Some scientists think that creatures in four-dimensional space are ghosts. Not only that, creatures like dragons in our imagination may all live in four-dimensional space.
Physics explains four dimensions that three dimensions plus time can form four dimensions. Therefore, for four-dimensional creatures, they can see time. Maybe they can travel freely in all time and space, either to the future or to the past.
For ants, when we humans suddenly run away, it will think that this picture has disappeared, but it can't understand why it has disappeared; Similarly, if a four-dimensional creature disappears from human eyes, so do we humans, and we will never understand why it disappears.
Four-dimensional space is the concept of time
The space we live in is a three-dimensional space, with two-dimensional world and a part of four-dimensional world. In the research and exploration of many scientists, it can be temporarily understood that the space of each layer will be superimposed accordingly, from point to line and from line to surface. Each layer of space not only controls the content of the previous dimension space, but also is controlled by the higher dimension space, just like the set in mathematics.
Each floor of space has its own unique characteristics. Length exists in the first dimension, and length and width exist in the second dimension. Their superposition creates a three-dimensional space and a four-dimensional space. Therefore, scientists have separated the unique characteristics of space and simplified the four-dimensional space into the concept of time.
The development of this theory can be started from Minkowski, who fused independent space and time, and made a four-dimensional treatment in electrodynamics, and then obtained the equation S=r+(ict) of the concept of time and space. The appearance of this equation was developed by Einstein into general relativity, which further popularized the concept of time axis.