Preprint Article Version 2 Preserved in Portico This version is not peer-reviewed

The Second Law Of Thermodynamics as a Force Law

Version 1 : Received: 8 February 2018 / Approved: 8 February 2018 / Online: 8 February 2018 (18:14:41 CET)
Version 2 : Received: 4 March 2018 / Approved: 5 March 2018 / Online: 5 March 2018 (05:54:00 CET)

A peer-reviewed article of this Preprint also exists.

Schlitter, J. The Second Law of Thermodynamics as a Force Law. Entropy 2018, 20, 234. Schlitter, J. The Second Law of Thermodynamics as a Force Law. Entropy 2018, 20, 234.


The second law of thermodynamics states the increase of entropy, ΔS > 0, for real processes from state A to state B at constant energy from chemistry over biological life and engines to cosmic events. The connection of entropy to information, phase-space and heat is helpful, but does not immediately convince observers of the validity and basis of the second law. This gave grounds for finding a rigorous, but more easily acceptable reformulation. Here we show using statistical mechanics that this principle is equivalent to a force law ⟨⟨f⟩⟩> 0 in systems where mass centres and forces can be identified. The sign of this net force - the average mean force along a path from A to B - determines the direction of the process. The force law applies to a wide range of processes from machines to chemical reactions. The explanation of irreversibility by a driving force appears more plausible than the traditional formulation as it emphasizes the cause instead of the effect of motions.


statistical mechanics; irreversibility; arrow of time; chemical dynamics


Chemistry and Materials Science, Physical Chemistry

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