# Internal entropy

In thermodynamics, internal entropy diS is the entropy variation inside (i) a system, referring to irreversible processes, defined as:

$dS= d_e S + d_i S\,$

where deS is the entropy exchanged (e) with the surroundings. This distinction between two types of entropy was formulated by Belgian chemist Ilya Prigogine in 1945. [1]

Aging theories
According to the use of this type of summational entropy logic, supposedly, according to the second law it is argued that the total internal entropy change brought about by the metabolism of a mature organism is always positive. [2] To compensate this decrease, it is reasoned that because the body is open that local decreases in entropy are naturally coupled processes, according to which the forms they create can act as constraints on subsequent dynamics, giving new shape to old processes or to new processes.

In revenue management, according to American revenue optimization theorist Robert Cross, it is argued that internal entropy, characterized by the expenditure of unproductive energy within an organization, is one of the two types of entropies affecting business, the other being external entropy, being associated with disorder and chaos in the market place. [3] Specifically, according to Cross:

Internal entropy is created by people within an organization who are focused on the wrong issues; this in turn renders that energy unavailable (see: available energy) for useful work. External entropy is the disorder caused by outside forces that affect companies but cannot be directly controlled, such as consumer attitudes, new competition, competitive actions, technological advances, geopolitical factors, economic gyrations, and cataclysmic events.”

These extrapolations, to note, are very rudimentary compared to the original definition by German physicist Rudolf Clausius, based on the mechanical equivalent of heat effects of molecules moving and doing work on each other internal to a body of steam, and to the later interpretations by Prigogine, but are nevertheless interesting first approximations.

References
1. Prigogine, Ilya. (1945). Etude Thermodynamics des Phenomenes Irreversibles (Study of the Thermodynamics of Irreversible Phenomenon). Presented to the science faculty at the Free University of Brussels (1945); Paris: Dunod, 1947.
2. Birren, James E. and Bengston, Vern L., Deutchman, Donna E. (1988). Emergent Theories of Aging, (pgs. 92, 101-09, etc.). Springer.
3. Cross, Robert G. (1998). Revenue Management: Hard-core Tactics for Market Domination (pgs. 10-11, etc.). Broadway Books.