How Does Light Propagate?

In the 19th century a number of physicists worked hard to understand the mechanism of the propagation of electromagnetic radiation. They failed utterly. I claim that the physicists of the 20th century did no better. I am allowed to speculate on this mechanism. I said earlier that to ignore the underlying electric fields of charged particles and to focus only on the net fields is an error, an error that goes back to Michael Faraday and James Clerk Maxwell among others.

We start with the choice that the electric fields of charged particles are real, are of infinite extent, and overlay each other everywhere. Already we almost have a medium. In the case when one charged particle moves with respect to the others (a rather artificial special case), necessarily its electric field must move with it. I claim that it does not move instantaneously. Rather, the adjustment of the electric field takes place in a measured fashion as it moves with respect to the others. With each increment of motion of the particle, the adjustment of the electric field is "telegraphed" outward from the particle at a characteristic speed, known to us as the speed of light. Why? To put it in homey language, the electric field of a charged particle "knows" it wants to be symmetrically disposed about the particle, and in moving over it encounters a miniscule bit of "resistance" as it slides through the overlaid electric fields of all the other particles. Hence, there's a bit of delay as the adjustment takes place. That's the medium for you. There's no elastic solid-like monolithic aether. There's no sea of ultra-mundane particles zipping around. The medium consists only of what we always knew was there if we had only chosen to look at it clearly. Of course, there's plenty of details to figure out. And of course, we don't know exactly what these electric fields are, nor do we know exactly how they work, but its a start.

Electric Fields Are Real

O.K. Let's say we have a charged particle or charged object at some location. At some distance away, in principle, we can place a small test charge, release it, and observe it's acceleration. From that we can know the magnitude and direction of the electric field strength. From my point of view there are two options here. On the one hand we might say that by pure magic, i.e., with nothing physically present at the location of the test charge, the charged particle or charged object attracts or repulses the test charge. On the other hand we might say that 'something' that we call an electric field is physically present at the location of the test charge, in fact, is physically present everywhere in space. It's still magic, but only because we don't know exactly what it is or exactly how it does what it does. Personally I prefer the second option. In other words, the electric field of a charge particle or charged object is something real, physically present.

Following that line it seems to me that the physical presence of that electric field is completely independent of whether there are other charges with their electric fields in the vicinity. In other words electric fields of charges 'overlay' each other at any location. One can determine the net electric field at that location, but whatever the net electric field turns out to be, it in no way obviates the physical presence of the underlying primary electric fields.

Continuing that line, since each charged particle has an electric field of infinite extent, it follows that right here in this room where I'm sitting writing the primary electric fields of every single charged particle in the universe is physically present. Can anyone make an argument that this is not the case? You may say, o.k., but so what? Who cares? I'll come back to that.

What About Electric Fields?

In school we learned about electric fields. Charged particles have electric fields. They are infinite in extent, and the electric field strength falls off as the inverse square of distance away from the particle. We learned that one can calculate the net electric field at some location by doing a vector addition of the electric fields of all the charged particles under consideration. We also learned an operational definition of the net electric field at some location. One takes a small test charge at the point in question and releases it. The instantaneous acceleration of the test charge determines the strength and direction of the net electric field at that location.

Later we are taught that the net electric and magnetic fields are all that matter, that one can have a complete description of electromagnetic phenomena knowing the net fields. In fact, Maxwell's Equations provides just such a supposedly complete theory. We are also told that the underlying fields can't matter since we cannot measure them in any case. Now I would like to take issue with that. Little by little I would like to make the case that the underlying fields do matter and that a deeper understanding of electromagnetism is impossible without including them. The complete failure of 19th-century physicists to arrive at an understanding of the medium of light propagation is a good example.