And in #411:
but a wave needs a medium. If you look out at waves in the ocean just what exactly do you see? You probably don't see water molecules going in circles, but that is what is happening.
You seem here to be mixing up different domains of concepts, in trying speak as if radio/light waves were the exact same species as waves on water or through air.
But these are actually 3 different kinds of waves. Radio/light is the one, and the other two, which are in an entirely different realm, are Pressure and Surface waves.
Let me explain.
Surface waves are like those on the ocean. They move very very slowly, compared to all other kinds of waves. Pressure waves, on the other hand, are like those which carry sound through a substance with mass (like water and air). Pressure waves are much much faster then Surface waves for any given medium. It is true and well demonstrated that Pressure and Surface waves do require a medium.
But radio and light (heretofore just 'radio') waves are of a completely different species from pressure/surface waves.
For example, pressure and sound waves are the actual movement of atoms of mass - it is a purely mechano-kinetic process. No electric fields are produced from them, and they are not produced directly from electric fields. And they must always travel inside a medium. (Or at least every experiment so far has concluded that.)
Radio waves, on the other hand, are generated by oscilating electric fields, and radiowaves do themselves carry an electric field as well as a current field. They can be detected either by the voltage they induce upon an antenna or by the magnetic field they induce into an iron bar.
The standard method for measuring the strength of a radio signal at a certain distance from a radio station transmitter is to measure the "Microvolts per meter."
That's why we call radio waves and light "Electro Magnetic Field."
Furthermore, radiowaves have been demonstrated to propagate through what we call empty space -- as a matter of fact, that is where they work the very best.
I would be most helpful to your study and understanding of science if you can begin to think intuitively about these differences.
-Jesse
PS Ethan Clive Osgood: Check out the results from my experiments this weekend involving the wave properties of light!
Indeed very good stuff. I commend your diligence. I like the books in the pictures. Nice touch.
The demonstration on your page reminds me of Lord Kelvin's "drawing room" demonstration concerning the wavelength of light. From time to time Kelvin would gather round some British society and give talks and demonstrations while they smoked cigars or whatever. It's a great talk and when I dig up the book in which it appears, I'll send you the link. Faraday also used to give these sort of demonstrations. Much of this is published in old books and I'm sure you'd enjoy reading it.
I note that you are a fan of J.J. Thomson. Have you read Notes on Recent Researches in Electricity and Magnetism? The first part is out of this world. Thomson forgoes the usual "field" picture of EM and goes back to Faraday lines, because he says that it's simply easier to think in terms of Faraday lines. He develops all the usual EM theory this way, and, on top of it, by means of a remarkable argument, the dependence of the electron inertia on velocity.
What are those fields composed of? In the second part of your statement you seemed to contradict the first part of your statement by implying that the waves "carry" a field.
Could you please elaborate a little?