2. Entropy in a conservative vector field
The increase in entropy of an isolated system in a spontaneous thermodynamic process under transfer of heat from
higher to lower temperature resulting in thermal equilibrium is the basic postulate of the second law of thermodynamics [1].
Heat transfer in a material mainly happens due to transfer of kinetic energy from electrons, molecules and lattice walls of
higher temperature to neighbouring systems at lower temperature. The transfer of energy and momentum during thermal
transport also results in an increase in finite value of potential energy of the neighbouring particles immersed in different
kinds of conservative vector field resulting in energy concentration in localized regions and a reduction in total number
of accessible states. For example, when heat is applied to mass m of set of coupled harmonic oscillators through a jet of
hot liquid having energetic molecules having an effective mass, μ and acceleration α resulting in a force F = μα, there is
a change in its momentum and the mass gains an acceleration a (Fig. 1). The net force F exerted on mass m results in an
acceleration which can be expressed as,