Programmable matter

Programmable matter refers to matter which has the ability to change its physical properties (shape, density, moduli, 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.

History

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 [1]

In the early 1990s there was a significant amount of work in reconfigurable modular robotics with a philosophy similar to programmable matter [2].

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.

In 2007, programmable matter was the subject of a DARPA research solicitation and subsequent program.

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 instantiations 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 (e.g., [3][4][5][6]. At the nanoscale end of the spectrum there are a tremendous number of different bases for programmable matter, ranging from shape changing molecules (e.g., [7]) 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. (This needs to be filled out.)

"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.

• Complex fluids. The physical properties of several complex fluids can be modified by applying a current or voltage, as is the case with liquid crystals.

• Metamaterials. 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."

• Shape Changing Molecules. 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.

Robotics-based approaches

• Reconfigurable modular robotics. Self-Reconfiguring Modular Robotics is a field of robotics in which a group of usually identical robots work together to dynamically form shapes suitable for each task. See (Yim et al. 2007, pp. 43-52) for an overview of recent work and challenges.

• Claytronics. 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. Cellular automata are a useful concept to abstract some of the concepts of discrete units interacting to give a desired overall behavior.

Quantum wells

• Quantum wells can hold one or more electrons. Those electrons behave like artificial atoms which, like real atoms, can form covalent bonds. Because of their larger sizes, other properties are widely different.

Synthetic biology

• 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. For example (This list is very incomplete):

• The T-1000 from Terminator 2 fits the definition of programmable matter, although it is not described that way in the film.

• It is called "wellstone" in many of Wil McCarthy's books and stories, e.g., McCarthy, Wil (2003). The Wellstone.

• It is called "Trillions" in the children's book "Trillions", by Nicholas Fisk (1973), ISBN-10: 0394926013

• It is called "reality graphics" in Vinge, Vernor (1992). A Fire Upon the Deep.

• Brin, David (2002). Kiln people.

• It is called "Computronium" in Stross, Charles (2005). 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.

References

• Goldstein, Seth Copen; Campbell, Jason; Mowry, Todd C. (June, 2005), "Programmable Matter", IEEE Computer, 38 (6): 99–101 CS1 maint: date and year (link)

• McCarthy, Wil (2006), Programmable Matter FAQCS1 maint: date and year (link)

• McCarthy, Wil (2003), Hacking Matter: Levitating Chairs, Quantum Mirages, and the Infinite Weirdness of Programmable Atoms, ISBN 0-465-04428-XCS1 maint: date and year (link)

• Rothman, D.H.; Zaleski, S. (1997), Lattice Gas Cellular Automata, Cambridge University PressCS1 maint: date and year (link)

• Toffoli, Tommaso; Margolus, Norman (1991), "Programmable matter: concepts and realization", Physica D, 47: 263–272CS1 maint: date and year (link)

• 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)CS1 maint: date and year (link)

External links

• "Boston University's Programmable Matter Group".
• "Synthetic Biology at Boston University".
• "Claytronics Project at Carnegie Mellon University".
• "Universally Programmable Intelligent Matter Project".