From: jos.bergervoet@xs4all.nl   
      
   On 21/08/31 7:26 AM, Phillip Helbig (undress to reply) wrote:   
   > In article <1peqwo1.1pvreq6wg61gwN%nospam@de-ster.demon.nl>,   
   > nospam@de-ster.demon.nl (J. J. Lodder) writes:   
   >   
   >> Phillip Helbig (undress to reply)    
   >> wrote:   
   >   
   >> The problem with your position is that you postulate   
   >> that what has to be shown,   
   >> namely that there is such a thing as the speed of light,   
   >> and that it is a constant of nature.   
   >>   
   >> As far as we know now there is no such a thing.   
   >> We can formulate all known laws of nature in such a way   
   >> that the speed of light doesn't occur in any of them.   
   >>   
   >> What remains is that the 'speed of light' is an artefact   
   >> caused by maladroit choices in the definition of our unit systems.   
   >> It has no more physical reality than Boltzmann's constant,   
   >> or the impedance of the vacuum.   
   >>   
   >> If you want to have a 'speed of light' as a constant of nature   
   >> you must invent new, and fundamentally different laws of physics   
   >> in which there is such a thing,   
   >   
   > Please explain.  There are various sources of light.  We can measure a   
   > distance.  We can measure a time.  Thus, we can measure a speed.  We   
   > find that the speed of light is always the same.  Similar results for   
   > the speed of sound at a given temperature and pressure.   
      
   This may again just show the ambiguity of the question, due to   
   mixing up the two concepts:   
   1)  The maximum speed allowed by the metric.   
   2)  The propagation speed of a certain quantum field.   
      
   If we talk about 1) then changing the speed of light is changing   
   the scale factor ratio between the time dimension and the space   
   dimensions. That's only slightly less strange than changing the   
   scale factor between one of the space dimensions and the other two.   
   Why would one do it? How could it ever be justified? (But still,   
   I can't see why there absolutely never would be a reason for it..)   
      
   If we talk about 2) then changing the (self) interaction of the   
   quantum fields (e.g. by vacuum decay, auxiliary fields, etc.)   
   could obviously change the propagation speed of its particles.   
   But in our currently used field theories this would probably only   
   give the photon a mass, so it would still leave the high-energy   
   limit of the speed the same, coinciding with definition 1) of   
   the concept. (Other theories, where this is not necessarily the   
   case may exists, of course..)   
      
   > Your position seems to be that the speed of light is merely a conversion   
   > factor, and might as well be set to 1 (not uncommon in some fields of   
   > physics).  However, that is possible only if the speed of light is a   
   > constant of nature.  Thus, it seems to me that you are the one making   
   > the assumption that the speed of light is some fundamental physical   
   > quantity.   
   >   
   > Yes, it is possible to have units where the speed of light is just a   
   > conversion factor, or is 1, or whatever, but that is possible only if it   
   > IS a constant of nature.   
      
   And it would be similar to using the meter to measure length, height   
   and width, instead of having 3 different units. It's not *obviously*   
   correct, only correct if the universe is absolutely isotropic. So do   
   we accept that as a given? What exactly *can* we accept as given?   
      
   --   
   Jos   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)