From: nicolaas.vroom@pandora.be   
      
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   Op vrijdag 17 september 2021 om 06:16:55 UTC+2 schreef Phillip Helbig   
   (undress to reply):   
      
   > c to be constant and that we believe that it is constant. I don't think   
   > that likely; my point is merely that we cannot prevent the speed of   
   > light from changing simply by defining it to be constant. Rather, it is   
   > defined to be constant as a practical matter because we have evidence   
   > that it is.   
   If that is true you should explain us what that evidence is.   
   I prefer to write: because we have no evidence that it is not.   
      
   My point is mainly that if 'you' define c to be physical constant,   
   that means that photons always have the same speed, 'you' should   
   also define how this speed is calculated.   
   What R=C3=B6mer did (very cleverly) was to calculate the average   
   speed of light between Jupiter and the Earth. This calculation is   
   a mathematical description of the mechanical Sun, Earth, Jupiter   
   system. Assuming my understanding of book "Einstein's theory of   
   relativity" page 93 is correct.   
      
   Is his result valid for the whole of the universe?   
   We use the speed of light to measure hugh distances.   
   Is it realy correct to claim that this speed, along that whole path, is   
   everywhere the same?   
   What about the influence if 'space' is a vacuum?   
   What about the influence of matter?   
      
   Nicolaas Vroom.   
      
   --- SoupGate-Win32 v1.05   
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