TA106 (Müller)

Response 6 (to C12 by Peter Beamish)


by Herbert FJ Müller
2 April 2008, posted 12 April 2008


Thank you for your answer concerning the speed of light.  However, I have a question :  you say that

‘The velocity of light in empty space is an "absolute constant" of Nature and is independent of the motion of the emitting body, AND/OR OF ANY SUCH SUBJECT.’

My question is :
            How do you support this opinion ?

There is no reality without subjects; this fiction is only postulated in traditional metaphysics.  There can thus be no such thing as a subject-exclusive speed-(of light or of anything else)-in-itself; nor is this a mathematical constant like pi.  An operational definition has to specify how the speed of light is determined.  The speed of light is a quantifiable aspect, with a magnitude, of a physical event (movement of light).  My understanding is that it has been measured and was found to be equal for light coming from a star whether the earth approaches it or recedes from it.  That result was one of the reasons for Einstein to propose relativity theory.  But if it is measured by someone (on earth), the speed of the movement is relative to, and not independent of, that ‘observer’; s/he can only measure it in distance over time, as seen from where s/he is now.  Einstein postulated that the speed is independent of the speed of the emitting source, not that it is independent of the observer. 

I would much appreciate a wider debate by physicists, and by others too, on this particular point, which might be of some relevance for understanding (see the questions in my R3).


Herbert FJ Müller
     e-mail <herbert.muller (at) mcgill.ca>