Clarification of Onsager reciprocal relations based on thermomass theory

The fluxes in transport processes expressed as a time derivative of state variables is a crucial requirement in Onsager's proof of his reciprocal relations, which is a much debated question existing in nonequilibrium thermodynamics. Thermomass theory is used to show that the linear decay of the fluctuation is a balance between the inertial forces and resistant force. Therefore, products of the drift velocities and relaxation times, namely, the displacements from equilibrium, can be used as the state variables, whose time derivatives give the transport fluxes. The Onsager reciprocal relations can be macroscopically derived from the principle that every action has an equal and opposite reaction, applicable in steady nonequilibrium systems and nonlinear couplings.