Double the questions, double the fun!
1. My knowledge of maths/geometry is pretty limited, so I don't quite understand a couple of things. In your description of a 1D object (and in fact anything larger than 0D), you refer to it as an object made of points (0D objects), which are infinitly small. Now, if a point is infinitly small (and by the way, does "infinitly small" mean absolute zero, or approx. (~) zero? ...or neither?), then how come that when you combine several points together, they become meausrable objects (lines)? Surely zero plus zero will always remain... zero? I don't follow the logic.
2. According to modern science, are there 4D or even bigger-dimensioned objects in our universe? (I'm not talking about the spacetime continuum where time is the fourth dimension.)
...and one ultra-tangled bonus question: Whenever Fred sees a sphere, he will view it as demonstrated in here. Whenever Bob sees a sphere his brain will process it using his 2D view. Whenever Bob sees a tetrasphere he will view it as demonstrated in here (a sphere emerging out of nowhere, growing, shrinking and disappearing). But how will Bob, our 3D friend, react to a "quintesphere" - a 5D sphere? (Surely he won't see a tetrasphere doing the grow-shrink thingy, since he cannot grasp tesseracts?) And when 4D Emily sees a quintesphere, will she see it as a tetrasphere appearing out of nowhere, growing, shrinking and disappearing?
I've been trying to do projections of this in my head but I could use some help.
P.S.: This is a great website and I'd like to kudos its owner(s) for hosting and updating it.