Editing Invisibility (section)

{{short description|State of a matter that cannot be seen}}
{{Redirect|Invisible}}
{{original research|date=September 2011}}
[[Image:INVIS MIRROR.png|thumb|By using two parabolic cylindric mirrors and one plane mirror, the image of the background is directed around an object, making the object itself invisible - at least from two sides.]]

'''Invisibility''' is  the state of an object that cannot be [[Visual perception|seen]]. An object in this state is said to be ''invisible'' (literally, "not visible"). The phenomenon is studied by [[physics]] and [[perceptual psychology]].

Since objects can be seen by [[light]] from a source reflecting off their surfaces and hitting the viewer's [[eye]]s, the most natural form of invisibility (whether real or fictional) is an object that neither reflects nor absorbs light (that is, it allows light to pass through it). This is known as 
[[Transparency and translucency|transparency]], and is seen in many naturally occurring materials (although no naturally occurring material is 100% transparent).<!-- dark matter --><!-- i would argue that for something to be invisible that it's index of refraction would have to be equal to the substance it is submerged in.if this were not not the fact it would distort light. -->

Invisibility perception depends on several optical and visual factors.<ref>{{cite journal|last1 = Moreno|first1 = Ivan|last2 = Jauregui-Sánchez|first2 = Y.|last3 = Avendaño-Alejo|first3 = Maximino|year = 2014|title = Invisibility assessment: a visual perception approach|url = http://fisica.uaz.edu.mx/~imoreno/Publicaciones/JOSA2014.pdf|journal = Journal of the Optical Society of America A|volume = 31|issue = 10|pages = 2244–2248|doi = 10.1364/josaa.31.002244|pmid = 25401251|bibcode = 2014JOSAA..31.2244M|access-date = 2016-01-24|archive-url = https://web.archive.org/web/20170808173026/http://fisica.uaz.edu.mx/~imoreno/Publicaciones/JOSA2014.pdf|archive-date = 2017-08-08|url-status = dead}}</ref> For example, invisibility depends on the eyes of the observer and/or the instruments used. Thus an object can be classified as "invisible" to a person, animal, instrument, etc. In research on sensorial [[perception]] it has been shown that invisibility is perceived in cycles.<ref>{{cite journal | last1 = Craig | first1 = Eugene A. | last2 = Lichtenstein | first2 = M. | year = 1953 | title = Visibility-Invisibility Cycles as a Function of Stimulus-Orientation | jstor=1418951 | journal = The American Journal of Psychology | volume = 66 | issue = 4| pages = 554–563 | doi=10.2307/1418951| pmid = 13124563 }}</ref>

Invisibility is often considered to be the supreme form of [[camouflage]], as it does not reveal to the viewer any kind of [[vital signs]], [[visual]] effects, or any  frequencies of the [[electromagnetic spectrum]] detectable to the [[human eye]], instead making use of [[radio]], [[infrared]] or [[ultraviolet]] wavelengths.

In [[illusion optics]], invisibility is a special case of illusion effects: the illusion of free space.

The term is often used in [[fantasy]] and [[science fiction]], where objects cannot be seen by means of [[Magic (paranormal)|magic]] or [[hypothetical technology]].