From: nicolaas.vroom@pandora.be   
      
   The two postulates of SR are:   
   1. The laws of physics take the same form in all inertial frames.   
   2. In any given inertial frame, the velocity of light c is the same whether   
   the light be emitted by a body at rest or by a body in uniform motion.   
   This text is from the book 1 "Subtle is the Lord" by A Pais at page 141.   
      
   In the book 2 "Spacetime Physics" by Taylor and Wheeler we can read:   
   All the laws of physics are the same in every free-float (inertial) reference   
   frame (page 55)   
   The principle of relativity rests on emptiness (page 56)   
   Accordingly to the theory of Relativity, the speed of light must be the same   
   in all free-float frames in uniform relative motion (page 60 - line 1)   
      
   In the book 3 "The evolution of scientific thought from Newton to Einstein"   
   by A.d'Abro at page 451 we can read:   
   "the velocity of light is invariant only for Galilean observers; it is   
   variable from place to place when accelerated observers are considered,   
   and it is also variable in the neighbourhood of matter."   
      
   Each of these 3 quotes seem simple at first sight, but become complex   
   when you compare them.   
      
   My first thought is what exactly are the laws of physics. The laws of physics   
   can be defined as descriptions of physical processes.   
   This raises the question do we mean all sorts of physical processes or   
   only some.   
      
   At page 60 of book 2 we can read:   
   "All the laws of motion are the same in the one free-float frame as in   
   the other."   
   Such a sentence is of not much help to answer the question:   
   "Is the behaviour of a clock at rest the same as a moving clock."   
      
   To answer: Yes, based on the first postulate of SR seems too simple.   
   To find the answer based on a real experiment seems to me the   
   primary strategy to follow.   
      
   1) Also at page 60 (After page 60 - line 1) we can read:   
   "Has observation checked this conclusion? Yes, many experiments demonstrate   
   it daily and hourly in every particle-accelerating facility on Earth."   
      
   2) Also at page 60 of book 2 we can read:   
   "Values of the speed of light as measured by laboratory and by rocket   
   observer turn out to be identical."   
   This defines an experiment.   
      
   3) Immediate there after we can read;   
   "This agreement has cast a new light on light. Its speed rates no longer   
   as a constant of nature. Instead, today the speed of light ranks as a   
   mere conversion factor between the meter and the second. etc. This decree   
   assumes the invariance of the speed of light. No experimental   
   result contradicts this assumption."   
      
   All these 3 cases are most probably true, but if you trully want to understand   
   you must know the details of how these experiments are performed.   
   Unfortunate no such detail is supplied.   
      
   In fact IMO if you want to do science you should start from bottom up   
   from experiments. Even better from experiments which are slightly different.   
   The problem is to perform experiments involving lightsignals is   
   very difficult. For example, it is very difficult to measure the speed   
   of light accurately in a laboratory and even more difficult in a rocket.   
   In a rocket you need a clock and to measure the speed of light which   
   a clock which also uses lightsignals, IMO seems nearly impossible.   
      
   The conclusion, that certain experiments are impossible is of extreme   
   importance, because its creates a type of physical limit.   
   The next step to define a certain number of concepts, we all agree   
   upon, seems to me a healthy solution.   
      
   To start from the idea that the universe is empty and that we can have   
   frames, which are in relative linear motion, does physical not make sense   
   because in fact each frame requires at least one object and in order   
   to create movement, forces are required, which introduce accelerations   
   which inturn create frames, which are not in linear motion.   
      
   It are the laws which describe the objects (processes), in these non inertial   
   frames which are the most important, to unravel.   
      
   Just some thoughts.   
      
   Nicolaas Vroom   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)