From: helbig@asclothestro.multivax.de   
      
   In article <1pbx3kk.jywko91341fc9N%nospam@de-ster.demon.nl>,   
   nospam@de-ster.demon.nl (J. J. Lodder) writes:=20   
      
   > Tom Roberts  wrote:   
   >=20   
   > > On 6/29/21 1:41 AM, J. J. Lodder wrote:   
   > > > [...] The speed of light cannot 'really' be variable. [...]   
   > >=20   
   > > You make far too many assumptions to be reasonable.   
   > >=20   
   > > Certainly the (vacuum) speed of light COULD vary, it's just that in t=   
   he   
   > > world we inhabit, with current technology, it is observed to not vary   
   > > significantly (when measured using standard clocks and rulers at rest=   
    in   
   > > some locally inertial frame).   
   >=20   
   > That's where you are mistaken.   
   > There is no such thing as a god-given 'standard clock'   
   > or 'standard ruler'.   
   >=20   
   > > But it certainly is possible that in the=20   
   > > future we will develop technology with greatly improved resolution an=   
   d   
   > > discover that it actually does vary in the world we inhabit.   
   >=20   
   > A meaningless statement.   
   > If variation is found we will have to discover (or decide!)   
   > what it is that varies.   
   > (speed?, rulers?, clocks?, all three?, some 'fundamental' 'constant'?)   
   >=20   
   > > It is also possible we will never find it varies -- science is a JOUR=   
   NEY,   
   > > not a destination.   
   >=20   
   > Empty ideology.=20   
   > This is not a matter that can be settled   
   > by means of naive empiricism,   
   > by just 'measuring' the 'speed of light',   
      
   One could measure the speed of light via several different types of=20   
   rulers and clocks, or by measuring wavelength and frequency, or=20   
   whatever, in the lab.  It is theoretically possible that the speed of=20   
   light could change with time and that we could measure it.   
      
   The fact that the speed of light is now a defined quantity does not=20   
   somehow magically make it impossible to make a measurement which was=20   
   possible with the original SI definitions.   
      
   Obviously, if such a change were detected, then it would be a good idea=20   
   to change the definition of the metre.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)