finska-engelska översättning av entropia

entropy
us
The thermodynamic free energy is the amount of work that a thermodynamic system can perform; it is the internal energy of a system minus the amount of energy that cannot be used to perform work. That unusable energy is given by the entropy of a system multiplied by the temperature of the system.[http://en.wikipedia.org/wiki/Thermodynamic_free_energy] (Note that, for both Gibbs and Helmholtz free energies, temperature is assumed to be fixed, so entropy is effectively directly proportional to useless energy.)Ludwig Boltzmann defined entropy as being directly proportional to the natural logarithm of the number of microstates yielding an equivalent thermodynamic macrostate (with the eponymous constant of proportionality). Assuming (by the fundamental postulate of statistical mechanics), that all microstates are equally probable, this means, on the one hand, that macrostates with higher entropy are more probable, and on the other hand, that for such macrostates, the quantity of information required to describe a particular one of its microstates will be higher. That is, the Shannon entropy of a macrostate would be directly proportional to the logarithm of the number of equivalent microstates (making it up). In other words, thermodynamic and informational entropies are rather compatible, which shouldnt be surprising since Claude Shannon derived the notation H for information entropy from Boltzmanns H-theorem.

termodynamiikan perussuure, joka ilmaisee epäjärjestyksen määrää systeemissä; symboli on S
informaatioteorian suure, joka ilmaisee informaation satunnaisuuden määrää

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