Volume 87, Number 3, August 2009
Article Number 30005
Number of page(s) 6
Section General
Published online 27 August 2009
EPL, 87 (2009) 30005
DOI: 10.1209/0295-5075/87/30005

Stationarity, ergodicity, and entropy in relativistic systems

D. Cubero1 and J. Dunkel2

1   Departamento de Física Aplicada I, EUP, Universidad de Sevilla - Calle Virgen de África 7, 41011 Sevilla, Spain, EU
2   Rudolf Peierls Centre for Theoretical Physics, University of Oxford - 1 Keble Road, Oxford OX1 3NP, UK, EU

received 31 March 2009; accepted in final form 24 July 2009; published August 2009
published online 27 August 2009

Recent molecular-dynamics simulations show that a dilute relativistic gas equilibrates to a Jüttner velocity distribution if ensemble velocities are measured simultaneously in the observer frame. The analysis of relativistic Brownian motion processes, on the other hand, implies that stationary one-particle distributions can differ depending on the underlying time parameterizations. Using molecular-dynamics simulations, we demonstrate how this relativistic phenomenon can be understood within a deterministic model system. We show that, depending on the time parameterization, one can distinguish different types of “soft” ergodicity on the level of the one-particle distributions. Our analysis further reveals a close connection between time parameters and entropy in special relativity. A combination of different time parameterizations can potentially be useful in simulations that combine molecular-dynamics algorithms with randomized particle creation, annihilation, or decay processes.

02.70.Ns - Molecular dynamics and particle methods.
05.70.-a - Thermodynamics.
03.30.+p - Special relativity.

© EPLA 2009