Penrose staircase
The
Penrose staircase is an
optical illusion consisting of a staircase that appears to go continulaal upward (or, in the other direction, downward) while circumambulating a square path. The design was created by the
Swedish artist Oscar Reutersvard, (independently) the
English geneticist Lionel Penrose and his son, the
mathematician Roger, as well as by the
Dutch artist
M. C. Escher. Escher's work,
Ascending and Descending, is the best known representation of this figure.
External reference
"Impossible Staircase"