# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 5 Search : entropy
 Boltzmann's entropy formula   دیسول ِ درگاشت ِ بولتسمن   disul-e dargâšt-e BoltzmannFr.: formule d'entropie de Boltzmann   In → statistical thermodynamics, a probability equation relating the → entropy S of an → ideal gas to the quantity Ω, which is the number of → microstates corresponding to a given → macrostate: S = k. ln Ω. Same as → Boltzmann's relation.→ Boltzmann's constant; → entropy; → formula. entropy   درگاشت   dargâšt (#)Fr.: entropie   1) A measure of the energy that is not available for work during a → thermodynamic process. It is defined by dS = dQ/T, where dS is the differential change in entropy, dQ is the differential amount of heat introduced to the system in a → reversible process, and T the → absolute temperature of the system. Entropy remains constant during → reversible processes and increases during → irreversible processes without ever decreasing. According to the → second law of thermodynamics, an → isolated system evolves toward a state of maximum entropy. See also → Maxwell's demon. 2) Statistical physics: A measure of → disorder of the configuration of → microstates which make up a → macrostate. → Boltzmann's relation, → Boltzmann's entropy formula. Highly disordered systems have a large entropy; highly ordered systems have low entropy. 3) Math.: A measure of information content. → information entropy.From Ger. Entropie, coined 1865 by physicist Rudolf Clausius (1822-1888) from Gk. entropia "a turning toward," from en- "in" + trope "a turning, change," related to tropos "a turn, way, manner," from tropein "to turn," from PIE base *trep- "to turn" (cf. L. trepit "he turns").Dargâšt, from dar "in" + gâšt present stem of gâštan "to cause to revolve, to turn," transitive of gaštan, variant gardidan "to turn, to change" (Mid.Pers. vartitan; Av. varət- "to turn, revolve;" cf. Skt. vartati; L. vertere; O.H.G. werden "to become;" PIE base *wer- "to turn, bend"). information entropy   درگاشت ِ ازدایش   dargâšt-e azdâyešFr.: entropie de l'information   The measure of information, which is usually expressed by the average number of bits needed for storage or communication. In other words, the degree to which the values of a → random variable X are dispersed. If the → probability density function of X is P(x), the entropy is defined by: H(X) = -Σ P(x) log P(x). Also called → Shannon entropy.→ information; → entropy. maximum entropy method (MEM)   روش ِ درگاشت ِ بیشینه   raveš-e dargâšt-e bišinéFr.: méthode d'entropie maximum   A deconvolution algorithm which functions by minimizing a smoothness function in an image. The MEM seeks to extract as much information from a measurement as is justified by the data's signal-to-noise ratio.→ maximum; → entropy; → method. Shannon entropy   درگاشت ِ شانون   dargâšt-e ShannonFr.: entropie de Shannon   Claude Elwood Shannon (1916-2001), an American mathematician and pioneer of → information theory; → entropy.