Hi Kevmo! Ultimately, isn't the speed of light a function of time? Our "human view" of time is that it is serial and linear, moving inexorably from past, to present, to future. Our concept of time is pretty "flat." Now we have these virtual particles that wink in and out of existence. These particles do not appear (to me) to be the sort of things that conform to our standard model of serial, linear time which is essentially based on observation and convention. The idea of a universal vacuum field also does not comport with this model for this vacuum is universal. Rather it seems the behavior of virtual particles points to anther temporal dimension that is not directly observable by humans, and is definitely not "flat."
I dunno. I'm reasoning as a philosopher, not a scientist. What I do know is that certain high-energy physicists/cosmologists for example the distinguished Israeli physicist Avshalom Elitzur have suggested that our current notions of time are very likely inadequate and are acting as a constraint on new breakthroughs in the physical understanding of our universe.
Just some thoughts, FWTW.
Thanks for the ping!
Ultimately, isn’t the speed of light a function of time?
***It could be a function of (dependent upon) something else as well. In Physics we see C all over the map in equations, and if it’s a function rather than a constant, then our universe is far more complicated.