When two persons meet each other in one point, one standing still (can be moving too) and the other moving (compared with the other) and in that point a light wave has started 90 degrees up and reflects (mirror 0 degrees), both persons will see the light wave back, the moving person in another location. This is right I think (otherwise movement cound be detected). Is there already theory how this is possible, because when there would be only 1 lightwave, what is happening after the relection. It is not an illusion for the moving person, he really sees the light wave back. Maybe I know now (suddenly I see) it's explained because of time delation, during the movement time stands still (compared to the other) so he sees the same light wave, right (hmm, not sure with 1 lightwave) ? If this is right, is there already theory about this time delation (it is still strange, unsolved) ?