Fate of Boltzmann's Breathers: Stokes Hypothesis and Anomalous Thermalization

Boltzmann showed that in spite of momentum and energy redistribution through collisions, a rarefied gas confined in a isotropic harmonic trapping potential does not reach equilibrium; it evolves instead into a breathing mode where density, velocity, and temperature oscillate. This counterintuitive p...

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Bibliographic Details
Published in:Physical review letters 2024-01, Vol.132 (2), p.027101-027101, Article 027101
Main Authors: García de Soria, M I, Maynar, P, Guéry-Odelin, David, Trizac, Emmanuel
Format: Article
Language:English
Subjects:
Condensed Matter
Physics
Statistical Mechanics
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Summary:Boltzmann showed that in spite of momentum and energy redistribution through collisions, a rarefied gas confined in a isotropic harmonic trapping potential does not reach equilibrium; it evolves instead into a breathing mode where density, velocity, and temperature oscillate. This counterintuitive prediction is upheld by cold atoms experiments. Yet, are the breathers eternal solutions of the dynamics even in an idealized and isolated system? We show by a combination of hydrodynamic arguments and molecular dynamics simulations that an original dissipative mechanism is at work, where the minute and often neglected bulk viscosity eventually thermalizes the system, which thus reaches equilibrium.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.132.027101