The Science of Discworld

by Terry Pratchett

  'I demand you put something on, man, you look thoroughly unhygienic!'

  There was another crack of discharged magic. Sparks flew off the end of Ridcully's fingers.

  'I felt that one!' he said, running back into his room.

  Beyond the window, on the other side of the gardens, the air wavered over the High Energy Magic building. As the Archchancellor watched, the two huge bronze globes on its roof became covered in crawling, zig-zagging purple lines —

  He hit the floor rolling, as wizards are wont to do, just before the shock of the discharge blew the windows in.

  Melted snow was pouring off the rooftops. Every icicle was a streaming finger of water.

  A large door bumped and scraped its way across the steaming lawns.

  Tor goodness' sake, Dean, handle your end, can't you?'

  The door skidded a little further.

  'It's no good, Ridcully, it's solid oak!'

  'And I'm very glad of it!'

  Behind Ridcully and the Dean, who were inching the door forward largely by arguing with each other, the rest of the faculty crept forward.

  The bronze globes were humming now, in the rapidly decreasing intervals between discharges. They had been installed, to general scoffing, as a crude method of releasing the occasional erratic build-up of disorganized magic in the building. Now they were outlined in unhealthy-looking light.

  'And we know what that means, don't we, Mister Stibbons?' said Ridcully, as they reached the entrance to the High Energy Magic building.

  'The fabric of reality being unravelled and leaving us prey to creatures from the Dungeon Dimensions, sir?' mumbled Stibbons, who was trailing behind.

  'That's right, Mister Stibbons! And we don't want that, do we, Stibbons?'

  'No, sir.'

  'No, sir! We don't, sir!' Ridcully roared. 'It'll be tentacles all over the place again. And none of us wants tentacles all over the place, do we?'

  'No, sir.'

  'No, sir! So switch the damned thing off, sir!'

  'But it'd be certain death to go into —’ Ponder stopped, swallowed and restarted. 'In fact it would be uncertain death to go into the squash court at the moment, Archchancellor. There must be million of thaums of random magic in there! Anything could happen!'

  Inside the HEM the ceiling was vibrating. The whole building seemed to be dancing.

  'They certainly knew how to build, didn't they, when they built the old squash court,' said the Lecturer in Recent Runes, in an admiring tone of voice. 'Of course, it was built to contain large amounts of magic ...'

  'Even if we could switch it off, I don't think that'd be such a good idea,' said Ponder.

  'Sounds a lot better than what's happening now,' said the Dean.

  'But is falling through the air better than hitting the ground?' said Ponder.

  Ridcully sucked in his breath between his teeth.

  'That's a point,' he said. 'Could be something of an implosion, I suppose. You can't just stop something like this. Something bad would happen.'

  'The end of the world?' quavered the Senior Wrangler.

  'Probably just this part of it,' said Ponder.

  'Are we talking here about a sort of huge valley about twenty miles across with mountains all round it?' said Ridcully, staring at the ceiling. Cracks were zig-zagging across it.

  'Yes, sir, I'm wondering if whoever tried this at Loko actually did manage to switch it off ...'

  The walls groaned. There was a rattling noise behind Ponder. He recognized it, even above the din. It was the sound of HEX resetting its writing device. Ponder always thought of it as a kind of mechanical throat-clearing.

  The pen jerked in its complex network of threads and springs, and then wrote:

  +++ This May Be Time For The Roundworld Project +++

  'What are you talking about, man?' snapped Ridcully, who'd never quite understood what HEX was.

  'Oh, that? That's been around for ages,' said the Dean. 'No one's ever taken it seriously. It's just a thought experiment. You couldn't do it. It's completely absurd. It needs far too much magic.'

  'Well, we've got far too much magic,' said Ridcully. 'Right now we need to use it up.'

  There was a moment's silence. That is, the wizards were silent. Overhead, magic flared into the sky with a sound like roaring gas.

  'Can't let it build up here,' Ridcully went on. 'What's the Roundworld project then?'

  'It was, er ... there was once some suggestion that it might be possible to create a ... an area where the laws of magic don't apply,' said Ponder. 'We could use it to learn more about magic.'

  'Magic's everywhere' said Ridcully. 'It's part of what everywhere is'

  'Yes, sir,' said Ponder, watching the Archchancellor carefully.

  The ceiling creaked.

  'What use would it be, anyway?' said Ridcully, still thinking aloud.

  'Well, sir, you could ask what use is a new-born child ...'

  'No, that's not the sort of question I ask,' said Ridcully. 'And it's a highly suspicious one, too.'

  The wizards ducked as the latest discharge crackled overhead. It was followed by a louder explosion.

  'I think the balls have just exploded, sir,' said Ponder.

  'All right, then, how long would the project take to set up?' said Ridcully.

  'Months,' said the Dean firmly.

  'We've got about ten seconds to the next discharge, sir,' said Ponder. 'Only ... now the balls have gone it will simply earth itself...'

  'Ah. Oh. Really? Well, then ...' Ridcully looked around at his fellow wizards as the wall began to shake again. 'It's been nice knowing you. Some of you. One or two of you, anyway ...'

  The whine of increasing magic rose in pitch.

  The Dean cleared his throat.

  'I'd just like to say, Mustrum,' he began.

  'Yes, old friend?'

  'I'd just like to say ... I think I'd have made a much better Archchancellor than you.'

  The whine stopped. The silence twanged. The wizards held their breath.

  Something went 'ping'.

  A globe about a foot across hung in the air between the faculty. It looked like glass, or the sheen of a pearl without the pearl itself.

  From the squash court next door there was, instead of the wild roar of disorganized thaums, the steady thrum-thrum of purpose.

  'What the heck is that?' said Ridcully, as the wizards unfolded themselves.

  HEX rattled. Ponder picked up the piece of paper.

  'Well, according to this, it's the Roundworld Project,' he said. 'And it's absorbing all the energy from the thaumic pile.'

  The Dean brushed some dust off his robe.

  'Nonsense,' he said. 'Takes months. Anyway, how could that machine possibly know the spells?'

  'Mr Turnipseed did copy in a lot of the grimoires last year,' said Ponder. 'It's vital that HEX knows basic spell structure, you see .,.'

  The Senior Wrangler peered irritably at the sphere.

  'Is this all it is?' he said. 'Doesn't seem much for all that effort.'

  There was a frightening moment as the Dean walked up to the sphere and his nose, enormously magnified, appeared in it.

  'Old Archchancellor Bewdley devised it,' he said. 'Everyone said it was impossible ...'

  'Mr Stibbons?' said Ridcully.

  'Yes, sir?'

  'Are we in danger of blowing up at the moment?'

  'I don't think so, sir. The ... project is sucking up everything.'

  'Shouldn't it be glowing, then? Or something? What's in there?'

  HEX wrote: +++ Nothing +++

  'All that magic's going into empty space?'

  +++ Empty Space Is Not Nothing, Archchancellor. There Is Not Even Empty Space Inside The Project. There Is No Time For It To Be Empty In +++

  'What's it got in it, then?'

  +++ I Am Checking +++, HEX wrote patiently.

  'Look, I can stick my hand right in it,' said the Dean.

  The wizards watched in horror. The Dea
n's fingers were visible, darkly, within the sphere, outlined in thousands of tiny sparkling lights.

  'That was a really very foolish thing you just did,' said Ridcully. 'How did you know it wasn't dangerous?'

  'I didn't,' said the Dean cheerfully, 'It feels ... cool. And rather chilly. Prickly, in a funny sort of way'

  HEX rattled. Ponder walked back and looked down at the paper. 'It almost feels sticky when I move my fingers,' said the Dean.

  'Er ... Dean?' said Ponder, stepping back carefully. 'I think it would be a really good idea if you pulled your hand out very, very carefully and really very soon.'

  'That's odd, it's beginning to tingle —'

  'Right now, Dean! Right now!'

  For once, the urgency in Ponder's voice got through the Dean's cosmic self-confidence. He turned to argue with Ponder Stibbons just a moment before a white spark appeared in the centre of the sphere and began to expand rapidly.

  The sphere flickered.

  'Anyone know what caused that?' said the Senior Wrangler, his face bathed in the growing light of the Project.

  'I think,' said Ponder slowly, holding up HEX's write-out, 'it was Time and Space starting to happen.'

  In HEX's careful writing, the words said: +++ In The Absence Of Duration And Dimension, There Must Be Potentiality. +++

  And the wizards looked upon the universe that was growing within the little sphere and spake amongst themselves, saying, 'It's rather a small one, don't you think? Is it dinner time yet?'

  Later on, the wizards wondered if the new universe might have been different if the Dean had waggled his fingers in a different way. Perhaps, within it, matter might have naturally formed itself into, say, garden furniture, or one giant nine-dimensional flower a trillion miles across. But Archchancellor Ridcully pointed out that this was not very useful thinking, because of the ancient principle of WYGIWYGAINGW*.

  'What You Get Is What You’re Given And It’s No Good Whining. '

  SIX

  BEGINNINGS AND BECOMINGS

  POTENTIALITY IS THE KEY.

  Our immediate task is to start from a lot of vacuum and a few rules, and convince you that they have enormous potentiality. Given enough time, they can lead to people, turtles, weather, the Internet — hold it. Where did all that vacuum come from? Either the universe has been around forever, or once there wasn't a universe and then there was. The second statement fits neatly with the human predilection for creation myths. It also appeals to today's scientists — possibly for the same reason. Lies-to-children run deep.

  Isn't vacuum just . . . empty space? What was there before we had space? How do you make space? Out of vacuum? Isn't that a vicious circle? If in the past we didn't have space, how can there have been a 'there' for whatever it was to exist in? And if there wasn't anywhere for it to exist, how did it manage to make space? Maybe space was there all along . . . but why? And what about time? Space is easy compared to time. Space is just ... somewhere to put matter. Matter is just ... stuff. But time — time flows, time passes, time makes sense in the past and the future but not in the instantaneous, frozen present. What makes time flow? Could the flow of time be stopped? What would happen if it did?

  There are little questions, there are medium-sized questions, and there are big questions. After which there are even bigger questions, huge questions, and questions so vast that it is hard to imagine what kind of response would count as an answer.

  You can usually recognize the little questions: they look immensely complicated. Things like 'What is the molecular structure of the left-handed isomer of glucose?' As the questions get bigger, they become deceptively simpler: 'Why is the sky blue?' The really big questions are so simple that it seems astonishing that science has absolutely no idea how to answer them: 'Why doesn't the universe run backwards instead?' or 'Why does red look like that?’

  All this goes to show that it's a lot easier to ask a question than it is to answer it, and the more specialized your question is, the longer are the words that you must invent to state it. Moreover, the bigger a question is, the more people are interested in it. Hardly anybody cares about left-handed glucose, but nearly all of us wonder why red looks the way it does, and we vaguely wonder whether it looks the same to everybody else.

  Out on the fringes of scientific thought are questions that are big enough to interest almost everybody, but small enough for there to be a chance of answering them reasonably accurately. They are questions like 'How did the universe begin?' and 'How will it end?' ('What happens in between?' is quite a different matter.) Let us acknowledge, right up front, that the current answers to such questions depend upon various questionable assumptions. Previous generations have been absolutely convinced that their scientific theories were well-nigh perfect, only for it to turn out that they had missed the point entirely. Why should it be any different for our generation? Beware of scientific fundamentalists who try to tell you everything is pretty much worked out, and only a few routine details are left to do. It is just when the majority of scientists believe such things that the next revolution in our world-view creeps into being, its feeble birth-squeaks all but drowned by the earsplitting roar of orthodoxy.

  Let's take a look at the current view of how the universe began. One of the points we are going to make is that human beings have trouble with the concept of 'beginning'. And even more trouble, let it be said, with 'becoming'. Our minds evolved to carry out rather specific tasks like choosing a mate, killing bears with a sharp stick, and getting dinner without becoming it. We've been surprisingly good at adapting those modules to tasks for which they were never 'intended', that is, tasks for which they were not used during their evolution, there being no conscious 'intention', such as planning a route up the Matterhorn, carving images of sea-lions on polar bears' teeth,* and calculating the combustion point of a complex hydrocarbon molecule. Because of the way our mental modules evolved, we think of beginnings as being analogous to how a day begins, or how a hike across the desert begins; and we think of becomings in the same way that a polar bear's tooth becomes a carved amulet, or a live spider becomes dead when you squash it.

  That is: beginnings start from somewhere (which is where whatever it is begins), and becomings turn Thing One into Thing Two by pushing it across a clearly defined boundary (the tooth was not carved, but now it is; the spider was not dead, but now it is). Unfortunately the universe doesn't work in such a simple-minded manner, so we have serious trouble thinking about how a universe can begin, or how an ovum and a sperm can become a living child.

  Let us leave becomings for a moment, and think about beginnings. Thanks to our evolutionary prejudices, we tend to think of the beginning of the universe as being some special time, before which the universe did not exist and after which it did. Moreover, when the universe changed from not being there to being there, something must have caused that change — something that was around before the universe began, otherwise it wouldn't have been able to cause the universe to come into being. When you bear in mind that the beginning of the universe is also the beginning of space and the beginning of time, however, this point of view is distinctly problematic. How can there be a 'before' if time has not yet started? How can there be a cause for the universe starting up, without space for that cause to happen in — and time for it to happen?

  Maybe there was something else in existence already ... but now we have to decide how that got started, and the same difficulties arise. All right, let's go the whole hog: something — perhaps the universe itself, perhaps some precursor — was around forever. It didn't have a beginning, it just was, always.

  Satisfied? Things that exist forever don't have to be explained, because they don't need a cause? Then what caused them to have been around forever?

  It now becomes impossible not to mention the turtle joke. Stephen Hawking tells it at the start A Brief History of Time, but it goes back a lot further. According to Hindu legend, the Earth rides on the back of four elephants, which ride on a turtle. But wha
t supports the turtle? In Discworld, Great A'Tuin needs no support, swimming through the universe unperturbed by any thought about what holds it up. That's magic in action: world-carrying turtles are like that. But according to the old lady who espoused the Hindu cosmology, and was asked the same question by a learned astronomer, there is a different answer: 'It's turtles all the way down!' The image of an infinite pile of turtles is instantly ludicrous, and very few people find it a satisfying explanation. Indeed very few people find it a satisfying kind of explanation, if only because it doesn't explain what supports the infinite pile of turtles. However, most of us are quite content to explain the origins of time as 'it's always been there'. Seldom do we examine this statement closely enough to realize that what it really says is 'It's time all the way back.' Now replace 'time' by 'turtle' and 'back' by 'down' ... Each instant of time is 'supported', that is, a causal consequence of, the previous instant of time. Fine, but that doesn't explain why time exists. What caused that infinite expanse of time? What holds up the whole pile?

  All of which puts us in a serious quandary. We have problems thinking of time as beginning without a precursor, because it's hard to see how the causality goes. But we have equally nasty problems thinking of time as beginning with a precursor, because then we hit the turtle-pile problem. We have similar problems with space: either it goes on forever, in which case it's 'space all the way out' and we need somewhere even bigger to put the whole thing, or it stops, in which case we wonder what's outside it.

  The real point is that neither of these options is satisfactory, and the origins of space and time fit neither model. The universe is not like a village, which ends at a fence or an imaginary line on the ground, neither is it like the distant desert which seems to vanish into eternity but actually just gets too far away for us to see it clearly. Time is not like a human lifespan, which starts at birth and ends at death, nor is it like the extended lifespan found in many religions, where the human soul continues to live indefinitely after death, and the much rarer belief (held, for example, by Mormons) that some aspect of each person was somehow already alive in the indefinite past.