Measurements made by Albert Michelson and Edward Morley in 1887 of the speed of light resulted in the same speed in every direction, leading to the assumption that there was no ether.
The only way that an ether might exist and give the same measurement results in different directions, is if the ether following the Earth in its journey through space.
If there exist an ether (particles, for example electrons) it must have a mass.
All planets around the sun have a velocity as depends on the distance from the sun independent of the mass, therefore a particle or Jupiter have the same velocities around the sun as the earth if they have the same distance to the sun as the earth.
If there exist an ether it must follow the earth, have the same velocity as the earth and measurements of speed light must result in the same speed in every direction.
Measurements made by Albert Michelson and Edward Morley are showing that it can exist an ether or not.
Einstein wrote the following on the findings from Miller’s measurements to demonstrate the existence of ether:
I believe that I have really found the relationship between gravitation and electricity, assuming that the Miller experiments are based on a fundamental error. Otherwise, the whole relativity theory collapses like a house of cards.
Albert Einstein, in a letter to Robert Millikan, June 1921.
Conclusion: All measurements of light and electromagnetic radiation indicate that it is a pure wave function, therefore, it is better to assume an ether than assuming photons and that the speed of light must be constant.