An approach to a unified field theory from thermodynamics
Thermodynamics states that heat and work are inexact differentials of internal energy but does not apply this to external energy. It can state that heat Q is dQ = T dS (equation 1) and work W is F dX = integral(infinity to X) (dT)s dS (equation 2 ) Since equation 2 can only be evaluated at the high end, since we do not know the absolute value of entropy, physics assumes that it is zero for work against external energy. The temperature changes are small for most work inputs. But for work input against electric and magnetic fields the temperature rises are measurable. It should therefore be assumed that work input is always an inexact differential at least for work on multi-bodied systems against any force field. All energy is thereby internal.