Editing Impossible object (section)

==Explanations==
Impossible objects can be unsettling because of our natural desire to interpret 2D drawings as three-dimensional objects. This is why a drawing of a [[Necker cube]] would most likely be seen as a [[cube]], rather than "two squares connected with diagonal lines, a square surrounded by irregular planar figures, or any other planar figure". Looking at different parts of an impossible object makes one reassess the 3D nature of the object, which confuses the mind.<ref>{{cite web |url=http://www.fink.com/papers/impossible.html |title=Impossible Figures in Perceptual Psychology |publisher=Fink.com |access-date=11 February 2014}}</ref>

In most cases the impossibility becomes apparent after viewing the figure for a few seconds. However, the initial impression of a 3D object remains even after it has been contradicted. There are also more subtle examples of impossible objects where the impossibility does not become apparent spontaneously and it is necessary to consciously examine the [[geometry]] of the implied object to determine that it is impossible.

Roger Penrose wrote about describing and defining impossible objects mathematically using the [[algebraic topology]] concept of [[cohomology]].<ref>{{cite web|last=Phillips|first=Tony|title=The Topology of Impossible Spaces|publisher=American Mathematical Society|url=http://www.ams.org/publicoutreach/feature-column/fc-2014-10}}</ref><ref>{{cite journal|last=Penrose|first=Roger|title=On the Cohomology of Impossible Figures|journal=Leonardo|year=1992 |volume=25|number=3,4|pages=245–247|publisher=The MIT Press|doi=10.2307/1575844|jstor=1575844 |s2cid=125905129 }}</ref>