Just received a PM from a character whose handle is "Blackshadow" re a SR question. The question was....... heading of PM: Collision of particles the question If a particle of mass M moving at speed 2/3 speed of light collides linearly with another particle of mass 3M moving at 2/3 speed of light what would happen ? The PM was open to the following participants.....Bells, BlackShadow, ,Enmos,,Michael, paddoboy, PhysBang. My reply: Start a thread and you may get your answer. Otherwise read up on SR. And I have no idea who you are [well perhaps an inkling] so do not PM me please.