It is a book about First Contact with a difference. My problem is... How does the alien from Antarch (Earth, I guess) breath the Arbre Oxygen and vice versa?
Stephenson tries to cover over this on page 816, but it is just not possible in my view. If they come from other Cosmi where the fundamental constants are different; with atomic nuclei so different that chemistry is affected; that enzymes don't work, bacteria cannot infect, food passes through the gut undigested; well then in that case, Oxygen could not be respired either.