Now, of course, the question arises of how one can prove the absolute theory through experiments. The first thing I would think of was an experiment with photons. Unfortunately, these have fallen into disrepute due to the Michelson-Morley Experiment. In the past, the idea of an ether held physics under its spell. It was thought that it could be detected by the fact that photons were deflected from it. An attempt was made to prove this with a complicated mirror construction on mercury. The experiment failed. My personal opinion is that if there is an ether and a primordial substance, these should be the photons themselves, which have elemental mass, no further substance and no further flow that deflects these basic particles. In addition, if one wanted to revive the idea of the ether, one should concentrate on the background noise, which is valid as evidence for the big bang theory, or as the reverberation of this big bang. I see the fact that photons have mass, by the way, already proven, by Einstein's predictions about the solar eclipse, which made him famous overnight. Here the light rays are slightly deflected by the mass of the moon, so that it is proven that they are subject to gravity and also have a mass.
Experiment 1: Photons of different energies move at different speeds
With the speed of light itself only photons move with the elementary energy. This elementary energy is the elemental mass multiplied by the square of the speed of light. The more energy the photons have, the slower they move. It should be possible to demonstrate this deviation by means of a suitable experimental setup, but it is very small, so that one would have to rely on quantum computers. You should send off two beams of light in an approximate vacuum and measure the time using a time measurement similar to the 100 meter sprint. Then you will see that the photons with more energy are a little slower.
Addendum to experiment 1: What a shame, I could have come up with the idea during this experiment that neutrinos are faster than photons because they have less total energy and thus less mass, as it was now apparently demonstrated in the opera experiment.
Experiment 2: Checking the addition theorem of the speeds according to Einstein
Today one should be able to check Einstein's addition theorem of velocities. I'm still on Newton's side with simple vector addition. According to the Opera experiment, neutrinos that have less energy than photons also move faster than these. As a rule of thumb, you should be 30 km / h faster, but you still have to calculate the exact value. Accordingly, if I were right with the vector addition and Einstein's theorem would be wrong, one should be able to measure particles in the light beam with a light source that moves in a vacuum at 30 km / h, which have the energy on neutrino level. Ultimately, due to the speed, the total energy of the light beam remains the same, but the particles of the light beam should become more in number and less in terms of energy and mass.
Experiment 3: Different speeds in different media of light
Experiment 3 hits the same line as Experiment 1, but should be even easier to check. It is well known that light moves faster in space than through the air and faster in the air than through water. According to the absolute theory, light that crosses water should have a higher energy than light that crosses air. I'm not the biggest fan of E = hf, but you should be able to measure a higher frequency here. Simply position a light source above the water and record the light source with an underwater camera. The light from the light source should have a higher frequency under water. Accordingly, the light should exhibit a blue shift, because higher frequency means lower wavelength and that means blue shift.