Photon propagation in a medium

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Re: Photon propagation in a medium

#21  Postby cavarka9 » Nov 28, 2011 3:23 pm

this made me think that because not all light is absorbed, we can hence see through things by x-rays and in the same way there might be other wavelenghts of light by which we can see through opaque objects. Then I remembered something like this has been achieved last year or so.
http://www.sciencedaily.com/releases/20 ... 132052.htm
http://www.newscientist.com/article/dn1 ... glass.html
http://physics.aps.org/articles/v3/22
http://arxiv.org/abs/0910.5436
http://physics.aps.org/featured-article ... 104.100601
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Re: Photon propagation in a medium

#22  Postby twistor59 » Nov 29, 2011 7:39 am

zaybu wrote:
twistor59 wrote:
But, if you read the paragraph carefully:

You could then, in principle, compute a modified propagator - an amplitude for propagation through glass. In this propagator, the photon would have a mass. It would be off-shell.


Are we talking about the same paper, the Zhang paper at http://arxiv.org/PS_cache/arxiv/pdf/110 ... 5783v3.pdf , ???

If we are, I can't find that sentence, "In this propagator, the photon would have a mass." Could you direct me to the page and paragraph? ( I did a search with MS-word, and that sentence is not in that paper.)


No, I'm talking about the paragraph that I wrote. I didn't copy it from a paper. I thought it up all by myself.

zaybu wrote:
As that paper maintains, off-shell is from the controversy that p = ℏk/n (Abraham) OR p = n ℏk (Minkowski). It has nothing to do with the speed of a photon, it doesn't slow down, or its mass, it doesn't acquire any mass.


twistor59 wrote:

small in magnitude for opaque media
large in magnitude for transparent media
have a phase behaviour which is the same as you'd get by giving the photon a mass whilst it was in the medium


Never heard of such explanation and I don't think it's right. It's just based on your Feynman's speculation.


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Re: Photon propagation in a medium

#23  Postby zaybu » Nov 29, 2011 1:30 pm

twistor59 wrote:
zaybu wrote:

Never heard of such explanation and I don't think it's right. It's just based on your Feynman's speculation.


FIFY


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Re: Photon propagation in a medium

#24  Postby twistor59 » Nov 30, 2011 8:26 am

zaybu wrote:
twistor59 wrote:
zaybu wrote:

Never heard of such explanation and I don't think it's right. It's just based on your Feynman's speculation.


FIFY


Feynman would not be proud.


Well, Feynman was a fairly modest person, but I'm sure he would feel just a little bit proud, secretly, that he could now use his models of elementary processes to explain macroscopic phenomena such as refraction.
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Re: Photon propagation in a medium

#25  Postby zaybu » Nov 30, 2011 3:01 pm

twistor59 wrote:
zaybu wrote:
twistor59 wrote:


FIFY


Feynman would not be proud.


Well, Feynman was a fairly modest person, but I'm sure he would feel just a little bit proud, secretly, that he could now use his models of elementary processes to explain macroscopic phenomena such as refraction.


Of course, he would, as the Zhang paper is one of many examples. However, he would not be proud of your speculation. (Photon slowing down, acquiring mass, :yuk: :confused: :ill: :scratch: :shifty: :shock: :facepalm: :banghead: :dizzy: :sick: :wall: )
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Re: Photon propagation in a medium

#26  Postby twistor59 » Dec 01, 2011 8:17 am

zaybu wrote:
twistor59 wrote:
zaybu wrote:

Feynman would not be proud.


Well, Feynman was a fairly modest person, but I'm sure he would feel just a little bit proud, secretly, that he could now use his models of elementary processes to explain macroscopic phenomena such as refraction.


Of course, he would, as the Zhang paper is one of many examples. However, he would not be proud of your speculation. (Photon slowing down, acquiring mass, :yuk: :confused: :ill: :scratch: :shifty: :shock: :facepalm: :banghead: :dizzy: :sick: :wall: )


You seem to be having difficulty understanding the terminology and concepts. I'll repeat my entire paragraph just so that the correct context remains:

It is an effective propagator designed to compute the amplitude PhotonIntoMedium -> PhotonOutOfMedium

As strict Copenhagenists, the nature and behaviour of the photon while in the medium, we can't determine, all we can do is add up all the possibilities according to the rules. This will result in a propagation amplitude which will be:

small in magnitude for opaque media
large in magnitude for transparent media
have a phase behaviour which is the same as you'd get by giving the photon a mass whilst it was in the medium


Do you not understand the highlighted phrases ?
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Re: Photon propagation in a medium

#27  Postby zaybu » Dec 01, 2011 11:29 pm

twistor59 wrote:
zaybu wrote:
twistor59 wrote:

Well, Feynman was a fairly modest person, but I'm sure he would feel just a little bit proud, secretly, that he could now use his models of elementary processes to explain macroscopic phenomena such as refraction.


Of course, he would, as the Zhang paper is one of many examples. However, he would not be proud of your speculation. (Photon slowing down, acquiring mass, :yuk: :confused: :ill: :scratch: :shifty: :shock: :facepalm: :banghead: :dizzy: :sick: :wall: )


You seem to be having difficulty understanding the terminology and concepts. I'll repeat my entire paragraph just so that the correct context remains:

It is an effective propagator designed to compute the amplitude PhotonIntoMedium -> PhotonOutOfMedium

As strict Copenhagenists, the nature and behaviour of the photon while in the medium, we can't determine, all we can do is add up all the possibilities according to the rules. This will result in a propagation amplitude which will be:

small in magnitude for opaque media
large in magnitude for transparent media
have a phase behaviour which is the same as you'd get by giving the photon a mass whilst it was in the medium


Do you not understand the highlighted phrases ?


Yes, and in no way does it support your claim.

BTW, your article in the physicsforum says,


On the other hand, if a photon has an energy beyond the phonon spectrum, then while it can still cause a disturbance of the lattice ions, the solid cannot sustain this vibration, because the phonon mode isn't available. This is similar to trying to oscillate something at a different frequency than the resonance frequency. So the lattice does not absorb this photon and it is re-emitted but with a very slight delay. This, naively, is the origin of the apparent slowdown of the light speed in the material. The emitted photon may encounter other lattice ions as it makes its way through the material and this accumulate the delay.


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Re: Photon propagation in a medium

#28  Postby twistor59 » Dec 02, 2011 8:11 am

zaybu wrote:
twistor59 wrote:

You seem to be having difficulty understanding the terminology and concepts. I'll repeat my entire paragraph just so that the correct context remains:

It is an effective propagator designed to compute the amplitude PhotonIntoMedium -> PhotonOutOfMedium

As strict Copenhagenists, the nature and behaviour of the photon while in the medium, we can't determine, all we can do is add up all the possibilities according to the rules. This will result in a propagation amplitude which will be:

small in magnitude for opaque media
large in magnitude for transparent media
have a phase behaviour which is the same as you'd get by giving the photon a mass whilst it was in the medium


Do you not understand the highlighted phrases ?


Yes, and in no way does it support your claim.



I'm just not understanding what you're not getting.
Could you state, in your own words, what you think it is that I'm claiming ?
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Re: Photon propagation in a medium

#29  Postby newolder » Dec 05, 2011 12:28 pm

iz this revelant? :ask: control electron flow (current) wif polarized photons... if not, itz still neat. :thumbup:
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