Programmable matter refers to matter which has the ability to change its physical properties (shape, density, moduli, conductivity, optical properties, etc.) in a programmable fashion, based upon user input or autonomous sensing. Programmable matter is thus linked to the concept of a material which inherently has the ability to perform information processing.
Programmable matter is a term originally coined in 1991 by Toffoli and Margolus to refer to an ensemble of fine-grained computing elements arranged in space (Toffoli & Margolus 1991). Their paper describes a computing substrate that is composed of fine-grained compute nodes distributed throughout space which communicate using only nearest neighbor interactions. In this context, programmable matter refers to compute models similar to cellular automata and lattice gas automata (Rothman & Zaleski 1997). The CAM-8 architecture is an example hardware realization of this model. This function is also known as "digital referenced areas" (DRA) in some forms of self-replicating machine science.
In the early 1990s, there was a significant amount of work in reconfigurable modular robotics with a philosophy similar to programmable matter.
As semiconductor technology, nanotechnology, and self-replicating machine technology have advanced, the use of the term programmable matter has changed to reflect the fact that it is possible to build an ensemble of elements which can be "programmed" to change their physical properties in reality, not just in simulation. Thus, programmable matter has come to mean "any bulk substance which can be programmed to change its physical properties."
In the summer of 1998, in a discussion on artificial atoms and programmable matter, Wil McCarthy and G. Snyder coined the term "quantum wellstone" (or simply "wellstone") to describe this hypothetical but plausible form of programmable matter. McCarthy has used the term in his fiction.
In 2002, Seth Goldstein and Todd Mowry started the claytronics project at Carnegie Mellon University to investigate the underlying hardware and software mechanisms necessary to realize programmable matter.
In 2004, the DARPA Information Science and Technology group (ISAT) examined the potential of programmable matter. This resulted in the 2005–2006 study "Realizing Programmable Matter", which laid out a multi-year program for the research and development of programmable matter.
Finally, in 2007, Alex Wissner-Gross at Harvard University proposed a comprehensive taxonomy for classifying programmable matter according to its physical input and output types. For example, since a field-effect transistor transduces one electrical signal (a voltage) to another (a current), it can be classified as electrical-to-electrical programmable matter.
Approaches to programmable matter
In one school of thought the programming could be external to the material and might be achieved by the "application of light, voltage, electric or magnetic fields, etc." (McCarthy 2006). For example, in this school of thought, a liquid crystal display is a form of programmable matter. A second school of thought is that the individual units of the ensemble can compute and the result of their computation is a change in the ensemble's physical properties. An example of this more ambitious form of programmable matter is claytronics, where the units in the ensemble "compute" and the result is a change in the shape of the ensemble.
There are many proposed implementations of programmable matter. Scale is one key differentiator between different forms of programmable matter. At one end of the spectrum reconfigurable modular robotics pursues a form of programmable matter where the individual units are in the centimeter size range. At the nanoscale end of the spectrum there are a tremendous number of different bases for programmable matter, ranging from shape changing molecules to quantum dots. Quantum dots are in fact often referred to as artificial atoms. In the micrometer to sub-millimeter range examples include claytronics, MEMS-based units, cells created using synthetic biology, and the utility fog concept.
Examples of programmable matter
There are many conceptions of programmable matter, and thus many discrete avenues of research using the name. Below are some specific examples of programmable matter.
"Simple" programmable matter
These include materials that can change their properties based on some input, but do not have the ability to do complex computation by themselves.
The physical properties of several complex fluids can be modified by applying a current or voltage, as is the case with liquid crystals.
Metamaterials are artificial composites that can be controlled to react in ways that do not occur in nature. One example developed by David Smith and then by John Pendry and David Schuri is of a material that can have its index of refraction tuned so that it can have a different index of refraction at different points in the material. If tuned properly this could result in an "invisibility cloak."
An active area of research is in molecules that can change their shape, as well as other properties, in response to external stimuli. These molecules can be used individually or en masse to form new kinds of materials. For example, J Fraser Stoddart's group at UCLA has been developing molecules that can change their electrical properties.
Self-reconfiguring modular robotics
Self-Reconfiguring Modular Robotics is a field of robotics in which a group of basic robot modules work together to dynamically form shapes and create behaviours suitable for many tasks. Like Programmable matter SRCMR aims to offer significant improvement to any kind of objects or system by introducing many new possibilities for example: 1. Most important is the incredible flexibility that comes from the ability to change the physical structure and behavior of a solution by changing the software that controls modules. 2. The ability to self-repair by automatically replacing a broken module will make SRCMR solution incredibly resilient. 3. Reducing the environmental foot print by reusing the same modules in many different solutions. Self-Reconfiguring Modular Robotics enjoys a vibrant and active research community see Self-Reconfiguring Modular Robotics for more information and links.
Claytronics is an emerging field of engineering concerning reconfigurable nanoscale robots ('claytronic atoms', or catoms) designed to form much larger scale machines or mechanisms. The catoms will be sub-millimeter computers that will eventually have the ability to move around, communicate with other computers, change color, and electrostatically connect to other catoms to form different shapes.
Cellular automata are a useful concept to abstract some of the concepts of discrete units interacting to give a desired overall behavior.
Quantum wells can hold one or more electrons. Those electrons behave like artificial atoms which, like real atoms, can form covalent bonds, but these are extremely weak. Because of their larger sizes, other properties are also widely different.
Synthetic biology is a field that aims to engineer cells with "novel biological functions." Such cells are usually used to create larger systems (e.g., biofilms) which can be "programmed" utilizing synthetic gene networks such as genetic toggle switches, to change their color, shape, etc.
Programmable matter in fiction
Programmable matter is still, for the most part, a fantastic vision for the future. The ideas behind it are explored in many works of science fiction. Examples:
- The T-1000 from Terminator 2 fits the definition of programmable matter, although it is not described that way in the film. (The term was only just coined the year of the film’s release.)
- It is called "wellstone" in many of Wil McCarthy's books and stories.
- It is called "Trillions" in the 1973 children's book Trillions by Nicholas Fisk
- It is called "reality graphics" in Vernor Vinge's book A Fire Upon the Deep.
- It is called "the Flesh" in Doctor Who.
- David Brin's Kiln People
- It is called "Computronium" in Charles Stross' Accelerando.
- Programmable Silicon is used to quickly erect buildings in Peter F Hamilton's Night's Dawn Trilogy
- The Replicators from the Stargate universe are based on this technology.
- In the Pendragon Adventure series, "Forge" is a programmable matter device created by Mark Dimond and Andy Mitchell.
- The Caeliar are an alien race in the Star Trek novel trilogy "Star Trek: Destiny" whose bodies are made up of catoms (or claytronic atoms).
- In the book Extras by Scott Westerfeld a substance called smart matter is a very useful type of programmable matter. It is capable of anything one can program it to do as read in the book.
- In the book Anathem by Neal Stephenson, a substance called "new matter" can alter its physical properties through the application of electrical charges.
- In the movie Super 8 the alien spacecraft is composed of programmable matter.
- In the Pokemon universe, it is possible that Ditto is a form of programmable matter.
- Gort from The Day the Earth Stood Still
- In just about any work of fiction, biological systems such as humans may be regarded as programmable matter, with the source code written into the DNA of almost every cell in the body
- "CAM8: a Parallel, Uniform, Scalable Architecture for Cellular Automata Experimentation". Ai.mit.edu. Retrieved 2013-04-10.
- http://www.geocities.com/charles_c_22191/temporarypreviewfile.html?1205202563050[dead link]
- "DARPA research solicitation".[dead link]
- DARPA Strategic Thrusts: Programmable Matter[dead link]
- Physically programmable surfaces, Alex Wissner-Gross, Ph.D. Thesis, Department of Physics, Harvard University (2007)
- [dead link]
- "UCLA Chemistry and Biochemistry". Stoddart.chem.ucla.edu. Retrieved 2013-04-10.
- (Yim et al. 2007, pp. 43–52) An overview of recent work and challenges
- McCarthy, Wil (2003). The Wellstone.
- Nicholas Fisk (1973). Trillions. ISBN 0-394-92601-3.
- Vinge, Vernor (1992). A Fire Upon the Deep.
- Brin, David (2002). Kiln People.
- Stross, Charles (2005). Accelerando.
- Goldstein, Seth Copen; Campbell, Jason; Mowry, Todd C. (June, 2005). "Programmable Matter". IEEE Computer 38 (6): 99–101. doi:10.1109/MC.2005.198.
- McCarthy, Wil (2006). "Programmable Matter FAQ".
- McCarthy, Wil (2003). Hacking Matter: Levitating Chairs, Quantum Mirages, and the Infinite Weirdness of Programmable Atoms. New York: Basic Books. ISBN 0-465-04428-X.
- Rothman, D.H.; Zaleski, S. (1997). "Lattice Gas Cellular Automata". Cambridge University Press. doi:10.2277/.
- Toffoli, Tommaso; Margolus, Norman (1991). "Programmable matter: concepts and realization". Physica D 47: 263–272. doi:10.1016/0167-2789(91)90296-L.
- Yim, Mark; Shen, Wei-Min; Salemi, Behnam; Rus, Daniela; Moll, Mark; Lipson, Hod; Klavins, Eric; Chirikjian, Gregory (March 2007). "Modular Self-Reconfigurable Robot Systems". IEEE Robotics & Automation Magazine 14 (1): 43. doi:10.1109/MRA.2007.339623.
- "Boston University's Programmable Matter Group".
- "Synthetic Biology at Boston University".
- "Claytronics Project at Carnegie Mellon University".
- "World with controllable Matter".
- "Universally Programmable Intelligent Matter Project".
- "DARPA (US Military) Programmable Matter Thrust".