  Physical processes are computations only when we use them to externalize
thought. Computation is the performance of one or more fixed processes within a
contingent environment. We reformulate the Church-Turing thesis so that it
applies to programs rather than to computability. When suitably formulated
agent-based computing in an open, multi-scalar environment represents the
current consensus view of how we interact with the world. But we don't know how
to formulate multi-scalar environments.
