I've seen other posts about this, but would appreciate an explanation if anyone knows. I've read that travelling faster than the speed of light could affect causality. Example: item I travelling in a tube could be seen arriving at end B before it ever left end A. A=======I=B Is this an actual affect on causality or just the light reaching the observer? I am trying to compare it with speed of sound. Travelling faster than the speed of sound may affect when an observer hears something, but not actually when the sound is made.