h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

see post 17!


How does this explain that photons are emitted when photons rearrange the sea of electrons? And why do the emitted photons come oput at the angle they do and the point they do?

If we are dealing with a sea of electrons then an incoming wave at point A could result in an outgoing wave at point C. In a direction completely other than that equal and opposite to the incoming.

Surely, if the outgoing photon is emitted from the same point that the incoming one impacted then the effect must be a localised one?

Goodness me. I don't know but I'll have a think about it.

Alex.

Part of the problem here is that you're using the language of "photons", when in this instance, the problem is more easily solved by just thinking of the classical electromagnetic wave. If, when you ignore photons, is the answer understandable? If not, then I can work to improve it.

I don't know how to describe this in terms of photons and absorption, etc. I could look it up - but in my experience, this is a case where it gets incredibly complicated to treat the situation in terms of photons, and not just classical electromagnetic waves.

Also, even when we talk about photons. Remember, photons have polarization - the same polarization as their classical EM wave equivalents. *In general* (and very rigorously) a photon that is polarized in the x-y plane will not be able to excite a transition that occurs in one of the other planes (e.g. y-z, x-z planes).

OK, point taken, I've never understood particle/wave duality and usually just ignore the wave side since it seems to be less useful than the particle view. Only here it isn't ho hum!

I think I may have it...let me know.

So a wave approaches the surface of this sea of electrons. We can think of a classic sine wave travelling throuhgh the old space time thingy.
Where it interacts with the electron sea (I am getting to like that phrase, very poetic!) it has an effect on the electrons it encounters, with an obvious knock on effect to the electrons that are near that electron etc. Presumably diminishing like some form of ripple in a fluid. I'm imagining the troughs of the sine wave pushing the electrons away in a pulse as they pass, thus setting up the frequenecy of 'pushes' required to regenerate the wave as the outgoing light.

However, the electrons and forces between them push back I assume? Resulting in a wave being generated at the point of impact of the incoming wave. Presumably with complicated stuff about angles and so forth.

That's pretty much it!

The term "electron sea" is surprisingly accurate. The electrons in the metal actually do have several properties that are the same as liquids.