From: eric@flesch.org   
      
   [Moderator's note: As Eric quoted too LITTLE post to provide context, I   
   have extended his quotation in order to provide enough.  -P.H.]   
      
   On Fri, 26 Jul 2019 08:57:08 PDT, "Phillip Helbig (undress to reply)"   
    wrote:   
      
   > What is difficult to understand is the twin paradox: After A goes away   
   > and comes back while B stays at home and they then compare clocks at   
   > rest, EVERYONE agrees that A's clock has ticked less.  Recent discussion   
   > here shows that acceleration is not the "cause", since the effect   
   > depends on the length of the journey, and not on the acceleration.   
   > Since all clocks (mechanical, electronic, atomic, biological, nuclear)   
   > are equally affected, it is a) hard to imagine that some mechanism   
   > affects them all equally and b) no-one has any idea what such a   
   > mechanism could be.   
      
   > Yes, one can adopt the   
   > "shut up and calculate" approach and calculate the strength of the   
   >effect, and it agrees with observations, but this is not the same as   
   >understanding.  The question is whether such an understanding is   
   >possible.   
      
   I wonder if Mach's Law is involved.  Nobody understands that either,   
   but both issues involve an unseen reference frame of some kind.  Maybe   
   it's the same one.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)