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Thread: 'Cloaking device' idea proposed by British scientists.

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    'Cloaking device' idea proposed by British scientists.

    'Cloaking device' idea proposed that could have potential military uses.

    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".

    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.

    Paul.Rincon-INTERNET@bbc.co.uk

    http://news.bbc.co.uk/2/hi/science/nature/4968338.stm

  2. #2
    Military Professional canoe's Avatar
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    Interesting science, but where hundreads of years (at least) from being able to use any of it for practical applications.

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    Isn't this the erroneous and fictitious "Philadelphia Experiment" all over again?

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    Even if it's true, it seems to me that preventing an object from emitting light wouldn't make it invisible. It would just leave a black spot. The problem isn't preventing emission of light, the problem is emitting the proper light, i.e. what you would see if the object wasn't there.
    I enjoy being wrong too much to change my mind.

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    Anyone who doesn't believe in invisibility has never ridden a motorcycle in heavy traffic.
    USS North Dakota

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    Quote Originally Posted by 2DREZQ
    Anyone who doesn't believe in invisibility has never ridden a motorcycle in heavy traffic.
    LOL........OR a German Supercar.

    I had some FREAKING MORON in his SUV just SWERVE(his idea of a lane change i think) into my lane today- into airspace that i was currently occupying- on the phone, didn't bother looking, didnt wave or acknowledge his mistake afterwards.

    I JUST barely stopped and swerved out of the way in time.

    Thank god for a near 1G skid pad rating and the most awesome braking system i have ever experienced in my life....

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    Defense Professional RustyBattleship's Avatar
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    Maybe there's something to this after all. This just appeared in this morning's edition of the Long Beach Press-Telegram. Sort of reminds me of the early 90's when I was the project leader on a Stealth program for the Navy. It was written as a Shipalt and later as an Installation Procedure on a very accessible Sun computer. I hid the texts in various other projects and titled the Shipalt as "Klingon" and the Installation as "Romulan".

    Article Launched: 05/26/2006 12:00:00 AM PDT

    Future of invisibility becoming clear
    By Andrew Bridges, Associated Press

    WASHINGTON — The key to creating a Harry Potter-like invisibility cloak lies in man-made materials unlike any in nature or the Hogwarts School of Witchcraft and Wizardry, researchers say.
    They're laying out a blueprint for turning science fiction into reality. And they say that, in theory, nothing's stopping them from making such a cloak.

    Well, almost nothing: They still need to perfect the manufacture of those exotic materials with an ability to steer light and other forms of electromagnetic radiation around a cloaked object, rendering it as invisible as something tucked into a hole in space.

    "Is it science fiction? Well, it's theory and that already is not science fiction. It's theoretically possible to do all these Harry Potter things, but what's standing in the way is our engineering capabilities," said John Pendry, a physicist at the Imperial College London. Details of the study, which Pendry co-wrote, appear in Thursday's online edition of the journal Science.

    Scientists not involved in the work said it presents a solid case for making invisibility an attainable goal.

    "This is very interesting science and a very interesting idea and it is supported on a great mathematical and physical basis," said Nader Engheta, a professor of electrical and systems engineering at the University of Pennsylvania. Engheta has done his own work on invisibility using novel materials called metamaterials.

    Pendry and his co-authors also propose using metamaterials because they can be tuned to bend electromagnetic radiation radio waves and visible light, for example in any direction.

    A cloak made of those materials, with a structure designed down to the submicroscopic scale, would neither reflect light nor cast a shadow.

    Instead, like a river streaming around a smooth boulder, light and all other forms of electromagnetic radiation would strike the cloak and simply flow around it, continuing on as if it never bumped up against an obstacle. That would give an onlooker the apparent ability to peer right through the cloak, with everything tucked inside concealed from view.

    "Yes, you could actually make someone invisible as long as someone wears a cloak made of this material," said Patanjali Parimi, a Northeastern University physicist and design engineer at Chelton Microwave Corp. in Bolton, Mass. Parimi was not involved in the research.

    Such a cloak does not exist, but early versions that could mask microwaves and other forms of electromagnetic radiation could be as close as 18 months away, Pendry said. He said the study was "an invitation to come and play with these new ideas."

    "We will have a cloak after not too long," he said.

    The Pentagon's Defense Advanced Research Projects Agency supported the research, given the obvious military applications of such stealthy technology.

    While Harry Potter could wear his cloak to skulk around Hogwarts, a real-world version probably would not be something just to be thrown on, Pendry said.

    "To be realistic, it's going to be fairly thick. Cloak is a misnomer. 'Shield' might be more appropriate," he said.

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    Now that sounds more like it. If you can get the light from one side to come out the other side in the same direction, it should work. Sweet.
    I enjoy being wrong too much to change my mind.

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    I would've killed for that cloak in my former profession.

    What am i saying...i'd kill for it in my current profession.

    LOL.

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    Ha! You can be invisible now! Ever stood in line at the DMV right before lunch?
    USS North Dakota

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    innit?

    Well, good to see that I am not the only old sod that appreciates good cartoons!

    Steath can, and I gather, has, been achieved with radioactve coatings. That being purely for radar. The earliest, of course, were WWII exp with transparent aircraft and those with flashlamps over the Atlantic. I'd stll take an armoured airship any day. But That is because I'm probably senile.
    Where's the bloody gin? An army marches on its liver, not its ruddy stomach.

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    Hey Chap, where you been? It seems like you're some sort of migratory internet beast, just comes over the horizon one day, stops and eats, then disappears over the other horizon. Where to? Nobody knows.
    I enjoy being wrong too much to change my mind.

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    Defense Professional RustyBattleship's Avatar
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    Quote Originally Posted by The Chap
    Steath can, and I gather, has, been achieved with radioactve coatings. That being purely for radar. The earliest, of course, were WWII exp with transparent aircraft and those with flashlamps over the Atlantic. I'd stll take an armoured airship any day. But That is because I'm probably senile.
    Stealth (on ships) is not done with "radioactive coatings". I wrote the Shipalt and installation instructions for Stealth of a certain class of warships and know that the material is not radioactive. Otherwise I wouldn't have a sample of it in my desk drawer right now.

    I believe "transparent" aircraft was experimented with in the FIRST World War but the "transparent" material reflected more light than just painted fabric coatings.

    Flash lamps was a form of counter lighting to eliminate the shadows of aircraft. But it was soon discarded as it interfered with the aerodynamics of the planes as well as adding weight and requiring more electrical power. Plus it was difficult for the crew to adjust the intensity of the lights depending upon atmospheric conditions. They worked best on Hazy Days.
    Which is also why Navy ships are painted "Haze Gray" instead of loading up the topsides with variable intensity counter lights and extra generators to power them.

    It was more economical to paint all sides of a ship Haze Gray with the undersides of platforms and major overhangs an off-white to reduce shadowing. Since it was actually the Hornet that launched Doolittle's B-25's and NOT the Shangrilla (as announced by Roosevelt though it didn't exist then) we also found a neat trick by painting the same hull number of ships of the same class to confuse German U-boats just off our East Coast. So they wouldn't know if, say an Escort Destroyer with the number 173, was in Philly, Norfolk or in the Bahamas.
    Last edited by RustyBattleship; 28 May 06, at 23:17.

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    Update

    Researchers say they are rapidly closing in on new types of materials that can throw a cloak of invisibility around objects, fulfilling a fantasy that is as old as ancient myths and as young as "Star Trek" and the Harry Potter novels.

    Unlike those tales of fictional invisibility, the real-life technologies usually have a catch. Nevertheless, limited forms of invisibility might be available to the military sooner than you think.

    "We're very confident that at radar frequencies, these materials can be implemented on a time scale of 18 months or so," John Pendry of Imperial College London told MSNBC.com.

    Pendry's research team is one of two groups whose results were posted Thursday on the journal Science's Web site in advance of print publication. The two papers lay out different theoretical methods for creating invisibility, not only for radar but potentially for optical wavelengths as well.

    Still more teams are out there with ideas to make things invisible — using methods ranging from superlenses that cancel out the light from nearby objects to actual cloaks onto which video can be projected as a moving camouflage. The most exotic technologies involve "metamaterials," blends of polymers and tiny coils or wires that twist the paths of electromagnetic radiation.

    "There are recipes for controlling metamaterials," explained University of Pennsylvania electrical engineer Nader Engheta, who published his own invisibility recipe last year. "Metamaterials are very interesting products."

    The latest research papers describe how metamaterial could be fabricated to bend light in carefully curved paths around the object to be hidden, so that an observer would see right through it — or more accurately, right around it — to the other side.

    "The cloak would act like you've opened up a hole in space," Duke University's David Smith, one of Pendry's co-authors, explained in a news release. "All light or other electromagnetic waves are swept around the area, guided by the metamaterial to emerge on the other side as if they had passed through an empty volume of space."

    Pendry told MSNBC.com that the cloak wouldn't reflect any light, and wouldn't cast a shadow either. "It would be like Peter Pan had lost his shadow," he said, referring to the fictional character who had to have his shadow stitched back on.

    Dreams come true, with a few catches
    Theoretically at least, the metamaterial could work like the helmet of invisibility celebrated in Greek myth, or the cloaking device that hid Romulan and Klingon vessels in the "Star Trek" series, or the invisibility cloak that came in so handy for Harry Potter in J.K. Rowlings' novels.

    "Fiction has predicted the course of science for some time. ... Maybe these Harry Potter novels were ahead of their time," Pendry said, half-jokingly.

    Of course, there are some scientific catches that the tale-tellers never had to worry about:

    * For a total invisibility effect, the waves passing closest to the cloaked object would have to be bent in such a way that they would appear to exceed relativity's light speed limit. Fortunately, there's a loophole in Albert Einstein's rules of the road that allows smooth pulses of light to undergo just such a phase shift.
    * The invisibility effect would work only for a specific range of wavelengths. "There is a price to be paid if you want a thin cloak, in that it operates only over a narrow range of frequencies," Pendry said.
    * The cloak could be made to cover a volume of any shape, but "you can't flap your cloak," Pendry said. Moving the material around would spoil the effect.
    * The tiny structures embedded in the metamaterial would have to be smaller than the wavelength of the electromagnetic rays you wanted to bend. That's a tall order for optical invisibility, because the structures would have to be on the scale of nanometers, or billionths of a meter. It's far easier to create radar invisibility, Pendry said: "You're talking millimeters" — that is, thousandths of a meter.

    The radar application is of great interest to military outfits such as the Defense Advanced Research Projects Agency, which funded Pendry's team. "Radar is a defense technology, and if you wish to hide from it, this sort of cloak would be a good way of doing it," he said. Such a technology would be "far superior to stealth," he said.

    If optical cloaks could be designed, that would be of interest to the military as well. "One obvious thing would be that you could construct a hutch in which you could hide a tank, and the hutch would make it appear as though the tank wasn't there. ... You could also think of weightier things, like submarines or battleships, where you might want to put some of this stuff," Pendry said.

    Civilian applications, too
    There'd be plenty of applications in the civilian world as well, even for rudimentary cloaking devices. For example, you could create receptacles to shield sensitive medical devices from disruption by MRI scanners, or build cloaks to route cellphone signals around obstacles. "You may wish to put a cloak over the refinery that is blocking your view of the bay," Duke University's David Schurig, another of Pendry's co-authors, was quoted as saying.

    While Pendry's team proposed constructing all-over cloaking devices, the other research paper published Thursday describes a simpler method that would involve shaping the metamaterials into cylindrical cloaking devices. The method could also work to block sound waves — like the cone of silence on the "Get Smart" TV show, but not as silly.

    The catch here is that the invisibility effect would work only if you were on the same plane as the hidden object. "You could look on top of it, and look inside the cloak," said the paper's author, Ulf Leonhardt of the University of St. Andrews in Scotland.

    Leonhardt told MSNBC.com that "potentially a mixture of the two schemes will lead to a practical design." He said the paper from Pendry's team gave him some additional ideas to work with.

    "I read it for the first time just last Friday, and I've come up already with something new," he said.

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    Quote Originally Posted by ArmchairGeneral
    Hey Chap, where you been? It seems like you're some sort of migratory internet beast, just comes over the horizon one day, stops and eats, then disappears over the other horizon. Where to? Nobody knows.
    Working! Nice to know someone cares though!
    Where's the bloody gin? An army marches on its liver, not its ruddy stomach.

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