I've spent the last six weeks upside down. Well, that's only if you believe that the world is indeed spherical. A few months ago, it struck me that most of my travel has been restricted to the Northern Hemisphere. This was neither intentional nor surprising, given the lay of the land in the world as we know it. But, having realised this somewhat random fact, I had two options—either shrug it off as nothing more than interesting or, well…