Editing Impossible object (section)

==Notable examples==
Notable impossible objects include:
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{{Gallery
|File:Borromean Rings Illusion.png |[[Borromean rings]] – although conventionally drawn as three linked circles in three-dimensional space, any realization must be non-circular.<ref>{{cite book |contribution=Chapter 15: The Borromean Rings Don't Exist |title=Proofs from THE BOOK |title-link=Proofs from THE BOOK |pages=99–106 |first1=Martin |last1=Aigner |author1-link=Martin Aigner |first2=Günter M. |last2=Ziegler |author2-link=Günter M. Ziegler |edition=6th |publisher=Springer |doi=10.1007/978-3-662-57265-8_15 |isbn=978-3-662-57265-8 |year=2018}}</ref>
|File:Impossible staircase.svg |[[Penrose stairs]] – created by [[Oscar Reutersvärd]] and later independently devised and popularised by [[Lionel Penrose]] and his mathematician son [[Roger Penrose]].<ref name=p1958/> A variation on the [[Penrose triangle]], it is a two-dimensional depiction of a staircase in which the stairs make four 90-degree turns as they ascend or descend yet form a continuous loop, so that a person could climb them forever and never get any higher.
|File:Penrose-dreieck.svg|[[Penrose triangle]] (tribar) – first created by the Swedish artist [[Oscar Reutersvärd]] in 1934. Roger Penrose independently devised and popularised it in the 1950s, describing it as "impossibility in its purest form".
|File:Poiuyt.svg| [[Impossible trident]] (or devil's tuning fork) – also known as a "blivet", this has three cylindrical prongs at one end, which then mysteriously transform into two rectangular prongs at the other end.<ref name=IFMW>{{cite web |title=Impossible Fork |url=http://mathworld.wolfram.com/ImpossibleFork.html |publisher=[[Wolfram Research]] |access-date=10 February 2014}}</ref>
|File:Waterfall.svg|[[Waterfall (M. C. Escher)|Impossible waterfall]]
|File:Reutersvärd’s triangle.svg |[[Oscar Reutersvärd]]'s optical illusion (1934)
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