If a tree casts a shadow is it telling the time?

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 reformula te the Church-Turing thesis so that it applies to programs rather than to c omputability. 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. Keywords: agents, agent-based, agent-based computation, Church-Turing thesis, Church's thesis, computing, computation, envir onment ideas, interaction, interactive computation, models, multi-scalar envir onment, thought, thought tools, unconventional computation.