The riddle of the four-dimensional space Introduction The concept of multiple dimensions is confusing, because people talking about dimensions, usually have in mind the space-time system. Besides the three-dimensional space and one-dimensional time, we typically invent new dimensions, representing properties like color, weight, cost etc. The "fourth dimension" studied here has nothing to do with time or any other user-defined properties, but it does with space. Therefore, if we restate the title of this paper in a form of a question that would be: Is there any other spatial dimension except the three we already know about? next