From: hitlong@yahoo.com   
      
   On Saturday, September 2, 2017 at 8:33:52 AM UTC-6, Nicolaas Vroom wrote:   
   >   
   > For GPS clocks you can do a simular experiment. One GPS clock you keep   
   > on earth and one other you bring in orbit for 1 year and you bring it back.   
      
   That would be a nice experiment, but it cannot be done.  GPS clocks fail   
   if subjected to more than two g's acceleration.  They are shut off during   
   launch because of that and would experience more than 2 g's on reentry.   
      
   Another factor is that their vehicle doesn't have reentry capability, but I   
   suppose a shuttle could pick one up.  It would be useless, though, because   
   the clock wouldn't operated during reentry.   
      
   A proper test would have to be done with both clocks in space.  They would   
   be synchronized when both are together and then one would be accelerated   
   (gently) to a different trajectory and then brought back later and compared.   
      
   > Also here the question is: is the duration the same?   
   > I doubt this.   
      
   So does every scientist who understands relativity.   
      
   > In fact you should do one experiment to test both.   
   > 1) One clock stays for one year on earth,   
   > 2) One clock travels for half a year away and for half a year back (fast)   
   > 3) One clock which travels for one year around the earth (stays in orbit)   
   > when they meet which clock shows longest duration (highest # of ticks)   
   > and which the shortest?   
      
   It most likely won't be done because (1) every knowledgeable person knows   
   what will happen, (2) satisfying the whims of doubters is a waste of time and   
   money, and (3) spacecraft are better used discovering what we DON'T know.   
      
   > Specific what type of experiment do you have in mind to demonstrate   
   > "time dilation"? Is it one above?   
      
   (1) The postulates of special relativity are well-established experimentally,   
   (2) the derivation of the LT is logically correct and predicts TD and the   
   twin paradox, and (3) there is abundant experimental evidence to support   
   various aspects of both SR and GR and none to refute them.   
      
   So why would you continue to doubt?   
      
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