Figure 26-24: Hidden Dimensions of Space Hidden dimensions of space might exist provided they are curled up so tightly that we cannot observe them. This drawing shows how an ordinary two-dimensional plane might contain two additional dimensions. At every point on the plane, there is a very tiny sphere so small that it cannot be seen. To pinpoint a particular location, you need to give not only a position on the plane but also a position on the sphere. Thus, if at every point, space really has additional curled up dimensions represented by these spheres, then space has more than the three regular dimensions of space we are familiar with. Like a hamster running endlessly on its wheel, moving in a curled up dimension is not the same as traveling through regular space.
(Adapted from D. Freedman and P. Van Nieuwenhuizen)