I've been doing some work with amateur radio recently, and realized that I don't have an adequate detailed, low-level understanding of the basic physics behind exactly how electricity and radio work. My background is in math, chemistry, biology and the physics of "medium sized" objects (orbital dynamics, Newtonian motion, etc). I've looked for books and online references about this, and haven't had any luck. My first point of confusion is about "electron flow." What does that really mean? A single electron doesn't really move from one end of the wire to the other, does it? Doesn't it actually collide with a neighboring electron, causing it to move? That's the DC side. AC is much more confusing. What is really happening with AC at the atomic level? What does it mean for electricity to have a certain frequency? I understand that voltage goes up-and-down, but how? And how can voltage and current get out of phase? Then AC, which has to do with electrons, can be converted into radio waves (photons) at an antenna. I understand how it works with DC and a wire / lightbulb -- the wire heats up, which causes photons to be emitted. But how does it work for RF? What about ground / earth? Why do electons and radio waves need to flow back to ground? Why is earth such an active part of their flow? Also, how do photons (light or RF) really manifest a particular frequency? It seems to always be drawn as big sine waves in the sky. But does a single photon really swing back-and-forth in space across the width of its wavelength?