Neil,
We're on the same wavelength … [boom-boom]
The really interesting/mind-boggling bit being:
As a matter of dogma "the Speed of Light in vaccuo" is one of the Universal Constants
Ref. Diagram showing the SI Constants.
But … Speed = Distance/Time … and we now define the metre in terms of time.
So … our Universal Constant has a circular definition !!!
and "Time" [something which is not really comprehensible, and has had many defiinitions] seems to be our ultimate reference.
MichaelG.
I would welcome your thoughts on this … but it's probably unfair to take the thread too far off-topic. Please eMail if you want to discuss.