Christianity is heading for a full allegorization

[polymath257]

I think its already been mentioned, but photons absolutely do interact with electrons.  

A photon is literally a quanta of electro-magnetic energy.  While it does not interact with static electric or magnetic fields, it interacts with electrons by causing them to accelerate.  If there is no scattering or absorption, this interaction instead delays the photon.

These interactions being the basis of lasers.

We see literally everything we see is because light interacts with electrons.

[brewer]

These interactions being the basis of lasers.

We see literally everything we see is because light interacts with electrons.

There is no excitement in the dark.

[Disagreeable]

Glad I got that right, there were two ways to go with it, either that - or, learn everything there is about the universe..and matter is still fundamentally unexplained.  Either way, it's the suggestion that something or everything is fundamentally unknowable.  Not just unknown or difficult.  Unknowable.

Like the hard problem of chocolate chip cookies.  Everything that a baker knows or can know about them, but, ultimately... chocolate chip cookies are inexplicable.

Have you heard of Mary's Room?

[The Grand Nudger]

Yeah, I think we discussed it in this thread awhile back, or briefly referenced it. Could have been another, they all bleed together at some point.

[Disagreeable]

Sounds like fun.

[Ferrocyanide]

This is not correct. A magnetic field that varies can affect the polarization of light going through it. it doesn't change the direction, but it does change the characteristics of the light.

Well, there is the magneto-optical effect but I think this is done by sending photons through a material and you apply a magnetic field that is parallel to the light beam. This changes the polarization and light speed.

What if you don’t use a material all? Send the beam of light through a vacuum?

This is not correct. The electrons *will* interact with the photons. One way is via Compton scattering. Another is simply from the changing electric field of the light beam.

Is is my understanding that Compton scattering is usually observed with an X-ray beam and some material.
I don’t know if a beam of electron and a beam of photons has ever been used.

close, but not quite right. The photons have to be tuned to the *difference* in energy between two available orbitals. This does NOT require the sample to be a gas. it is also possible for the photon to interact with the electron and ionize the atom.

Yes.

This is correct to a very high degree of accuracy, but not absolutely so. A photon can produce a positron/electron pair, which interacts with another photon before the pair collapses back into a photon. The effect is small, but it exists.

Where did you read about that?

The magnetic moment gives the strength of the dipole part of the magnetic field.

What is a dipole part?

Yes. More precisely, the magnetic field cannot be uniform. It needs to vary with position to produce a force on the neutron.

Why? What is the shape of the magnetic field around a moving neutron?

[polymath257]

This is not correct. A magnetic field that varies can affect the polarization of light going through it. it doesn't change the direction, but it does change the characteristics of the light.

Well, there is the magneto-optical effect but I think this is done by sending photons through a material and you apply a magnetic field that is parallel to the light beam. This changes the polarization and light speed.

What if you don’t use a material all? Send the beam of light through a vacuum?

I would guess the effect is very small in that case. The E&M equations are almost linear, which prevents a strong change.

This is not correct. The electrons *will* interact with the photons. One way is via Compton scattering. Another is simply from the changing electric field of the light beam.

Is is my understanding that Compton scattering is usually observed with an X-ray beam and some material.
I don’t know if a beam of electron and a beam of photons has ever been used.

It also happens in space, with x-rays (which are photons) interacting with free electrons. The version in a material is still the xray interacting with the electron. For xray energies, the electrons around an atom are, essentially, free electrons.

In answer to your question, yes, the interaction of a free electron beam and a photon beam is used  is synchrotron radiation facilities:

https://en.wikipedia.org/wiki/Compton_scattering

"Some synchrotron radiation facilities scatter laser light off the stored electron beam. This Compton backscattering produces high energy photons in the MeV to GeV range[10][11] subsequently used for nuclear physics experiments. "

[/quote]

close, but not quite right. The photons have to be tuned to the *difference* in energy between two available orbitals. This does NOT require the sample to be a gas. it is also possible for the photon to interact with the electron and ionize the atom.

Yes.

This is correct to a very high degree of accuracy, but not absolutely so. A photon can produce a positron/electron pair, which interacts with another photon before the pair collapses back into a photon. The effect is small, but it exists.

Where did you read about that?

[/quote]

This is a *very* weak effect produced because there can be pair production from one of the photons. This leas to a four-vertex Feynman diagram for the photon-photon interaction. This produces a small non-linear effect in a vaccum for photon-photon interactions.

Again, this is a *very* small effect (I basic estimate is one part in a billion) and tends to only be relevant in very intense sources.

The magnetic moment gives the strength of the dipole part of the magnetic field.

What is a dipole part?

I'm not understanding the question. The strength of the dipole part is what we call the magnetic moment. Or are you asking what a dipole is?

Yes. More precisely, the magnetic field cannot be uniform. It needs to vary with position to produce a force on the neutron.

Why? What is the shape of the magnetic field around a moving neutron?

To a very good approximation, it is a dipole (like a magnetic bar). In external magnetic fields, the neutron can develop a quadrupole moment as well.

In general, you cannot change the direction of motion of a dipole by a uniform magnetic field. You nee a field that changes from place to place.

[Jehanne]

Does light accelerate?

[HappySkeptic]

Does light accelerate?

That's not a dumb question.  It highlights how different massless particles are.

The answer is "no".  Light always travels at its natural speed, given the medium it is traveling in.  It always wants to travel at the speed of light in vacuum, but interactions with dielectric materials affects its phase and therefore its actual velocity (slowing it down).

Particles that have no mass cannot slow down or speed up - they can only be delayed by inference in a dielectric (though one can argue that is really a continuous destruction and recreation, and it is this effect that is "apparently" causing the photon to slow - but they are really new photons all the time). 

If I were a photon, I would figuratively "see" my creation and destruction simultaneously, and have no concept of time.

[Ferrocyanide]

Well, there is the magneto-optical effect but I think this is done by sending photons through a material and you apply a magnetic field that is parallel to the light beam. This changes the polarization and light speed.

What if you don’t use a material all? Send the beam of light through a vacuum?

I would guess the effect is very small in that case. The E&M equations are almost linear, which prevents a strong change.

Is is my understanding that Compton scattering is usually observed with an X-ray beam and some material.
I don’t know if a beam of electron and a beam of photons has ever been used.

It also happens in space, with x-rays (which are photons) interacting with free electrons. The version in a material is still the xray interacting with the electron. For xray energies, the electrons around an atom are, essentially, free electrons.

In answer to your question, yes, the interaction of a free electron beam and a photon beam is used  is synchrotron radiation facilities:

https://en.wikipedia.org/wiki/Compton_scattering

"Some synchrotron radiation facilities scatter laser light off the stored electron beam. This Compton backscattering produces high energy photons in the MeV to GeV range[10][11] subsequently used for nuclear physics experiments. "

close, but not quite right. The photons have to be tuned to the *difference* in energy between two available orbitals. This does NOT require the sample to be a gas. it is also possible for the photon to interact with the electron and ionize the atom.

Yes.

This is correct to a very high degree of accuracy, but not absolutely so. A photon can produce a positron/electron pair, which interacts with another photon before the pair collapses back into a photon. The effect is small, but it exists.

Where did you read about that?

This is a *very* weak effect produced because there can be pair production from one of the photons. This leas to a four-vertex Feynman diagram for the photon-photon interaction. This produces a small non-linear effect in a vaccum for photon-photon interactions.

Again, this is a *very* small effect (I basic estimate is one part in a billion) and tends to only be relevant in very intense sources.

What is a dipole part?

I'm not understanding the question. The strength of the dipole part is what we call the magnetic moment. Or are you asking what a dipole is?

Why? What is the shape of the magnetic field around a moving neutron?

To a very good approximation, it is a dipole (like a magnetic bar). In external magnetic fields, the neutron can develop a quadrupole moment as well.

In general, you cannot change the direction of motion of a dipole by a uniform magnetic field. You nee a field that changes from place to place.

I guess you deleted a quote tag and the formatting is messed up. The forum software should not allow an unpaired quote tag.
I think I understand. A neutron has 2 poles, sort of like a bar magnetic.
Aren't electrons and protons dipoles as well?


But the shape of the magnetic field around a beam of electrons/proton is circular and perpendicular. So, it is possible to use a uniform magnetic field to exert a force on a beam of electron/proton.
Source:
http://hyperphysics.phy-astr.gsu.edu/hba...agcur.html


So, perhaps, that is the shape of the magnetic field around each individual electron.
This would also mean that one electron pushes on another electron because of the individual magnetic field and their individual charge. So a beam of eletron always diverges.