Penrose Triangle

The Penrose triangle is a triangular impossible object, an optical illusion in which a two-dimensional perspective drawing depicts an object that cannot exist as an ordinary three-dimensional solid, appearing to be built from three straight beams that meet at right angles to form a closed triangle, a configuration that is geometrically impossible in normal three-dimensional space even though its surface can be mathematically embedded in five-dimensional Euclidean space. The Swedish artist Oscar Reutersvard originally created the figure in 1934, and the psychiatrist Lionel Penrose and his mathematician son Roger Penrose independently rediscovered and popularized it during the 1950s, describing it as impossibility in its purest form; the figure is also known as the Penrose tribar or the impossible tribar. The Dutch artist M. C. Escher featured elongated versions of the triangle in his 1961 lithograph Waterfall, bringing it to wide cultural prominence. If a line is traced once around the figure's outline, the path it traces is equivalent to a four-loop Mobius strip, and physical sculptures have been built that create the illusion of an impossible triangle only when viewed from one specific angle.