Notices
Results 1 to 17 of 17

Thread: Cloak of Invisibility

  1. #1 Cloak of Invisibility 
    Forum Freshman Kosta's Avatar
    Join Date
    Oct 2006
    Posts
    86
    Awesome stuff going on here

    http://news.yahoo.com/s/ap/20061019/...f_invisibility
    The idea is to bend light around an object. Since the light does not hit the object and reflect back into the eye, it does not appear to be there.


    Reply With Quote  
     

  2.  
     

  3. #2  
    Guest
    I'll believe it when I don't see it.. :wink:


    Reply With Quote  
     

  4. #3 Re: Cloak of Invisibility 
    New Member
    Join Date
    Oct 2006
    Location
    Delhi
    Posts
    2
    Quote Originally Posted by Kosta
    Awesome stuff going on here

    http://news.yahoo.com/s/ap/20061019/...f_invisibility
    The idea is to bend light around an object. Since the light does not hit the object and reflect back into the eye, it does not appear to be there.
    The Idea proposed is nice one but we need to look onto the other side of the coin.

    If one gets invisible then technically he/she gets blind.

    Don't believe!!

    Think and you will surely get the answer.
    Know Nature Know Thyself
    Reply With Quote  
     

  5. #4  
    Forum Freshman Kosta's Avatar
    Join Date
    Oct 2006
    Posts
    86
    Yea I thought about that.... no one can see you (person being cloaked) because light is bent around you and therefore does not reflect back to their eyes. If you are the one that is cloaked, that means that light does not touch your eyes either and therefore you cannot see past the cloak- like you in a solid bubble.
    Reply With Quote  
     

  6. #5  
    Forum Freshman
    Join Date
    Oct 2006
    Posts
    30
    can light pass through you and you are able to recieve light to you eyes? Can we build a cloaking device where light can pass throught the object and the person wearing it can still see everything?
    Reply With Quote  
     

  7. #6  
    Cooking Something Good MacGyver1968's Avatar
    Join Date
    Aug 2006
    Location
    Dallas, Texas
    Posts
    2,051
    Yeah...what's the point of a cloak of invisiblity if you can't see anything when you sneak into the women's locker room. :-D
    Fixin' shit that ain't broke.
    Reply With Quote  
     

  8. #7  
    Forum Sophomore
    Join Date
    Oct 2006
    Posts
    107
    little tiny *pinprick size* view hole ought to do it Ok so now it's not completley invisible, but a tiny little 2mm wide hole (which is enough for you to see through if you are up close enough to the hole) shouldn't be noticed. After all who takes notice of little dust particles floating around?
    Reply With Quote  
     

  9. #8  
    Guest
    I think it's a hell of a lot easier just to hide behind a Bush, unless it's one of them Dubya types.. 8)

    I can see it now, all you guys go into the cloakroom after the match or whatever to get your coats, are they there? have they been stolen? what peg did I use?......

    Don't fall asleep on the road...

    And in the courthouse "Is this the cloak you wearing on the night the train hit you?"


    Come on get real, it's science fiction, (for the moment at least)....
    Reply With Quote  
     

  10. #9  
    Forum Freshman Kosta's Avatar
    Join Date
    Oct 2006
    Posts
    86
    Check out the article I linked Mega, does not seem to be Sci-fi :P
    Reply With Quote  
     

  11. #10  
    Guest
    Quote Originally Posted by Kosta
    Check out the article I linked Mega, does not seem to be Sci-fi :P
    I have - twice - My initial thought is another 'cold fusion' scare, with some wavelengths I agree it is possible and is one of the principles in operation in your transistor radio (the ferrite rod causing EM waves to concentrate within it) but I'll do some checking, it would help if they put some clues in...


    http://news.bbc.co.uk/2/hi/science/nature/5016068.stm

    http://www.sciam.com/article.cfm?cha...7F0000&ref=rss

    http://www.sciencenews.org/articles/20061021/fob6.asp

    From this last one, I can tell you that your original article is wrong to suggest things can be hidden.
    Reply With Quote  
     

  12. #11  
    Forum Freshman Kosta's Avatar
    Join Date
    Oct 2006
    Posts
    86
    I read the articles that you posted and it seems that only the last one claims that bending light in this fashion is "not feasible." However, the one I posted and the other 2 you provided seem to say otherwise.

    Reply With Quote  
     

  13. #12  
    Suspended
    Join Date
    Sep 2006
    Posts
    320
    great power require great responsibility, what would you do if you were invisible?
    Reply With Quote  
     

  14. #13  
    Guest
    They are talking about a single wavelength of light and not the whole spectrum. If you read the articles closely you will see that the scientists are talking about 'microwaves, a form of light' which the jounalists then interpret as 'light' and leave out the 'single wavelength'.

    You can cloak objects to microwave/radar frequencies simply because they 'couple into' conductive structures. (in the same way you can bend microwaves and radio waves through wires). Visible light does not behave in this fashion, it needs a completely different technology, optics.

    As to the word feasible, let me put it this way, I can jump a gap. The grand canyon is a gap, therefore it is feasible I can jump the grand canyon. A feasiblilty stdudy would quickly show I cannot jump the grand canyon

    From the sciam link:-
    Quote Originally Posted by Scientific American
    Ametamaterial is a composite structure, built of metal rings and wires embedded in fiberglass, that makes light behave in weird ways. Metamaterials can be used, for example, to bend light sharply or to focus it to a higher resolution than is normally possible. More recently, researchers pointed out that the technology should make it possible to construct spheres or cylinders capable of cloaking an object almost perfectly from detection by a single wavelength of light. When light strikes a metamaterial it causes the electrons in the metal pieces to vibrate; these vibrations in turn affect the speed of the light. A metamaterial shell with the right gradient of metal elements should cause light of a particular wavelength to wrap around the shell's interior.
    Now imagine you spread out the colours of the rainbow over table say 10 metres long so you have blue at one end and red at the other, a 'single wavelength of light' would be less than 1cm in width, (infact it would be a line with no width but I'll make it wider to help your case). So now we need 1000 of these devices all in the same place to make something invisible (assuming we can do it at light frequency, which so far we cannot).

    So at present we cannot do it for light only microwaves,
    we can only do it for a finite frequency.
    The materials used for microwave cloaking are not suitable for light.

    SO if you or anyone else goes around saying "we can become invisible" you are deluding yourself.

    Hence my earlier statement:- Come on get real, it's science fiction, (for the moment at least)....
    Reply With Quote  
     

  15. #14  
    Forum Radioactive Isotope MagiMaster's Avatar
    Join Date
    Jul 2006
    Posts
    3,440
    Actually, nothing in optics ever affects just a single wavelength of light. It always has a spectrum. That spectrum may be narrow, but it's never 0 width. As for cloaking in the visible spectrum there are two problems. The visible spectrum may be narrow, but currently, metamaterials' target wavelengths are narrower, so you might can make something invisible to blue light, but not red (at least not yet). Secondly, it's not that visible light behaves differently from microwave light (it doesn't, fundamentally), but that the metamaterials required to affect visible light would require extremely tiny metal structures that are currently difficult and expensive (but not impossible) to produce. Together, this means that it will be a while before this can be applied to an invisibility cloak.
    Reply With Quote  
     

  16. #15  
    Guest
    Quote Originally Posted by MagiMaster
    Actually, nothing in optics ever affects just a single wavelength of light. It always has a spectrum. That spectrum may be narrow, but it's never 0 width. As for cloaking in the visible spectrum there are two problems. The visible spectrum may be narrow, but currently, metamaterials' target wavelengths are narrower, so you might can make something invisible to blue light, but not red (at least not yet). Secondly, it's not that visible light behaves differently from microwave light (it doesn't, fundamentally), but that the metamaterials required to affect visible light would require extremely tiny metal structures that are currently difficult and expensive (but not impossible) to produce. Together, this means that it will be a while before this can be applied to an invisibility cloak.
    Er.. The artcle clearly states that cloaking via the proposed method of opical wavelengths would be of a narrow frequency. My analogy of the table was to try and educate the guy on the difference between a spectrum and a single wavelength. The rest of your post seems broadly in agreement.
    Reply With Quote  
     

  17. #16  
    New Member
    Join Date
    Nov 2006
    Posts
    3
    Reply With Quote  
     

  18. #17  
    Guest
    All that work and here's how you can defeat it!

    The propogation time for the microwaves in air will be faster than through the 'cloaking device' so all you you have to do is produce a 'shifting carrier' whether the object is stationary or in motion using phase detection you will see it. Note they say it is only invisible to instruments at present and not the naked eye....

    It's still as far from star trek 'cloaking' as a kid's tricycle is from being a star ship.
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •