Condensed Matter Physics, 2005, vol. 8, No. 4(44), p. 655-664, English

Title: The concept of entropy. Relation between action and entropy
  J.-P.Badiali (LECA, ENSCP-Université Pierre et Marie Curie, 4 Place Jussieu, 75230 Paris Cedex 05, France) ,

The Boltzmann expression for entropy represents the traditional link between thermodynamics and statistical mechanics. New theoretical developments like the Unruh effect or the black hole theory suggest a new definition of entropy. In this paper we consider the thermodynamics of black holes as seriously founded and we try to see what we can learn from it in the case of ordinary systems for which a pre-relativistic description is sufficient. We introduce a space-time model and a new definition of entropy considering the thermal equilibrium from a dynamic point of view. Then we show that for black hole and ordinary systems we have the same relation relating a change of entropy to a change of action.

Key words: thermodynamics, entropy
PACS: 03.65.Ca, 05.30.-d, 05.70.-a, 47.53.+n

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