> Luminiferous aether or ether[1] ("luminiferous", meaning "light-bearing") was the postulated medium for the propagation of light.[2] It was invoked to explain the ability of the apparently wave-based light to propagate through empty space, something that waves should not be able to do. The assumption of a spatial plenum of luminiferous aether, rather than a spatial vacuum, provided the theoretical medium that was required by wave theories of light.
> The aether hypothesis was the topic of considerable debate throughout its history, as it required the existence of an invisible and infinite material with no interaction with physical objects.
I found out about it by way of a novel taking place in the 1800s (written in modern times): https://www.goodreads.com/book/show/22929563-the-watchmaker-...