Why Aether or Consciousness was declared by the scientific community as non-existent in 1887 while i
First of all, ether is not consciousness, and consciousness obviously exists.
As for the ether, it was posited to explain the transmission of light, because it was assumed (for reasons described below) that a medium of some kind was needed to transmit any kind of influence.
In 1887, it turned out that the speed of light was framework-invariant, meaning that its speed relative to a given observer did not depend on how quickly that observer was moving or in what direction.
This meant that the ether was completely undetectable and therefore, in effect, non-existent.
Some ancient philosophers, e.g. Aristotle, did indeed believe motion to be impossible in a vacuum and therefore posited the existence of an ether-like ‘medium of motion.’ Other more recent thinkers, e.g. Newton, followed suit.
Their reasoning seemed to be as follows.
Premise: Sound, heat, and other forms of causal influence can be transmitted through seemingly non-porous media, such as water and metal.
Premise: Given that motion sometimes demands the existence of a medium, it stands to reason that it always does, even when that medium cannot be detected.
Conclusion: Light travels through a medium of some kind.
The flaw in this argument is that seemingly non-porous propagators of causal influence, such as water and metal, are decidedly porous; and when they propagate sound, light, heat or any other form of causal influence, it is because their component-parts have empty space to move around in.