Then is light constant?

What we know is that the engineer needs an infinitely divisible X axis on his graph paper.  Infinitely divisible means that unit always samples the other units with perfect clarity, no aliasing.  That is a necessary condition for using graph paper and assuming rectangularity.

Now I stretch my assumptions, but it seems to me the physicist could have chosen another X axis, say say momentum, and said the exact speed of light was known only to planks constant, but momentum could always be keptin proper order underinfinite subdivision.

I would think the proper answer is, the unit of vacuum offer a finite dimensional superposition of all passages, and their total is constant relative to a mutli dimensional coordinate axis.  But in our less compressed world, we never see more than a three dimensional superposition, except possiblly on some rare occasions when some transmissions seem too fast.