Editing First law of thermodynamics (section)

==Conceptually revised statement, according to the mechanical approach==
The revised statement of the first law postulates that a change in the internal energy of a system due to any arbitrary process, that takes the system from a given initial thermodynamic state to a given final equilibrium thermodynamic state, can be determined through the physical existence, for those given states, of a reference process that occurs purely through stages of adiabatic work.

The revised statement is then

::For a closed system, in any arbitrary process of interest that takes it from an initial to a final state of internal thermodynamic equilibrium, the change of internal energy is the same as that for a reference adiabatic work process that links those two states. This is so regardless of the path of the process of interest, and regardless of whether it is an adiabatic or a non-adiabatic process. The reference adiabatic work process may be chosen arbitrarily from amongst the class of all such processes.

This statement is much less close to the empirical basis than are the original statements,<ref name="Pippard 15"/> but is often regarded as conceptually parsimonious in that it rests only on the concepts of adiabatic work and of non-adiabatic processes, not on the concepts of transfer of energy as heat and of empirical temperature that are presupposed by the original statements. Largely through the influence of [[Max Born]], it is often regarded as theoretically preferable because of this conceptual parsimony. Born particularly observes that the revised approach avoids thinking in terms of what he calls the "imported engineering" concept of heat engines.<ref name="Born 1949 {{math|V}}">[[Max Born|Born, M.]] (1949), Lecture {{math|V}}, pp. 31–45.</ref>

Basing his thinking on the mechanical approach, Born in 1921, and again in 1949, proposed to revise the definition of heat.<ref name="Born 1949 {{math|V}}"/><ref name="Born 1921"/> In particular, he referred to the work of [[Constantin Carathéodory]], who had in 1909 stated the first law without defining quantity of heat.<ref name="Carathéodory 1909"/> Born's definition was specifically for transfers of energy without transfer of matter, and it has been widely followed in textbooks (examples:<ref name="Münster 23 24"/><ref name="Reif 122"/><ref name="Haase 1971"/>). Born observes that a transfer of matter between two systems is accompanied by a transfer of internal energy that cannot be resolved into heat and work components. There can be pathways to other systems, spatially separate from that of the matter transfer, that allow heat and work transfer independent of and simultaneous with the matter transfer. Energy is conserved in such transfers.