Origin of Negative Temperatures in Systems Interacting with External Fields
arXiv:1807.07148 · doi:10.1016/j.physleta.2019.04.027
Abstract
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 arise from an energy mis-attribution in which the interaction energy with the field is treated as a form of internal energy. We discuss how negative temperatures are avoided when using a proper thermodynamic formalism, which 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.
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Cited by in corpus (4)
- Observation of light thermalization to negative temperature Rayleigh-Jeans equilibrium states in multimode optical fibers
- Negative temperature states as exact equilibrium solutions of the Wave Kinetic equation for one dimensional lattices
- H-theorem at negative temperature: the random exchange model with bounds
- Thermodynamics of fluctuations in small systems interacting with the environment