OK, you're right. So I correct myself: In absolute void the speed of light is not infinite, but just simply does not exist, because it's undefined, 0/0 division, and there is actually no wave at all, because there is no medium to carry it. The speed of any wave is the square root of a driving force term divided by an inertial term, as in sqrt((1/epsilon) / mu) for electromagnetic waves, or sqrt(E/Rho) for mechanical waves, E being the Young modulus, or stiffness (potential energy), rho the mass density (inertia), epsilon the dielectric permittivity(potential energy), mu the magnetic permeability(inertia). In an almost perfect void inertial terms are zero, or very nearly so, infinitesimal, but we don't know how zero the potential terms are. It is the ratio of these residual infinitesimal quantities that determines the speed of the wave, and for light the potential energy inverse permittivity factor is much greater than the magnetic inertia factor, that's how we have a huge velocity. Obviously, in absolute void there is neither inertia nor potential energy, just as there is sound in air, but in absence of a medium, such as in outer space, you can yell all you want in your space suit, the other astronomers can't hear it, there is no air to propagate it, but through a radio that transmits waves through the non-perfect-void between you two he can, because the "aether", the electromagnetic medium between you two is still present, and were it not, there would be no means of communication such as light or radio, you'd be immersed in a completely blind and deaf world, other than actually shooting dee deet dah dah Morse code bullets at each other and maintaining the sense of touch, or even various chemicals, to maintain the sense of taste (imagine you were a metal robot with HF-like(hydrofluoric acid-reacting like) heavy liquid, that does not boil in outer space vaccuum, acid saliva, tasting rocks.) As a different view, imagine you only had ears like bats, and you were in outer space, and you did not even know light existed, so without air you can't see anything with your ultrasound ears, or talk to each other, but if you use a bunch of ping pong balls to shoot around you instead of ultrasound, and a sensor to detect if any bounce back at you, you got a rough image, and your buddy can ping ping some balls at you in a tee tee tah tah Morse code fashion and communicate. So in absolute void there is no wave of any kind, because there is no transmission medium of any kind. It's like saying what is the speed of sound in outer space? It is zero. It stops at the interface of the sound propagating medium, the hull of your spacesuit, and the high or low impedance outer space, with total reflection. I'm not sure the concept of "aether" that has been abandoned as a scientific concept deemed superfluous because we can't measure our speed against it in the Michelson Morley experiment, so it would require complicated behavior to adapt to these experiments, so I'm not sure this concept is useless, because it does provide a medium to discuss, through which a wave propagates. Enabling it with funky but complicated behavior might be an worthwhile thing to do, and maintain Newtonian absolute time and space, and all electromagnetic things bending in it according to the Lorentz rules, but space itself or time itself would not bend. If you can find any non-electromagnetic objects around you (good luck), you could see if that cares about the constancy of speed of light or not. We still don't know what Newtonian gravity is, is it a force that propagates through a medium, and then what are the potential and inertial terms of that medium that would determine the speed. Obviously gravity propagates either infinitely fast, or very fast, as a simple force measuring experiment along the lines of Eotvos Lorant suspending 50 kg lead Pb balls via a quartz hair, and a mirror to bounce light to measure the torsion and force, you could measure how fast the force signal reacts when you suddenly remove the gravitationally interacting objects, vs. initial distance, i.e. how long it took the other ball to realize the first ball disappeared or got moved away. It's really difficult to move big weights really fast, or get any kind of gravity between widely separated objects, as it decays by r-square. So gravity may or may not move through electromagnetic "aether", and once you have a medium, you have one type of wave, as in sound is sound, and you can't really have transverse oscillations as sound, but interestingly, in aether you can have transverse and polarized waves, like on a water surface. On the water below it you could have a longitudinal wave, and the two waves propagate with different velocities, as the potential energy terms - one dependent on the gravity of earth or moon or space station you're one, the other one the Young modulus of water - are different from each other. So is there a way to also send longitudinal waves through "aether", and what would those be like? A charge exerts an electric field in an inverse r square just like gravity does, but there is two kinds of charges, and one kind of gravity, and magnetism arises only when you move not along the charge lines, but perpendicular to them, so "aether" must be some really funky substance or thing or model, and it may be a useful model just like caloric and phlogiston were for a while, until its deficiencies are highlighted. But we need a medium to intuit a wave with our stupid minds, and absolute void should mean no wave, and possibly no action at a distance?
A bat has no idea there is such a thing as light in the Universe, and misses out on looking at distant galaxies. I wonder how many such interactions there are that we have no sensors for. I mean a bat could still detect light just like we detect radio waves through a radio speaker, but it would be a hard job for him to adapt an speaker to depict Hubble telescope images in ultrasound for his ears to see. Picture a Hubble telescope image viewed in ultrasound, then transduced back into light for us. The image resolution must be horrible for bats, if they look at stuff like we look at pregnancy ultrasounds, but they are able to catch bugs with their sound vision, so maybe there is ways to go with our pregnancy images to get more quality. So just because we can't see an interaction with our present biological sensors like eyeballs and technological sensors like infrared detectors it does not mean it's not possible to transduce it to the other methods, and we probably know of all interactions there are out there, but there is always a possibility of something not very interacting escaping our attention, and it may be a while before we discover it, just like it may take thousands of years for bats with intelligence equivalent to humans, to happen upon light sensors, even if they know all about lightning strike thunders.