From: nicolaas.vroom@pandora.be   
      
   On Saturday, 23 June 2018 11:15:15 UTC+2, Ed Lake  wrote:   
   >   
   > < snip >   
   >   
   > Einstein's thought experiments produced papers which showed that   
   > time is variable: The faster you travel, the slower time advances   
   > for you, i,e., the slower your clocks will tick, the slower you   
   > will age, the slower your hair will grow, etc.  It took a long time   
   > for actual experiments to confirm that.  But they did.   
      
   What the actual experiments showed is that not all physical clocks   
   behave the same.   
   Considering a physical clock which use lightsignals and assuming   
   the clock at rest. In such a case it is easy to explain by means   
   of a sketch that a second identical moving clock ticks slower.   
      
   > If you have five people with identical clocks traveling at five   
   > different speeds, their clocks will tick at five different rates.   
   > You can rank the five by their relative speeds - A is moving faster   
   > than B, B is moving faster than C, C is moving faster than D, and   
   > D is moving faster than E.   
      
   The first issue is that you should consider your five clocks from one   
   reference frame.   
   The second issue is to answer the question: which clock ticks the slowest.   
   This raises immediate an new issue: is it possible   
   to introduce a sixth clock which ticks more slower?   
   The answer could be: that clock should have a slower speed.   
   This pops up a new question: How is the speed of each clock   
   measured?   
   To measure the speed you need clocks, which makes this discussion   
   more complex and somewhat circular (if that is the good wording)   
      
   In any way you can not solve this problem by means of a thought   
   experiment.   
      
   Nicolaas Vroom   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)