3-torus

This article is about the three-dimensional space. For the two-dimensional surface with three holes, see triple torus.

A view from inside a 3-torus. All of the cubes in the image are the same cube, since light in the manifold wraps around into closed loops.

The three-dimensional torus, or 3-torus, is defined as any topological space that is homeomorphic to the Cartesian product of three circles, $\mathbb {T} ^{3}=S^{1}\times S^{1}\times S^{1}.$ In contrast, the usual torus is the Cartesian product of only two circles.