Aether turned out not to exist, and the scientific challenges that prompted its developement were addressed, nominally solved & pragmatically retired, by other means. The ‘dual nature’ of light (particle-wave), and all electromagnetic radiation is the accepted answer. The problem is, we can no more directly demonstrate the existence of these light ‘particles’, than we could the proposed aether.
https://en.wikipedia.org/wiki/Luminiferous_aether
https://en.wikipedia.org/wiki/Aether_theories