Particles near absolute zero do not break the laws of physics (Vol. 45 No.4)

A free particle strongly coupled to a heat bath. Credit: Adamietz et al.

A change of models demystifies anomalous particle behaviour at very low temperatures, confirming that the third law of thermodynamics cannot be violated

In this work, the authors have demonstrated that a theoretical model of the environment’s influence on a particle does not violate the third law of thermodynamics, despite appearances to the contrary. These findings are relevant for systems at the micro or nanometer scale that are difficult to decouple from the heat or the quantum effects exerted by their environment.

Previous theoretical predictions suggested that, under certain circumstances, the specific heat—the amount of energy is needed to raise the temperature of a particle coupled to a heat bath by a certain amount—can decrease below zero at strictly zero temperature (−273.15 °C). This prediction appears to breach the third law of thermodynamics, indicating that the specific heat must drop to zero value at strictly zero temperature. Yet, these findings show that previous studies need to be modified in order to account for a spatial confinement of the particle.

R. Adamietz, G.-L. Ingold and U. Weiss, “Thermodynamic anomalies in the presence of general linear dissipation: from the free particle to the harmonic oscillator”, Eur. Phys. J. B, 87, 90 (2014)