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Thread: Invisibility - can it be complete?

  1. #1 Invisibility - can it be complete? 
    Forum Freshman toxicpie's Avatar
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    I saw many movies where you can be completely invisible, but after thinking about it I think it is a little more complicated than that.

    Okay, let's say we can warp light around a certain object, so that it becomes invisible. But we can see things because light bounces off them and into our eyes (I am not very sure of this, so correct me if I am wrong). So then, if we look at the invisible object, what would we see? Blackness? Weird blurry stuff? or would we be able to see right through it?


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  3. #2  
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    You can bend the light round the person, but it is very hard, but yes it is possible.


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    You would see the same kind of effect we see in Gravitational Lensing on light from distant galaxies. See the following image:

    http://en.wikipedia.org/wiki/Image:G..._lens-full.jpg
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  5. #4 Re: Invisibility - can it be complete? 
    Forum Professor sunshinewarrior's Avatar
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    Quote Originally Posted by toxicpie
    I saw many movies where you can be completely invisible, but after thinking about it I think it is a little more complicated than that.

    Okay, let's say we can warp light around a certain object, so that it becomes invisible. But we can see things because light bounces off them and into our eyes (I am not very sure of this, so correct me if I am wrong). So then, if we look at the invisible object, what would we see? Blackness? Weird blurry stuff? or would we be able to see right through it?
    In theory, you should see 'right through it'.

    Bear in mind, though, that this has not necessarily been well thought through (in films and books):

    1. If something/someone is entirely invisible, by definition there is no interaction between that person and visible light.

    2. Therefore, by definition that person perceives no visible light.

    3. Therefore an invisible person would perforce be blind.

    Doesn't sound like much of a super-power now, does it?
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  6. #5  
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    In his novel The Invisible Man, H.G. Wells suggests manipulating the refractive index of a human body and making it the same as that of air:

    http://en.wikisource.org/wiki/The_In...Man/Chapter_19

    Just one of those theories that suffer from the flaws mentioned by SunshineWarrior.
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  7. #6 Re: Invisibility - can it be complete? 
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    Quote Originally Posted by sunshinewarrior
    Quote Originally Posted by toxicpie
    I saw many movies where you can be completely invisible, but after thinking about it I think it is a little more complicated than that.

    Okay, let's say we can warp light around a certain object, so that it becomes invisible. But we can see things because light bounces off them and into our eyes (I am not very sure of this, so correct me if I am wrong). So then, if we look at the invisible object, what would we see? Blackness? Weird blurry stuff? or would we be able to see right through it?
    In theory, you should see 'right through it'.

    Bear in mind, though, that this has not necessarily been well thought through (in films and books):

    1. If something/someone is entirely invisible, by definition there is no interaction between that person and visible light.

    2. Therefore, by definition that person perceives no visible light.

    3. Therefore an invisible person would perforce be blind.

    Doesn't sound like much of a super-power now, does it?
    Isn't that why the Predators on AVP has there special helmet, to absorb the infra red or something and create am image of heat. That would work would it not?
    ~Edd
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    You could make a suite composed of LCD pixels and CMOS censors perfectly bound together so that the CMOS censors would send the signal of what they are seeing to the LCD pixels on the corresponding opposite side. This would make you near invisible at 7m and is possible with our current technology.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

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    Use your computing strength for science!
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    By the way....the junk wiring in my house finally gave out, so I am without internet right now. I cannot access this computer all the time....but I will try to contingently post in the next few days if this is not fixed soon.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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  10. #9 Re: Invisibility - can it be complete? 
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    Quote Originally Posted by sunshinewarrior
    Quote Originally Posted by toxicpie
    I saw many movies where you can be completely invisible, but after thinking about it I think it is a little more complicated than that.

    Okay, let's say we can warp light around a certain object, so that it becomes invisible. But we can see things because light bounces off them and into our eyes (I am not very sure of this, so correct me if I am wrong). So then, if we look at the invisible object, what would we see? Blackness? Weird blurry stuff? or would we be able to see right through it?
    In theory, you should see 'right through it'.

    Bear in mind, though, that this has not necessarily been well thought through (in films and books):

    1. If something/someone is entirely invisible, by definition there is no interaction between that person and visible light.

    2. Therefore, by definition that person perceives no visible light.

    3. Therefore an invisible person would perforce be blind.

    Doesn't sound like much of a super-power now, does it?
    Oh yeah, I knew about this one, that stinks really. So let's say your invisible, is there anyway for you to know where you're going?
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  11. #10  
    Forum Freshman toxicpie's Avatar
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    I am sort of confused.
    So if we bend the light around an object, when we look at it we would see weird things? That's according to Frenchi's link, but that's sort hard to understand for me....
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  12. #11  
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    If the invisible person is standing dead still then the light would in effect bend round him and then reflect off objects and bend back round, so it may looks slightly odd but would definitely if the object or person was moving. I'm not to sure though as i havn't looked out how light would be effected by bending it in a long while.

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  13. #12  
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    Quote Originally Posted by toxicpie
    So if we bend the light around an object, when we look at it we would see weird things?
    If you bent light around the object, you would see what is directly behind him with a large amount of distortion in the middle that lessens as you look further from the center of the distortion. So if the person being camouflaged was standing in front of a pole, you would see the pole blown out to the sides like you were staring at it with a magnifying glass, making it look much wider than it is. Everything would be stretched outwards from the center, with the most stretching being done in the center of the distortion and lessening in severity towards the edges.
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  14. #13  
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    Quote Originally Posted by toxicpie
    I am sort of confused.
    So if we bend the light around an object, when we look at it we would see weird things? That's according to Frenchi's link, but that's sort hard to understand for me....
    just bend the visible light part of the spectrum.
    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
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  15. #14  
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    Quote Originally Posted by Cold Fusion
    You could make a suite composed of LCD pixels and CMOS censors perfectly bound together so that the CMOS censors would send the signal of what they are seeing to the LCD pixels on the corresponding opposite side. This would make you near invisible at 7m and is possible with our current technology.
    How do you locate the direction with which the light hits the CMOS censors? If you can't do that it on't work. :-D
    373 13231-mbm-13231 373
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  16. #15  
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    Play the game Metal Gear Solid, the optic camoflauge on that is very visible, with about a 30% distortion error.
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  17. #16  
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    Total invisibility can't be achieved with today's current technology and thinking. Well, as far as I believe. I agree with the above post about it.

    1. If something/someone is entirely invisible, by definition there is no interaction between that person and visible light.

    2. Therefore, by definition that person perceives no visible light.

    3. Therefore an invisible person would perforce be blind.
    This makes sense to me, but invisibility for us is absence of interaction with white light. This doesn't include other light waves like infrared (which is what was used in the AvP movie to detect them).

    By what I believe is available in today's fields, semi-invisibility may be a possibility. We have glasses which, when worn we don't see the actual glass (unless it's marred, dirty or has stuff on it) but it does have a shadow it casts because it does block light rays partially while letting in a sufficient amount that we can see cleanly and clearly though. The same applies towards glass.

    If we were to utilize this somehow, not sure how, I think we may be able to make semi-invisibility possible.

    By using a few prisms to bend light waves around, we can make directional invisibility when viewed from a certain direction. :? :?
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