impossible figure

Impossible object

An impossible object (also known as an impossible figure or an undecidable figure) is a type of optical illusion consisting of a two-dimensional figure which is instantly and subconsciously interpreted by the visual system as representing a projection of a three-dimensional object although it is not actually possible for such an object to exist (at least not in the form interpreted by the visual system).

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.

Impossible objects are of interest to psychologists, mathematicians and artists without falling entirely into any one discipline.

Notable examples

Notable undecidable figures include:


Swedish artist Oscar Reutersvärd was the first to deliberately design many impossible objects. He has been called "the father of impossible figures". In 1934 he drew the Penrose triangle, some years before the Penroses. In Reutersvärd's version the sides of the triangle are broken up into cubes.

In 1956, British psychiatrist Lionel Penrose and his son, mathematician Roger Penrose, submitted a short article to the British Journal of Psychology titled Impossible Objects: A Special Type of Visual Illusion. This was illustrated with the Penrose Triangle and Penrose stairs. The article referenced Escher, whose work had sparked their interest in the subject, but not Reutersvärd, whom they were unaware of. The article was only published in 1958.

From the 1930s onwards Dutch artist M. C. Escher produced many drawings featuring paradoxes of perspective gradually working towards impossible objects. In 1957 he produced his first drawing containing a true impossible object: Cube with Magic Ribbons. He produced many further drawings featuring impossible objects, sometimes with the entire drawing being an undecidable figure. His work did much to draw the attention of the public to impossible objects. Some contemporary artists are also experimenting with impossible figures, for example, Jos de Mey, Shigeo Fukuda, Sandro del Prete, István Orosz (Utisz), Guido Moretti, Tamás F. Farkas and Mathieu Hamaekers.

In fiction

  • In the Star Trek: The Next Generation episode "I, Borg", a plan was made to destroy the entire race of Borg—malevolent cybernetic aliens whose minds were interconnected—by showing one of the Borg a picture of a highly complex impossible object. This image would be transmitted back to the Borg hive, overloading its consciousness in larger and larger attempts to understand the image. This plan was dismissed as being genocide, so its potential results were never seen.
  • In the computer game Diablo II, the "Arcane Sanctuary" region was based on impossible drawings.
  • Alan Moore's miniseries 1963 features a character called the Hypernaut that lives in a space station shaped like an impossible object.
  • In the video game Eternal Darkness: Sanity's Requiem the Essence of Xel'lotath, the Sigil of Xel'lotath, is an impossible artifact resembling a warped angel.
  • In The Simpsons episode "Treehouse of Horror VIII", a blivet (or devil's tuning fork) can be seen on Professor Frink's yard sale. In The Simpsons Movie, Homer falls down miles of the impossible infinite House of Stairs while having an epiphany.
  • The video game Echochrome for the PSP and PS3 features a mannequin who must traverse a series of impossible objects.
  • The set of the climactic scene in the Goblin King's castle in the 1986 fantasy film, Labyrinth, directed by Jim Henson, is based on M. C. Escher's "Relativity", and features impossible staircases and perspectives.
  • In Pokemon Platinum there is an area full of impossibilities such as these.


  • Mathematical Circus, Martin Gardner 1979 ISBN 0-14-022355-X (Chapter 1 — Optical Illusions)
  • Optical Illusions, Bruno Ernst 2006 ISBN 3-8228-5410-7

See also

External links

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