From: jos.bergervoet@xs4all.nl   
      
   On 21/08/29 8:04 PM, Nicolaas Vroom wrote:   
   > [[Mod. note -- I apologise to all for the delay in processing this   
   > article, which arrived in the moderation system on 22-Aug-2021.  -- jt]]   
      
   [[ Is there a processing speed limit? And does it vary with time?! ]]   
      
          ...   
   >>      ... the subject of this sub-thread,   
   >> which was the question if the speed of light can vary with -time-,   
   >> and if we could in principle measure this.   
       ...   
     ...   
   > First you must measure the speed of light. Or better, you have to describe   
   > a general accepted way, how the speed of light is measured.   
      
   But we have that! Observing the propagation of light using length and   
   time units based on the propagation of light. The outcome is fixed.   
      
   > If you have such a recipe, you can measure and decide if the speed of light   
   > is everywhere the same and if this speeed is the same in -time- at a   
   > specific location   
      
   The only way to change it is to abandon the accepted definition (which   
   always keeps the speed fixed). And perhaps this could happen, if   
   for instance all speeds in physics suddenly became 10% higher, except   
   light. Then most physicists would be open to the idea that actually we   
   should change this definition.   
      
   > The same type of problems exists between: what is mass and how is this   
   > directictly measured or calculated based on different measurements.   
      
   There it is even more complicated since the word has undergone a change   
   in meaning. "Mass" without qualifier used to be the total mass (so in   
   those days E=mc^2 was always true, people said mass would increase with   
   velocity). But today the word "mass" by default means "rest mass", and   
   you have to specify "kinetic mass" or "total mass" if you mean one of   
   those. (So now E=mc^2 is wrong for moving particles!)   
      
   Fortunately we do not (yet?) have such a shift in meaning for "speed".   
      
   --   
   Jos   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)