Sorry Alex, I forgot about the hypothetical situation you gave with John and Bob. It seems as though I answered every question except for the one you actually asked, LOL.

John and Bob are in symmetrical case as far as I can tell.

I would ask you who underwent the initial acceleration to get relative motion started, but of course, they need not have started from same place at same time (thereby synchronizing clocks and agreeing on initial frame).

Since you imply that they started at different spatial locations, and simultaneity is not absolute but rather relative, then you cannot guarantee that they have synchronized their clocks (even if they did, clocks would be synchronized at different moments in each individuals proper time). Because of this, there is no verifiable evidence of who is right and who is wrong. In a court case, no verifiable evidence means case dismissed!

Just like two observers need not agree on simultaneity... they also need not agree on time dilation in symmetric case. The loophole arises when you consider John and Bob as having come from two different moments in time at two different locations in space. How can either contest a case in court, when neither can give any special reason why it is that the other one should be wrong and they should be right? In this case, they are both equal space/time travelers, with equal stake in valid claim that it is the other who is moving.

• Don't argue with Alex - doctordick - November 1, 2001 - 16:22 UTC
  • Mark (and Dick) - alexander - November 1, 2001 - 18:46 UTC
    • Alex, this case is symetric, however you fail to realize... - smartguy - November 1, 2001 - 19:39 UTC
      • Alex, I think the thing that troubles you... is that... - smartguy - November 1, 2001 - 23:53 UTC
        • So, there is no "sloving of motion trough time" - alexander - November 2, 2001 - 01:06 UTC
          • As far as I know... - smartguy - November 2, 2001 - 19:12 UTC
            • Way incorrect. Proper past/present/future is ABSOLUTE. - alexander - November 2, 2001 - 20:11 UTC
              • Alex, Alex, Alex... - smartguy - November 2, 2001 - 21:08 UTC
                • Pretty impressive - harvey1 - November 2, 2001 - 21:26 UTC
                  • Thanx a lot Harv!! - smartguy - November 2, 2001 - 21:46 UTC
                • Ditto - luis_hamburgh - November 2, 2001 - 22:28 UTC
                • Mark, "proper" is a relativistic term. It means - alexander - November 3, 2001 - 17:34 UTC
                  • If it means anything to you... - smartguy - November 3, 2001 - 18:51 UTC
                    • Ouch! (nt) - harvey1 - November 4, 2001 - 03:58 UTC
            • Yes, but proper height/width/length are ALSO ABSOLUTE - luis_hamburgh - November 2, 2001 - 22:27 UTC