|  Entropy | 
In General
  > s.a. chaos; MaxEnt (Maximum Entropy Principle);
  history of physics; statistical mechanics;
  thermodynamics.
  * Thermodynamic entropy:
    An extensive thermodynamical function of state which is non-decreasing for
    adiabatic transformations (constant in reversible ones); In most systems,
    it grows monotonically with E; The concept was introduced by
    Clausius in the 1860s and the Clausius entropy is defined, up to an
    additive constant, by the relation dS = dQ/T.
  * Statistical interpretation:
    A measure of how spread out a classical distribution function or quantum density
    ρ matrix is; For a system that can be in Ω equiprobable states
    the Boltzmann entropy is SB =
    kB ln Ω; More generally, for
    a classical probability distribution the Gibbs entropy is SG
    = −kB ∑i
    pi ln pi,
    and for a quantum density matrix the von Neumann entropy is S
    = −kB tr ρ ln ρ;
    > s.a. types of entropies.
  * And classical / quantum mechanics:
    In classical mechanics one assumes entropies are finite, but if one takes the
    \(\hbar\) → 0 limit of any quantum entropy expression, this diverges; So
    classical thermodynamics is not the classical limit of quantum statistical
    mechanics, it knows about quantum mechanics.
  @ Articles, II: Han et al cm/97,
    AJP(99)jan [tracing over degrees of freedom];
    Styer AJP(00)dec [examples and meaning];
    Lieb & Yngvason PT(00)apr [without thermodynamics];
    Styer AJP(08)oct [and evolution];
    Salagaram & Chetty AJP(11)nov [computation].
  @ Books: Martin & England 81;
    Denbigh & Denbigh 85;
    Leff & Rex ed-90;
    Dugdale 96 [II];
    Scully & Scully 07
      [Maxwell's demon, information, and the quantum];
    Grandy 08 [and probability];
    Ben-Naim 16 [I].
  @ General references:
    Wehrl RMP(78);
    in Sorkin PRL(86);
    Mackey RMP(89) [increasing entropy and ergodicity];
    Lavenda et al NCB(95);
    Leff AJP(96)oct [and energy sharing];
    Levy math/06 [mathematical interpretation];
    Kozlov & Treshchev TMP(07) [coarse-grained];
    Bernstein a1109 [pedagogical];
    Baumgartner FP(14)-a1206 [axiomatic characterization and derived facts];
    Zanchini & Beretta Ent(14)-a1403 [general definition];
    Phillips TPT(16) [entropy as the spread of energy];
    Jakšić a1806 [and information theory];
    Kycia a1908 [formal overview].
  @ Conceptual: Leff FP(07) [language and interpretation];
    Topsoe a0807 [entropy and truth vs belief];
    Timberlake TPT(10) [statistical interpretation];
    Swendsen AJP(11)apr [definitions and meaning];
    Baez et al Ent(11)-a1106 [characterization in terms of information loss];
    Davey PhSc(11) [and probability];
    Swendsen FP(12) [argument for probabilistic definition];
    Dieks a1209-in [thermodynamical vs statistical-mechanical definitions];
    Benguigui EJP(13)-a1209 [different definitions];
    Caticha M&M-a1412
      [entropic inference as a general framework for reasoning under conditions of uncertainty];
    in Oltean et al PRD(16)-a1607 [nature of S];
    Toffoli Ent(16)-a1705 [and "honest entropy"];
    Styer TPT(19)sep [entropy isn't always disorder];
    Weaver a2004 [Boltzmann and Clausius entropy];
    Brandsen et al a2103 [perspective from games of chance].
  @ And observation: Steane NJP(16)-a1510
      [determining absolute entropy without quantum theory or the third law].
Related Concepts and Generalizations
  > s.a. Coarse Graining; Disentropy;
  dissipation; Entropic Dynamics;
  Homogeneity.
  @ And area law:
    Mäkelä gq/06-GRF;
    Masanes PRA(09)-a0907 [for low-energy states].
  @ Other properties: Kay & Kay JPA(01)mp/98 [strong subadditivity and volume];
    Touchette AJP(08)jan [(non)-concavity].
  @ Subsystems: Hotta & Joichi PLA(99)cm [additivity];
    Baumgartner JPA(02)mp/01;
    Dupuis et al a1607 [additivity, "accumulation"].
  @ Entropy current: Bhattacharyya JHEP(14)-a1403,
    JHEP(14) [and the equilibrium partition function];
    Banerjee et al JHEP(14) [non-relativistic fluid].
  @ Beyond equilibrium situations: Beretta & Zanchini in(11)-a1010;
    Beretta & Zanchini a1411,
    AAPP(19)-a1911 [and few-particle systems];
    > s.a. non-equilibrium thermodynamics.
  @ And time: Hotke-Page & Page in(92) [clock time];
    Ben-Naim 16 [no relationship].
  @ Entropy production and arrow of time:
    Parrondo et al NJP(09);
    Martyushev & Shaiapin Ent(16)-a1605;
    Mintchev & Sorba a2003-proc.
  @ Related topics: Hall PRA(99)qp/98 [geometric, ensemble volume];
    Leff AJP(99)dec [dimensionless];
    Dover PhyA(04) [and scaling laws];
    Hanel et al PNAS(12)-a1211 [generalized, for systems violating the Shannon-Khinchin axioms];
    Lieb & Yngvason PRS(14)-a1403 [entropy meters and the entropy of non-extensive systems];
    Plastino et al PhyA(14)
      [partition function and entropy from thermodynamics];
    Chafaï AFST(15)-a1405 [aspects of entropy in different disciplines].
   Related topics:
    see entropy bounds; entropy in quantum theory;
    types of entropies and entanglement entropy.
 Related topics:
    see entropy bounds; entropy in quantum theory;
    types of entropies and entanglement entropy.
Systems
  > Gravity-related:
    see black-hole entropy; gravitational
    thermodynamics; horizons.
  > Other systems:
    see casimir effect [negative entropies];
    cell complex; cellular
    automaton; networks; thermodynamic
    systems; tilings.
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  send feedback and suggestions to bombelli at olemiss.edu – modified 25 mar 2021