  There is an intense debate in the recent literature about the correct
generalization of Maxwell's velocity distribution in special relativity. The
most frequently discussed candidate distributions include the Juettner function
as well as modifications thereof. Here, we report results from fully
relativistic one-dimensional (1D) molecular dynamics (MD) simulations that
resolve the ambiguity. The numerical evidence unequivocally favors the Juettner
distribution. Moreover, our simulations illustrate that the concept of 'thermal
equilibrium' extends naturally to special relativity only if a many-particle
system is spatially confined. They make evident that 'temperature' can be
statistically defined and measured in an observer frame independent way.
