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A blend of negative +‎ entropy, coined by the French physicist Léon Brillouin (1889–1969). The term negative entropy was introduced by the Austrian physicist Erwin Schrödinger (1887–1961) in his book What is Life? (1944, based on lectures delivered in February 1943).[1]



negentropy (countable and uncountable, plural negentropies)

  1. (thermodynamics) The difference between the entropy of a system and the maximum possible entropy of the same system. [from 1950s]
    • 1956 April, Brillouin, Léon, “Summary of Thermodynamics”, in Science and Information Theory, New York, N.Y.: Academic Press, OCLC 954181035, section 2 (The Two Principles of Thermodynamics; Entropy and Negentropy), pages 116–117:
      An isolated system contains negentropy if it reveals a possibility for doing mechanical or electrical work: [] A tank of compressed gas in a room at atmospheric pressure, a vacuum tank in a similar room, a charged battery, any device that can produce high grade energy (mechanical work) or be degraded by some irreversible process (thermal conduction, electrical resistivity, friction, viscosity) is a source of negentropy. [] If a living organism needs food, it is only for the negentropy it can get from it, and which is needed to make up for the losses due to mechanical work done, or simple degradation processes in the living system. Energy contained in food does not really matter, since energy is conserved and never gets lost, but negentropy is the important factor.
    • 1977, Kuznetsov, Boris G., Philosophy of Optimism, Moscow: Progress Publishers, page 35:
      The same magnitude, but with a minus sign, i.e., the measure of macroscopic ordering, the measure of non-uniformity in the distribution of heat, the measure of the differences in temperature—temperature gradients—is called negentropy.
    • 2013, Mayfield, John E., “The Evolution of Complexity”, in The Engine of Complexity: Evolution as Computation, New York, N.Y.: Columbia University Press, →ISBN, page 277:
      Negentropy is the difference between the entropy of a system and the entropy of the same system at equilibrium (i.e., when it has its maximum possible entropy). Since entropy measures the amount of disorder, negentropy measures order.
  2. (information theory) The difference between the entropy of a probability distribution and the maximum possible entropy of the same probability distribution.
    • 1990, Zotin, Aleksandr I., “Thermodynamics of Nonequilibrium Processes”, in Thermodynamic Bases of Biological Processes: Physiological Reactions and Adaptations, Berlin; New York, N.Y.: Walter de Gruyter, →ISBN, section 1.3.2 (Maxwell’s Demon and Negentropy Effects), page 46:
      Brillouin (1956) made an attempt to link thermodynamic notions to the notions of information theory. To this end he employs the idea of bound information or information consistent with some microstates of a physical system. [] Brillouin has shown that bound information is equal to entropy decrease or negentropy increase. This is a so called negentropy principle of information, according to which negentropy can be turned into information and vice versa as follows from (1.103).



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