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  1. #1
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    Invisibility Cloak?

    A US-British team of scientists has successfully tested a cloak of invisibility in the laboratory.

    The device mostly hid a small copper cylinder from microwaves in tests at Duke University, North Carolina.

    It works by deflecting the microwaves around the object and restoring them on the other side, as if they had passed through empty space.

    But making an object vanish before a person's eyes is still the stuff of science fiction - for now.

    The cloak consists of 10 fibreglass rings covered with copper elements. This is classed as a "metamaterial" - an artificial composite that can be engineered to produce a desired change in the direction of electromagnetic waves.

    The precise variations in the shape of copper elements patterned on to the ring surfaces determines their properties.

    Like light waves, microwaves bounce off objects making them visible and creating a shadow, though at microwave frequencies the detection has to be made by instruments rather than the naked eye.

    The metamaterial cloak channelled the microwaves around the object like water in a river flowing around a smooth rock. The microwave frequency was about 8GHz - in the same range as radar.

    Gone from view

    When water flows around a rock, the water recombines on the opposite side. Someone looking at the water downstream would never guess it had passed by an obstacle.

    In the experiment, the scientists first measured microwaves travelling across a plane of view with no obstacles. Then they placed a copper cylinder in the same plane and measured the disturbance, or scattering, in the microwaves.


    Scientists were able to watch waves bending around the cloak
    Finally, the researchers placed the invisibility cloak over the copper cylinder. The cloak did not completely iron out the disturbance, but it greatly reduced the microwaves being blocked or deflected.

    "This cloak guides electromagnetic waves around a central region so that any object at call can be placed in that region and will not disturb the electromagnetic fields," explained co-author Dr David Schurig from Duke University.

    "There is reduced reflection from the object, and there is also reduced shadow."

    In principle, the same theoretical blueprint could be used to cloak objects from visible light. But this would require much more intricate and tiny metamaterial structures, which scientists have yet to devise.

    "As an application it's not clear that you're going to get the invisibility that everyone thinks about - as in Harry Potter's cloak, or the Star Trek cloaking device," said co-author David Smith of Duke.

    Professor John Pendry, of Imperial College London, who was an author on the paper, said: "There's a rule about the internal structure of the metamaterial: it has to be smaller than the wavelength of radiation. So for radar waves that's 3cm. You can easily engineer something a few millimetres across.

    "You go up to optical radiation - light - and the wavelength is less than a micron. So your microstructure has to be a few tens of nanometres across. and we're only just learning how to do nanotechnology. It's some way off if ever.

    "Maybe in five or 10 years time you could do this, but not today."

    The researchers say that if an object can be hidden from microwaves, it can be hidden from radar - a possibility that will fascinate the military.

    Cloaking differs from stealth technology, which does not make an aircraft invisible but reduces the cross-section available to radar, making it hard to track.


    http://news.bbc.co.uk/1/hi/sci/tech/6064620.stm


    Hmm.

  2. #2
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    Re: Invisibility Cloak?

    Cloak of invisibility: Fact or fiction?
    Scientists boldly go where only science fiction has been before
    The Associated Press


    Updated: 11:46 a.m. ET Oct 19, 2006
    WASHINGTON - Harry Potter and Captain Kirk would be proud. A team of American and British researchers has made a Cloak of Invisibility.

    Well, OK, it’s not perfect. Yet.

    But it’s a start, and it did a pretty good job of hiding a copper cylinder.

    In this experiment the scientists used microwaves to try and detect the cylinder. Like light and radar waves, microwaves bounce off objects making them visible and creating a shadow, though it has to be detected with instruments.

    If you can hide something from microwaves, you can hide it from radar — a possibility that will fascinate the military.

    Cloaking differs from stealth technology, which doesn’t make an aircraft invisible but reduces the cross-section available to radar, making it hard to track. Cloaking simply passes the radar or other waves around the object as if it weren’t there, like water flowing around a smooth rock in a stream.

    The new work points the way for an improved version that could hide people and objects from visible light.

    Conceptually, the chance of adapting the concept to visible light is good, cloak designer David Schurig said in a telephone interview. But Schurig, a research associate in Duke University’s electrical and computer engineering department, added, “From an engineering point of view it is very challenging.”

    Nonetheless, the cloaking of a cylinder from microwaves comes just five months after Schurig and colleagues published their theory that it should be possible.


    Their first success is reported in a paper in Friday’s issue of the journal Science.

    “We did this work very quickly ... and that led to a cloak that is not optimal,” said co-author David R. Smith, also of Duke. “We know how to make a much better one.”

    Casting a shadow
    The first working cloak was in only two dimensions and did cast a small shadow, Smith acknowledged. The next step is to go for three dimensions and to eliminate any shadow.

    Viewers can see things because objects scatter the light that strikes them, reflecting some of it back to the eye.

    “The cloak reduces both an object’s reflection and its shadow, either of which would enable its detection,” said Smith.

    In effect the device, made of metamaterials — engineered mixtures of metal and circuit board materials, which could include ceramic, Teflon or fiber composite materials — channels the microwaves around the object being hidden.

    When water flows around a rock, Smith explained, the water recombines after it passes the rock and people looking at the water downstream would never know it had passed a rock. The cloaking has to be designed for specific bandwidths of radiation.

    In this case it’s microwaves, and someone measuring them wouldn’t be able to tell they had passed around an object. The hope is to do the same for light waves.

    Looking at a cloaked item, Smith explained: “One would see whatever is behind the cloak. That is, the cloak is, ideally, transparent. Since we do not have a perfect cloak at this point, there is some reflection and some shadow, meaning that the background would still be visible just darkened somewhat.

    The ideal cloak would have nearly negligible reflection and virtually no shadowing, Smith said. “This first experiment has provided a confirmation that the mechanism of cloaking can be realized, we now just need to improve the performance of cloaking structures.”

    Other possibilities
    In addition to hiding things, redirecting electromagnetic waves could prove useful in protecting sensitive electronics from harmful radiation, Smith commented.

    In a very speculative application, he added, “one could imagine ’cloaking’ acoustic waves, so as to shield a region from vibration or seismic activity.”

    Natalia M. Litchinitser, a researcher at the University of Michigan department of electrical engineering and computer science, said this appears to be the “first, to the best of my knowledge, experimental realization of the fascinating idea of cloaking based on metamaterials at microwave frequencies.”

    “Although the invisibility reported in this paper is not perfect, this work provides a proof-of-principle demonstration of the possibility,” said Litchinitser, who was not part of the research team.

    She added that the next breakthrough is likely to be an experimental demonstration of the cloaking in visible light. “These ideas represent a first step toward the development of functional materials for a wide spectrum of civil and military applications.”

    Joining Schurig and Smith in the work were researchers at Imperial College in London and SensorMetrix, a materials and technology company in San Diego, Calif.

    The research was supported by the Intelligence Community Postdoctoral Research Fellowship Program and the United Kingdom Engineering and Physical Sciences Research Council.

    © 2006 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
    URL: http://www.msnbc.msn.com/id/15329396/

  3. #3
    Johnny Angel Guest

    Re: Invisibility Cloak?

    Invisibility Cloaks are common.

    Lexx has one.

    I can't see a damn thing he posts.




    Thank God.

  4. #4
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    Re: Invisibility Cloak?

    R O T F L !!! Johnny you are killing me!! hehe just askin""(()))@#$%%&^&*

  5. #5
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    Re: Invisibility Cloak?

    YES, THEY ARE VERY COMMON...

    I believe Tokyo Scientists were some of the first people to screw around with them....

    invisibility is always fun!

  6. #6
    Lord_jag's Avatar
    Lord_jag is offline I am God because I say I am. Prove me wrong. User Rank
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    Re: Invisibility Cloak?

    Quote Originally Posted by Johnny Angel
    Invisibility Cloaks are common.

    Lexx has one.

    I can't see a damn thing he posts.




    Thank God.
    LOL! :D

    Works for me too!

  7. #7
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    Re: Invisibility Cloak?

    you cant see me and you THANKED GOD!!.....how can i feel any loss!?we're both invisible!?hehe!!...just askin....

  8. #8
    Johnny Angel Guest

    Re: Invisibility Cloak?

    Was that a 'hint of lexx'? Thank God I can't see his tedious loonyposts!

  9. #9
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    Re: Invisibility Cloak?

    Quote Originally Posted by Clown Hunter
    A US-British team of scientists has successfully tested a cloak of invisibility in the laboratory.

    Hmm.
    Cool! :)


  10. #10
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    Re: Invisibility Cloak?

    Maybe they'll sell em soon on those scam sites.

    You'll get a box of nothing but they'll insist it's there.
    Never start the day without some skepticism. My absolutely fave sites:
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