Talk:Invisibility

no cloning theorem ??

"According to the laws of physics as presently understood, an invisible person would necessarily be blind, no matter how their invisibility were achieved. In order to see light, it must be absorbed by the retina, but in order for a person to be invisible, the body must not absorb light. In fact, according to the no cloning theorem of quantum mechanics, they could not even make a copy of the photons so they could see one copy and allow the other copy to pass through or around them."

But of course you can make a copy of the photons if you don't care about their quantum state. You'll achieve a great deal of invisibility if you just clone them any old way because the human eye is not all that polarization sensitive. Of course the no cloning theorem says that the person can be detected by some polarization tricks then, but without of those devices...

Moving here because it is speculative:

An alternative for true transparency, also fictional but perhaps a little closer to realizability, is a system of sensors and displays on the outside of the cloak etc. such that light arriving at a sensor from a particular direction is reproduced at the other side of the body, at the corresponding position, and emitted onward in the same direction. For an observer this would be equivalent to transparency.

Covering the head with the same 'clothing' this would also allow the head to become invisible, while the invisible person can still see (retinas absorbing light would conflict with true transparency).

It's part of sci-fi in the same way that magic potions are part of fantasy. -Martin

Then cite specific examples. --Eloquence

Deleted the following because (a) it's a dictionary definition and (b) it's untrue:

Invisibility is used colloquially (though inaccurately) to mean camouflaged or well-hidden. For example The paras are so well trained that they can remain invisible until they are within twenty feet of the target.

I say it's untrue because of the word inaccurately. If someone's camouflaged so well that you can't see him, then he is invisible. Heron

Could the image from CNN's site be used under 'fair use'? Nikola 04:36 7 Jul 2003 (UTC)

The entire "Invisibility in physics" section is poorly written and requires cleanup or deletion. To describe something as a potentail cause of invisability and then saying that "unfortunately, this would not make it invisable" is both clumsy and confusing.

I agree. In fact, I have two points to make:

• The sections "Physics" and "Technology" seem to have significant overlap, and also points that shouldn't be there. Suggest division into two sections: "Invisibility in Physics/Technology" and "Invisibility in Fiction", as the only real-world "cloaking" device that exists has been made by physicists (and some electrical engineers), and it is going to remain this way for the forseeable future.
• Something whose escape velocity exceeds the speed of light (e.g. a black hole) appears black. Most people would argue that it therefore isn't invisible (and indeed it doesn't really satisfy the definition on the page). Rlfb 17:13, 23 November 2006 (UTC)

The entire article badly mixes up fiction with fact and requires a serious going over.

Image

The picture of the empty rocking chair is cute, but does it really add anything? On the other hand, I doubt we can find a better image of invisibility (an oxymoron!) so maybe it should stay... —Keenan Pepper 06:26, 17 January 2006 (UTC)

• LOL at the rocking chair caption. Wiki doesn't usually have jokes like that, but this one's good :) and not exactly "wrong". Although speaking of images of invisibility, we might add the famous picture of the Invisible Pink Unicorn? —EatMyShortz 17:08, 22 January 2006 (UTC)
• Well I could find a different image such as this invisible horse in a meadow, but yeah, I agree the image is an accurate portrayal of the effects of invisibility. --TexasDex 04:57, 31 January 2006 (UTC)
• I vote to keep the image, it's amusing and actually does do the job of giving a visual image of invisibility (as opposed to transparent or whatever). Thumbs up.Markeer 23:58, 30 March 2006 (UTC)

• The image is funny, but ridiculous. Perhaps we could get a fair use image of one of the many films/tv shows where theyve shown someone "invisible". the old gag of the hat and glasses without the face would be good. Also see the german article where they have many images and are looking more at the scientific aspects of it -- Astrokey44|talk 09:34, 15 April 2006 (UTC)

The new image is still in German. I suggest removing it until it is translated. —Keenan Pepper 17:14, 15 April 2006 (UTC)

Remove it please. It's ridiculous and shammy. --Mkeroppi 17:32, 15 April 2006 (UTC)

Hey, three people above said they liked the invisible girl. Image:UNSIBA-5 Unsichtbarkeit mit Spiegeln.jpg isn't exactly serious either (what the heck are those little creatures?), and it has the added drawback of not being in the right language. —Keenan Pepper 17:48, 15 April 2006 (UTC)

At least that showed the mechanism in question. It should be removed once it's translated. The "invisible" girl does not contribute to the context of the article, or at least some blurb/explanation has to be written to expand the definition. Right now, it's confusing. I'd agree to using films/tv caps, but not something "made up" made up. --Mkeroppi 17:14, 19 April 2006 (UTC)

It should be removed once it's translated. I don't follow you. The invisible girl is already removed. Why translate the diagram only to remove it? —Keenan Pepper 17:41, 19 April 2006 (UTC)

invisibility of nonexistent things

I added this section. It overlaps with invisibility in fiction, but it's different because invisible fern seeds, for example, were not intentionally fictitious. This section is about how invisibility is used to help explain a supposedly true thing rather than to describe an intentionally fictitious thing. Jonathan Tweet 16:24, 18 July 2006 (UTC)

Duplicates or not?

Consider these two bullet points:

• [A] A recent breakthrough (2006) at Imperial College London has shown that invisibility is possible by using specifically patterened crystals made up of nanoscale boxes that hold electrons. When light hits these crystals, it becomes entangled within the boxes, causing the object to become transparent.

• [B] Although it has been shown that making opaque objects perfectly invisible ("non-scattering scatterers") is impossible, 2006 theoretical work predicts that the imperfections need not be serious, and metamaterials may make real-life "cloaking devices" practical. The technique is suspected to be applied to radio waves within five years, and eventually visible light is a possibility.

Do these refer to the same research or not? They're both from 2006, and they both involve people from Imperial College London. I think the first is simply a hyped-up pop-sci version of the second, but I can't be sure because http://www.royalsoc.ac.uk/exhibit.asp?tip=1&id=4659 doesn't cite any papers. —Keenan Pepper 01:17, 20 August 2006 (UTC)

They are not the same researcher(s), and they seem to be describing different phenomena. • Bullet point [A] summarizes The Royal Society web article "Invisibility at the flick of a switch", (undated despite the WP reference), which is signed by Profs. Frogley and Phillips of Imperial College, plus Profs. Dynes, Beck, and Faist of U's elsewhere. • Bullet point [B] is an amalgam of four research conclusions from Nachman, et al, 1988; Wolf, et al, 1993; Pendry, et al, 2006; and Leonhardt, et al, 2006. Cho appears to be a popular science abstract writer citing Pendry, et al, 2006, and Leonhardt, et al, 2006. Of the four original research citations, only J. B. Pendry is with Imperial College London, and Pendry's coauthors are at Duke U. of North Carolina.

Making no judgements about the scientists or the value of their underlying science, the "Invisibility at the flick of a switch" article is nearly incomprehensible as popular science writing. No invisibility switch or any kind of switching is ever mentioned. As educated readers are likely to understood it, "entangled" light boxes sounds like a nano hall of mirrors. If the light never exited, it would presumably have the same effect of blackness as absorption. The interaction of light with normal "wave patterns of the electrons" was not in texts that I've casually read, so the interaction of light with canceled electron waves remains unexplained to me by the contrast and compare method. • Worse yet, the article illogically segues to the "fundamental physical effect creating the transparency" as a data storage application that potentially could stop and store light — yet another equivalent to absorption blackness. • IMHO, bullet point [A] should be either deleted along with its poorly sourced reference, or rewritten to reflect ambiguity about an interesting concept in a new field — with its numbered source reference to include a popsci caution. Milo 05:23, 20 August 2006 (UTC)

Okay, I agree with that. Also, I think I found the real paper on which the Royal Society article is based: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1561070 I'm trying to wade through it, but I have a feeling I need a few more years of physics courses just to understand the basics... —Keenan Pepper 06:54, 20 August 2006 (UTC)

Examples in fiction

Someone has tagged the "Examples in fiction" section as needing cleanup, and rightly so. We cannot include every movie and video game that features invisibility, even though everyone sure wants to highlight their favorite movie/game and add it. The list would become (and in my opinion already is) ridiculously long. (And it's still missing NetHack!) I'm tempted to remove the whole list with just some brief section on how often the invisibility theme appears in fiction, listing few selected examples, such as The Invisible Man. What other examples do you think should be included and what should be left out? --ZeroOne 11:28, 20 August 2006 (UTC)

Keep Ring of Gyges, The Invisible Man, and maybe a few others, but ditch the rest. If too many people whine, we can make a separate article Invisibility in fiction or whatever. —Keenan Pepper 02:38, 21 August 2006 (UTC)

I appeal to save this mythic fiction list by spawning a standard list article, "List of Invisibility Examples in Fiction". A list article is Wikipedia guide approved for just this situation. Under that heading the present 38 or so will not be overlong, and fascinated list readers can peruse and continue adding their favorites to it without its bulk annoying the main article readers. In the main article you could draw up a list of firsts in invisibility fiction: first ancient myth, first printed book, first movie, etc., then link to the complete list of examples article. Firsts are brief and don't provoke much debate. • Why spawn an invisibility fiction list article? It's popular with readers as well as an academically important myth. Human fascination with the fictional desire for invisibility could be rooted in evolutionary biology traceable to our primitive sea ancestors. To be invisible (enough), is to not be eaten and so continue reproducing in the usual pleasant way. :) Invisibility is a fiction of mythic status even greater than wealth devices like the Touch of Gold — in comic books there is Invisible Woman, but no Midas Man. Milo 04:17, 21 August 2006 (UTC)

List of invisibility examples in fiction does sound like a good solution. --ZeroOne 23:03, 6 September 2006 (UTC)