The theory of relativity didn't disprove aether, but it provided a simpler explanation that didn't require an absolute omnipresent medium for the motion of light. ... He found that electron particles may also have the properties of a wave, and matter on an atomic scale has the same dual nature as light.

Why the aether does not exist?

The idea was that since the Earth orbits the Sun, it must be moving relative to this aether, just as we can move through the air. ... The solution to this mystery was eventually found in Einstein's theory of special relativity, which said there was no aether. Instead light had an absolute speed in all reference frames.

Did Einstein believe in aether?

Einstein's general relativity resolved conflicts between Newton theory of gravity and the special theory of relativity. ... In special relativity Einstein rejecting the ether theory: ether do not exist. In this theory Einstein believe in Michelson-Morley experiments.