Dimension 0 is a point and has no length. 1 dimensional space is a line with only length and no width. A two-dimensional space is a plane with a length and a width, that is, an area. Three-dimensional length, width and height. Three-dimensional objects are the objects we feel every day, including flowers, water and beds. 4-dimensional space is 3-dimensional object plus time, and the space where we exist is 4-dimensional space, that is, we humans travel in 4-dimensional space. 5-dimensional space: If the 3-dimensional space is regarded as a point, the time axis becomes a line, and the 5-dimensional space is a time plane composed of 4-dimensional space lines. Countless 4-dimensional spaces converge on one axis, resulting in parallel universes and time travel. PS: Low-dimensional objects can't interfere with high-dimensional, and high-dimensional objects can know the motion state of low-dimensional objects (for example, 3-dimensional objects can only move in 4-dimensional space, and humans can't change time.