Ascendency

Create a rabbit (free energy diagram)
American thermal physicist Daniel Schroeder’s 2000 depiction of Gibbs free energy in relation to the creation of a rabbit; the citation-source definition of free energy upon which American ecosystem engineer Robert Ulanowicz models his ecological principle of ascendency: something that self-organizing, dissipative systems are hypothesized to optimize in their development over time. [4]
In ecological thermodynamics, ascendency, as distinguished from the standard-spelling dictionary term ascendancy, meaning “governing or controlling influence: domination”, is a pseudo-thermodynamical construct blend of average mutual information (Atlan, 1974), a concept from information theory, and Gibbs free energy (in the form of a modeled analogy), specifically the product of the former by the "total activity" (sum of all flows) inherent in an ecosystem. [1] In lay terms, ascendency is an information theory based version of Gibbs free energy, posited to represent the organization driving growth (see: driving force) of ecosystems. [2]

Etymology
The concept of ascendency was conceived in 1979 by American ecosystem engineer Robert Ulanowicz who sought to quantitatively extend the biological information theories of French biophysicist Henry Atlan (student of Aharon Katchalsky), particularly his concept of “average mutual information”, as explained in his 1974 article “On a Formal Definition of Organization”, wherein Atlan attempts to argue that the time derivative of Claude Shannon's telegraph line information H-function (an apocryphal claimed version of Ludwig Boltzmann's gas theory average particle velocity H-theorem):

Ascendency - Hmolpedia

defines the organization of an ecosystem on the basis of a kinetics of change of information content of a system under the effects of environmental noise-producing factors accumulated in time. [3] In his own retrospect words, as explained in a chapter footnote to his 2009 book A Third Window: Natural Life Beyond Darwin and Newton, Ulanowicz states: [4]

“My method of scaling was not motivated by Bateson’s considerations, about which I was unaware at the time. I had simply drawn upon my background in thermodynamics to define in analogy to Gibbs or Helmholtz free energies (measures of the capacity of a system to do effective work [Schroder, 2000]). Both of these quantities take the form of a scalar measure of the system’s energy multiplied by a logarithmic term (as with AMI) indicative of its constituents.”

What is rather ironic or possibly telling is that in spite of the fact that Ulanowicz supposedly has spent four decades on this free energy based or analogized “ascendency” concept and that his 2009 A Third Window is supposed to be a verbalized summary of this argument, he completely avoids any discussion of free energy in his book, aside from the above footnote and a prefaced mention of the origin of the term, which amounts to a comment that "the mathematical form of mutual information resembled a familiar quantity from thermodynamics called Gibbs-Helmholtz free energy" (a statement that amounts to the conclusion that ascendency is a thermodynamic isomorphism).

Beyond this, Ulanowicz fails to differentiate, in his work, between Helmholtz free energy (applicable to volume-confined [isochoric] systems, e.g. explosive research), which he uses in his 1986 Growth and Development, and between Gibbs free energy (applicable to volume-changing system, e.g. ecosystems), which he convolutes together in his 2009 book as "Gibbs-Helmholtz free energy" (which is not even a thermodynamic variable: it's either Gibbs free energy or Helmholtz free energy) is rather telling that his grasp of thermodynamics or at least ability to present thermodynamics correctly is very limited—not to mention of the fact that his citation of American thermal physicist Daniel Schroeder as the go-to source for the definition of free energy (Schroeder’s summary of Gibbs free energy, depicted above), a relative anon in the thermodynamics community.

References
1. (a) Ulanowicz, Robert E. (2009). A Third Window: Natural Life beyond Newton and Darwin (ascendency: etymology, pg. xxiii; spelling, note 1, pg. 169; free energy, pgs. xxiii, 171). Templeton Foundation Press.
(b) Ascendancy – Merriam-Webster Collegiate Dictionary.
2. Ulanowicz, Robert E. (1986). Growth and Development: Ecosystems Phenomenology (ascendency, pgs. 5-8, 102-21, 129-65, 174). New York: toExcel Press.
3. (a) Atlan, Henri. (1974). “On a Formal Definition of Organization” (abs), Journal of Theoretical Biology, 45: 295-304.
(b) Henri Atlan – Wikipedia.
(c) Rutledge, Robert W., Basorre, Bennett L. and Mulholland, Robert J. (1976). “Ecological Stability: An Information Theory Viewpoint” (abs), Journal of Theoretical Biology, 57(2): 355-71.
(a) Ulanowicz, Robert E. (2009). A Third Window: Natural Life beyond Newton and Darwin (free energy, pgs. xxiii, 171). Templeton Foundation Press.
(b) Schroeder, Daniel V. (2000). An Introduction to Thermal Physics. Addison Wesley Longman.
(c) Bateson, Gregory. (1972). Steps to an Ecology of Mind. Ballantine Books.
4. (a) Schroeder, Daniel V. (2000). An Introduction to Thermal Physics. Addison Wesley Longman.
(b) Ulanowicz, Robert E. (1980). "An Hypothesis on the Development of Natural Communities", Journal of Theoretical Biology, 85:223-45.

External links
‚óŹ Ascendency – Wikipedia.

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