Re: The motion of waves
From: jahn (susysewnshow_at_yahoo.com.au)
Date: 03/27/05
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Date: Sun, 27 Mar 2005 11:39:07 -0500
"bz" <bz+sp@ch100-5.chem.lsu.edu> wrote in message news:Xns962666E02D30CWQAHBGMXSZHVspammote@130.39.198.139...
> "jahn" <susysewnshow@yahoo.com.au> wrote in
> news:3ao023F65gui7U1@individual.net:
>
> >
> > "bz" <bz+sp@ch100-5.chem.lsu.edu> wrote in message
> > news:Xns962655B0EC4B4WQAHBGMXSZHVspammote@130.39.198.139...
> >> "jahn" <susysewnshow@yahoo.com.au> wrote in news:3anq8aF6c9vi6U1
> >> @individual.net:
> >>
> >> > Is their like... some kind of choreographer to keep all of the
> >> > photons in step... or cadence... or whatever you call it?
> >> >
> >> > Sue...
> >> >
> >>
> >> If they are generated 'in step', as in a laser, they stay in step. This
> >> is called phase coherence.
> >
> > I don't think lasers exist naturally do they ? Maybe short ones.
>
> That is a good question. It is possible that the 'jets' of energy and
> matter that are seen coming from collapsing star(s) might be a similar
> phenomina. You have a lot of ions confined by a magnetic field.
>
> >>
> >> If the E field points in the same direction, they are plane polarized.
> > How do atoms "point the same way" ?
> >>
> >> If the EM fields rotate as the photons travel, the photons are
> >> circularly polarized.
> > Circular... you mean like the shape of an atom?
>
> No [what makes you think atoms are circular?]. I mean that the wave/photon
> spins about an axis that represents its direction of travel, like a bullet
> spins around an axis that is parallel to its direction of travel.
>
> Lets look at microwave photons. They can be launched from a 1/2 wave
> dipole. In which case the receiving antenna dipole should be parallel to
> the transmitting antenna dipole. If it is perpendicular, most of the signal
> is lost. If the dipole is aligned vertically, the wave is said to be
> vertically polarized. If the dipole is aligned horizontally, the wave is
> said to be horizontally polarized because the 'E field' oscillates in the
> horizontal plane.
>
> An antenna can be constructed with a 'corkscrew shaped antenna'. This will
> launch a 'circularly polarized' signal. The wave/photons can rotate either
> clockwise or counterclockwise, depending on how the antenna is constructed.
>
> Light can also be plane polarized or circularly polarized. Some chemicals
> line up in patterns that filter out plane polarized light in one plane.
> Polaroid sunglasses use such a material.
>
> Some chemicals allow light that is circularly polarized in one direction to
> pass and filter out the other orientation. Such filters are used in some
> liquid crystal displays. If you put on your polaroid sun glasses and look
> at a liquid crystal display and the image on the display disappears when
> you turn your head at a certain angle, then your display uses plane
> polarized filters. On the other hand, if the tilt of your head does NOT
> make the image go away, your screen uses circular polarization.
>
>
> >>
> >> photons emitted by a hot surface, like a light bulb are neither
> >> coherent nor polarized.
> >
> > Are hot surfaces made of atoms ?
>
> Depends on how hot the surface is. But as long as it is a 'surface' it is
> made of atoms.
>
> If you get matter hot enough, the atoms lose electrons and become ions.
> They are still atoms, just excited ones.
>
> If you get matter even hotter and put it under enough pressure to keep it
> together, the protons and electrons can combine to form neutrons. THEN you
> have no atoms, you just have a mass of very hot neutrons.
>
> > Self deprication will get you every-where ;-)
>
> I have yet to be every-where. :}
>
> There is also the implication that we are ALL ignorant and have something
> worth while to learn from each other.
>
> I am SURE that there are things that YOU know that I do not know.
>
> For example, what you had for breakfast this morning. :)
>
> --
> bz
>
> please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
> infinite set.
>
> bz+sp@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
Well... thank you for the explanation and clarifying a few points.
I think I will stick with Planck's definition that a photon is the
*quantity* emitted or absorbed by an atomic oscillator and
defer to classical models for the details of propagation. That
way I don't have to fret about how an in-flight photon knows
to split four ways to interfer with itself in the VLT interferometer.
http://www.eso.org/outreach/press-rel/pr-2000/phot-26-00.html
http://www.eso.org/projects/vlti/images/vlti-array-smallsize.jpg
Elsewhere in this thread I posted a few links that explain that
approach.
Sue...
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