The most famous of these is the : There exists a function (the entropy) whose maximization governs equilibrium.
Using the convexity of entropy, he derives the conditions for : positive heat capacity, positive compressibility, etc. But more importantly, he introduces the concept of phase transitions as a failure of stability . When the entropy function stops being convex, the system must break into multiple phases. callen termodinamica
Beyond the Boiler Room: Why Herbert Callen’s View of Thermodynamics is a Game Changer The most famous of these is the :
He treats thermodynamics like geometry or classical mechanics. You don't prove postulates; you accept them because they match reality. This approach strips away the historical baggage and reveals the pure logical skeleton of the theory. etc. But more importantly