Can Magnets Bend Light for Invisibility Cloaks?

[Born2bwire]

Darn. There goes my invisibility cloak lol. The only other option to bend light around myself would be gravity, but I am sure a suit like that would have some major consequencies(everything flying at it lol). Oh well, thanks for the reply :)

Oh, we already know how to do that... theoretically.. and not very practically... and in all essence we can currently only do this at a single frequency... but the problem is solved!

I can't remember the name of the articles, I think there was at least a general one published in Nature, but http://news.bbc.co.uk/2/hi/science/nature/6064620.stm . They do have a theoretical design for a complete 3D cloak, but really you would have to be enclosed in a hamster ball of sorts.

 

[Vanadium 50]

One effect a magnet has on a photon is rotate it's plane of polarization (must be very strong). Maybe u could use that for your invisibility cloak.

I've been reading some Maxwell lately and found that magnetic field has power to rotate the plane of polarisation...
greetings Janm

I think you're confusing a medium in a magnetic field rotating the plane of polarization and the magnetic field itself rotating the plane of polarization.

 

[Vanadium 50]

We have not yet seen any photon-photon interaction, which is one of the higher-order interactions predicted within QED.

Actually, we have. Melissinos and collaborators did this at SLAC (E-144) in the late 90's. They took GeV-scale photons from the beam stop and a laser, and observed upscattered photons. This is not a simple experiment: not only is it difficult getting enough photons in one place, once you do that, it's difficult to put detectors there without them getting fried.

But this is a digression. A magnetic field does not bend light. Full stop. The closest one could get, even in theory, would be for an ultra-intense magnetic field to scatter light (just as light can be scattered by the intense electric field surrounding an electron). I would challenge the folks here who are trying to defend this position to write down a calculation that shows how much this supposed deflection is.

Gravity is a red herring: light is gravitationally deflected by a magnet by the exact same amount that it would be deflected by an unmagnetized chunk of iron with the same mass.

 

[elect_eng]

One effect a magnet has on a photon is rotate it's plane of polarization (must be very strong). Maybe u could use that for your invisibility cloak.

That is a very good comment. There are practical devices called "optical isolators" and "optical circulators" that affect light differently based on whether the light is going forward or backward. These are common in the optical fiber industry. These devices are very strange since usually light rays follow the same path whether going forward or backward. (reflection, refraction, polarization rotation etc)

The principle used is called the Faraday Effect and is induced by magnets in a strongly birefringent crystal. The strong magnets induce a change in the polarization of light and then the light interacts with optical polarizers. The interesting and amazing thing is that even though this is a polarization effect, people have been clever enough to make devices that are polarization independent.

Still, I don't think this effect can make one invisible. Or, at least the encasement of magnets and crystals would give away your position.

 

[jtbell]

Maxwell talks about through a Medium.

The internal magnetic dipoles of the medium are an essential component of the effect. The applied magnetic field and the electromagnetic wave both interact with those dipoles, and it is these interactions that produce the change in the plane of polarization of the wave. The applied field and the wave do not interact directly with each other.

The principle used is called the Faraday Effect and is induced by magnets in a strongly birefringent crystal.

Right, not just any old medium will do, it has to have special properties.

 

[ImAnEngineer]

If you want an invisibility cloak, what we need is a flexible high resolution screen and a lot of sensors. The image that is displayed is measured by the sensors on the other side of the cloak. This would be hard to realize as there are no flexible screens yet (although I've heard they're working on it), but it sounds like cool sci-fi :P .

 

[Born2bwire]

If you want an invisibility cloak, what we need is a flexible high resolution screen and a lot of sensors. The image that is displayed is measured by the sensors on the other side of the cloak. This would be hard to realize as there are no flexible screens yet (although I've heard they're working on it), but it sounds like cool sci-fi :P .

Except that setup still casts a shadow and will reflect and diffract electromagnetic waves. The crude solutions they have come up with using metamaterials are true invisibility cloaks.