Einstein believed that the universe perceived by human beings belongs to the structure of four-dimensional space-time, that is, three-dimensional space + one-dimensional time, but space is really only three-dimensional? Is time really only one dimension?
In physics' latest string theory and superstring theory, four-dimensional space-time is only a macroscopic scale, and there are as many as 11 dimensions curled up in the microscopic world that humans cannot directly perceive.
Even there, time does not take the shape of a one-dimensional single arrow, but has an extra dimension, becoming a two-dimensional scattered plane, in which things will no longer develop single-threaded, but emit countless possibilities in a flash, just like the instantaneous unfolding of a kaleidoscope.
But the current question is, we can imagine two dimensions from one dimension, and three dimensions from two dimensions, why can't we imagine from three dimensions to four dimensions?
The scientific community believes that this is related to the limitations of the human brain itself, because the brain itself is only a lump of meat in a three-dimensional space, no matter how subtle the thoughts attached to this lump of flesh, he cannot imagine a dimension that he has never experienced and seen, nor can he imagine another direction, just as the ancients of a thousand years ago could not dream of the operating systems of mobile phones and computers, because he had never seen it.
The four-dimensional pictures simulated by the computer so far are only the projections of real four-dimensional objects in three dimensions, which is the embodiment of the formulas when mathematicians describe four-dimensional space, and these pictures are essentially three-dimensional.
In the movie "Interstellar", the protagonist finally enters the multidimensional space-time set for him by the future human beings, where he sees all the sections in his daughter's bedroom in the time occasion, which is one of the most typical manifestations of multidimensional space-time, that is, the multidimensionalization of time, so the protagonist can reach the daughter's bedroom in any time section at will like a door, and use gravitational waves or things that look like strings to influence the watch hands.
To use simple popular science language to describe, one dimension is a point, two dimensions is a plane, three dimensions is a space that exists in length, width and height and distinguishes between inside and outside, four dimensions are also a space, but because four dimensions are more than three dimensions, we can not imagine a direction, so from four dimensions to three dimensions, you can directly see the interior of three-dimensional space, you can directly see the contents of the box without opening the box, or even take it out.
This kind of miracle-like operation, in fact, in the three-dimensional world also often occurs, such as when we take away a sugar placed in front of the ant's eyes, the sugar disappears out of thin air in front of the ant that is similar to a two-dimensional creature, in the same way, we want to trap the ant may only need to draw a circle to circle it, but if you want to trap the human in the three-dimensional space, the circle is definitely not useful, you have to add the wall plus the roof.
Thinking about it, the only thing in the universe that can really be called the entrance or passage of four-dimensional space is the wormhole in Einstein's general theory of relativity.
Because just like folding two points on a piece of paper and poking a hole together, the wormhole is also connecting the two points together, the difference is that the wormhole is connected to two points in three-dimensional space-time, so in a sense, the existence of the wormhole is equivalent to adding another direction on the three-dimensional space station, so that the object passing through the wormhole can span tens of millions of light years in an instant.
Even the wormhole itself may not be a hole or a ball, what we see is just its projection in three-dimensional space, in any case, four-dimensional space is very mysterious to humans.
The scientific community believes that it is unlikely, because in the four-dimensional space with one more direction, the three-dimensional structure of human beings is likely to be unable to breathe normally, but if the future can create a four-dimensional spacesuit, the human brain that has obtained a new perspective may usher in a new round of change, and human beings will evolve again.