Invisibility.

Discussion in 'Free Thoughts' started by TheFrogger, Dec 18, 2018.

  1. TheFrogger Valued Senior Member

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    Hi there.

    Just a question. Do you think an invisible person would make something disappear (invisible) simply by picking the object up, like a parallel universe (defying gravity) or would the object appear to float? This raises all sorts of theoretical questions. Would clothes be seen on an invisible person? What happens in the rain? Any answers?
     
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  3. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    Since you are making up the invisible person - you can choose to make up what would happen.
    It does?
    Again, since this is your made up scenario, it is your choice to make up whatever you want.
    Things get wet.
    See above.
     
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  5. TheFrogger Valued Senior Member

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    How am I inventing it? Air is invisible. Is that fictional? I'm behind you (or a wall) and you cannot see me. Am I creating that?

    The Japanese have invented a suit with flexible screens on the front and cameras on the rear. The screens show what the camera is filming (what's behind the person.) The effect is invisibility.
     
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  7. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    people can't become invisible in real life.
    Air is invisible and that is not fictional. People are not air.
    If your scenario is that a person hiding is 'invisible' then there cloths and anything they are holding would also be 'invisible'.
    Not really...
     
  8. TheFrogger Valued Senior Member

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    Yes really.
     
  9. sideshowbob Sorry, wrong number. Valued Senior Member

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    That's an illusion. It's the equivalent of playing peek-a-boo with a baby.
     
  10. TheFrogger Valued Senior Member

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    What, covering your own eyes..?
     
  11. Write4U Valued Senior Member

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    We have demonstrated that invisibility can be achieved by bending light around the object.
    This configuretion makes the object invisible but allows for viewing what is behind the object giving an illusion of total transparency. NOVA had some excellent series presentations on "How to make Stuff (smarter, stronger, smaller, etc). Invisibility is one of the subjects covered. All of them are entertaining and really informative on the latest technologies.
    Start at 50:00 for the invisibily subject.


    I just had an flash: a lifesize unidirectoal fibre optic enclosure which wraps around the object redirecting light around and back to the original trajectory.

    One of the problems with invisibility cloaks is that the wearer also cannot see outside the cloak. However, with a bundled fiber optic system you can add fibre optics starting inside the cloak to the bundled screen and the person inside the cloak can see what's ahead. Doable?
     
    Last edited: Dec 18, 2018
  12. sideshowbob Sorry, wrong number. Valued Senior Member

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    Yup. Covering your eyes is one way of making things invisible. So is a camera/screen system.

    If that's what you're calling invisible, you can answer your own OP questions: Clothes worn under the suit would be invisible. Clothes worn over the suit would be visible.
     
  13. Janus58 Valued Senior Member

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    No, the effect is adaptive camouflage. Flexible screens can't reproduce the true 3D "looking through a window" effect you would need for true invisibility. If the observer shifts position he would note oddities that would be a give away. (objects that would be in the foreground of the image would not shift with respect to background objects like they would if you were viewing them directly, etc. It's the difference between looking at a scene on your TV vs. looking at one through a window. If you move your head from side to side, the scene out the window changes slightly, while doing the same while looking at the TV produces no such change*.

    * I did once read about a system that would reproduce the "looking through a window" effect on a TV screen. It involved the viewer wearing a device that tracked his head movements. The relative position of this device to the TV screen determined what the screen showed. Move your head to one side and the scene would shift to show you what was around the edge of the screen, or behind objects in the foreground, etc. I think the main aim was for use in video games like first person shooters. One limiting factor was that it only worked for one viewer at a time
     
  14. RainbowSingularity Valued Senior Member

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    i am trying to comprehend this, however i am unable to construct a model of what you are discribing by the content of the words you have used.
    please elaborate with more detail on what is where and the difference between inside and outside.

    note cables going frmo inside to outside could be joined to other cables that also go front to back...
    though that level of optical splitting and movement and display would require a computer that would likely cost the same as the average family house.

    are you suggesting a dumb system of simply refraction ? it would be vaulnerable to shadows and shading


    i have seen movies where this type of technology is shown as science fiction.
    a computer that tracks the eyes of people and adjusts the screen image as the person moves about.

    technically it looks quite do-able. just not yet and extremely expensive.
    once there is a break through in smart fabric materials technology. it will be all on.
    note quantum computers are already here so thats not an issue.
    camera size is already here with cell phones.
     
  15. Janus58 Valued Senior Member

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    The method I saw demonstrated just used a Wii type remote strapped to the user's head to track the movement and adjusted the image accordingly. For example they showed a "viewer's eye" video of a TV image of a stadium. As the camera to which the remote moved side to side, different parts of the stadium were visible, if it moved closer to the screen you saw what was originally "off screen become visible. The effect was very much like looking through a opening or window.
     
  16. RainbowSingularity Valued Senior Member

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    this bit is a bit of a give-away when you ask someone to stand still while you strap something to their head so it makes something invisible.
     
  17. Write4U Valued Senior Member

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    Visualize a river flowing around a small island. This effect can be used to divert light waves and bring them back together after the light has passed the object

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    Smith's metamaterials proved the method. The recipe to invisibility lay in adapting it to different waves.
    https://science.howstuffworks.com/invisibility-cloak2.htm
    https://science.howstuffworks.com/nanotechnology.htm
    Yes, the technology would be expensive. Bending light waves is no mean feat. One advantage with fibre optics is that they are able to transmit the entire wave spectrum of light and do not need to be tuned to each wavelength and are cheap to make.

    On second thought any fibre optic extending from the inside to the outside would negate the cloak and you would no longer be invisible to the outside. Only if the fibre optics are arranged like the river flowing around (cloaking) an island and diverting the light from behind, around the person and back together again in front of the cloaked object. The optics will only show what's behind the cloaked figure and anyone behind the cloaked person will also be able to see ahead of the cloak but neither side will be able to see "inside" the cloak as much as the person inside the cloak is unable to see what's outside the cloak.
    Not necessarily. Fibre optics are excellent wave transporters, but you would need maybe millions of strands to form a life sized semi solid flat plane from the ends.

    Could fibre optics replace metamaterials? It would be able to handle all visible spectrum wavelengths.
     
    Last edited: Dec 19, 2018
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  18. RainbowSingularity Valued Senior Member

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    brings to mind, Gravitational lensing...

    the bit about the wearer not being able to see outside is quite a big issue i should imagine.
    invisibility is not invulnerability per-say. only takes time until the immovable object comes in contact with the other object and the invissibility is useless because what ever has been made invisible has sustained damage.
    being able to see out and consequentially move about seems to be the key to avoid eventual damage/(easy)detection(mobile-usefulnes).

    i am still stuck on the shadow bit.
    when a shadow is cast over the cloak it will be unable to move the light image, (and)only(able to move) the shading which will make it become camoflage rather than cloaking. [?]
    some type of crystal possibly or self organising orbs that transfer their internal focus into the adjacent orb/sphere.
    this would allow a spray on coating of translucent beads that would bend all light around to the next bead making them light absorbing(not a cloak but a big easy difference to simple optics?)
    useles in rain as it would turn them into mirror balls but im just pondering the future big step to be able to have a spray on crystal or bead that is able to have a non focussing depth range so the distance of the observer is not disrupted.

    currently it seems that it is uni-directional ?
     
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  19. Write4U Valued Senior Member

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    I'm not sure. Perhaps with the metamaterials.
     
  20. RainbowSingularity Valued Senior Member

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    current puublicly shown tech is just mini cameras projecting on to surfaces or producing a picture on a screen.

    i am referring to your idea about fibre optics,(i think i missed out[forgot to add some explanation inside 1 of my questions] some details from my previous post now i think about it)

    pipes/fibres/tubes/ etc the fibre optic cables/ cables...
    while being able to bend, have only 1 inward direction.
    while being able to bend around something they can not recieve input from 360 degrees and more the point re my uni-D thingey... can only put out details in a single direction.
    if the cables had black hole properties where they sucked in light then that would make a huge difference but that would make the object a big dark black lump which would make it more visible than less visible.
    etc...

    because of the binocular depth perception of humans, the display must be reading at all depths to deliver complete cover[?]
    3d rotation rendering depth creates the main problem with current technology[?]

    thus ... bending the data around the object may well be useful, however... being able to render the data to any 3d point of distance is the key while maintaining a 360 degree field etc .. [?]

    making something become non visible may be easier in the short term than invisible and the rest is outside of my knowledge
     
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  21. Write4U Valued Senior Member

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    Very much so....

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  22. RainbowSingularity Valued Senior Member

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    reminds me of a screen saver graphic where a circle moves around bending all the picture around its outer surface.
    it makes the outter edge of the circle look like a rainbow as it pulls the colours in.
    i should imagine it would be quite hard to hide a gravity field strong enough to bend light

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  23. Janus58 Valued Senior Member

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    That's more or less the point. Without a system that actively adjusts the projected images to respond to the viewer's viewing position, a camera, flexible screen system won't imbue any true invisibility, and even with the eye-tracking system you mentioned, it could only work for one viewer at a time.
     

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