If a Tree Casts a Shadow is it Telling the Time?
Physical processes are computations only when we use them to externalize thought. Entities provide nature with a way to preserve structure over time. We think in terms of entities because they are so central to how the world is. 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 software 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.