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The principle of microscopic reversibility in physics and chemistry is twofold: * First, it states that the microscopic detailed dynamics of particles and fields is time-reversible because the microscopic equations of motion are symmetric with respect to inversion in time (T-symmetry); * Second, it relates to the statistical description of the kinetics of macroscopic or mesoscopic systems as an ensemble of elementary processes: collisions, elementary transitions or reactions. For these processes, the consequence of the microscopic T-symmetry is: ''Corresponding to every individual process there is a reverse process, and in a state of equilibrium the average rate of every process is equal to the average rate of its reverse process.〔Lewis, G.N. (1925) (A new principle of equilibrium ), PNAS March 1, 1925 vol. 11 no. 3 179-183.''〕 ==History of microscopic reversibility== The idea of microscopic reversibility was born together with physical kinetics. In 1872, Ludwig Boltzmann represented kinetics of gases as statistical ensemble of elementary collisions.〔Boltzmann, L. (1964), Lectures on gas theory, Berkeley, CA, USA: U. of California Press.〕 Equations of mechanics are reversible in time, hence, the reverse collisions obey the same laws. This reversibility of collisions is the first example of microreversibility. According to Boltzmann, this microreversibility implies the principle of detailed balance for collisions: at the equilibrium ensemble each collision is equilibrated by its reverse collision.〔 These ideas of Boltzmann were analyzed in detail and generalized by Richard C. Tolman.〔Tolman, R. C. (1938). ''The Principles of Statistical Mechanics''. Oxford University Press, London, UK.〕 In chemistry, J. H. van't Hoff (1884)〔Van't Hoff, J.H. Etudes de dynamique chimique. Frederic Muller, Amsterdam, 1884.〕 came up with the idea that equilibrium has dynamical nature and is a result of the balance between the forward and backward reaction rates. He did not study reaction mechanisms with many elementary reactions and could not formulate the principle of detailed balance for complex reactions. In 1901, Rudolf Wegscheider introduced the principle of detailed balance for complex chemical reactions.〔Wegscheider, R. (1901) (Über simultane Gleichgewichte und die Beziehungen zwischen Thermodynamik und Reactionskinetik homogener Systeme ), Monatshefte für Chemie / Chemical Monthly 32(8), 849--906.〕 He found that for a complex reaction the principle of detailed balance implies important and non-trivial relations between reaction rate constants for different reactions. In particular, he demonstrated that the irreversible cycles of reaction are impossible and for the reversible cycles the product of constants of the forward reactions (in the "clockwise" direction) is equal to the product of constants of the reverse reactions (in the "anticlockwise" direction). Lars Onsager (1931) used these relations in his well known work,〔Onsager, L. (1931), (Reciprocal relations in irreversible processes. ) I, Phys. Rev. 37, 405-426.〕 without direct citation but with the following remark:
The quantum theory of emission and absorption developed by Albert Einstein (1916, 1917)〔Einstein, A. (1917). Zur Quantentheorie der Strahlung (the quantum theory of radiation ), Physikalische Zeitschrift 18 (1917), 121-128. (English translation ): D. ter Haar (1967): The Old Quantum Theory. Pergamon Press, pp. 167-183.〕 gives an example of application of the microreversibility and detailed balance to development of a new branch of kinetic theory. Sometimes, the principle of detailed balance is formulated in the narrow sense, for chemical reactions only〔(''Principle of microscopic reversibility.'' ) Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2012.〕 but in the history of physics it has the broader use: it was invented for collisions, used for emission and absorption of quanta, for transport processes〔Gorban, A.N., Sargsyan, H.P., and Wahab, H.A. (Quasichemical Models of Multicomponent Nonlinear Diffusion ), Mathematical Modelling of Natural Phenomena, Volume 6 / Issue 05, (2011), 184−262.〕 and for many other phenomena. In its modern form, the principle of microreversibility was published by Lewis (1925).〔 In the classical textbooks〔〔 Vol. 10 of the Course of Theoretical Physics(3rd Ed).〕 full theory and many examples of applications are presented. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「microscopic reversibility」の詳細全文を読む スポンサード リンク
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