I want to ask a question about the Three-torus model of the universe, as described in wikipedia:
"is a proposed model describing the shape of the universe as a three-dimensional torus."
I'm not sure i understand the maths of three-dimensional tori, but I want to ask:
Does this model posit that the shape of the universe is that of a ring doughnut? If so, is the universe contained inside the ring doughnut, or is it supposed to exist only on the surface?
Or does the model say that the universe has the shape of a higher dimensional version of a ring doughnut? If so, does it exist inside the higher dimensional ring doughnut, or on its surface?