In new Scientist 4 March article about What if… Starts with the speed of light were infinite? Stuart Clark talks about inflation faster than speed of light and several experiments to investigate. Depending on wave form we know there are slight speed variations possible.
I like to think more about space time than time and space as separate identities. I see it as one ruler with metric and imperial marks on one line. For small objects a caliper, for large objects a projected ruler. Philosophical I think it is utterly wrong to separate space and time as the small building blocks are constantly shifting although the projected ruler might not measure the change.
If we investigate the speed of light why not investigate the mass of light? Could light have had mass shortly after the big bang?
Light doesn’t react with dark matter. Could dark matter be much smaller vibration? Could dark matter and light originally be the same? When pressure in space time becomes less the two separate out? Galaxies have influence of gravity with cosmic super clusters there is a light but no gravity connection.
Simply through the expansion of the universe dark matter is of such a small scale that it can separate out from a photon? Could this be possible? What was first linked by gravity becomes independent through a process of annihilation (matter + antimatter) forces driving the galaxy further and further apart creating more dark matter.