Physicists have found a material where heat and electricity travel completely independently, breaking a 'universal' law of physics.
April 17, 2026
Original Paper
Spectroscopy of Heat Transport and Violation of the Wiedemann--Franz Law in a GaAs Hydrodynamic Mesoscopic Channel
arXiv · 2604.12943
The Takeaway
For 170 years, the Wiedemann-Franz law has been a bedrock of science, stating that heat and electricity in metals always move in a fixed ratio. But in this 'hydrodynamic' GaAs channel, that law just... fails. The researchers found that electrons can flow like a liquid, allowing heat to zip ahead or lag behind the electrical current. This 'breakdown' of a fundamental constant means we could design materials that are amazing at conducting electricity but terrible at conducting heat (or vice versa). Imagine a smartphone that stays ice-cold while it’s charging at lightning speeds—that’s the kind of technology this discovery makes possible.
From the abstract
The Wiedemann--Franz law, which determines the universality of the ratio of thermal conductivity to electrical conductivity, is studied in the hydrodynamic electron transport regime, where electron--electron scattering predominates over scattering by disorder. In this case, the different relaxation of electric and thermal currents can lead to a violation of the Wiedemann--Franz law, which is expected to be even more pronounced in mesoscopic electron systems. This paper reports the propagation of