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Sound is nothing more than compressions and decompressions of air.? Look at a speaker and?
?it is a serious mistake to use the above "speaker example" to illustrate how sound waves travelled because the above eg. has nothing to do with sound waves,

What is that comming from the speaker, prop wash. Of course it's sound. The pebble in the water example is used because it is very
visible. Sometimes speakers emit low frequency sound and that can
be seen AND heard.

it simply decode the the signal from the microphone

It's not so much a? decoding, although if you used that
concept the microphone encodes the sound and the speaker
decodes the signal back into sound. However, microphones
and speakers are transducers, they convert sound, i.e.
acoustics, to electrical voltage so that the input circuit can
amplify it. The speaker then converts the amplified elecrical
signal back into acoustic sound.
?I personally think that electro-magnetism is a force, therefore electromagnetic waves = electromagnetic force. and force can travel thru vacumn, thats how our rockets flies to the moon.

What is a force. There are lots of them, electrical force, electromotive
force, gravity, magnetic force.? Waves do not consist of particles traveling through space, but of changes in the medium which in such a
way that it seems like particles are traveling. Of course that seem to
break down when we get to a vacuum because em waves will travel in a
vacuum. There is a great dialog among physists about waves vs. particle
motion. I don't pretend to understand it at their level, I just know it
because of an interesting PBS special a few years ago.

Jim