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Old 10-May-2005, 04:05 PM
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Quote:
Originally Posted by lyndonashmore
But they are the same effect Papageno, only in glass the electrons don't recoil because they are fixed in a crystal lattice.
Wrong. You still do not understand.
The electrons in glass are bound to nuclei, which have a positive charge. Nuclei and electron forms atoms, which in turn form the crystal.
Light in glass interacts with the atoms, not with free electrons.
Photons are absorbed by the system (electron+nucleus), not just by the electron.
Without the nucleus, the electron would not have quantized states to jump to, hence it would not be able to absorb a photon.
The description of absorption and emission is always presented in terms of electrons, because it is the electrons that change most noticeably (frame of reference where the nucleus is at rest).

In low-density plasma electrons are not bound to positive charges.
Photons in a plasma interact with single charges, not with atoms.

The two effects are different.


Quote:
Originally Posted by lyndonashmore
In the plasma of space the electrons recoil on absorption and re-emission so energy is lost to the electron.
A photon scattering on an electron in plasma is Compton scattering.
If the direction of the photon is not changed during the scattering event, there is no loss of energy.
The electron alone cannot absorb a photon.
In order for absorption and emission to occur as you envision, you need to have an atom, electrons bound to a positive nucleus.


Quote:
Originally Posted by lyndonashmore
Photon loses energy, frequency reduces wavelength increases. It is redshifted. easy.
Except that energy is lost by the photon only if its direction changes.
In which case you have to explain how we get nice pictures of distant objects, without blurring and with red-shift.
The red-shift is the same in observations performed in different places and at different times.
Also, you would expect a change in the broadening of the spectral lines related to distance.

Quote:
Originally Posted by lyndonashmore
So they are the same effect so they have the same name.
Your "broken record" tactic in all its glory!

Quote:
Originally Posted by lyndonashmore
As for mono poles etc, plasma is neutral there is a positive charge for every negative one.
You misunderstand: an electric charge is a monopole.
The plasma as a whole is neutral: the density of positive charge equals the density of negative charge.
But positively and negatively charged particles are separated from each other, and are not bound.


Quote:
Originally Posted by lyndonashmore
in fact some treatments of plasma divide it into 'virtual atoms' - cubes containing equal quantities of positive and negative charge, and they oscillate!
The charge densities oscillates, not the charge carriers.
You keep confusing the charge with charge carriers, which is why you still do not understand plasma oscillations.

Do you remember my analogy with sound?
Sound waves in air are oscillations in the density of air molecules.
However, single molecules do not oscillate back and forth.
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