From: none@znet.com   
      
   On 3/25/2022 3:57 AM, Mike Fontenot wrote:   
   > On 3/20/22 4:44 AM, I (Mike Fontenot) wrote:   
   >> On 3/19/22 12:27 PM, Tom Roberts wrote:   
   >>>   
   >>> Observation implies a physical quantity is being observed. Simultaneity   
   >>> at different spatial points is not any kind of physical quantity, it is   
   >>> a CONVENTION based on the time coordinate of a particular inertial   
   >>> frame   
   >>>   
   >>   
   >> Tom, what is your "take" on the use of an array of clocks, stationary in   
   >> some inertial frame, that have been synchronized using only the   
   >> assumption that the speed of light is equal to the universal constant   
   >> "c" in that frame.  Each of those clocks is attended by a human "helper   
   >> friend" (HF), who can observe his immediate local surroundings.  Another   
   >> particular observer (whom I'll refer to as "he"), also stationary in   
   >> that inertial frame, wants to know (when his watch shows time tau) the   
   >> current reading on a particular distant clock which is NOT stationary   
   >> with respect to that array of clocks.  It seems reasonable that he is   
   >> entitled to say that the current reading on that distant clock is what   
   >> the HF, who happens to be colocated with that distant clock at the   
   >> instant when the HF's clock reads tau, directly observes it to be.   
   >> Doesn't that convey a sense of "meaningfulness", to the observers who   
   >> are stationary in that frame?  I think Einstein thought it does.   
   >   
   > Tom hasn't responded yet.  Maybe he will shortly.  But while waiting,   
   > I'd like to add a bit to my above argument.   
   >   
   > I think a sizeable number of physicists DO believe that simultaneity at   
   > a distance is a meaningless concept, and I've even noticed a trend of   
   > trying to de-emphasize talking about simultaneity-at-a-distance in   
   > introductory special relativity courses.  But I think that is a big   
   > mistake.  It certainly wasn't Einstein's view, at least for inertial   
   > observers.  (I've seen a quote from Einstein somewhere where he said he   
   > hardly recognizes his theory when he reads some modern descriptions of   
   > it.)   
   >   
   > My above question of Tom Roberts was prompted mostly by his use of the   
   > word "Convention" in describing simultaneity at a distance for an   
   > inertial observer.  To me, the term "Convention" implies that there is   
   > more than one possible answer to the question "How old is that distant   
   > person (she), right now", when asked and answered by a particular   
   > inertial observer.  "Convention" implies that one can pick from among   
   > multiple alternatives, all equally good.   
   >   
   > But I don't believe that is true, given my above description of how an   
   > array of synchronized clocks (all permanently stationary with respect to   
   > the given inertial observer) can be set up, creating a common "NOW"   
   > instant for him and for all of the HF's ("helper friends") co-located   
   > and co-stationary with the clocks.  At any given instant "tau" in the   
   > life of the given inertial observer, it's clear that there is just a   
   > single answer to the question "How old is that particular distant person   
   > (she) right now (at the given time "tau" in the life of the inertial   
   > observer): it is what the particular HF (he) who happens to be   
   > momentarily co-located with the distant person (she), says it is, at the   
   > instant when he is age "tau".  The only way there could be any other   
   > allowable answer is if the synchronization of the clocks isn't valid,   
   > and that is impossible if the velocity of light in that inertial   
   > reference frame is equal to the universal constant "c".   
   >   
      
   What if the twins (or clocks) were quantum-entangled?   
      
   --- SoupGate-Win32 v1.05   
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