Calabi–Yau manifolds are shapes that satisfy the requirement of space for the six spatial dimensions of string theory, which may be smaller than our currently observable lengths. To get around the physics of being a single dimension you need string theory.
They are the closest thing to a single dimension as can be measured in the practical world, beyond which we enter quantum land. fundamental natural units for length, mass, time and energy. What if adding to the largest number or splitting in half the smallest number does not make it actual if it has no relative meaning? Is there a point where amounts become fiction? I happened upon Planck units. In essence, that there is actually a largest and smallest number rather than infinite amount. In a wander down the rabbit hole in regards to infinity and negative infinity, I pondered, what if numbers must represent something to exist.