P.S. Tom, since you personally favor the Bipolar model (you offered it to explain the dilemma), you must believe that Sydney and LA are the two farthest major cities on Earth. According to the bipolar map, the distance is almost 90% that of Earth itself. But the direct flights are even shorter (13-14 hours), and they're even more frequent. If you look out the window during such a flight, you would only see ocean. But this would mean that the plane is taking an ever longer route around the continents - (>50,000 kilometers!) and has no possibility of expanding its range, aside from mid-air refueling!