James Clerk Maxwell revolutionized the theory of electromagnetism. He published the famous Maxwell's equations, which predicted electromagnetic waves. He also found out that light was actually electromagnetic waves. This brought the wave theory of light to the consensus of physics, and with it the luminiferous aether. The idea of the luminiferous aether changed; and the concept of relative motion to the luminiferous aether was introduced.
However the luminiferous aether's life was short. The Michelson-Morley experiment, which tried to calculate the relative motion of the Earth and the aether found nothing. This puzzled many scientist at the time.
Hendrik Lorentz proposed his solution to this apparent problem. Though this solution relied on too many assumptions, it paved the towards Einstein's theory of special relativity, and towards modern physics as we know it.