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Originally Posted by papageno
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Originally Posted by lyndonashmore
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Originally Posted by papageno
At length-scales much larger than the average distance between particles, one sees a density of charges, not single charge carriers.
The density is nearly unifrom, because of the relatively high speed and random motion of the electrons.
An electromagnetic wave with a wavelength comparable to these length-scales, does not interact with one electron at a time, but with a high number of electrons at the same time.
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And what do these electrons do when the wave interacts with them?
I mean how do they move? |
At those length-scales, talking about motions of single electrons is not very helpful, which is why you always find the charge density in your sources. |
But it is helpful to me.
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If you treat the electromagnetic wave as a macroscopic oscillating electric field, the single electron is accelerated.
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As it is accelerated what does it do, What path does this acceleration cause the electron to follow?
A wave is a predictable thing, so we must be able to determine the effects of the acceleration on the electron.
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If you treat it as a collection of photons, you have lots of electron scattering lots of photons.
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So how do we get a density wave - a predictable thing with a calculable frequency if the electrons are all scattering the photons randomly?
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(An electron oscillates in a high-power laser light, because it is scattering a lot of photons: for each photon it recoils, and adding up all the recoils, you end up with an oscillation. This is Feynman's picture in his QED book, as far as I understand.)
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A laser beam travelling from left to right can only cause the electron to recoil from left to right. How does 'adding up all these recoils' cause it to 'oscillate back and forth'?
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But in your "theory" you try to explain the red-shift as a sum of single-electron/single-photon scattering, which is not the same as macroscopic electormagnetic waves and plasma oscillations.
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Macroscopic effects are the net result of microscopic effects.
Cheers,
Lyndon