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
se