Vorlesungen über Gastheorie, Ludwig Boltzmann (1896) vol.Ludwig Boltzmann: the Man who Trusted Atoms, Oxford University Press, Oxford UK, ISBN 9780198501541, p.

'Über die Mechanische Bedeutung des Zweiten Hauptsatzes der Wärmetheorie'. ^ Max Planck (1914) The theory of heat radiation equation 164, p.119.Eric Weisstein's World of Physics (states the year was 1872). Since entropy is proportional to the log of the size of the phase space, we see that each additional unit of heat must increase the entropy by less and less. ^ See: photo of Boltzmann's grave in the Zentralfriedhof, Vienna, with bust and entropy formula.Specific Entropy have units of joule per kilogram times kelvin. The SI unit for entropy is joule per kelvin, J/K. The probability distribution of the system as a whole then factorises into the product of N separate identical terms, one term for each particle and when the summation is taken over each possible state in the 6-dimensional phase space of a single particle (rather than the 6 N-dimensional phase space of the system as a whole), the Gibbs entropy What is Unit of Entropy Definition Units of Entropy. The Boltzmann entropy is obtained if one assumes one can treat all the component particles of a thermodynamic system as statistically independent.

This is exact for an ideal gas of identical particles that move independently apart from instantaneous collisions, and is an approximation, possibly a poor one, for other systems. The term Boltzmann entropy is also sometimes used to indicate entropies calculated based on the approximation that the overall probability can be factored into an identical separate term for each particle-i.e., assuming each particle has an identical independent probability distribution, and ignoring interactions and correlations between the particles. In every situation where equation ( 1) is valid,Įquation ( 3) is valid also-and not vice versa.īoltzmann entropy excludes statistical dependencies That is, equation ( 1) is a corollary ofĮquation ( 3)-and not vice versa. Gibbs gave an explicitly probabilistic interpretation in 1878.īoltzmann himself used an expression equivalent to ( 3) in his later work and recognized it as more general than equation ( 1). He interpreted ρ as a density in phase space-without mentioning probability-but since this satisfies the axiomatic definition of a probability measure we can retrospectively interpret it as a probability anyway.

Unit of entropy