Models are experiments, experiments are models

A model is a representation of something beyond itself in the sense of being used as a representative of that something, and in prompting questions of resemblance between the model and that something. Models are substitute systems that are directly examined in order to indirectly acquire information about their target systems. An experiment is an arrangement seeking to isolate a fragment of the world by controlling for causally relevant things outside that fragment. It is suggested that many theoretical models are ('thought') experiments, and that many ordinary experiments are ('material') models. The major difference between the two is that the controls effecting the required isolation are based on material manipulations in one case, and on assumptions in the other.