The Science of Discworld IV Judgement Da

The Science of Discworld IV Judgement Da - By Terry Pratchett, Ian Stewart



PROLOGUE



* * *



WORLDS, DISC AND ROUND





There is a sensible way to make a world.

It should be flat, so that no one falls off accidentallyfn1 unless they get too near the edge, in which case it’s their own fault.

It should be circular, so that it can revolve sedately to create the slow progression of the seasons.

It should have strong supports, so that it doesn’t fall down.

The supports should rest on firm foundations.

To avoid an infinite regression, the foundations should do what foundations are supposed to do, and stay up of their own accord.

It should have a sun, to provide light. This sun should be small and not too hot, to save energy, and it should revolve around the disc to separate day from night.

The world should be populated by people, since there is no point in making it if no one is going to live there.

Everything should happen because people want it to (magic) or because the power of story (narrativium) demands it.

This sensible world is Discworld – flat, circular, held up by four world-bearing elephants standing firmly on the back of a giant space-faring turtle and inhabited by ordinary humans, wizards, witches, trolls, dwarves, vampires, golems, elves, the tooth fairy and the Hogfather.

But—

There is also a stupid way to make a world. And sometimes, that is necessary.

When an experiment in fundamental thaumaturgy on the squash court of Unseen University ran wild and threatened to destroy the universe, the computer Hex had to use up a huge quantity of magic in an instant. The only option was to activate the Roundworld Project, a magical force field that – paradoxically – keeps magic out. When the Dean of Unseen University poked his finger in to see what would happen, Roundworld switched on.

Roundworld isn’t entirely sure which bit of itself its name applies to. Sometimes the name refers to the planet, sometimes to the entire universe. There have been a few mishaps along the way, but the Roundworld universe has now been running fairly successfully for thirteen and a half billion years; all of it started by an old man with a beard.

In the absence of magic, and lacking natural narrativium, the Roundworld universe runs on rules. Not rules made by people, but rules made by Roundworld itself; which is weird, because Roundworld has no idea what its rules ought to be. It seems to make them up as it goes along, but it’s hard to be sure.

Certainly, it doesn’t know what size it ought to be. From outside, as it gathers dust on a shelf in Rincewind’s office, the Roundworld universe – a globe about 20 centimetres in diameter – resembles a cross between a foot-the-ball and a child’s snowstorm toy. From inside, it appears to be somewhat larger: a sphere whose radius is about 400 sextillion kilometres. As far as its only knownfn2 inhabitants can tell, it may be much larger still; perhaps even infinite.

Such a huge universe seems to be cosmic overkill, because those inhabitants occupy only the tiniest part of its awe-inspiring volume, namely the surface of an approximate sphere a mere twelve thousand kilometres across.

The wizards call this sphere Roundworld too. Its inhabitants call it Earth, because that’s what the surface is usually made of (except for the wet, rocky, sandy and icy bits): a typically parochial attitude. Until a few centuries ago they thought that Earth was fixed at the centre of the universe; the rest, which revolved around it or wandered crazily across the sky, was of minor importance since it didn’t contain them.

Roundworld the planet, as the name suggests, is round. Not round like a disc, but round like a foot-the-ball. It is younger than Roundworld the universe: about one third of its age. Though cosmically minuscule, the planet is fairly big compared to its inhabitants, so that if you live there, and you’re stupid, you can be fooled into imagining that it’s flat.

To prevent the planet’s inhabitants falling off, the rules state that a mysterious force glues them on. Thankfully, there are no world-bearing elephants. If there were, the inhabitants would be able to walk round their world to the point where it meets an elephant. This world-bearing beast of immense power would appear to be lying on its back, its feet in the air. (Paint the soles yellow and you wouldn’t be able to see it floating in a bowl of custard …)

Roundworld’s rules are democratic. Not only does this mysterious force glue people to their world: it glues everything to everything else. But the glue is weak, and everything can – and usually does – move.

This includes Roundworld the planet. It does have a sun, but this sun does not go round the planet. Instead, the planet goes round the sun. Worse, that doesn’t create day and night; instead, it produces seasons, because the planet is tilted. Also, the orbit isn’t circular. It’s a bit squashed, which is typical of Roundworld’s jerry-built construction. So to get day and night, the planet has to spin as well. It works, in its way: if you’re really stupid, you can be fooled into imagining that the sun goes round the planet. But – wouldn’t you just know it – the spin also prevented Roundworld from being a sensible sphere, because when it was molten it got sort of squashed, just like its orbit … oh, forget it.

As a consequence of this hopelessly bungled arrangement, the sun has to be enormous, and a very long distance away. So it has to be ridiculously hot: so hot that special new rules have to come into play to allow it to burn. And then almost all of its prodigious energy output is wasted, trying to warm up empty space.

Roundworld has no supports. It appears to think it’s a turtle, because it swims through space, tugged along by those mysterious forces. Its human inhabitants are not bothered by a sphere that swims, despite the absence of flippers. But then, people turned up at most four hundred thousand years ago, one hundredth of a per cent of the lifetime of the planet. And they seem to have turned up by accident, starting out as little blobs and then spontaneously becoming more complex – but they argue a lot about that. They’re not terribly bright, to be honest, and they only started to work out modern scientific rules of the universe they live in four hundred years ago, so they’ve got a lot of catching up to do.

The inhabitants refer to themselves optimistically as Homo sapiens, meaning ‘wise man’ in an appropriately dead language. Their activities seldom fit that description, but there are occasional glorious exceptions. They should really be called Pan narrans, the storytelling ape, because nothing appeals to them more than a rollicking good yarn. They are narrativium incarnate, and they are currently refashioning their world to resemble Discworld, so that things do happen because people want them to. They have invented their own form of magic, with spells like ‘make a dugout canoe’, ‘switch on the light’, and ‘login to Twitter’. This kind of magic cheats by using the rules behind the scenes, but if you’re really, really stupid you can ignore that and pretend it’s magic.

The first The Science of Discworld explained all that, and much more, including the giant limpet and the ill-fated crab civilisation’s great leap sideways. An endless series of natural disasters established something that the wizards intuitively knew from the word go: a round world is not a safe place to be. Fast-forwarding through Roundworld history, they managed to skip from some not very promising apes huddled around a black monolith to the collapse of the space elevators, as some presumably highly intelligent creatures, having finally got the message, fled the planet and headed for the stars to escape yet another ice age.

They couldn’t really be descended from those apes, could they? The apes seemed to have only two interests: sex, and bashing each other over the head.

In The Science of Discworld II, the wizards were surprised to find that the intelligent star-farers were indeed descended from the apes – a strange new use of the word ‘descend’, and one that caused serious trouble later. They found that out because Roundworld had taken the wrong leg of the Trousers of Time and had therefore deviated from its original timeline. Its ape-derived humans had become barbarians, their society vicious and riddled with superstition. They would never leave the planet in time to escape their doom. Something had interfered with Roundworld’s history.

Feeling somehow responsible for the planet’s fate, much as one might worry about a sick gerbil, the wizards entered their bizarre creation, to find that it was infested by elves. Discworld’s elves are not the noble creatures of some Roundworld myths. If an elf told you to eat your own head, you’d do it. But going back in time to when the elves had arrived, and kicking them out, just made everything worse. The evil had gone, but it had taken with it any shred of innovation.

Examining Roundworld’s history on what ought to have been its correct timeline, the wizards deduced that two key people – prominent among those very few wise ones – had never been born. This omission had to be repaired to get the planet back on track. They were William Shakespeare, whose artistic creations would give birth to a genuine spirit of humanity, and Isaac Newton, who would provide science. With considerable difficulty, and some interesting failures along the way requiring ceilings to be painted black, the wizards nudged humanity back onto the only timeline that would save it from annihilation. Shakespeare’s A Midsummer Night’s Dream tipped the tables decisively by exposing the elves to ridicule. Newton’s Principia Mathematica completed the job by pointing humanity at the stars. Job done.

It couldn’t last.

By the time of The Science of Discworld III, Roundworld was in trouble again. Having safely entered its Victorian era, which should have been a hotbed of innovation, it had once more departed from its proper history. New technology was developing, but at a snail’s pace. Some vital spur to innovation had been lost, and the gerbil of humanity was sick once more. This time, a key figure had written the wrong book. The Reverend Charles Darwin’s Theology of Species, explaining the complexity of life through divine intervention, had been so well received that science and religious belief had converged. The creative spark of rational debatefn3 had been lost. By the time the Reverend Richard Dawkins finally wrote The Origin of Species (by Means of Natural Selection &c &c &c …) it was too late to develop space travel before the ice came down.

This time, getting Darwin born was not the problem. Getting him to write the correct book … that was where everything went pear-shaped, and it proved remarkably hard to nudge history back on track. Contrary to the proverb, supplying a missing nail from a horse’s shoe does not save a kingdom. It generally has no effect, aside from making the horse feel a bit more comfortable, because hardly anything important has a single cause. It took a huge squad of wizards, making over two thousand carefully choreographed changes, to get Darwin onto the Beagle, stop him jumping ship when he was being as sick as a dog, and perk his interest in geology so that he stayed with the expeditionfn4 until it got to the Galápagos Islands.

They wouldn’t have succeeded at all, but the wizards eventually realised that something was actively interfering with their efforts to reset history to manufacturer’s specifications. The Auditors of Reality are the ultimate Health and Safety officers: they much prefer a universe in which nothing interesting ever happens, and they are willing to go to extreme lengths to ensure that it doesn’t. They had been blocking the wizards’ every move.

It was a near thing. Even when the wizards successfully arranged for Darwin to visit the Galápagos and notice the finches and mockingbirds and turtles, it took years for him to understand the significance of those creatures – by which time all the turtle shells were long gone, tossed overboard after their contents were eaten, and he’d given away the finches to a bird expert. (He had realised that the mockingbirds were interesting.) It took even longer to get him to take the plunge and write The Origin instead of The Ology; he kept writing scholarly books about barnacles instead. Then, when he had finally managed to write The Origin, he still messed up with Origin II, calling it The Descent of Man – oh dear. The Ascent of Man would have been a better marketing ploy.

Anyway, the wizards finally achieved success, even contriving to bring Darwin into Discworld to meet the God of Evolution and admire the wheels on his elephant. The publication of The Origin established the corresponding timeline as the only one that had ever happened. (The Trousers of Time are like that.) Roundworld was saved again, and could rest undisturbed on its shelf, gathering dust …

Until—

fn1 Falling off deliberately is another matter, about which they can be as imaginative as they wish. See The Light Fantastic, The Colour of Magic and The Last Hero.

fn2 This may be misleading since it is the opinion of the inhabitants concerned.

fn3 That is, insults, name-calling and shameless point-scoring.

fn4 Loosely speaking. He remained on land whenever feasible, about 70% of the entire ‘voyage’.