Cloaking Devices Possible!

[GrandMasterTerwynn]

Say two mathematicians

'Cloaking device' idea proposed
By Paul Rincon
BBC News science reporter

The work brings science fiction closer to science fact - just a little
The cloaking devices that are used to render spacecraft invisible in Star Trek might just work in reality, two mathematicians have claimed.

They have outlined their concept in a research paper published in one of the UK Royal Society's scientific journals.

Nicolae Nicorovici and Graeme Milton propose that placing certain objects close to a material called a superlens could make them appear to vanish.

It would rely on an effect known as "anomalous localised resonance".

If the speck of dust is close enough it induces a very aggressive response in the cloaking material
Professor Sir John Pendry, Imperial College London

However, the authors have so far only done the maths to verify that the concept could work. Building such a device would undoubtedly pose a significant challenge.

Starting small

Cloaking devices are a form of stealth technology much favoured by Star Trek baddies such as the Romulans and Klingons.

The complex mathematical phenomenon outlined by Milton and Nicorovici closes the gap a little between science fiction and fact.

The phenomenon is analogous to a tuning fork (which rings with a single sound frequency) being placed next to a wine glass. The wine glass will start to ring with the same frequency; it resonates.

The cloaking effect would exploit a resonance with light waves rather than sound waves.

The concept is at such a primitive stage that the scientists talk only at the moment of being able to cloak particles of dust - not spaceships.

In this example, an illuminated speck of dust would scatter light at frequencies that induce a strong, finely tuned resonance in a cloaking material placed very close by.

The resonance effectively cancels out the light bouncing off the speck of dust, rendering the dust particle invisible.

One way to construct a cloaking device is to use a superlens, made of recently discovered materials that force light to behave in unusual ways.

Vanishing point

Professor Sir John Pendry, of Imperial College London, who helped pioneer superlenses, said: "If the speck of dust is close enough it induces a very aggressive response in the cloaking material which essentially acts back on the speck of dust and forces it to stop shining.

"Even though light is hitting the speck of dust, scattering of the light is prevented by the cloak which is in close proximity," he told the BBC News website.

The authors of the paper argue that the cloak needn't just work with a speck of dust, but could also apply to larger objects.

But they admit the cloaking effect works only at certain frequencies of light, so that some objects placed near the cloak might only partially disappear.

"I believe their claims about the speck of dust and a certain class of objects. In the paper, they do give an instance about a particular shape of material they can't cloak. So they can't cloak everything," said Professor Pendry.

"Nevertheless, it's a very neat idea to get this aggressive response from the material to stop tiny things emitting light."

The Imperial College physicist agreed this particular concept had potential military uses: "Providing the specks of dust are within the cloaked area, the effect will happen. A cloak that only fits one particular set of circumstances is very restrictive - you can't redesign the furniture without redesigning the cloak."

Details are published in Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

Um, wow? I think that's the word. Not only does it seem that there is some mathematical basis to those sci-fi cloaking devices, but that the cloaking device won't be double-blind. (At least if I'm understanding the part I emphasized correctly. Light will strike the cloaked object, but it won't be scattered off it.)

[Shroom Man 777]

Damn, and the answer was rather obvious. None of this bending light shit, but cancelling lightwaves!

[Guardsman Bass]

Hmm. So how would you go about building one of these things? I'd imagine even slight invisibility would be nice, and invisibility in the visible or infrared spectrum would be ideal.

[Spetulhu]

A space ship made of glass and shaped like a big lens?

[GrandMasterTerwynn]

Hmm. So how would you go about building one of these things? I'd imagine even slight invisibility would be nice, and invisibility in the visible or infrared spectrum would be ideal.

It seems to involve the use of so-called superlenses, i.e. lenses constructed using exotic materials with 'negative' refraction of light. Perhaps you build one by coating an object in a superlens material, which cancels light reflected from the object's regular hull. So it would be less a cloaking device, and more an advanced system of stealthing. I'm sure someone with a better understanding of the math or physics involved will be along to provide a better answer.

[AMX]

The device only prevents reflection, it doesn't stop the cloaked object from blocking light.

In other words: It makes stuff black, rather than invisible.

[Admiral Valdemar]

The device only prevents reflection, it doesn't stop the cloaked object from blocking light.

In other words: It makes stuff black, rather than invisible.

That's what I thought, in which case, it's not really therm-optic or active camo, but a gap generator a la C&C:RA. We've had other exotic ideas other than the flexible film that emulates an image of the surroundings. There was that idea of a special cold plasma that not only screwed with radar, but could block one specific wavelength entirely.

[Base Delta Zero]

a gap generator a la C&C:RA.

Somehow, I doubt it works by creating a gap in the space/time continuum. Other than that, I have no idea, the article isn't exactly clear, though it says 'invisible' several times...

[Lord Revan]

a gap generator a la C&C:RA.

Somehow, I doubt it works by creating a gap in the space/time continuum. Other than that, I have no idea, the article isn't exactly clear, though it says 'invisible' several times...

what he means is that rather then allowing us to see thru the object (like trek cloak works) it just prevents us from seing the object.

[Covenant]

The device only prevents reflection, it doesn't stop the cloaked object from blocking light.

In other words: It makes stuff black, rather than invisible.

That's what I thought, in which case, it's not really therm-optic or active camo, but a gap generator a la C&C:RA. We've had other exotic ideas other than the flexible film that emulates an image of the surroundings. There was that idea of a special cold plasma that not only screwed with radar, but could block one specific wavelength entirely.

It's not hard to absorb light. But really, it's not a cloak persay. A cloak as we understand it needs not only to not reflect any light, but also to emit light coming from specular sources on the opposite side. Otherwise it'll be like a perfectly nonreflective shape--a big inky shadow. This would work if the intended result is to look black, but you could really just use black matte paint for the same sort of effect. Black is, afterall, the color you get when a substance is coated with a material that re-emits none of the normal specular colors.

To be more clear, you see things not by beams of light shooting from your eyes and 'scanning' a particle, but by light from a specular source slamming into a particle and bouncing back at various wavelengths. If a cloaked object like this was placed on a white table you would see light return from the table, and you'd see the table, except where the cloaked object was. There you would see a perfect black shape, with no refraction effects on the surface. If this object was suspended, you'd see the background except for where the object was, which would be a featureless black 'hole' in your sight.

The real advantage is, then, not the fact you can't see it. You most certainly can! But that it is so featureless that it becomes nearly impossible to tell depth. You don't know if it's a big object far away or a small object up close.

Just a question--if it's forcing it to not to emit light, wouldn't it heat up?