From: jos.bergervoet@xs4all.nl   
      
   [Moderator's note: The idiosyncratic characters result from not using a   
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   moderation process I always try to repair this as far this is possible   
   in an automized way. hvh.]   
      
   On 8/8/2017 9:36 AM, LuigiFortunati wrote:   
     ...   
   > =A0=A0   
   > =A0=A0 I ask you:   
      
   Luigi, can you please post more readable text? I do not know what   
   you mean with "=A0=A0" and similar insertions.   
      
   > can the transition from one reference to another only be   
   > achieved with acceleration (as in this case) or is there any other way   
   > to achieve it?   
      
   There is no prescribed reference frame to use. Everyone is free   
   to use any reference system, *also* those in which he himself is   
   not at rest. So the transition to another reference frame can be   
   achieved simply by a decision: "let me now use reference frame   
   Y instead of X for my calculations".   
      
   If, for whatever reason, you insist (unnecessarily) on using only   
   the reference frame in which you are at rest, then (by your own   
   choice) you need to change your velocity to be able to use another   
   reference frame. But then this is just your own chosen rule.   
      
   A reference frame is just a grid of coordinates. There is no law   
   in physics that forces you to use any specific grid. You can even   
   use arbitrarily curved coordinate lines (which were not yet   
   considered in this discussion until now).   
      
   Your questions are only about your own superficial choices of   
   choosing some specific reference frame. You maybe have the idea   
   that there is only one choice allowed, from popular descriptions   
   of the theory of relativity. But those descriptions are wrong!   
      
   It is *not true* that if you are moving at some speed, you're only   
   allowed to use one reference frame. Please change your beliefs.   
      
   --   
   Jos   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)