Triangle/

    Impossible objects typically look at first as if they could exist in reality, but on closer inspection, you find some aspect that just cannot make sense... Artists have designed impossible objects, like the classic impossible triangle. M.C. Escher, created impossible objects, illusions, and tessellations. Swedish artist, Oscar Reutersvard, known as the father of impossible figures, was the first to purposely structure impossible objects. Click to enlarge The impossible triangle design is perhaps the most famous of all impossible objects. Swedish illustrator Oscar Reutersvärd was the first to explore and popularize impossible designs.

    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 artefacts 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.