Suppose that before the quinoa is cooked, the water fills its volume completely. However, after cooking, the water is absorbed into the quinoa and forced to share its packing fraction. The quinoa stays at the same packing fraction before and after cooking, so the water must be responsible for the volume growth.
Also, the floor can be bumpy but has to be free of steps - if the table is on a staircase, as you often find in outdoor cafes in Tuscan hill towns like San Gimignano, the math doesn't work. But then, if you are sitting on a restaurant terrace in Tuscany, who cares?
The volume of the unit -sphere goes to 0 as grows! A high dimensional unit sphere encloses almost no volume! The volume increases from dimensions one to five, but begins decreasing rapidly toward 0 after dimension six.
Next time someone asks me how there can still be open questions in Mathematics, I will tell them that we still don't know everything about higher dimensional kissing.