Just as a terrestrial globe cannot be flattened without distorting the distances, it seemed impossible to visualize abstract mathematical objects called flat tori in ordinary three-dimensional space.

Folding a flat piece of paper into a torus — a shape with a hole in the middle — demands origami skill. That’s something mathematician Richard Evan Schwartz lacks. Yet he answered a lingering ...

Imagine that you want to know the most efficient way to make a torus—a doughnut-shaped mathematical object—from origami paper. But this torus, which is a surface, looks drastically different than the ...