Comments on: Twin Paradox in a Closed Universe http://4by12.com/blog/archives/115 by Guy Gur-Ari Sat, 14 Aug 2010 23:42:00 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: Guy Gur Ari http://4by12.com/blog/archives/115/comment-page-1#comment-8734 Guy Gur Ari Sat, 05 Dec 2009 19:15:08 +0000 http://4by12.com/blog/archives/115#comment-8734 Bob receives both photons at the same time. This statement is true in any frame of reference, so Alice will agree with it. Perhaps it will be easier to think about it another way. Suppose only Alice exists. She sends out two photons simultaneously and then measures the time difference of their arrival. She then accelerates a bit and repeats the experiment. In the second experiment, she will measure a different time difference. If Alice accelerates by a certain amount, she can make the time difference between the received photons vanish. Alice then knows she reached the special rest frame. Bob receives both photons at the same time. This statement is true in any frame of reference, so Alice will agree with it.

Perhaps it will be easier to think about it another way. Suppose only Alice exists. She sends out two photons simultaneously and then measures the time difference of their arrival. She then accelerates a bit and repeats the experiment. In the second experiment, she will measure a different time difference.

If Alice accelerates by a certain amount, she can make the time difference between the received photons vanish. Alice then knows she reached the special rest frame.

]]> By: amir http://4by12.com/blog/archives/115/comment-page-1#comment-8732 amir Sat, 05 Dec 2009 18:17:45 +0000 http://4by12.com/blog/archives/115#comment-8732 so why can't one argue that Alice sees bob move and so she sees Bob getting one of the signals before the other. still the same experiment leads to different results but this does not show which frame is the special one. I do not know much about GR but know a bit about special relativity so if you could explain using that I will appreciate it. so why can’t one argue that Alice sees bob move and so she sees Bob getting one of the signals before the other. still the same experiment leads to different results but this does not show which frame is the special one. I do not know much about GR but know a bit about special relativity so if you could explain using that I will appreciate it.

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