objects/systems”. Such a distinction draws an epistemological scaffolding which provides a relevant contribution
to reach two aims: i) to help students to understand the physical concept of temperature, and ii) to enable
students to face explicitly why that type of abstractness is needed to account for phenomena whose perception is
commonly described by familiar words.
b. Processes and steady states – in spite of the name thermo-“dynamics”, the dynamical explanation of the
systems’ evolution disappears behind the weird choice of modelling processes as sequences of equilibrium states
in the pV diagram. Traces of the dynamical processes are only recognisable in the distinction between process
and state variables. In order to make the dynamical model of thermodynamics explicit, an epistemological
reflection is needed to stress how the ideal, quasi-static, transformations implement a mechanistic view of
interaction. The system is assumed to have, at any time, well-defined properties whose change is interpreted in
terms of “inter-actions” with an external causal agent that controls, deterministically and step by step, the whole
process (See §3.2, Part I).
c. Reversibility and irreversibility – even though the second principle aims at finding out a quantity (entropy) for
describing the intrinsic irreversibility of phenomena, such a quantity is defined on reversible transformations. A
system which evolves in an irreversible way forgets the initial conditions and it does not come back
spontaneously to its initial state; a system which evolves in a reversible way remembers the initial conditions and
it can come back and go on. In order to address this seeming paradox, an epistemological reflection about the
various meanings of entropy is needed as they emerge from the game between models and reality (See §3.2, Part
II).