Programmable matter is matter which has the ability to change its physical
properties 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. 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. The CAM-8 architecture is an example
hardware realization of this model. This function is also known as "digital
referenced areas" 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" 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 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.". For example, 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.
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. 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."
A further example of programmable -mechanical- metamaterial is presented
by Bergamini et al. Here, a pass band within the phononic bandgap is
introduced, by exploiting variable stiffness of piezoelectric elements
linking aluminum stubs to the aluminum plate to create a phononic crystal as in
the work of Wu et al. The piezoelectric elements are shunted to ground over
synthetic inductors. Around the resonance frequency of the LC circuit
formed by the piezoelectric and the inductors, the piezoelectric elements
exhibit near zero stiffness, thus effectively disconnecting the stubs from
the plate. This is considered an example of programmable mechanical metamaterial.
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.
Electropermanent magnets An electropermanent magnet is a type of
magnet which consists of both an electromagnet and a dual material
permanent magnet, in which the magnetic field produced by the electromagnet is
used to change the magnetization of the permanent magnet. The permanent magnet
consists of magnetically hard and soft materials, of which only the soft
material can have its magnetization changed. When the magnetically soft and
hard materials have opposite magnetizations the magnet has no net
field, and when they are aligned the magnet displays magnetic behaviour.
They allow creating controllable permanent magnets where the magnetic
effect can be maintained without requiring a continuous supply of
electrical energy. For these reasons, electropermanent magnets are essential
components of the research studies aiming to build programmable magnets
that can give rise to self-building structures.
= Robotics-based approaches = 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.
Claytronics Claytronics is an emerging field of
engineering concerning reconfigurable nanoscale robots 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, but these are extremely weak. Because of their larger
sizes, other properties are also 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 which can be "programmed" utilizing synthetic gene
networks such as genetic toggle switches, to change their color, shape,
etc. Such bioinspired approaches to materials production has been
demonstrated, using self-assembling bacterial biofilm materials that can be
programmed for specific functions, such as substrate adhesion, nanoparticle
templating, and protein immobilization. See also
Nanotechnology Computronium
Smart material Utility fog
Smartdust Claytronics
Ubiquitous computing Universal Turing machine
References Goldstein, Seth Copen; Campbell, Jason;
Mowry, Todd C.. "Programmable Matter". IEEE Computer 38: 99–101.
doi:10.1109/MC.2005.198. McCarthy, Wil. "Programmable Matter
FAQ". McCarthy, Wil. 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. ISBN 9780521607605. Toffoli, Tommaso; Margolus, Norman.
"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. "Modular Self-Reconfigurable Robot Systems". IEEE Robotics &
Automation Magazine 14: 43. doi:10.1109/MRA.2007.339623.
External links "World with controllable Matter".
"Boston University's Programmable Matter Group".
"Synthetic Biology at Boston University".
"Claytronics Project at Carnegie Mellon University".
"Universally Programmable Intelligent Matter Project".
"DARPA Programmable Matter Thrust".