Amorphous Computing

ABSTRACT

The first age of computing is coming to a close. Current computers are precise arrangements of reliable parts. Current computations depend upon this precision, and they control logical abstractions that are only loosely coupled to their physical environment.

We look forward to computations performed by myriads of unreliable parts -- microelectronic computing elements, sensors, and actuators -- so inexpensive that they are mixed into bulk materials such as paints, gels, and concrete.

We can imagine constructing such elements, but we have very little idea how to program them. The limitations here are not the limitations of our technology, but the limitations of our minds.

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

These questions have of course been anticipated, for example, in studies of self-organizing systems. But the phenomena there are largely observed rather than controlled. As engineers, we must assert control. We must devise the programming principles, engineering languages for design, and tools for the analysis of amorphous machines and processes.

One area to look to for guidance is developmental biology, where the processes of differentiation and morphogeneis appear able to carry out such "computations". Many details of the low-level mechanisms are known here, mechanisms such as diffusion, gradient following, growing points, regularization, dominance, activation and inhibition, although the overall organizing principles in developmental biology remain elusive.

Nevertheless, we can exploit these mechanisms to program amorphous machines. We will demonstrate programs based on purely local parallel processes, having no a priori knowedge of the detailed interconnect, that are able to construct patterns with detailed prespecified useful topologies. We will describe some initial attempts at language appropriate for controlling such processes.

By learning how to organize processes for amorphous machines we will begin the development of the information technology necessary to coopt biological processes to allow us to manufacture novel materials and structures at a molecular scale.