Ether's hypothesis

While looking at stars, we sometimes assume that there is nothing  in between stars and us, but maybe we are wrong or only some group of scientists think so that we are wrong, 

From childhood, we are taught that there is nothing in the space between stars planets. But what if told there was a theory that suggests that the entire universe is filled with a mysterious substance called Luminiferous Ether (sometimes called aether).

At present time, we know that light has dual nature, but when Christiaan Huygens published his wave theory against the world, he concluded that light is a wave. Huygen proposed that light is a mechanical wave, a wave that requires a medium to propagate. But many physicists of that time started to debate that in space there is a vacuum then how a mechanical wave can be propagated in a vacuum, in defending the above talk Huygen concluded that Space is filled with a mysterious luminiferous aether which is very elastic and weightless, transparent, a frictionless substance which provides medium for light to propagate.

Then, how do we get to know that Eather is a hypothetical material?

From 1902 to 1905 Michelson and Morley did series of experiments that that light wave propagates in the ether 

Experimental setup

The basic idea of the experiment was as same as boating or swimming  in a river  

When we swim in the direction of a stream or river (downstream), we get our swimming speed greater than when we swim opposite a stream or river(upstream). 

according to them, when the earth moves in this aether wind is generated, 

, the speed of light should change from season to season because the relative motion between light and aether is changing continuously. 

They performed this experiment several times, but nothing got concluded, 

But the experiment got failed. Which proved that the existence of luminiferous ether is purely hypothetical.