  Smart matter consists of many sensors, computers and actuators embedded
within materials. These microelectromechanical systems allow properties of the
materials to be adjusted under program control. In this context, we study the
behavior of several organizations for distributed control of unstable physical
systems and show how a hierarchical organization is a reasonable compromise
between rapid local responses with simple communication and the use of global
knowledge. Using the properties of random matrices, we show that this holds not
only in ideal situations but also when imperfections and delays are present in
the system. We also introduce a new control organization, the multihierarchy,
and show it is better than a hierarchy in achieving stability. The
multihierarchy also has a position invariant response that can control
disturbances at the appropriate scale and location.
