yup, it's true they were searching for some sort of ether. Maxwell and friends had already established a pretty strong theory for light which we still use a lot today (although since then we have discovered quantum electrodynamics).
Scientists knew that waves needed to propagate through a medium so they came up with this "ether" to explain why light could apparently travel through a vacuum. Now of course there would have to be some preferred reference frame where the ether was stationary. With the exception of string theorists, scientists only like to believe stuff if we can do an experiment. So right around the beginning of the 20th century Albert Michelson and Edward Morley set up this cool device to measure the earths relative movement to the ether as it moved around the sun.
well anyways they found nothing, no ether. kinda weird right? how the hell can a wave propagate through space without and ether?
Well anyways at the same time a lot of people were frustrated. They were frustrated because maxwells equations were not invariant under a galilean transformation (like newtons laws were). Anyways this dude you may have heard of named Albert Einstein really liked Maxwells equations but knew that there was something fishy going on. He knew there was something BIG missing. Basically either the galilean transformations and newtons laws were incorrect or the laws of electromagnetism were not the same in all inertial reference frames. The later couldn't be because of the MM experiment, Einstein may have not been aware of these results, but picked the first option anyways
and it worked
HOLY SHIT
At the same time a lot of other crazy shit happened with blackbody radiation and the discovery of subatomic particles. We had began the transformation to modern physics. Newtons laws were taken from the top shelf of science and thrown to the engineers like scrap food at dogs. They were approximations. Anyways If you want to learn more about it I would highly reccomend you get a university degree in physics.
In short, yes they were looking for the ether
over 100 years ago but not because they had evidence that light couldn't travel through a vacuum. In fact it was because they thought they needed it to
explain why they could observe light travelling through a vacuum. Turns out they didn't need this, they just needed new physics altogether.
