You’ve given me much food for thought, thanks! I know that at one time we did mathematics without the number zero and that its introduction was a profound (and

You’ve given me much food for thought, thanks! I know that at one time we did mathematics without the number zero and that its introduction was a profound (and controversial) change. The empty set seems like a perfectly natural extension of zero as a concept. Perhaps the universe with no empty set also has no zero? Would be very interesting to see how mathematics would develop without either construct.