Manipulating light electro/magnetically

• motorman
In summary, the conversation discussed the possibility of manipulating light with magnets and the effects of magnetic fields on light. It was mentioned that classical equations of electromagnetism are linear, so magnetic fields have no direct influence on light. However, in a medium, the equations become non-linear and there can be an interaction between light and a magnetic field. It was also mentioned that at high energies, electromagnetic equations become non-linear even in a vacuum. The conversation also touched on the topic of photon-photon interactions and the creation of mass through pair creation. The possibility of manipulating a magnetic field in "free space" and its effects on photons was also discussed. Overall, the conversation generated a lot of interesting discussion and questions about the nature of light and its
motorman
Hi Guys,

Sorry if this is a daft question, but...

if light is a form of electromagnetic radiation (as we're all taught) then is is possible to manipulate it with magnets?

Cheers,
Motorman

Generally the problem is, that light doesn't have mass to manipulate, of course according to Einstein gravity can bend light

Not directly.

But it is possible to modify some materials with magnets (or magnetic fields), such that the material's effect on light is varied according to the magnet's influence.

One simple answer to the OP's question is that the classical equations of electromagnetism are completely linear, so a magnetic field (or an electric field) has no influence on light - the light waves just propagate right through it. In a medium, as Dr Lots-o-watts said, then the equations become non-linear so there can be an interaction between light and a magnetic field.

A good example of light manipulated by magnetic field in a medium is the Faraday Effect.

Also, at REALLY high energies, EM equations become non-linear even in vacuum, but that's quantum electrodynamics already, and way outside of this scope.

When light scatters in our atmosphere doesn't that have something to do with the E and B fields affected by the nitrogen molecules?

Just curious, and with respect to the OP's question...
Is it possible to manipulate a magnetic field in "free space" such that there WOULD be an effect on photons?
That is, pulsation, rotation, etc... of that magnetic field.

Note: What I mean by "free space" in this context is the magnetic field outside of a medium.

Likely the answer is no, just curious.

Similarly, if one had a very fast rotating laser beam going through a very fast counter-rotating magnetic field, would there be any difference?

No.

As K^2 says, with insanely high field of gamma rays, it may be possible to alter properties of vacuum itself, but this has not been verified experimentally to my knowledge.

What is standard is that photons can become mass (which could affect a third-party photon) through pair creation, but even this needs a massive nucleus in the picture, if only to conserve momentum.

What is on the forefront of research is that (extremely high energy density) photon-photon collisions seem to have created mass (again by pair creation). But again, this needed the presence of electrons, acting essentially as a mirror, emitting bremsstrahlung photons in response to the incident beam and colliding with it.

As far as I know, there is no standard, bullet proof, independently verified, experimental evidence that photons can see each other.

Remember that a magnetic field is also nothing but photons, like light (which is also a magnetic field right?

Dr Lots-o'watts said:
Remember that a magnetic field is also nothing but photons, like light (which is also a magnetic field right?

Then why can I bend B field lines with another magnet . Are we saying photons affect other photons .

cragar said:
Then why can I bend B field lines with another magnet . Are we saying photons affect other photons .

You don't "bend B field lines with another magnet" . The result of having two magnetic fields is simply the vector sum of the two fields. They have no impact on each other.

Dr Lots-o'watts said:
As K^2 says, with insanely high field of gamma rays, it may be possible to alter properties of vacuum itself, but this has not been verified experimentally to my knowledge.
And electron-positron creation/annihilation processes don't verify non-linearity of EM field?

K^2 said:
And electron-positron creation/annihilation processes don't verify non-linearity of EM field?

Standard pair creation needs a nucleus, which is mass, to balance momentum.

Pair creation from what seems to be colliding photons only is very recent. And even these experiments need electrons (mass) in the picture:
"Possibility of Prolific Pair Production with High-Power Lasers", Phys. Rev. Lett. 101, 200403 (2008)

What seems to be still missing to experimentally prove a non-linear vacuum is pair production from two independent photons in vacuum, without any help from any mass.

I'm not sure how all this fits in with photons being bosons however.

All,
I hope you have had a good weekend!

Thank you for the many interesting replies. I didn't realize the topic would generate this much discussion.

Karoka, electrons have very little mass from what I remember, but they are highly influenced by an em field, ok they are charged, but if gravity can bend light (I think this is the gravitation lensing effect some astronmers us to look beyond a heavy object) wouldn't this suggest that photons are either:

1) pulled in by a mass towards the centre of the same mass, or;
2) pulled towards a mass as a result of other particles that are 'falling' towards the mass colliding with the photons and altering their path as a result?

Dr Lots-o'watts, altering a material's optical props using magnets is sort of , well, like 'cheating'. I agree to what you're saying tho'.

If a magnetic field (electric or otherwise) is simpley a region of photons of a different kind, then if I had 2 lasers,ie. 2 sources of photons of identical properties, then if I were to place them at an angle where they intersect, shouldn't I expect to see the 2 beams and also see photons break away from the beams in a manner that would fit statistical modelling of collisions?

Or to put another way, the magnetic photons and laser photons are different, agreed, so if I were to use 2 identical lasers an cause an interesection between the 2 beams, then i would expect to see some of the photons to deviated fromt he original path of the 2 parent lasers.

I think it was Rutherford that did something similar with and alpha source and gold leave. He was able to predict mathematically the number of alpha particles that would bounce back off the gold leaf.

Essentially doing so would indicate collision/interactions of sorts.

1. How does electromagnetic manipulation of light work?

Electromagnetic manipulation of light involves using electromagnetic fields to control the behavior of light. This can be achieved through various methods such as changing the refractive index of a material or altering the polarization of light.

2. What are the applications of manipulating light electro/magnetically?

There are many applications for manipulating light electro/magnetically, including telecommunications, data storage, medical imaging, and optical computing. It is also used in technologies such as lasers, fiber optics, and solar cells.

3. Can light be manipulated to travel faster than its normal speed?

No, the speed of light in a vacuum is a fundamental constant and cannot be changed. However, by manipulating the properties of materials, it is possible to slow down or speed up the propagation of light through them.

4. Are there any limitations to manipulating light electro/magnetically?

One limitation is the range of electromagnetic frequencies that can be used for manipulation. Another is the materials used, as not all materials have the necessary properties to interact with light in the desired way. Additionally, certain methods of manipulation may have limited efficiency or precision.

5. How can electromagnetic manipulation of light be used in everyday life?

Electromagnetic manipulation of light has many practical applications in our daily lives, such as in the screens of electronic devices, fiber optic internet connections, and medical imaging technologies. It also plays a crucial role in industries such as telecommunications, transportation, and energy production.

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