Article,
Non-local observables and lightcone-averaging in relativistic thermodynamics
Nature Physics, (September 2009)
DOI: 10.1038/nphys1395
Abstract
The unification of relativity and thermodynamics has been a subject of considerable debate over the past 100 years. The reasons for this are twofold. First, thermodynamic variables are non-local quantities and therefore single out a preferred class of hyperplanes in spacetime. Second, there exist different ways of defining heat and work in relativistic systems and all of them seem equally plausible. These ambiguities have led, for example, to various proposals for the Lorentz-transformation law of temperature. However, traditional 'isochronous' formulations of relativistic thermodynamics are neither theoretically satisfactory nor experimentally feasible. Here, we demonstrate how these deficiencies can be resolved by defining thermodynamic quantities with respect to the backward-lightcone of an observation event. This approach yields new predictions that are, in principle, testable and allows for a straightforward extension of thermodynamics to general relativity. Our theoretical considerations are illustrated through three-dimensional relativistic many-body simulations.
