- Programmable matter
Programmable matter is a term originally coined in 1991 by Toffoli andMargolus to refer to an ensemble of fine-grained computing elementsarranged in space harv|Toffoli|Margolus|1991. In thiscontext, programmable
matterrefers to compute models similar to cellular automataand Lattice Gas Automataharv|Rothman|Zaleski|1997. The [http://www.ai.mit.edu/projects/im/cam8/ 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 machinescience [http://www.geocities.com/charles_c_22191/temporarypreviewfile.html?1205202563050]
semiconductortechnology nanotechnologyand self-replicating machine technology have advanced, the useof the term programmable matter has changed to reflect the fact thatit is possible to build an ensemble of elements which can be" programmed" to change their physical properties in reality, not justin simulation. Thus, programmable matter has come to mean "any bulksubstance which can be programmed to change its physical properties."In one school of thought the programming could be external to thematerial and might be achieved by the "application of light, voltage,electric or magnetic fields, etc." harv|McCarthy|2006. Forexample, in this school of thought an LCDdisplay is a form ofprogrammable matter. A second school of thought is that theindividual units of the ensemble can compute and the result of theircomputation is a change in the ensemble's physical properties. Anexample 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. Scaleis one key differentiator between different forms of programmablematter. At one end of the spectrum reconfigurable modular roboticspursues a form of programmable matter where the individual units arein the centimeter size range (e.g., [http://groups.csail.mit.edu/drl/research.html] [http://www.robotics.upenn.edu/people/yim.html] [http://www.mip.sdu.dk/~kaspers/research.php] [http://www.geocities.com/charles_c_22191/temporarypreviewfile.html?1205202563050] .At the nanoscale end of the spectrum there are a tremendous number ofdifferent bases for programmable matter, ranging from shape changingmolecules (e.g., [http://stoddart.chem.ucla.edu/] ) 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 fogconcept.
In 1991, Toffoli and Margolus published the first paper to describe a programmable matter system harv|Toffoli|Margolus|1991. Their paper describes a computing
substratethat is composed of fine-grained compute nodes distributed throughout space which communicate using only nearest neighbor interactions.
In the early 1990s there was a significant amount of work in reconfigurable modular robotics with a philosophy similar to programmable matter [http://www.geocities.com/charles_c_22191/temporarypreviewfile.html?1205202563050] .
In the summer of 1998, in a discussion on artificial atoms and programmable matter,
Wil McCarthyand G. Snyder coined the term "quantum wellstone" (or simply "wellstone") to describe this hypothetical but plausible form ofprogrammable matter. McCarthy has used the term in his fiction.
In 2002, [http://www.cs.cmu.edu/~seth Seth Goldstein] and [http://www.cs.cmu.edu/~tcm Todd Mowry] started the
claytronicsproject at Carnegie Mellon University to investigate the underlying hardware and software mechanisms necessary to realize programmable matter.
Examples of Programmable matter
Below are some specific examples of programmable matter. (This needsto be filled out.)
The physical properties of several complex fluids can be modified byapplying a current or voltage, as is the case with
Quantum wells can hold one or more electrons. Thoseelectrons behave like artificial atoms which, like real atoms,can form covalent bonds. Because of their larger sizes, otherproperties are widely different.
Metamaterials are artificial
compositesthat can be controlled toreact in ways that do not occur in nature. One example developed byDavid Smith and then by John Pendry and David Schuri is of a materialthat can have its index of refractiontuned so that it can have adifferent index of refraction at different points in the material. Iftuned properly this could result in an "invisibility cloak." For more see Metamaterial.
Shape Changing Molecules
An active area of research is in molecules that can change theirshape, as well as other properties, in response to external stimuli.These molecules can be used individually or en masse to form new kindsof materials. For example, [http://stoddart.chem.ucla.edu/ J Fraser Stoddart's] group at UCLA has been developing molecules that canchange their electrical properties.
Reconfigurable Modular Robotics
Self-Reconfiguring Modular Roboticsis a field of robotics inwhich a group of usually identical robots work together to dynamicallyform shapes suitable for each task. See harv|Yim|Shen|Salemi|Rus|2007|pp=43-52 for an overview of recent work and challenges.
Synthetic biologyis a field that aims to engineer cells with"novel biological functions." Such cells are usually used to createlarger systems (e.g., biofilms) which can be "programmed" utilizing synthetic gene networks such as genetic toggle switches, to changetheir color, shape, etc.
Programmable Matter in fiction
Programmable matter is still, for the most part, a fantastic visionfor the future. The ideas behind it are explored in many works ofscience fiction. For example (This list is very incomplete):
* It is called "Trillions" in the children's book "Trillions", by Nicholas Fisk (1973), ISBN-10: 0394926013
* It is called "reality graphics" in cite book|last=Vinge|first=Vernor|title=A Fire Upon the Deep|year=1992
* It is called "wellstone" in many of Wil McCarthy's books and stories, e.g., cite book|last=McCarthy|first=Wil|title=The_Wellstone|year=2003
* It is called "Computronium" in cite book|last=Stross|first=Charles|title=Accelerando|year=2005
* Programmable Silicon is used to quickly erect buildings in Peter F Hamilton's
Night's Dawn Trilogy
last3 = Mowry
first3 = Todd C.
date = June, 2005
year = 2005
last = McCarthy
first = Wil
title = Programmable Matter FAQ
url = http://www.programmablematter.com/FAQ.html#A1
date = 2006
year = 2006
last = McCarthy
first = Wil
title = Hacking Matter: Levitating Chairs, Quantum Mirages, and the Infinite Weirdness of Programmable Atoms
isbn = 0-465-04428-X
date = 2003
year = 2003
first2 = S.
title=Lattice Gas Cellular Automata
publisher=Cambridge University Press
year = 1997
last = Toffoli
first = Tommaso
last2 = Margolus
first2 = Norman
title = Programmable matter: concepts and realization
journal = Physica D
volume = 47
pages = 263-272
url = http://portal.acm.org/citation.cfm?id=104699.104736
date = 1991
year = 1991
url = http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4141032
title = Modular Self-Reconfigurable Robot Systems
journal = IEEE Robotics & Automation Magazine
date = March 2007
volume = 14
issue = 1
last = Yim
first = M.
last2 = Shen
first2 = Wei-Min
last3 = Salemi
first3 = B.
last4 = Rus
first4 = D.
year = 2007
* cite web
title=Universally Programmable Intelligent Matter Project
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