>>before the velocity of light was “fossilized” in proceding time.
If spatial density is variant, then so too is the velocity of light.
I think Space is to Energy as Energy is to Mass... and Gravity the manifest relationship between all of them.
The velocity of light does change it’s refractive indices through various densities.
Could you demonstrate your “space to energy” hypothesis your own Chair would be established at a university of your choosing.