Amorphous Computing

Rohit Khare (
Tue, 10 Dec 1996 12:18:58 -0500

Amorphous Computing

Harold Abelson, Thomas F. Knight, Gerald Jay Sussman, and friends<Picture=

A colony of cells cooperates to form a multicellular organism under the
direction of a genetic program shared by the members of the colony. A swa=
of bees cooperates to construct a hive. Humans group together to build
towns, cities, and nations. These examples raise fundamental questions fo=
the organization of computing systems:=20

=95How do we obtain coherent behavior from the cooperation of large numbe=
of unreliable parts that are interconnected in unknown, irregular, and
time-varying ways?=20

=95What are the methods for instructing myriads of programmable entities =
cooperate to achieve particular goals?=20

These questions have been recognized as fundamental for generations. But
this paper argues that now is an opportune time to tackle the engineering
of emergent order: to identify the engineering principles and languages
that can be used to observe, control, organize, and exploit the behavior =
programmable multitudes.=20

We call this effort the study of amorphous computing.=20

The objective of this research is to create the system-architectural,
algorithmic, and technological foundations for exploiting programmable
materials. These are materials that incorporate vast numbers of
programmable elements that react to each other and to their environment.
Such materials can be fabricated economically, provided that the computin=
elements are amassed in bulk without arranging for precision interconnect
and testing. In order to exploit programmable materials we must identify
engineering principles for organizing and instructing myriad programmable
entities to cooperate to achieve pre-established goals, even though the
individual entities are unreliable and interconnected in unknown,
irregular, and time-varying ways. We call this effort the study of
amorphous computing.=20

Amorphous computing is inspired by the recent astonishing developments in
molecular biology and in microfabrication. Each of these is the basis of =
kernel technology that makes it possible to build or grow huge numbers of
almost-identical information-processing units, with integral actuators an=
sensors (e.g. MEMS), at almost no cost. Microelectronic components are so
inexpensive that we can imagine mixing them into materials that are
produced in bulk, such as paints, gels, and concrete. Such ``smart
materials'' will be used in structural elements and in surface coatings,
such as skins or paints.=20

Engineers will use smart materials to reduce the need for strength and
precision in mechanical and electrical apparatus, through the application
of computation. It will be possible to coat a building or a bridge with
``smart paint'' that reports on traffic loads and wind loads, that monito=
the integrity of the structure, that resists buckling, or even heals smal=
cracks by shifting material around. It will be possible to make a clean
room with ``active skin,'' lined with cilia, that can push dirt and dust
into a corner for removal. It will be possible to make a wall that can
sense vibration (and move slightly on its own) to monitor for intrusion o=
to actively cancel noise.=20

Because amorphous computing will provide means to amass and control
computing agents at prices comparable to the raw material costs, we expec=
to invent ways to use amorphous systems to attack previously impossible
simulation problems. Because amorphous computing gives us the means to
coordinate information from vast numbers of distributed sensors and to us=
it to control equally vast numbers of distributed effectors, we can use
amorphous computing to build systems that have unprecedented responsivene=
to their environment.=20

To exploit the potential of these technologies will require new insights
into the programming and organization of systems that have so many parts
that they cannot even be named. There are principles from physics,
mathematics, and biology that we can bring to bear. For example, to repor=
a crack in a bridge a smart-paint coating must name locations on the
bridge. We can generate solutions of differential equations to construct
coordinate patches, and combine these to build a description of the globa=
geometry of the bridge. This bootstrap process determines the geometry of
the smart paint, even though we started with no a priori knowledge of the
actual positions or orientations of communicating neighbors beyond the
assumption of local communication.=20

Rohit Khare -- World Wide Web Consortium -- Technical Staff
w: 617/253-5884  --   f: 617/258-5999   --  h: 617/491-5030
NE43-344,  MIT LCS,  545 Tech Square,  Cambridge,  MA 02139