From: mlfasf@comcast.net   
      
   On 4/8/22 1:05 AM, Mike Fontenot wrote:   
   >   
   > What is really new, though, in my latest results, is the fact that the   
   > accelerating observer can assemble an array of clocks (and attending   
   > "helper friends" (HF's)), which give him a "NOW" that extends throughout   
   > all space (analogous to what Einstein did for inertial observers).  And   
   > THAT guarantees that the accelerating observer's conclusions about the   
   > home twin's age are fully MEANINGFUL to him.  His conclusions agree with   
   > the CMIF simultaneity method, which means that the CMIF simultaneity   
   > method is the only correct simultaneity method.   
   >   
      
      
   > [[Mod. note -- I think you're mistaken in a couple of places [...]:   
      
   I WOULD like to hear your "take" on my arguments here:   
      
   First, consider a perpetually-inertial observer (PIO).  Einstein showed   
   us how that PIO (he) can construct an array of synchronized clocks that   
   are stationary wrt him, extending throughout all of space.  The clocks   
   have been synchronized by using light signals.  The fundamental (and   
   really only) assumption that defines special relativity is that, in ANY   
   inertial reference frame, the velocity of light is always equal to the   
   universal constant "c".  We can also imagine that, co-located with each   
   clock is a "helper friend" (HF), whose age is always the same as the   
   PIO's age.   
      
   So, if the PIO wants to know "How old is that distant person (she)   
   "right now" (say, when the PIO is age T1), he just needs to know which   
   HF is momentarily co-located with her when the HF's age is T1.  He can   
   eventually determine that, from messages sent him by all the HF's.   He   
   has previously told all HF's to report to him all encounters with all   
   people, telling him what the encountered person's age was, who it was,   
   and what the observing HF's age was then.  The PIO reviews all those   
   responses, and eventually will find one that tells him that, when that   
   HF was T1 years old, he was momentarily co-located with the particular   
   distant person the PIO is interested in, and her age was T2.   
      
   Now, here is the important question: Given the above, should the PIO   
   regard that age of the distant person (that he has eventually   
   determined) to be MEANINGFUL?  Many people tell me the answer is NO.   
   But I claim that, if the PIO says that, he will effectively be saying   
   that he doesn't believe that the speed of light is equal to "c" in his   
   inertial frame.  And if he doesn't believe that, he doesn't believe in   
   special relativity.   
      
   All of the above applies equally well to the array of clocks and   
   helper-friends I've described for someone (the "AO") who is initially   
   unaccelerated, but who then undergoes a constant non-zero acceleration   
   for some length of time.  That AO can also be mutually stationary with   
   respect to an array of clocks that establish a "NOW" moment for him,   
   extending throughout all space.  The previous arguments all apply to the   
   AO as well.  The only difference is that, if the AO doesn't regard the   
   answer he has gotten for the distant person's current age to be   
   MEANINGFUL, that doesn't imply that he doesn't believe that the speed of   
   light is "c" (he already knows that the speed of light in his frame is   
   NOT "c").  If the AO doesn't regard the answer he has gotten for the   
   distant person's current age to be MEANINGFUL, that implies that he   
   doesn't believe that the equations he has used to calculate the current   
   reading on each of the HFs' clocks are correct.  If he DOES believe   
   those equations are correct, then he MUST conclude that the distant   
   person's current age he has determined IS meaningful.  I believe those   
   equations are correct.  Others may believe they are not correct.  I   
   think they ARE potentially testable.   
      
   [[Mod. note --   
   What do you mean by the word "meaningful"?   
      
   If the AO accelerates, he will assign a different CMIF-time to a given   
   (fixed) event (e.g., the explosion of the first hydrogen bomb on Earth),   
   and correspondingly assign the label "now @ Earth worldline" to a   
   different event along the Earth's worldline.   
      
   But does anything in the universe (other than AO's motion and the   
   observations AO makes) change when the AO accelerates?  If not, then   
   what is the basis for declaring changes in AO-CMIF-time "meaningful"?   
      
   It might be useful to conceptualize the AO and his CMIF definition of   
   "now @ Earth worldline" as a "time viewer" than can observe the Earth   
   at any point (event) on the Earth's past worldline.  Accelerating the AO   
   (changing the AO's velocity with respect to some inertial reference frame)   
   then corresponds to turning the control knob on this "time viewer" back   
   and forth (and hence moving the AO's "now @ Earth worldline" observation   
   point forwards and backwards in time along the Earth's past worldline).   
   Do you consider this change in observation point to be "meaningful"   
   (beyond its obvious change in what AO himself observes)?   
      
   This change in observation point is certainly not unique -- another   
   accelerating observer AO' will in general ascribe a different observation   
   point.  And, this observation point can move superluminally both forwards   
   and backwards in time.  And, no observation on Earth (apart from asking   
   AO to report what he is observing) changes when AO moves his observation   
   point.   
      
   To me, this all (very strongly) suggests that the motion of this   
   observation point (i.e., AO's CMIF-time definition of "now" at the Earth's   
   position) doesn't deserve to be called "physically meaningful".   
   -- jt]]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)