Yes, another interesting conclusion that one can make based on the recursive problem you mentioned is that everything is space (i.e. no solidity). Well, look at the make up of an atom and it is mostly space… in fact they say that the size of the particles that make up an atom and their relative orbits are comparable in size and distance from one another to the planets in our solar system. Then they find these sub particles and the same thing is true of them… all this space and no real “solidity” to speak of. In fact, I heard that in a recent calculation they estimated that if all the space were removed between all the particles (at least the known ones that make up atoms) then the entire mass of the universe would find into about a cubic inch… and of course that size will be reduced if they discover even smaller particles (which I would bet they will). Yeah, all that space, and yet if I slam my hand on the desk it doesn’t pass through it… kind of makes you smile, like a good magic trick!