You're absolutely correct that there was consensus at one point about luminiferous aether, and it was proven to be BS because of new evidence. (reddit.com)
In 1704 Isaac Newton chimed in and declared that it consisted of particles that moved through a medium called luminiferous aether, which pervaded the universe. (discovermagazine.com)
They were trying to detect variations in the speed of light to prove the existence of the «luminiferous aether,» a perfectly immobile, transparent, and mysterious substance that was thought to pervade the universe. (discovermagazine.com)