Penrose stairs is a famous geometric paradox, which means that a ladder always goes up or down, but it can't go to the end. It can be regarded as a variant of Penrose Triangle, and the highest or lowest point can never be found on this ladder. Penrose ladder was put forward by British mathematician roger penrose and his father geneticist Leonid Penrose in 1958.

Penrose staircase is one of the famous paradoxes in mathematics and geometry. Theoretically speaking, people keep going up stairs, but they keep spinning on the same horizontal plane, resulting in the disintegration of infinite cycle. We can find that the highest or lowest point can never be found on the stairs of Penrose.

Penrose staircase is actually a process from the basic point to the basic point, and it is a process of going up and down. But all we see is going upstairs or downstairs, which is the illusion of Penrose stairs. In fact, the height difference of each staircase is due to the slope of the staircase, and the height difference of each staircase is greater than the height increase caused by the slope of the base.

When people go up the stairs in the middle, the height difference of each step is actually smaller than the height increase caused by the slope of the base, so you feel that you are going upstairs, but the height is actually falling. Penrose staircase uses the height difference to give people an intuitive feeling. According to the test in reality, it is found that as long as each staircase has a certain inclination, it can give people a feeling of going up the stairs, but it is always on the horizontal plane.

Penrose ladder may not exist in three-dimensional space, but it is easy to realize as long as it is placed in a higher-order space. Such as Mobius ring and Klein bottle.