From: nospam@de-ster.demon.nl   
      
   Nicolaas Vroom  wrote:   
      
   > Op dinsdag 31 augustus 2021 om 07:26:18 UTC+2 schreef Phillip Helbig:   
   > > In article <1peqwo1.1pvreq6wg61gwN%nos...@de-ster.demon.nl>,   
   > > nos...@de-ster.demon.nl (J. J. Lodder) writes:   
   >   
   > > > 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.   
   > > >   
   > > > 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 (1) a   
   > > distance. We can measure (2) a time. Thus, we can measure a (3) speed.   
   >   
   > Yes we can measure a speed and a distance and using both calculate a speed.   
   > This is rather straight forward when you want to calculate the speed of a car   
   > , but very difficult when you want to calculate the speed of light or the   
   > speed of a neutrino. The main problem is the reference frame.   
   >   
   > The first step is to describe exactly how (1) and (2) are measured such that   
   > we all can perform the same experiment and compare the results (at different   
   > locations or circumstances).   
   > To measure the time you can use two atomic clocks, but than you have to   
   > agree how to synchronise these clocks.   
   >   
   > To measure the distance you could start with two points A,B, a fixed distance   
   > apart. Next you can define a point C halfway between these two points AB   
   > and issue a synchronisation flash from C towards A and B.   
   > But the question is do both pulses arive simultaneous?   
   > Next you can issue a pulse from point A and measure the arriving time t1 of   
   > that pulse at point B.   
   > You can do the reverse from B to A and measure t2.   
   > The question is: Are these two arriving times t1 and t2 (durations) the same?   
   > If they are you can calculate c. If they are not you have a problem.   
   >   
   > Next you want to do with the same with a neutrino? Is that physical possible.   
   > IMO the best strategy is first to calculate the speed of light at that   
   > location and use the points (A,B) to measure the speed of a neutrino.   
   > This strategy is not simple.   
      
   Of course it is possible, and it is, at least in principle, simple.   
   And it has been done, in the CERN neutrino velocity experiment,   
   with (at first) disastrous results.   
   The distance CERN-Gran Sasso was measured by triangulation, using GPS.   
   The clocks were synchronised, again using GPS.   
   So the whole experiment was based on timing,   
   using (many) communicating atomic clocks.   
   The experiment was a direct comparison of the speed of the neutrinos   
   and the speed of light.   
   (the distance was measured in [light-]seconds)   
      
   As you probably know all went well,   
   up to the timing at the entrance of the Gran Sasso tunnel.   
   The supposed faster than light speed of the neutrinos   
   was due to a delay in an improperly fastened optical connector.   
   The deeper fault in the set-up was that they should have had   
   at least a dual link for bringing the timing into the mountain,   
      
   Jan   
      
   [snip other observers]   
   The experiment measures v_{neutrino}/v_{light},   
   which is a dimensionless world scalar,   
   so all observers should find the same result.   
   (note that E_{neutrino} >> m_{neutrino})   
   THere is no way to measure v_{neutrino} in some absolute way,   
   independently of assumptions about the speed of light.   
      
   --- SoupGate-Win32 v1.05   
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