At present, people only know one-dimensional time, two-dimensional plane, three-dimensional space and the concept of "four-dimensional space-time" mentioned by Einstein.
In addition, superstring theory predicts that there should be six other unknown spatial dimensions.
Then why can't the other six dimensions see it?
When people stand in front of this water pipe and look at it, the water pipe is a straight line. We only see its front and back, and it is one-dimensional.
When people stand on a plane and look at the water pipe, they can see the top, bottom, left and right sides of the water pipe, so what people see is two-dimensional.
When people look at this water pipe in three-dimensional space, its front, back, left and right are in their eyes, then it is three-dimensional.
But what if people put this water pipe in a two-dimensional plane and then put this two-dimensional plane in a three-dimensional space?
Therefore, scientists imagine that water pipes are as thin as hair. Scientists believe that six "hidden" spatial dimensions are curled up at every point in our universe with extremely tiny geometric shapes.