They say that there is no such thing as a stupid question. In a pedagogically pure sense, that's probably true. But some questions do seem to flirt dangerously close to being really quite ridiculous. One such question might well be, "How many dimensions of space are there?" I mean, it's pretty obvious that there are three: left/right, up/down, and forward/backward. No matter how you express an object's coordinate, be it Cartesian, spherical, cylindrical, or something exotic, it's eminently clear that we live in a three-dimensional universe.