The Science of Discworld IV

straightforward engineering technologies needed to put a man on the Moon. The theory that the Moon landings never happened makes perfect sense provided you think it is possible to sustain a global conspiracy ultimately involving millionsof people, prominent among whom were the Russians, who were trying to beat the Americans to their lunar prize.
    We don’t want to dissect conspiracy theories, or make any further attempt to convince you that Neil Armstrong and Buzz Aldrin really did land on the Moon in 1969, or, for that matter, that they didn’t. Instead, we want to examine one of the reasons why many people used to believe, and a fair number still believe, that the Earth is flat. Or some other shape that is not the nice round globe of the Earth we encounter in geography lessons.
    This reason is the role of inference, as opposed to direct observation. Inferences are always open to interpretation, and there is often enough wiggle-room to permit apparently logical escape routes. Devotees of a flat Earth have used this wiggle-room to devise more-or-less plausible explanations for most of the usual arguments that it is round. Explaining away one piece of evidence for a round Earth often conflicts with explaining away some other piece of evidence, but in a point-scoring debate, few in the audience notice. We, your humble authors, actually have a totally convincing proof that the Earth is round, which does not depend on photos from space, but we’ll save it until the end of this chapter.
    Before the 1960s, even the most technologically developed nations could not observe our planet from any vantage point higher than a plane could fly or a balloon could rise. In earlier times, the available evidence was limited to what a groundhog could observe with its own senses, and
Pan narrans
’s insatiable need to tell explanatory stories led to some imaginative proposals.
    One of the earliest cosmologies that we know something about is that of ancient Egypt in the early dynastic period, around 3000 BC . It remained surprisingly unchanged for much of the next three millennia, although new elements came in from time to time and fashions changed. The basis for Egyptian cosmology seems to have been informal observations of natural phenomena, laced with imagination and thickly coated in religious imagery.
    Egyptian thinking was strongly influenced by their natural coordinate system, which provided four very clear cardinal directions, each having a deep meaning. Egypt was the ‘black land’ sandwiched between two regions of ‘red land’: a thin fertile strip between wide deserts – though early on the desert areas were more like savannah than the arid expanses they are today. The Nile ran roughly from south to north, and the prevailing wind went the other way. The extent to which this axis was embedded in Egyptian thinking can be gauged from the hieroglyphs for south (a boat with its sails raised) and north (a boat with sails furled). The Sun – considered a god from predynastic times – rose in the east and set in the west.
    In Egyptian mythology, the Earth was flat, with a sort-of square aspect because of the importance of the cardinal directions. It was associated with the god Geb. The goddess Nut formed a gigantic arch above the Earth, corresponding to the sky and the heavens. In between was the air god Shu. Various features of the night sky echoed those on the ground; in particular, the Milky Way, a bright, dramatic band of light in the night-time desert sky, corresponded to the Nile. Since the Sun disappeared from the sky in the west and reappeared in the east, it obviously passed under the Earth, through the solid body of the ground. During the night, the Sun god Ra battled with the demons and gods of the underworld, emerging victorious – or at least, as a survivor – each morning. Thanks, you appreciate, to the strenuous efforts and rituals of the priesthood.
    Cosmology, you will recall, is the theory of the form of the universe, and it goes hand in hand with cosmogony, its origins. The Egyptians had several creation myths, originating in different regions of the country, and different myths were often combined in a mix-and-match way. A common element in most versions was mentioned earlier: the emergence of the Earth when the primal mound rose from the sea of chaos. The triangular shape of the pyramids is thought to represent, among other things, this primal mound. It has long been known that the Temple of Karnak in