Origin of negative temperatures in systems interacting with external fields


Journal Article

© 2019 Elsevier B.V. The controversial existence of negative temperatures has stirred interesting debates that have reached the foundations of thermodynamics, including questions on the second law, the Carnot efficiency and the statistical definition of entropy. Here we show that for systems interacting with an external field, negative temperatures may arise when the interaction energy with the field is treated as a form of internal energy. We discuss how negative temperatures are avoided when using a thermodynamic formalism that accounts for the intensive and extensive variables associated to the external field. We use the paramagnetic system and a perfect gas in a gravitational field to illustrate these ideas. Considerations about the isothermal and adiabatic work done by the field or the system also shed light on the inconsistency of super-Carnot efficiencies.

Full Text

Duke Authors

Cited Authors

  • Calabrese, S; Porporato, A

Published Date

  • June 26, 2019

Published In

Volume / Issue

  • 383 / 18

Start / End Page

  • 2153 - 2158

International Standard Serial Number (ISSN)

  • 0375-9601

Digital Object Identifier (DOI)

  • 10.1016/j.physleta.2019.04.027

Citation Source

  • Scopus