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The definition of "natural", as compared to "unnatural", for isothermal isobaric processes and reaction (Guggenheim, 1933).[1]

In science, natural (TR:489) (LH:7) (TL:496|#65), as compared to “unnatural”, refers to a reaction, process, or transformation, for an isothermal, isobaric system, e.g. freely running earth surface reactions and processes, that are exergonic.


In 1856, Rudolf Clausius, in generalized form, defined derived the rule that any system or body of the universe, with processes or reactions occurring will meet the conditions of the Clausius inequality.

In 1923, Gilbert Lewis, in his Thermodynamics and the Free Energy of Chemical Processes, defined processes and reactions that are ‘thermodynamically possible’, based on the various Gibbs inequalities, which he termed as a “universal rule” for freely reacting isothermal-isobaric processes, e.g. earth-bound surface reactions, such as chemicals reacting in beaker, plants growing, or humans reacting socially.[2]

In 1933, Edward Guggenheim, in his Thermodynamics by the Method of Willard Gibbs, building on the work of Lewis, defined a natural process as follows:[1]

meaning that for a spontaneous natural process to occur, the differential of the Gibbs energy dG must be negative, i.e. release Gibb energy.

In 1941, Fritz Lipmann, in his “Metabolic Generation and Utilization of Phosphate Bond Energy”, in solution to the problem of physiology of the powering of muscular contraction, outlined his ideas on how stored "bond energy" resides in phosphates and phosphate bonds of ATP, according to which, when cleaved, releases energy, which cells uses as "energy currency", so to say, to power various endergonic processes; therein showing that exergonic processes, aka natural processes, are "coupled" to endergonic processes.[3] Natural, in other words, drives unnatural, and both exist in the totality of nature, at least has been proved at the cellular level.


The following are related quotes:

Natural things are exactly those things which do move continuously, in virtue of the principle inherent in themselves, towards a determined goal; and the final development which results from any one such principle is not identical for any two species, nor yet is it any random result, but in each there is always a tendency towards an identical result if nothing interferes.”
Aristotle (322BC), Physics (2:8) [4]

End matter

See also



  1. 1.0 1.1 Guggenheim, Edward, A. (1933). Modern Thermodynamics: by the Methods of Willard Gibbs (natural, pgs. 5, 17). Methuen.
  2. Lewis, Gilbert N. (1923). Thermodynamics: and the Free Energy of Chemical Substances (amanuensis: Merle Randall). McGraw-Hill.
  3. (a) Lipmann, Fritz. (1941). “Metabolic Generation and Utilization of Phosphate Bond Energy”, Advances in Enzymology and Related Subjects, Volume One (pg. 99-162). Interscience Publishers. (b) Metabolic Generation and Utilization of Phosphate Bond Energy – Hmolpedia 2020.
  4. Brown, Richard H. (1977). A Poetic for Sociology: Toward a Logic of Discovery for the Human Sciences (natural, pg. 130). University of Chicago Press, 1989.

External links

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