I've been thinking about (and writing out my thoughts on) the real meaning of entropy in physics and how it relates to physical models. It should be obvious that entropy(physical system) isn't well-defined; only entropy(physical model, physical system) is defined. Here, 'physical model' might refer to something like the kinetic theory of gases, and 'physical system' would refer to, say, some volume of gas or a cup of tea. It's interesting to think about entropy from this perspective because it becomes related to the subjectivist interpretation of probability. I want to know if anyone knows of any links to similar ideas and thoughts.