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Thermodynamics

Not hotter than hot

Nature Physics volume 10, pages 7–8 (2014)Cite this article

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A careful revision of the rudiments of statistical physics shows that negative temperatures are artefacts of Boltzmann's approximate definition of entropy. Gibbs' version, however, forbids negative absolute temperatures and is consistent with thermodynamics.

From time to time, it is good to look back and reflect on the very foundations of science. Something that is now textbook material was usually once a topic of debate, and a generally accepted solution might still turn out to be incorrect. Writing in Nature Physics1, Jörn Dunkel and Stefan Hilbert have revisited the concepts of temperature and entropy — a timely rethink in the light of some beautiful recent experiments involving negative temperature states in ultracold quantum gases that are trapped in optical lattices2,3.

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Figure 1: Gibbs versus Boltzmann.

© INTERFOTO/Alamy

References

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Authors and Affiliations

  1. Igor M. Sokolov is at the Institute of Physics, Humbolt University of Berlin, Newtonstraβe 15, 12489 Berlin, Germany,

    Igor M. Sokolov

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  1. Igor M. Sokolov
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Correspondence to Igor M. Sokolov.

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Sokolov, I. Not hotter than hot. Nature Phys 10, 7–8 (2014). https://doi.org/10.1038/nphys2831

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