  In this paper, heat and Carnot's working substance are defined respectively
by the equations $E=3pV$ and $E=3/2pV$, relating the energy $E$, the pressure
$p$ and the volume $V$ of these two corpuscular systems. The
thermodynamic-kinetic theoretical analysis of their equilibrium reveals that
the constraints imposed by the second law on the working substance are the
consequence of the relativistic and the quantum taut constraints, respectively,
$|v|\le c$ and $|\Delta p\Delta q|\ge h$, imposed on the motion of its
molecules. It is further shown that the action of these restrictions is
described by the ladder operators.
  By revealing the laws that rule the entropy formation mechanism, thereby
explaining the time asymmetry, the present approach supersedes statistical
mechanics. Furthermore, it establishes the epistemological chain connecting the
laws of thermodynamics to the axioms of quantum mechanics, leading to yet
another unorthodox interpretation of that theory.
