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From the various sci-fi movies & games, Are there any logical theories for the concept of invisibilty?

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    What do you mean? Logical in what way? Mar 21, 2012 at 8:58
  • For instance, Sciene prognosticates that metamaterials will be the vanguard in developing an invisibility cloak.The behaviour of metamaterials in bending visible light in a different direction than the natural. I want to know if there are other theories prescribed in science fiction to make the concept of invisibility real and imaginable. It shouldnt stray faraway from science or be baseless like a magical cloak or potion of invisibility etc. Mar 21, 2012 at 9:27
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    You may want to try picking a single science fiction piece with invisibility and asking about how that individual case of invisibility operates.
    – Xantec
    Mar 21, 2012 at 14:34
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    Invisibility IRL has actually been achieved at frequencies up to about IR, a bit out of range of visible, through metamaterials that can actually bend light around an object.
    – Kevin
    Mar 21, 2012 at 15:19

5 Answers 5

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Logically, there are a few ways to become "invisible". I'll describe those I can think of, as well as a mechanism to accomplish the effect.

  1. You can become transparent, so that light passes through you. As has been pointed out, this should also cause you to become blind. The mechanism for this is to somehow change the refractive index of your body (or your ship and the entire contents thereof.)

  2. You can reflect no light, absorbing all light that hits your body. Again, this works only in space. I suppose a mechanism for this might be to emulate the characteristics of a black hole with respect to light. A detrimental side affect would surely be that your body/ship must now absorb serious amounts of energy from the light it must absorb, limiting the amount of time one could stay invisible without an explosion.

  3. You can avoid light reflection, by somehow bending light around your body. This has actually been accomplished at a minimal level by scientists, but it will be REALLY hard to do in practice. Perhaps a sci-fi mechanism might be to locally warp space from the point of view of the photons that pass through it. Again, a flaw with this scheme is you become blind. So perhaps the effect is specific to visible light, and you are allowed to see in infrared wavelengths.

  4. You can use the camera/projector scheme to effectively hide yourself from view. Here you mimic your background. You are not technically invisible, just difficult to see. This is achieved by animals like the chameleon and the octopus, and also in fiction (the Predator comes to mind.)

  5. You can step out of plane. Visualize the world of Flatland, wherein if you step out of the plane we live in, you are no longer visible to the inhabitants of that plane, since they see only what is in their space. This is not technically invisible, since you are no longer fully inhabiting the same space as those you choose to be invisible from.

  6. You can simply appear to be invisible, by clouding the mind of your observer. This mechanism, like the chameleon, makes you appear invisible to the observer even though you are still there technically to be seen.

  7. Finally, rather than simply absorbing all light, your body absorbs all incoming photons, changing their wavelengths, then re-emits them, perhaps at some other wavelength that will not be perceived. So while you are now invisible to the eye, you will glow brilliantly to the observer with the ability to see that wavelength of radiation. The mechanism is based on quantum mechanics and a bit of hand waving. (Of course, any scheme for invisibility requires a bit of magic.)

To be honest I like the last idea (#7), were I ever to write a sci-fi story. It has a semi-plausible pseudo-scientic explanation for the mechanism, and it has an interesting fatal flaw that can be exploited. It is also a scheme for invisibility I do not recall seeing elsewhere.

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    Wonderful summary. #7 is a concept new to me. It is quite fascinating, i must say. You'd better patent it fast (unless you read it in the internet yourself) Mar 26, 2012 at 3:17
  • While I really like #7, I've not read it anywhere that I know of. If I had even a scrap of ability to write fiction, I'd try to use it for a story myself, but I know better.
    – user93
    Mar 26, 2012 at 10:57
  • Ah, you could give it a shot you know. Pretty sad that this question is closed. You have provided a couple of detailed scenarios, worth viewing. Mar 26, 2012 at 11:30
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    Similar to #6 is "Kung-Fu" invisibility as depicted in the movie 3 Iron. Or "psychological" invisibility as described in Ralph Ellison's Invisible Man. Jun 3, 2012 at 4:49
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I'm not sure if James Bond counts but Mercedes have made an invisible car based on Bond technology.

The "logical" theory behind it was:

an "Adaptive Camouflage" [Cloaking] System, which allowed it to become effectively invisible (to the naked eye at least) at the push of a button: tiny cameras mounted on [all sides of] the car were used to capture the image facing that [respective] side of the vehicle [that the camera was on] and project it onto a light-emitting polymer skin on the other side, [effectively] making the car invisible.

(from Jamesbondwiki)

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  • A neat trick, but it would seem to only work from within a particular viewing area (distance, angle etc)
    – Xantec
    Mar 21, 2012 at 14:36
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The concept of invisibility in space science fiction is used mainly for dramatic purposes so that the audience can relate to the ship not being detected.

In the real world, something similar to the Mass Effect stealth technology is much more realistic, the idea is not to become invisible but to avoid appearing on common sensory of the enemy ships, whether they detect heat or any other kind of radiation. Reflected light in space is in reality almost nonexistent so in reality there's no need to actually be invisible... is REALLY dark out there.

A current real application are the phantom class aircraft which are considered stealth, not because they are invisible, but because they do not appear on radar.

Here you can find an excellent article on invisibility on space (or stealth in space). Of course non of this applies to other than space. In the more mundane scale, several technologies are being developed which try to either bend the light around the object or project the received light on the other side of the object.

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  • "REALLY dark out there" where? It depends on where you are in space. If you're close to a planet like earth or even close to a star, I'd imagine it gets pretty bright all of a sudden.
    – bitmask
    Mar 21, 2012 at 11:41
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Kim Süskind from Warren Ellis' Planetary became invisible because light went right through her. As a consequence of this, she was also blind while invisible, because light went through her eyes. She is one of The Four, the main villains of Planetary, who are an Homage of The Fantastic Four. She's the equivalent of Susan Storm, the invisble woman.

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The most common (that I am aware of) idea for making something invisible in science fiction is to coat it with a substance or surround it with a field that bends light around the object so that when the light gets to the other side it continues on its original course.

It might be possible to detect an object that was invisible in this way by examining the phase anomalies that it would cause, but that would require highly specialized advanced equipment.

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  • Yeah meta materials, follow a similar pattern of bending the light (or so i've read) Mar 26, 2012 at 3:18

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