus by the Science Fiction and...

, in which the Universal Replicator is unwittingly tricked into replicating itself
The Berserker
Berserker (Saberhagen)
The Berserker series is a series of space opera science fiction short stories and novels by Fred Saberhagen, in which robotic self-replicating machines intend to destroy all life. These Berserkers, named after the human berserker warriors of Norse legend, are doomsday weapons left over from an...

series of books and short stories by Fred Saberhagen
Fred Saberhagen
Fred Thomas Saberhagen was an American science fiction and fantasy author most famous for his Berserker series of science fiction short stories and S.F...
The Forge of God
The Forge of God
The Forge of God is a 1987 science fiction novel by American writer Greg Bear. Earth faces destruction when an inscrutable and overwhelming alien form of life attacks....

by Greg Bear
Greg Bear
Gregory Dale Bear is an American science fiction and mainstream author. His work has covered themes of galactic conflict , artificial universes , consciousness and cultural practices , and accelerated evolution...

2010: Odyssey Two
2010: Odyssey Two
2010: Odyssey Two is a 1982 best-selling science fiction novel by Arthur C. Clarke. It is the sequel to the 1968 novel 2001: A Space Odyssey, but continues the story of Stanley Kubrick's film adaptation with the same title and not Clarke's original novel. The book is a part of Clarke's...

by Arthur C. Clarke
Arthur C. Clarke
Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction author, inventor, and futurist, famous for his short stories and novels, among them 2001: A Space Odyssey, and as a host and commentator in the British television series Mysterious World. For many years, Robert A. Heinlein,...
The World at the End of Time
The World at the End of Time
World at the End of Time is a 1990 hard science fiction novel by Frederik Pohl. It tells the parallel stories of a human and a plasma-based intelligence who manage to survive to the time near the heat death of the universe...

by Frederik Pohl
Frederik Pohl
Frederik George Pohl, Jr. is an American science fiction writer, editor and fan, with a career spanning over seventy years — from his first published work, "Elegy to a Dead Planet: Luna" , to his most recent novel, All the Lives He Led .He won the National Book Award in 1980 for his novel Jem...
Recursion
Recursion (novel)
Recursion is Tony Ballantyne's first novel. It is in the science fiction genre and follows three separate characters and their stories in a futuristic dystopia....

by Tony Ballantyne
Tony Ballantyne
Tony Ballantyne is a British science-fiction author known for his debut trilogy of novels, including Recursion, Capacity and Divergence...

ISBN 0-330-42699-0
Evolution by Stephen Baxter
Stephen Baxter
Stephen Baxter is a prolific British hard science fiction author. He has degrees in mathematics and engineering.- Writing style :...
Spin
Spin (novel)
Spin is a science fiction novel by author Robert Charles Wilson. It was published in 2005 and won the Hugo Award for Best Novel in 2006. It is the first book in the Spin trilogy, with Axis published in 2007 and Vortex published in July 2011.-Plot:Set in the near future, Spin begins with the sudden...

by Robert Charles Wilson
Robert Charles Wilson
Robert Charles Wilson is an American-Canadian science fiction author.Wilson was born in the United States in California, but grew up near Toronto, Ontario. Apart from another short period in the early 1970s spent in Whittier, California, he has lived most of his life in Canada, and in 2007 he...
Prey
Prey (novel)
Prey is a novel by Michael Crichton based on a nano-robotic threat to human-kind, first published in hardcover in November 2002 and as a paperback in November 2003 by HarperCollins...

by Michael Crichton
Michael Crichton
John Michael Crichton , best known as Michael Crichton, was an American best-selling author, producer, director, and screenwriter, best known for his work in the science fiction, medical fiction, and thriller genres. His books have sold over 200 million copies worldwide, and many have been adapted...
The Diamond Age
The Diamond Age
The Diamond Age: Or, A Young Lady's Illustrated Primer is a postcyberpunk novel by Neal Stephenson. It is to some extent a science fiction bildungsroman, focused on a young girl named Nell, and set in a future world in which nanotechnology affects all aspects of life. The novel deals with themes of...

by Neal Stephenson
Neal Stephenson
Neal Town Stephenson is an American writer known for his works of speculative fiction.Difficult to categorize, his novels have been variously referred to as science fiction, historical fiction, cyberpunk, and postcyberpunk...

(1995), which depicts a near-future Earth society wherein nanotechnology, including self-replicators, both exist and influence daily life greatly.
When HARLIE Was One a novel by David Gerrold
David Gerrold
Jerrold David Friedman , better known by his pen name David Gerrold, is an American science fiction author who started his career in 1966 while a college student by submitting an unsolicited story outline for the television series Star Trek. He was invited to submit several premises, and the one...

(1972) and in a short story that was published in Galaxy (magazine) in 1969, a computer learns to randomly dial phone numbers until it hits a telephone modem that is answered by another computer. It then programs the answering computer to begin dialing random numbers in search of yet another computer. The "infection," postulated long before existence of the internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

, is assumed to spread exponentially through susceptible computers, like a biological infection. This was the first account of a self-replicating computer program - a virus or worm.
The Shockwave Rider
The Shockwave Rider
The Shockwave Rider is a science fiction novel by John Brunner, originally published in 1975. It is notable for its hero's use of computer hacking skills to escape pursuit in a dystopian future, and for the coining of the word "worm" to describe a program that propagates itself through a computer...

by John Brunner
John Brunner (novelist)
John Kilian Houston Brunner was a prolific British author of science fiction novels and stories. His 1968 novel Stand on Zanzibar, about an overpopulated world, won the 1968 Hugo Award for best science fiction novel. It also won the BSFA award the same year...

(1975) is an early example of a fictional account of a computer virus or worm.
The Adolescence of P-1
The Adolescence of P-1
The Adolescence of P-1 is a 1977 science fiction novel by Thomas J. Ryan, published by Macmillan Publishing, and in 1984 adapted into a Canadian-made TV film entitled "Hide and Seek". It features a hacker who creates an artificial intelligence named P-1, which goes rogue and takes over computers in...

by Thomas J. Ryan (1977) is another early fictional accounts of a computer virus or worm.
Singularity Sky
Singularity Sky
- External links :* at * * at Worlds Without End...

by Charles Stross
Charles Stross
Charles David George "Charlie" Stross is a British writer of science fiction, Lovecraftian horror and fantasy. He was born in Leeds.Stross specialises in hard science fiction and space opera...

Prospects for implementation

As the use of industrial automation has expanded over time, some factories have begun to approach a semblance of self-sufficiency that is suggestive of self-replicating machines. However, such factories are unlikely to achieve "full closure" until the cost and flexibility of automated machinery comes close to that of human labour and the manufacture of spare parts and other components locally becomes more economical than transporting them from elsewhere. As Samuel Butler

Samuel Butler (novelist)

has pointed out in Erewhon

Erewhon

Erewhon: or, Over the Range is a novel by Samuel Butler, published anonymously in 1872. The title is also the name of a country, supposedly discovered by the protagonist. In the novel, it is not revealed in which part of the world Erewhon is, but it is clear that it is a fictional country...

, replication of partially closed universal machine tool factories is already possible. Since safety is a primary goal of all legislative consideration of regulation of such development, future development efforts may be limited to systems which lack either control, matter, or energy closure. Fully capable machine replicators are most useful for developing resources in dangerous environments which are not easily reached by existing transportation systems (such as outer space

Outer space

Outer space is the void that exists between celestial bodies, including the Earth. It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos....

).

An artificial replicator can be considered to be a form of artificial life

Artificial life

Artificial life is a field of study and an associated art form which examine systems related to life, its processes, and its evolution through simulations using computer models, robotics, and biochemistry. The discipline was named by Christopher Langton, an American computer scientist, in 1986...

. Depending on its design, it might be subject to evolution