From: g.scholten@gmx.de   
      
   Tom Roberts wrote:   
      
   >>> [... twin paradox] the reason why A's clock is ticking faster is physical.   
   >>   
   >> Physical, but frame-dependent.   
   >   
   > I disagree with both claims, and I think SR disagrees with both of these   
   > statements, too. This is partly about English word usage, but there is an   
   > important aspect of physics here:   
   >   
   > A's clock is NOT ticking faster (than B's), it is ticking at its usual rate,   
   the   
   > same rate as clock B. This is required by the first postulate of SR.   
   >   
   > 	One can say: "A ticks more times than B". One can also say   
   > 	"As measured in frame A, A ticks faster than B". But when   
   > 	one says "A ticks faster than B", one is talking about JUST   
   > 	THE CLOCKS; it is wrong   
      
   It is immediately clear from the context that here, "A's clock ticks   
   faster than B's clock" is a statement based on doing considerations from   
   A's frame, so this statement is equivalent to "As measured in A's frame,   
   A's clock ticks faster than B's clock".   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)