Regarding the two 9V batteries in a parallel...
A better question is what happens if you put them at right angles....
you get 13.85V!!!!!
[This is the square root of the some of the squares for those who are
slightly innumerate]
If a "sufficiently advanced technogoloy is indistinguishable from magic" and
many people that magic once existed on earth, is it not possible that the
older civilizations were actually more advanced than ours?????