Issue I579 [81,traj,feature,resolved] Add option to omit relativistic effects (for debugging purposes). In 8.1.0, this is available via "View > Particles > more... > Omit relativistic effects" . See also http://simion.com/info/omit_relativistic_effects.html . Noted by theo-20110418. Implemented in 8.1.0-beta(20110423)