From: nobody@invalid.invalid   
      
   Am 21.05.2020 um 09:36 schrieb Luigi Fortunati:   
   > Twins A and B are stationary at point O of space:   
   > (-4)----(-3)----(-2)----(-1)----O----(+1)----(2+)----(+3)----(+ 4)   
   >   
   > If a twin moves away at constant relativistic speed, there is no   
   > difference between them, in the sense that twin A can safely say that it   
   > is B that is moving away from him, just as twin B can say (just as   
   > safely) which is A who is moving away.   
   >   
   > So, in the reference of the twin A, it is B goes, arrives at point +4 (4   
   > light-years away) and then returns to O.   
   >   
   Wrong. In the reference of A the twin B returns to A and not to 0.   
      
   > Instead, in the reference of the twin B, it is he who remains in O while   
   > the twin A goes, arrives at the point -4 and then returns.   
   >   
   Wrong. B does not stay in 0 but in B and the twin returns to B.   
      
   > If the speed corresponds to gamma=2, the travel the other twin (for BOTH   
   > twins) lasts 16 years, 8 for the outward journey and 8 for the return.   
   >  > Both will be 16 years old!   
   >   
   Right for the same age of A and B, but the ages will not be 16 years older.   
   > Where is the conceptual difference that should make the time of a twin   
   > different from that of the other, if we are talking about Special   
   > Relativity ONLY?   
   >   
      
   Why should there be a conceptual difference?   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)