The way contemporary thermodynamics works is based on hypotheses and measurements, both at the microscopic level of individual particles and at the macroscopic level of the "large" systems. The first kind of hypotheses and measurements are based on mechanical concepts such as position, mass, velocity, forces, kinetic/potential energy, or Newton's Laws. The second kind are based on the definition of new quantities such as temperature, amount of heat, entropy, and of their assumed properties. Statistical hypotheses complete this ensemble and explain how it is possible to go from the microscopic level to the macroscopic level (extensivity property, postulate of ergodicity, whether or not individual particles are discernable, definition and equiprobability of the microstates, etc.). The number of microscopic particles in the overall system has an effect on how we consider the transition between levels. The overall architecture of thermodynamics must allow these different hypotheses and measurements to co-exist in the four aspects. Different authors propose different ways to understand this overall architecture, as a function of whether or not sets of hypotheses are put forward, independently or not, at one or another level (or whether the question of scale even arises). This article touches upon these possibilities and, in a very general way, discusses the consistencies among these architectures and the potential degrees of freedom in their construction, based on the premise that any paths to progress in thermodynamics (or to refreshing our knowledge in this field) must be placed within this framework. A few examples are given to open up avenues for research.
