Message No.3709 from nakayama , 12 January 2008 03:28:
 îòâåò íà No.3649: Proposal for New Michelson-Morley Experiment îò nakayama , 09 October 2007:
Please allow me to add. Imagine an observer. With motion of pin-point of laser beam (that hits the slopes of prism), he moves. Both motions are the same.