Penrose stairs [SEP] discoverer or inventor
Penrose stairs
The Penrose stairs or Penrose steps, also dubbed the impossible staircase, is an impossible object created by Lionel Penrose and his son Roger Penrose. A variation on the Penrose triangle, it is a two-dimensional depiction of a staircase in which the stairs make four 90-degree turns as they ascend or descend yet form a continuous loop, so that a person could climb them forever and never get any higher. This is clearly impossible in three dimensions.
The "continuous staircase" was first presented in an article
tower of pillars that begins at the waterwheel. The water falls off the edge of the aqueduct and over the waterwheel in an impossible infinite cycle; in his notes on the picture, Escher points out that some water must be periodically added to this perpetual motion machine to compensate for evaporation. The use of the Penrose stairs is paralleled by Escher's "Ascending and Descending" (1960), where instead of the flow of water, two lines of monks endlessly march uphill or downhill around the four flights of stairs.