Impossible object

Two famous undecidable figures, the Penrose triangle and devil's pitchfork

The theme of impossible objects embraces the gamut of representations of mathematical constructs, fictional ideas, representational drawings, etc, which clearly and unambiguously purport to describe, define or otherwise represent artifacts which are contrary to the known physical natural laws. Drawings of objects that cannot exist are called "undecidable figures". A good example of a world defined by impossible objects is that of the well-known graphical artist M. C. Escher, whose (for example) symmetrical staircases lead inexorably and beautifully into infinity.

• impossible cube
• Penrose stairs
• Penrose triangle
• Unobtainium
• blivet

References

• Things Impossible