Realizing that most often when we discuss the speed of light we’re not actually discussing the speed of light, but rather the speed of causality, was a huge eye opener for me.

The speed of light is not always c. That’s why refraction happens. Because light slows down in certain mediums below c. It’s kid of a coincidence that the speed of light happens to be c in a vacuum (actually I’m not sure about this…maybe there’s an organic reason why electromagnetic waves will be c in a vacuum that is fundamental).

I do think it’s interesting that as humans our primary sense is to light which does happen to travel at c. I wonder how different our species would be if we couldn’t sense waves traveling at c, and for example, were only capable of detecting sound.

Alternatively it may be that a species which could not sense waves traveling at c would not be capable of becoming as sophisticated as humans.