If wave energy created by a stone thrown into a pond uses water as the medium to move and sound uses air as the medium then surely EM waves must be moving in an unknown medium Isn't this logical?

Answer 1

Yes.

Aristotle concluded that if you drop 2 weights from a height at the same time, one being twice the weight of the other, the heavier weight would hit the ground in half the time taken by the lighter one. This too is logical, and clearly in error.

Another answerWhy, yes. Yes, it is. Perfectly so.

And in the 19th century, investigators were using the aether or luminiferous aether as a designator for the medium through which light moved. Light is, of course, electromagnetic radiation. But let's back up just a touch to see where the idea of the aether came from. And, let's see.... How far back in time do we have to go for that? Ah, yes. Aristotle. You remember him. Earth, air, water, fire. And aether. The aether was the stuff that filled up the space above the sky, above clouds and air. Way up there.

So in "modern" times (the 1800's), science was looking at the aether (now called luminiferous aether) as the conducting medium for light. Water and air were both fluids, and they were a medium for water waves and sound respectively, so why not have something for light? After all, light couldn't travel through empty space (a vacuum) now, could it. (A statement, because that was a fact. That was the thinking back then. Fast forward to the 21st centruy. We have actually known for a long time that electromagnetic waves don't need a medium to travel in and can move perfectly well through a complete vacuum.)

More InformationOne of the most famous experiements ever was done by Michelson and Morley in the late 1800's. [See link below.] They thought that their well considered and designed experiement would start to explain the nature of the "luminiferous aether". Instead, it became the first powerful evidence refuting the existence of the aether. Interestingly, Morley doubted their results and continued to experiment with other researchers in the hope of uncovering the aether. More and more sophisticated methods and technology were developed, and no one has yet uncovered any evidence in support of the aether.

Remember too, that to call electromagnetic energy "waves" and to leave it at that is clearly wrong. One of the mysterious things about EM is that it behaves in many ways like a particle, and in many ways like a wave. So, although photons have zero rest mass (which by itself is mysterious enough), they do behave like particles and this may account in part for light's ability to propagate through vacuum. The particle nature of light is probably best understood within the realm of Quantum theory and mechanics.

AnswerSound travels through a medium according to classical physics, which is what most people are familiar with. With quantum physics, string theory etc it's hard to say what matter even is, let alone what's a medium and what isn't.

These are just attempts by our ill-equipped intellects to make stepping stones towards understanding something through an extended collective effort that is impossible to understand or percieve even though it is all around us, it is us.

Since this is perhaps also a metaphysical question, a little poetry from the Tao Te Ching (Tao te ching means both "the all-that-is (universe, ultimate reality) and "the way/path":

"Look for it, and it can't be seen.

Listen for it, and it can't be heard.

Grasp for it, and it can't be caught.

These three cannot be further described,

so we treat them as The One.

Its highest is not bright.

Its depths are not dark.

Unending, unnameable, it returns to nothingness.

Formless forms, and imageless images,

subtle, beyond all understanding.

Approach it and you will not see a beginning;

follow it and there will be no end."

"The Tao that can be described

is not the eternal Tao.

The name that can be spoken

is not the eternal Name.

The nameless is the boundary of Heaven and Earth.

The named is the mother of creation. "

"The Tao is like an empty container:

it can never be emptied and can never be filled.

Infinitely deep, it is the source of all things.

It dulls the sharp, unties the knotted,

shades the lighted, and unites all of creation with dust.

It is hidden but always present.

I don't know who gave birth to it.

It is older than the concept of God."