  Non-equilibrium thermodynamics of Onsager and Machlup and of Hashitsume is
reformulated as a gravity analog model, in which thermodynamic variables,
kinetic coefficients and generalized forces form, respectively, coordinates,
metric tensor and vector fields in a space of thermodynamic variables. The
relevant symmetry of the model is the general coordinate transformation. Then,
the entropy production is classified into three categories, when a closed path
is depicted as a thermodynamic cycle. One category is time reversal odd, and is
attributed to the number of lines of magnetic flux passing through the closed
path, having monopole as a source. There are two time reversal even categories,
one of which is attributed to the space curvature around the path, having
gravitational instanton as a source, which dominates for a rapid operation of
the cycle. The last category is the usual one, which remains even for the
quasi-equilibrium operation. It is possible to extend the model to include
non-linear responses. In introducing new terms, important is the dimensional
counting, using two parameters, the temperature and the relaxation time. The
effective action, being induced by the non-equilibrium thermodynamics, is
derived. This is a candidate for the action which controls the dynamics of
kinetic coefficients and thermodynamic forces. An example is given in a
chemical oscillatory reaction in a solvent of the van der Waals type.
Fluctuation-dissipation theorem is examined `a la Onsager, and a derivation of
the gravity analog thermodynamic model from quantum mechanics is sketched,
based on an analogy to the resonance problem.
