  In the works by the author it has been shown that the conservation laws for
material media (the conservation laws for energy, linear momentum, angular
momentum, and mass, that establish a balance between the variation of a
physical quantity and the corresponding external action), turn out to be
noncommutative. The noncommutativity of the conservation laws that leads to an
emergence of internal forces and an appearance of the nonequilibrium is a cause
of development of instability in material media (material systems). These
results were obtained with the help of the mathematical apparatus of
skew-symmetric differential forms. To study the causes of developing
instability it is necessary to inspect the evolutionary relation obtained from
equations of the balance conservation laws and to analyze the differential form
commutator that enters into this relation. In the present work the method of
skew-symmetric differential forms has been applied in study of the
thermodynamical and gas dynamical systems. It was shown that the principle of
thermodynamics follows from two conservation laws, namely, the balance
conservation laws for energy and linear momentum. In this case the second
principle of thermodynamics, from which the state function (which specifies a
state of the thermodynamical system) is obtained, follows from the first
principle. A mechanism of development of instability in gas dynamical systems
is described and there are explained such processes as emergence of waves,
vortices, turbulent pulsations and so on.
