The Science of Discworld IV

arguments.’
    Ponder nodded vigorously.
    Ridcully grinned and continued thoughtfully, with a certain amount of malice aforethought, ‘It does seem to me, Mister Stibbons, that we should send an agent in there to see how things are. After all, Miss Daw has stumbled into our world, and therefore we have a duty to see nothing untoward is happening in hers as a result of your … experiment. Indeed, in the interests of all concerned, I think we should definitely send someone the other way. We
are
responsible for the place.’ Mustrum Ridcully stroked his beard, a signal to all who knew him that he was feeling rather nasty and mysterious. ‘I think, yes, the Dean himself ought to go and have a look around.’ The beard was stroked again, and Ridcully continued, ‘For backup, you had better send Rincewind with him; he’s been looking a little peaky lately, so a change of air will do him good.’
    ‘Alas, sir,’ said Ponder, ‘if you recall, and I
know
you recall, the Dean is now Archchancellor of Pseudopolis University, and we haven’t inducted a new Dean yet.’
    Undeterred, Ridcully said, ‘Get him anyway! He was the one who created Roundworld. He can’t just shrug it off; he ought to see how the old place is doing. Send him a clacks. We need action today. We want no more seepages!’
    fn1 She had rather liked the name until she went to school; the other kids teased her until one day she took umbrage and there was an up-and-downer, after which they showed some respect.
    fn2 The Librarian of Unseen University, who gets a capital ‘L’, is an orangutan, because of an accident when a spell escaped from a book of magic. See
The Light Fantastic
.

FOUR
----
WORLD TURTLES

    Before the Large Hadron Collider was turned on, there were attempts to get court injunctions to stop it, in case it created a mini black hole and gobbled up the universe. This was not
totally
silly, but it ignored a worse problem: according to the cosmological theory of eternal inflation, any part of the universe could blow up at any moment – see chapter 18 .
    Thanks to the switching on of the Great Big Thing, Marjorie Daw has seeped into Discworld. Since she is a librarian, we suspect the seepage happened through L-space, the interconnected space of all libraries that ever have existed or ever could exist.
    This may not be the first time something has seeped from Roundworld into Discworld either. Long ago, when the Omnian religion was founded, its adherents came to believe that Discworld, belying its name, is actually round. Where did
that
idea come from? For that matter, how did many early Roundworld cultures get the complementary idea that their world is flat?
    We can gain some knowledge about early human beliefs from archaeology, the branch of science that examines evidence from our past. The artefacts and records that survive give us clues about how the ancients thought. Those clues can to some extent be clarified by another branch of science, psychology: the study of how people think. The pictures that emerge from the combination of these two sciences are necessarily tentative, because the evidence is indirect. Scholars can, and do, have a field day arguing about the interpretation of a cave painting or a stick with marks on it.
    Ancient myths and legends possess a number of common features. They often focus on deep, mysterious questions. And they generally answer those questions from a human-centred viewpoint. The Discworld series takes Roundworld mythology seriously, to humorous effect; nowhere more so than in its basic geography and its magical supports – elephants and turtle. Here we’ll take a look at how various ancient cultures imagined the form, and purpose, of our world, looking for common elements and significant differences. Especially flat worlds and world-bearing animals. Here elephants turn out to be particularly problematic, most likely a case of mistaken identity. In chapter 20 we revisit some of these ancient myths, which will illuminate the science of human belief systems.
    In a human-centred view, a flat world makes more sense than a round one. Superficially the world looks flat, ignoring mountains and suchlike and concentrating on the big picture. In the absence of a theory of gravity, people assumed that objects fell
down
because that was their natural resting-place. To prove it, just lift a rock off the ground and let go. So a round world seems implausible: things would fall off the bottom half. In contrast,