# the Ewald–Oseen extinction theorem

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In optics, the Ewald–Oseen extinction theorem, sometimes referred to as just "extinction theorem", is a theorem that underlies the common understanding of scattering (including refraction, reflection, and diffraction).

An important part of optical physics theory is starting with microscopic physics—the behavior of atoms and electrons—and using it to derive the familiar, macroscopic, laws of optics.

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On 11/20/2017 at 1:28 PM, Itoero said:

In optics, the Ewald–Oseen extinction theorem, sometimes referred to as just "extinction theorem", is a theorem that underlies the common understanding of scattering (including refraction, reflection, and diffraction).

An important part of optical physics theory is starting with microscopic physics—the behavior of atoms and electrons—and using it to derive the familiar, macroscopic, laws of optics.

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In optics, the Ewald–Oseen extinction theorem, sometimes referred to as just "extinction theorem", is a theorem that underlies the common understanding of scattering (as well as refraction, reflection, and diffraction).

It clearly indicates that refraction, reflection, and diffraction are distinct from scattering.

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When light traveling in vacuum enters a transparent medium like glass, the light slows down, as described by the index of refraction. Although this fact is famous and familiar, it is actually quite strange and surprising when you think about it microscopically. After all, according to the superposition principle, the light in the glass is a superposition of:

• The original light wave, and
• The light waves emitted by each of the atoms in the glass.

(Remember, light has an electric field that pushes atoms back and forth, which causes the atoms to emit dipole radiation.)

Individually, each of these waves travels at the speed of light in vacuum, not at the (slower) speed of light in glass. Yet when the waves are added up, they surprisingly create only a wave that travels at the slower speed.

The Ewald–Oseen extinction theorem says that the light emitted by the atoms has a component traveling at the speed of light in vacuum, which exactly cancels out ("extinguishes") the original light wave. Additionally, the light emitted by the atoms has a component which looks like a wave traveling at the slower speed of light in glass. Altogether, the only wave in the glass is the slow wave, consistent with what we expect from basic optics.

->When light traveling in vacuum enters a transparent medium like glass. The photons interact with atoms/electrons (depending on the material the glass is made of). The interaction electron/atoms - photons causes the refraction and is called scattering.

Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths due to localized non-uniformities in the medium through which they pas.https://en.wikipedia.org/wiki/Scattering

In glass, the 'glassmolecules'  scatter the photons.

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10 minutes ago, Itoero said:

The interaction electron/atoms - photons causes the refraction and is called scattering.

You may call it scattering, but as far as I can tell no one else does.

You have yet to provide any reference at all that says that the interaction of photons with atoms that causes refraction is called "scattering".

As you are so sure you are correct, it should be trivial to do this. So I'm not sure why you haven't done it yet.

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40 minutes ago, Itoero said:

Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths due to localized non-uniformities in the medium through which they pas.https://en.wikipedia.org/wiki/Scattering

In glass, the 'glassmolecules'  scatter the photons.

It says localized. Which glass molecule causes the refraction? Or put another way, will you get refraction from a single atom or molecule?

And what does this have to do with the Ewald–Oseen extinction theorem?

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23 hours ago, Strange said:

You may call it scattering, but as far as I can tell no one else does.

Many people call it scattering, especially the ones that know of the extinction theorem. Have a look on google.

23 hours ago, Strange said:

You have yet to provide any reference at all that says that the interaction of photons with atoms that causes refraction is called "scattering".

I think It's rather interaction with atomic electrons. and electrons. Rayleigh and compton scattering are both about the interaction of photons with particles.https://en.wikipedia.org/wiki/Compton_scattering   https://en.wikipedia.org/wiki/Rayleigh_scattering

Their is a feyman diagram that shows this. https://commons.wikimedia.org/wiki/File:Compton_Scattering_Feynman_Diagram.png

The fact that scattering implies a change in direction doesn't mean this change in direction is measurable/observable.

23 hours ago, Strange said:

s you are so sure you are correct, it should be trivial to do this. So I'm not sure why you haven't done it yet.

I have done what I could but I knew only about the theorem when the thread got closed and I got another warning point..

23 hours ago, swansont said:

says localized. Which glass molecule causes the refraction? Or put another way, will you get refraction from a single atom or molecule?

Refraction is the change in direction of wave propagation due to a change in its transmission medium. So for example when light enters an ocean, the first watermolecules the light interact with, cause the refraction.

When you take a vacuum as medium then al particles are localized non uniformities.
23 hours ago, swansont said:

And what does this have to do with the Ewald–Oseen extinction theorem?

Most of what I said is a copy-paste from the Wikipediapage about the theorem.

Edited by Itoero

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21 minutes ago, Itoero said:

Many people call it scattering, especially the ones that know of the extinction theorem. Have a look on google.

I have. I can't find anyone who says refraction is called scattering. So perhaps you can provide a link to some of these "many people".

22 minutes ago, Itoero said:

I think It's rather interaction with atomic electrons. and electrons. Rayleigh and compton scattering are both about the interaction of photons with particles.https://en.wikipedia.org/wiki/Compton_scattering   https://en.wikipedia.org/wiki/Rayleigh_scattering

That's not the point.

23 minutes ago, Itoero said:

I have done what I could but I knew only about the theorem when the thread got closed and I got another warning point..

You say you have done what you could, but you have not yet provided a reference where refraction is called scattering. Come on, according to you there are lots of them. Where are they?

24 minutes ago, Itoero said:

Most of what I said is a copy-paste from the Wikipediapage about the theorem.

And the only bit that says "refraction is called scattering" is the bit your DIDN'T copy. So it is still looking a lot like you are the only person who calls refraction scattering. Which is surprising, because your argument is quite convincing! It just appears to be wrong.

But you can easily prove me wrong by providing the evidence to support your claim.

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48 minutes ago, Strange said:

nd the only bit that says "refraction is called scattering" is the bit your DIDN'T copy. So it is still looking a lot like you are the only person who calls refraction scattering. Which is surprising, because your argument is quite convincing! It just appears to be wrong.

I never said scattering=refraction. you talk with your faith, it doesn't matter what I say.

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14 minutes ago, Itoero said:

I never said scattering=refraction. you talk with your faith, it doesn't matter what I say.

I didn't say you did. I said you claimed that refraction is called scattering, which you did:

On 15/02/2018 at 3:14 PM, Itoero said:

The interaction electron/atoms - photons causes the refraction and is called scattering.

1 hour ago, Itoero said:

Many people call it scattering

So please provide a source that supports this. It should be easy as "many people call it scattering".

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On ‎16‎-‎2‎-‎2018 at 5:38 PM, Strange said:

I didn't say you did. I said you claimed that refraction is called scattering, which you did:

So please provide a source that supports this. It should be easy as "many people call it scattering".

I said: The interaction electron/atoms - photons causes the refraction and is called scattering.

---> This means the interaction electron/atoms - photons  is called scattering and this interaction causes refraction.

Many people definitely know it but its not always called scattering. When people say photons/atoms  cause refraction then they acknowledge scattering causes refraction....they just don't call it 'scattering'. People that know of the theorem will call it scattering and people that study optical physics  call it scattering. Scattering implies a wave or particle(s) change in direction due to an interaction. The change in direction is not necessary measurable/observable.

Here is a nice explanation:

"

 Refraction occurs when a large number of dipoles scatter coherently. Each individual dipole scatters light in response to the incident radiation in (almost) all directions, but when you have a large collection of scatterers, each one scattering in many directions, you have to sum the contributions of each one in order to arrive at the total field. Each contribution interferes with every other contribution. When you do this at an abrupt interface, the result is reflection and refraction (and cancellation of the incident light, ala the Ewald-Oseen thm). So the main difference is that scattering generally refers to small scatterers (having a size on the order of the wavelength), and refraction requires a large number of scatterers, and a clean interface."https://physics.stackexchange.com/questions/247342/difference-between-scattering-and-refraction In this discussion it's often acknowledged  it's due to scattering, it's just not called 'scattering'.https://www.physicsforums.com/threads/why-does-light-slow-down-in-a-medium.613481/