COVER
ABOUT THE BOOK
ABOUT THE AUTHORS
ALSO BY TERRY PRATCHETT, IAN STEWART & JACK COHEN
TITLE PAGE
THE STORY STARTS HERE …
1 SPLITTING THE THAUM
2 SQUASH COURT SCIENCE
3 I KNOW MY WIZARDS
4 SCIENCE AND MAGIC
5 THE ROUNDWORLD PROJECT
6 BEGINNINGS AND BECOMINGS
7 BEYOND THE FIFTH ELEMENT
8 WE ARE STARDUST (OR, AT LEAST WE WENT TO WOODSTOCK)
9 EAT HOT NAPHTHA, EVIL DOG!
10 THE SHAPE OF THINGS
11 NEVER TRUST A CURVED UNIVERSE
12 WHERE DO RULES COME FROM?
13 NO, IT CAN’T DO THAT
14 DISC WORLDS
15 THE DAWN OF DAWN
16 EARTH AND FIRE
17 SUIT OF SPELLS
18 AIR AND WATER
19 THERE IS A TIDE …
20 A GIANT LEAP FOR MOONKIND
21 THE LIGHT YOU SEE THE DARK BY
22 THINGS THAT AREN’T
23 NO POSSIBILITY OF LIFE
24 DESPITE WHICH …
25 UNNATURAL SELECTION
26 THE DESCENT OF DARWIN
27 WE NEED MORE BLOBS
28 THE ICEBERG COMETH
29 GOING FOR A PADDLE
30 UNIVERSALS AND PAROCHIALS
31 GREAT LEAP SIDEWAYS
32 DON’T LOOK UP
33 THE FUTURE IS NEWT
34 NINE TIMES OUT OF TEN
35 STILL BLOODY LIZARDS
36 RUNNING FROM DINOSAURS
37 I SAID, DON’T LOOK UP
38 THE DEATH OF DINOSAURS
39 BACKSLIDERS
40 MAMMALS ON THE MAKE
41 DON’T PLAY GOD
42 ANTHILL INSIDE
43 OOK: A SPACE ODYSSEY
44 EXTEL OUTSIDE
45 THE BLEAT GOES ON
46 WAYS TO LEAVE YOUR PLANET
47 YOU NEED CHELONIUM
48 EDEN AND CAMELOT
49 AS ABOVE, SO BELOW
INDEX
COPYRIGHT
When a thaumic experiment goes adrift, the wizards of Unseen University find that they’ve accidently created a new universe. Within it is a planet that they name Roundworld, an extraordinary place where neither magic nor common sense seem to stand a chance against logic.
The universe, of course, is our own. And Roundworld is Earth. As the wizards watch their creation grow, we follow the story of our universe from the primal singularity of the Big Bang to the evolution of life on Earth and beyond.
This original Terry Pratchett story, interwoven with science chapters from Jack Cohen and Ian Stewart, offers a wonderful wizard’s-eye view of our own universe. Once you’ve seen the world from a Discworld perspective, it will never seem the same again…
Sir Terry Pratchett was the acclaimed creator of the global bestselling Discworld series; the first Discworld book, The Colour of Magic, was published in 1983. In all, he was the author of fifty bestselling books. His novels have been widely adapted for stage and screen, and he was the winner of multiple prizes, including the Carnegie Medal, as well as being awarded a knighthood for services to literature. Worldwide sales of his books now stand at 75 million. He died in March 2015.
Professor Ian Stewart is the author of many popular science books and appears frequently on radio and television. He is an Emeritus Professor of Mathematics at the University of Warwick. He was awarded the Michael Faraday Medal for furthering the public understanding of science, and in 2001 became a Fellow of the Royal Society.
Dr Jack Cohen is an internationally renowned reproductive biologist. He has retired to a small thatched cottage in Dorset. He writes, ponders, and plays with microscopes in a rather grand ‘garden shed’. He also throws boomerangs, but doesn’t catch them as often as he used to. In addition, he still enjoys lecturing and continues to have a passion for the public understanding of science.
TERRY PRATCHETT
The Discworld® series
THE COLOUR OF MAGIC • THE LIGHT FANTASTIC • EQUAL RITES • MORT • SOURCERY • WYRD SISTERS • PYRAMIDS • GUARDS! GUARDS! • ERIC (illustrated by Josh Kirby) • MOVING PICTURES • REAPER MAN • WITCHES ABROAD • SMALL GODS • LORDS AND LADIES • MEN AT ARMS • SOUL MUSIC • INTERESTING TIMES • MASKERADE • FEET OF CLAY • HOGFATHER • JINGO • THE LAST CONTINENT • CARPE JUGULUM • THE FIFTH ELEPHANT • THE TRUTH • THIEF OF TIME • THE LAST HERO (illustrated by Paul Kidby) • THE AMAZING MAURICE AND HIS EDUCATED RODENTS (for younger readers) • NIGHT WATCH • THE WEE FREE MEN (for younger readers) • MONSTROUS REGIMENT • A HAT FULL OF SKY (for younger readers) • GOING POSTAL • THUD • WINTERSMITH (for younger readers) • MAKING MONEY • UNSEEN ACADEMICALS • I SHALL WEAR MIDNIGHT (for younger readers) • SNUFF
The Science of Discworld series
(with Ian Stewart and Jack Cohen)
THE SCIENCE OF DISCWORLD II: THE GLOBE
THE SCIENCE OF DISCWORLD III: DARWIN’S WATCH
THE SCIENCE OF DISCWORLD IV: JUDGEMENT DAY
Other books about Discworld
TURTLE RECALL: THE DISCWORLD COMPANION … SO FAR (with Stephen Briggs)
NANNY OGG’S COOKBOOK (with Stephen Briggs, Tina Hannan and Paul Kidby)
THE PRATCHETT PORTFOLIO (with Paul Kidby)
THE DISCWORLD ALMANAK (with Bernard Pearson)
THE UNSEEN UNIVERSITY CUT-OUT BOOK (with Alison Batley and Bernard Pearson)
WHERE’S MY COW? (illustrated by Melvyn Grant)
THE ART OF DISCWORLD (with Paul Kidby)
THE WIT AND WISDOM OF DISCWORLD (compiled by Stephen Briggs)
THE FOLKLORE OF DISCWORLD (with Jacqueline Simpson)
MISS FELICITY BEEDLE’S THE WORLD OF POO (assisted by Bernard and Isobel Pearson)
Discworld Maps and Gazetteers
THE STREETS OF ANKH-MORPORK (with Stephen Briggs, painted by Stephen Player)
THE DISCWORLD MAPP (with Stephen Briggs, painted by Stephen Player)
A TOURIST GUIDE TO LANCRE – A DISCWORLD MAPP (with Stephen Briggs, illustrated by Paul Kidby)
DEATH’S DOMAIN (with Paul Kidby)
THE COMPLEAT ANKH-MORPORK (with the Discworld Emporium)
A complete list of Terry Pratchett ebooks and audio books as well as other books based on the Discworld series – illustrated screenplays, graphic novels, comics and plays – can be found on www.terrypratchett.co.uk
Non-Discworld books
THE DARK SIDE OF THE SUN • STRATA
THE UNADULTERATED CAT (illustrated by Gray Jolliffe)
GOOD OMENS (with Neil Gaiman)
THE LONG EARTH (with Stephen Baxter)
A BLINK OF THE SCREEN: COLLECTED SHORT FICTION
Non-Discworld novels for younger readers
THE CARPET PEOPLE • TRUCKERS • DIGGERS • WINGS • ONLY YOU CAN SAVE MANKIND • JOHNNY AND THE DEAD • JOHNNY AND THE BOMB • NATION • DODGER
Ian Stewart
CONCEPTS OF MODERN MATHEMATICS • GAME, SET, AND MATH • DOES GOD PLAY DICE? • ANOTHER FINE MATH YOU’VE GOT ME INTO • FEARFUL SYMMETRY • NATURE’S NUMBERS • FROM HERE TO INFINITY • THE MAGICAL MAZE • LIFE’S OTHER SECRET • FLATTERLAND • WHAT SHAPE IS A SNOWFLAKE? • THE ANNOTATED FLATLAND • MATH HYSTERIA • THE MAYOR OF UGLYVILLE’S DILEMMA • HOW TO CUT A CAKE • LETTERS TO A YOUNG MATHEMATICIAN • TAMING THE INFINITE (alternative title: THE STORY OF MATHEMATICS) • WHY BEAUTY IS TRUTH • COWS IN THE MAZE • MATHEMATICS OF LIFE • PROFESSOR STEWART’S CABINET OF MATHEMATICAL CURIOSITIES • PROFESSOR STEWART’S HOARD OF MATHEMATICAL TREASURES • SEVENTEEN EQUATIONS THAT CHANGED THE WORLD (alternative title: IN PURSUIT OF THE UNKNOWN) • JACK OF ALL TRADES (science fiction ebook) • THE GREAT MATHEMATICAL PROBLEMS (alternative title: VISIONS OF INFINITY) • SYMMETRY: A VERY SHORT INTRODUCTION
Jack Cohen
LIVING EMBRYOS • REPRODUCTION • PARENTS MAKING PARENTS SPERMS, ANTIBODIES AND INFERTILITY • THE PRIVILEGED APE STOP WORKING AND START THINKING (with Graham Medley)
Jack Cohen and Ian Stewart
THE COLLAPSE OF CHAOS
EVOLVING THE ALIEN (alternative title: WHAT DOES A MARTIAN LOOK LIKE?)
Ian Stewart and Jack Cohen
FIGMENTS OF REALITY
WHEELERS (science fiction) • HEAVEN (science fiction)
This ebook is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorized distribution or use of this text may be a direct infringement of the author’s and publisher’s rights and those responsible may be liable in law accordingly.
Epub ISBN 9781448176670
Version 1.0
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Ebury Press, an imprint of Ebury Publishing,
20 Vauxhall Bridge Road,
London SW1V 2SA
Ebury Press is part of the Penguin Random House group of companies whose addresses can be found at global.penguinrandomhouse.com
Copyright © Terry and Lyn Pratchett, Joat Enterprises, Jack Cohen 1999, 2002
Line drawings © Paul and Sandra Kidby 1999, 2002
Cover illustration by Paul Kidby
Terry Pratchett, Ian Stewart and Jack Cohen have asserted their right to be identified as the authors of this Work in accordance with the Copyright, Designs and Patents Act 1988
First published by Ebury Press in 1999
www.eburypublishing.co.uk
A CIP catalogue record for this book is available from the British Library
ISBN 9780091951702
ONCE UPON A time, there was Discworld. There still is an adequate supply.
Discworld is the flat world, carried through space on the back of a giant turtle, which has been the source of – so far – twenty-seven novels, four maps, an encyclopaedia, two animated series, t-shirts, scarves, models, badges, beer, embroidery, pens, posters, and probably, by the time this is published, talcum powder and body splash (if not, it can only be a matter of time).
It has, in short, become immensely popular.
And Discworld runs on magic.
Roundworld – our home planet, and by extension the universe in which it sits – runs on rules. In fact, it simply runs. But we have watched the running, and those observations and the ensuing deductions are the very basis of science.
Magicians and scientists are, on the face of it, poles apart. Certainly, a group of people who often dress strangely, live in a world of their own, speak a specialized language and frequently make statements that appear to be in flagrant breach of common sense have nothing in common with a group of people who often dress strangely, speak a specialized language, live in … er …
Perhaps we should try this another way. Is there a connection between magic and science? Can the magic of Discworld, with its eccentric wizards, down-to-Earth witches, obstinate trolls, fire-breathing dragons, talking dogs, and personified DEATH, shed any useful light on hard, rational, solid, Earthly science?
We think so.
We’ll explain why in a moment, but first, let’s make it clear what The Science of Discworld is not. There have been several media tie-in The Science of … books, such as The Science of the X-Files and The Physics of Star Trek. They tell you about areas of today’s science that may one day lead to the events or devices that the fiction depicts. Did aliens crash-land at Roswell? Could an anti-matter warp drive ever be invented? Could we ever have the ultra long-life batteries that Scully and Mulder must be using in those torches of theirs?
We could have taken that approach. We could, for example, have pointed out that Darwin’s theory of evolution explains how lower lifeforms can evolve into higher ones, which in turn makes it entirely reasonable that a human should evolve into an orangutan (while remaining a librarian, since there is no higher life form than a librarian). We could have speculated on which DNA sequence might reliably incorporate asbestos linings into the insides of dragons. We might even have attempted to explain how you could get a turtle ten thousand miles long.
We decided not to do these things, for a good reason … um, two reasons.
The first is that it would be … er … dumb.
And this because of the second reason. Discworld does not run on scientific lines. Why pretend that it might? Dragons don’t breathe fire because they’ve got asbestos lungs – they breathe fire because everyone knows that’s what dragons do.
What runs Discworld is deeper than mere magic and more powerful than pallid science. It is narrative imperative, the power of story. It plays a role similar to that substance known as phlogiston, once believed to be that principle or substance within inflammable things that enabled them to burn. In the Discworld universe, then, there is narrativium. It is part of the spin of every atom, the drift of every cloud. It is what causes them to be what they are and continue to exist and take part in the ongoing story of the world.
On Roundworld, things happen because the things want to happen.fn1 What people want does not greatly figure in the scheme of things, and the universe isn’t there to tell a story.
With magic, you can turn a frog into a prince. With science, you can turn a frog into a Ph.D and you still have the frog you started with.
That’s the conventional view of Roundworld science. It misses a lot of what actually makes science tick. Science doesn’t just exist in the abstract. You could grind the universe into its component particles without finding a single trace of Science. Science is a structure created and maintained by people. And people choose what interests them, and what they consider to be significant and, quite often, they have thought narratively.
Narrativium is powerful stuff. We have always had a drive to paint stories on to the Universe. When humans first looked at the stars, which are great flaming suns an unimaginable distance away, they saw in amongst them giant bulls, dragons, and local heroes.
This human trait doesn’t affect what the rules say – not much, anyway – but it does determine which rules we are willing to contemplate in the first place. Moreover, the rules of the universe have to be able to produce everything that we humans observe, which introduces a kind of narrative imperative into science too. Humans think in storiesfn2. Classically, at least, science itself has been the discovery of ‘stories’ – think of all those books that had titles like The Story of Mankind, The Descent of Man, and, if it comes to that, A Brief History of Time.
Over and above the stories of science, though, Discworld can play an even more important role: What if? We can use Discworld for thought experiments about what science might have looked like if the universe had been different, or if the history of science had followed a different route. We can look at science from the outside.
To a scientist, a thought experiment is an argument that you can run through in your head, after which you understand what’s going on so well that there’s no need to do a real experiment, which is of course a great saving in time and money and prevents you from getting embarrassingly inconvenient results. Discworld takes a more practical view – there, a thought experiment is one that you can’t do and which wouldn’t work if you could. But the kind of thought experiment we have in mind is one that scientists carry out all the time, usually without realizing it; and you don’t need to do it, because the whole point is that it wouldn’t work. Many of the most important questions in science, and about our understanding of it, are not about how the universe actually is. They are about what would happen if the universe were different.
Someone asks ‘why do zebras form herds?’ You could answer this by an analysis of zebra sociology, psychology, and so on … or you could ask a question of a very different kind: ‘What would happen if they didn’t?’ One fairly obvious answer to that is ‘They’d be much more likely to get eaten by lions.’ This immediately suggests that zebras form herds for self-protection – and now we’ve got some insight into what zebras actually do by contemplating, for a moment, the possibility that they might have done something else.
Another, more serious example is the question ‘Is the solar system stable?’, which means ‘Could it change dramatically as a result of some tiny disturbance?’ In 1887 King Oscar II of Sweden offered a prize of 2,500 crowns for the answer. It took about a century for the world’s mathematicians to come up with a definite answer: ‘Maybe’. (It was a good answer, but they didn’t get paid. The prize had already been awarded to someone who didn’t get the answer and whose prizewinning article had a big mistake right at the most interesting part. But when he put it right, at his own expense, he invented Chaos Theory and paved the way for the ‘maybe’. Sometimes, the best answer is a more interesting question.) The point here is that stability is not about what a system is actually doing: it is about how the system would change if you disturbed it. Stability, by definition, deals with ‘what if?’.
Because a lot of science is really about this non-existent world of thought experiments, our understanding of science must concern itself with worlds of the imagination as well as with worlds of reality. Imagination, rather than mere intelligence, is the truly human quality. And what better world of the imagination to start from than Discworld? Discworld is a consistent, well-developed universe with its own kinds of rules, and convincingly real people live on it despite the substantial differences between their universe’s rules and ours. Many of them also have a thoroughgoing grounding in ‘common sense’, one of science’s natural enemies.
Appearing regularly within the Discworld canon are the buildings and faculty of Unseen University, the Discworld’s premier college of magic. The wizardsfn3 are a lively bunch, always ready to open any door that has ‘This door to be kept shut’ written on it or pick up anything that has just started to fizz. It seemed to us that they could be useful…
Clearly, as the wizards of Unseen University believe, this world is a parody of the Discworld one. If we, or they, compare Discworld’s magic to Roundworld science, the more similarities and parallels we find. And when we didn’t discover parallels, we found that the differences were very revealing. Science takes on a new character when you stop asking questions like ‘What does newt DNA look like?’ and instead ask ‘I wonder how the wizards would react to this way of thinking about newts?’
There is no science as such on Discworld. So we have put some there. By magical means, the wizards on Discworld are led to create their own brand of science – some kind of ‘pocket universe’ in which magic no longer works, but rules do. Then, as the wizards learn to understand how the rules make interesting things happen – rocks, bacteria, civilizations – we watch them watching … well, us. It’s a sort of recursive thought experiment, or a Russian doll wherein the smaller dolls are opened up to find the largest doll inside.
And then we found that … ah, but that is another story.
TP, IS, & JC, DECEMBER 1998
PS We have, we are afraid, mentioned in the ensuing pages Schrödinger’s Cat, the Twins Paradox, and that bit about shining a torch ahead of a spaceship travelling at the speed of light. This is because, under the rules of the Guild of Science Writers, they have to be included. We have, however, tried to keep them short.
We’ve managed to be very, very brief about the Trousers of Time, as well.
PPS Sometimes scientists change their minds. New developments cause a rethink. If this bothers you, consider how much damage is being done to the world by people for whom new developments do not cause a rethink.
This second edition has been changed to reflect three years of scientific progress… forwards or backwards. (You will find both.) And we’ve added two completely new chapters: one on the life of dinosaurs, because the existing chapter on the death of dinosaurs seemed a bit depressing; and one on cosmic disasters, because in many ways the universe is depressing.
The Discworld story has proved more robust than the science. As should be expected. Discworld makes so much more sense than Roundworld does.
TP, IS, & JC, JANUARY 2002
fn1 In a manner of speaking. They happen because things obey the rules of the universe. A rock has no detectable opinion about gravity.
fn2 It took three years for this sentence to sink in. When it did, we wrote The Science of Discworld II: The Globe.
fn3 Like the denizens of any Roundworld university, they have unlimited time for research, unlimited funds and no worries about tenure. They are also by turns erratic, inventively malicious, resistant to new ideas until they’ve become old ideas, highly creative at odd moments and perpetually argumentative – in this respect they bear no relation to their Roundworld counterparts at all.
SOME QUESTIONS SHOULD not be asked. However, someone always does.
‘How does it work?’ said Archchancellor Mustrum Ridcully, the Master of Unseen University.
This was the kind of question that Ponder Stibbons hated almost as much as ‘How much will it cost?’ They were two of the hardest questions a researcher ever had to face. As the university’s de facto head of magical development, he especially tried to avoid questions of finance at all costs.
‘In quite a complex way,’ he ventured at last.
‘Ah.’
‘What I’d like to know,’ said the Senior Wrangler, ‘is when we’re going to get the squash court back.’
‘You never play, Senior Wrangler,’ said Ridcully, looking up at the towering black construction that now occupied the centre of the old university court.fn1
‘I might want to one day. It’ll be damn hard with that thing in the way, that’s my point. We’ll have to completely rewrite the rules.’
Outside, snow piled up against the high windows. This was turning out to be the longest winter in living memory – so long, in fact, that living memory itself was being shortened as some of the older citizens succumbed. The cold had penetrated even the thick and ancient walls of Unseen University itself, to the general concern and annoyance of the faculty. Wizards can put up with any amount of deprivation and discomfort, provided it is not happening to them.
And so, at long last, Ponder Stibbons’s project had been authorized. He’d been waiting three years for it. His plea that splitting the thaum would push back the boundaries of human knowledge had fallen on deaf ears; the wizards considered that pushing back the boundaries of anything was akin to lifting up a very large, damp stone. His assertion that splitting the thaum might significantly increase the sum total of human happiness met with the rejoinder that everyone seemed pretty happy enough already.
Finally he’d ventured that splitting the thaum would produce vast amounts of raw magic that could very easily be converted into cheap heat. That worked. The Faculty were lukewarm on the subject of knowledge for knowledge’s sake, but they were boiling hot on the subject of warm bedrooms.
Now the other senior wizards wandered around the suddenly-cramped court, prodding the new thing. Their Archchancellor took out his pipe and absent-mindedly knocked out the ashes on its matt black side.
‘Um … please don’t do that, sir,’ said Ponder.
‘Why not?’
‘There might be … it might… there’s a chance that…’ Ponder stopped. ‘It will make the place untidy, sir,’ he said.
‘Ah. Good point. So it’s not that the whole thing might explode, then?’
‘Er … no, sir. Haha,’ said Ponder miserably. ‘It’d take a lot more than that, sir –’
There was a whack as a squash ball ricocheted off the wall, rebounded off the casing, and knocked the Archchancellor’s pipe out of his mouth.
‘That was you, Dean,’ said Ridcully accusingly. ‘Honestly, you fellows haven’t taken any notice of this place in years and suddenly you all want to – Mr Stibbons? Mr Stibbons?’
He nudged the small mound that was the hunched figure of the University’s chief research wizard. Ponder Stibbons uncurled slightly and peered between his fingers.
‘I really think it might be a good idea if they stopped playing squash, sir,’ he whispered.
‘Me too. There’s nothing worse than a sweaty wizard. Stop it, you fellows. And gather round. Mr Stibbons is going to do his presentation.’ The Archchancellor gave Ponder Stibbons a rather sharp look. ‘It is going to be very informative and interesting, isn’t it, Mister Stibbons. He’s going to tell us what he spent AM$55,879.45p on.’
‘And why he’s ruined a perfectly good squash court,’ said the Senior Wrangler, tapping the side of the thing with his squash racket.
‘And if this is safe,’ said the Dean. ‘I’m against dabbling in physics.’
Ponder Stibbons winced.
‘I assure you, Dean, that the chances of anyone being killed by the, er, reacting engine are even greater than the chance of being knocked down while crossing the street,’ he said.
‘Really? Oh, well… all right then.’
Ponder reconsidered the impromptu sentence he’d just uttered and decided, in the circumstances, not to correct it. Talking to the senior wizards was like building a house of cards; if you got anything to stay upright, you just breathed out gently and moved on.
Ponder had invented a little system he’d called, in the privacy of his head, Lies-to-Wizards. It was for their own good, he told himself. There was no point in telling your bosses everything; they were busy men, they didn’t want explanations. There was no point in burdening them. What they wanted was little stories that they felt they could understand, and then they’d go away and stop worrying.
He’d got his students to set up a small display at the far end of the squash court. Beside it, with pipes looping away through the wall into the High Energy Magic building next door, was a terminal to HEX, the University’s thinking engine. And beside that was a plinth on which was a very large red lever, around which someone had tied a pink ribbon.
Ponder looked at his notes, and then surveyed the faculty.
‘Ahem …’ he began.
‘I’ve got a throat sweet somewhere,’ said the Senior Wrangler, patting his pockets.
Ponder looked at his notes again, and a horrible sense of hopelessness overcame him. He realized that he could explain thaumic fission very well, provided that the person listening already knew all about it. With the senior wizards, though, he’d need to explain the meaning of every word. In some cases this would mean words like ‘the’ and ‘and’.
He glanced down at the water jug on his lectern, and decided to extemporize.
Ponder held up a glass of water.
‘Do you realize, gentlemen,’ he said, ‘that the thaumic potential in this water … that is, I mean to say, the magical field generated by its narrativium content which tells it that it is water and lets it keep on being water instead of, haha, a pigeon or a frog … would, if we could release it, be enough to move this whole university all the way to the moon?’
He beamed at them.
‘Better leave it in there, then,’ said the Chair of Indefinite Studies.
Ponder’s smile froze.
‘Obviously we cannot extract all of it,’ he said, ‘But we –’
‘Enough to get a small part of the university to the moon?’ said the Lecturer in Recent Runes.
‘The Dean could do with a holiday,’ said the Archchancellor.
‘I resent that remark, Archchancellor.’
‘Just trying to lighten the mood, Dean.’
‘But we can release just enough for all kinds of useful work,’ said Ponder, already struggling.
‘Like heating my study,’ said the Lecturer in Recent Runes. ‘My water jug was iced up again this morning.’
‘Exactly!’ said Ponder, striking out madly for a useful Lie-to-Wizards. ‘We can use it to boil a great big kettle! That’s all it is! It’s perfectly harmless! Not dangerous in any way! That’s why the University Council let me build it! You wouldn’t have let me build it if it was dangerous, would you?’
He gulped down the water.
As one man, the assembled wizards took several steps backwards.
‘Let us know what it’s like up there,’ said the Dean.
‘Bring us back some rocks. Or something,’ said the Lecturer in Recent Runes.
‘Wave to us’, said the Senior Wrangler. ‘We’ve got quite a good telescope.’
Ponder stared at the empty glass, and readjusted his mental sights once more.
‘Er, no,’ he said. ‘The fuel has to go inside the reacting engine, you see. And then … and then …’
He gave up.
‘The magic goes round and round and it comes up under the boiler that we have plumbed in and the university will then be lovely and warm,’ he said. ‘Any questions?’
‘Where does the coal go?’ said the Dean. ‘It’s wicked what the dwarfs are charging these days.’
‘No, sir. No coal. The heat is … free,’ said Ponder. A little bead of sweat ran down his face.
‘Really?’ said the Dean. ‘That’ll be a saving, then, eh, Bursar? Eh? Where’s the Bursar?’
‘Ah … er … the Bursar is assisting me today, sir,’ said Ponder. He pointed to the high gallery over the court. The Bursar was standing there, smiling his distant smile, and holding an axe. A rope was tied around the handrail, looped over a beam, and held a long heavy rod suspended over the centre of the reaction engine.
‘It is … er … just possible that the engine may produce too much magic,’ said Ponder. ‘The rod is lead, laminated with rowan wood. Together they naturally damp down any magical reaction, you see. So if things get too … if we want to settle things down, you see, he just chops through the rope and it drops into the very centre of the reacting engine, you see.’
‘What’s that man standing next to him for?’
‘That’s Mr Turnipseed, my assistant. He’s the backup fail-safe device.’
‘What does he do, then?’
‘His job is to shout “For gods’ sakes cut the rope now!” sir.’
The wizard nodded at one another. By the standards of Ankh-Morpork, where the common thumb was used as a temperature measuring device, this was health and safety at work taken to extremes.
‘Well, that all seems safe enough to me,’ said the Senior Wrangler.
‘Where did you get the idea for this, Mister Stibbons?’ said Ridcully.
‘Well, er, a lot of it is from my own research, but I got quite a few leads from a careful reading of the Scrolls of Loko in the Library, sir.’ Ponder reckoned he was safe enough there. The wizards liked ancient wisdom, provided it was ancient enough. They felt wisdom was like wine, and got better the longer it was left alone. Something that hadn’t been known for a few hundred years probably wasn’t worth knowing.
‘Loko … Loko … Loko,’ mused Ridcully. ‘That’s up on Uberwald, isn’t it?’
‘That’s right, sir.’
‘Tryin’ to bring it to mind,’ Ridcully went on, rubbing his beard. ‘Isn’t that where there’s that big deep valley with the ring of mountains round it? Very deep valley indeed, as I recall.’
‘That’s right, sir. According to the library catalogue the scrolls were found in a cave by the Crustley Expedition –’
‘Lots of centaurs and fauns and other curiously shaped magical whatnots are there, I remember reading.’
‘Is there, sir?’
‘Wasn’t Stanmer Crustley the one who died of planets?’
‘I’m not familiar with –’
‘Extremely rare magical disease, I believe.’
‘Indeed, sir, but –’
‘Now I come to think about it, everyone on that expedition contracted something seriously magical within a few months of getting back,’ Ridcully went on.
‘Er, yes, sir. The suggestion was that there was some kind of curse on the place. Ridiculous notion, of course.’
‘I somehow feel I need to ask, Mister Stibbons … what chance is there of this just blowin’ up and destroyin’ the entire university?’
Ponder’s heart sank. He mentally scanned the sentence, and took refuge in truth. ‘None, sir.’
‘Now try honesty, Mister Stibbons.’ And that was the problem with the Archchancellor. He mostly strode around the place shouting at people, but when he did bother to get all his brain cells lined up he could point them straight at the nearest weak spot.
‘Well … in the unlikely event of it going seriously wrong, it … wouldn’t just blow up the university, sir.’
‘What would it blow up, pray?’
‘Er … everything, sir.’
‘Everything there is, you mean?’
‘Within a radius of about fifty thousand miles out into space, sir, yes. According to HEX it’d happen instantaneously. We wouldn’t even know about it.’
‘And the odds of this are …?’
‘About fifty to one, sir.’
The wizards relaxed.
‘That’s pretty safe. I wouldn’t bet on a horse at those odds,’ said the Senior Wrangler. There was half an inch of ice on the inside of his bedroom windows. Things like this give you a very personal view of risk.
fn1 Wizard or ‘Real’ Squash bears very little relationship to the high speed sweat bath played elsewhere. Wizards see no point in moving fast. The ball is lobbed lazily. Certain magical inconsistencies are built into the floor and walls, however, so that the wall a ball hits is not necessarily the wall it rebounds from. This was one of the factors which, Ponder Stibbons realized some time afterwards, he really ought to have taken into consideration. Nothing excites a magical particle like meeting itself coming the other way.
A SQUASH COURT can be used to make things go much faster than a small rubber ball…
On 2 December 1942, in a squash court in the basement of Stagg Field at the University of Chicago, a new technological era came into being. It was a technology born of war, yet one of its consequences was to make war so terrible in prospect that, slowly and hesitantly, war on a global scale became less and less likely.fn1 At Stagg Field, the Roman-born physicist Enrico Fermi and his team of scientists achieved the world’s first self-sustaining nuclear chain reaction. From it came the atomic bomb, and later, civilian nuclear power. But there was a far more significant consequence: the dawn of Big Science and a new style of technological change.
Nobody played squash in the basement of Stagg Field, not while the reactor was in place – but a lot of the people working in the squash court had the same attitudes as Ponder Stibbons … mostly insatiable curiosity, coupled with periods of nagging doubt tinged with a flicker of terror. It was curiosity that started it all and terror that concluded it.
In 1934, following a lengthy series of discoveries in physics related to the phenomenon of radioactivity, Fermi discovered that interesting things happen when substances are bombarded with ‘slow neutrons’ – subatomic particles emitted by radioactive beryllium, and passed through paraffin to slow them down. Slow neutrons, Fermi discovered, were just what you needed to persuade other elements to emit their own radioactive particles. That looked interesting, so he squirted streams of slow neutrons at everything he could think of, and eventually he tried the then obscure element uranium, up until then mostly used as a source of yellow pigment. By something apparently like alchemy, the uranium turned into something new when the slow neutrons cannoned into it – but Fermi couldn’t work out what.
Four years later three Germans – Otto Hahn, Lise Meitner, and Fritz Strassmann – repeated Fermi’s experiments, and being better chemists, they worked out what had happened to the uranium. Mysteriously, it had turned into barium, krypton, and a small quantity of other stuff. Meitner realized that this process of ‘nuclear fission’ produced energy, by a remarkable method. Everyone knew that chemistry could turn matter into other kinds of matter, but now some of the matter in uranium was being transformed into energy, something that nobody had seen before. It so happened that Albert Einstein had already predicted this possibility on theoretical grounds, with his famous formula – an equation which the orangutan Librarian of Unseen Universityfn2 would render as ‘Ook’.fn3 Einstein’s formula tells us that the amount of energy ‘contained’ in a given amount of matter is equal to the mass of that matter, multiplied by the speed of light and then multiplied by the speed of light again. As Einstein had immediately noticed, light is so fast it doesn’t even appear to move, so its speed is decidedly big … and the speed multiplied by itself is huge. In other words: you can get an awful lot of energy from a tiny bit of matter, if only you can find a way to do it. Now Meitner had worked out the trick.
A single equation may or may not halve your book sales, but it can change the world completely.
Hahn, Meitner and Strassmann published their discovery in the British scientific journal Nature in January 1939. Nine months later Britain was at war, a war which would be ended by a military application of their discovery. It is ironic that the greatest scientific secret of World War II was given away just before the war began, and it shows how unaware politicians then were of the potential – be it for good or bad – of Big Science. Fermi saw the implications of the Nature article immediately, and he called in another top-ranking physicist, Niels Bohr, who came up with a novel twist: the chain reaction. If a particular, rare form of uranium, called uranium-235, was bombarded with slow neutrons, then not only would it split into other elements and release energy – it would also release more neutrons. Which, in turn, would bombard more uranium-235 … The reaction would become self-sustaining, and the potential release of energy would be gigantic.
Would it work? Could you get ‘something for nothing’ in this way? Finding out was never going to be easy, because uranium-235 is mixed up with ordinary uranium (uranium-238), and getting it out is like looking for a needle in a haystack when the needle is made of straw.
There were other worries too … in particular, might the experiment be too successful, setting off a chain reaction that not only spread through the experiment’s supply of uranium-235, but through everything else on Earth as well? Might the atmosphere catch fire? Calculations suggested: probably not. Besides, the big worry was that if the Allies didn’t get nuclear fission working soon then the Germans would beat them to it. Given the choice between our blowing up the world and the enemy blowing up the world, it was obvious what to do.
That is, on reflection, not a happy sentence.
Loko is remarkably similar to Oklo in southeastern Gabon, where there are deposits of uranium. In the 1970s, French scientists unearthed evidence that some of that uranium had either been undergoing unusually intense nuclear reactions or was much, much older than the rest of the planet.
It could have been an archaeological relic of some ancient civilization whose technology had got as far as atomic power, but a duller if more plausible explanation is that Oklo was a ‘natural reactor’. For some accidental reason, that particular patch of uranium was richer than usual in uranium-235, and a spontaneous chain reaction ran for hundreds of thousands of years. Nature got there well ahead of Science, and without the squash court.
Unless, of course, it was an archaeological relic of some ancient civilization.
Until late in 1998, the natural reactor at Oklo was also the best evidence we could find to show that one of the biggest ‘what if?’ questions in science had an uninteresting answer. This question was ‘What if the natural constants aren’t?’
Our scientific theories are underpinned by a variety of numbers, the ‘fundamental constants’. Examples include the speed of light, Planck’s constant (basic to quantum mechanics), the gravitational constant (basic to gravitational theory), the charge on an electron, and so on. All of the accepted theories assume that these numbers have always been the same, right from the very first moment when the universe burst into being. Our calculations about that early universe rely on those numbers having been the same; if they used to be different, we don’t know what numbers to put into the calculations. It’s like trying to do your income tax when nobody will tell you the tax rates. From time to time maverick scientists advance the odd ‘what if?’ theory, in which they try out the possibility that one or more of the fundamental constants isn’t. The physicist Lee Smolin has even come up with a theory of evolving universes, which bud off baby universes with different fundamental constants. According to this theory, our own universe is particularly good at producing such babies, and is also particularly suited to the development of life. The conjunction of these two features, he argues, is not accidental (the wizards at UU, incidentally, would be quite at home with ideas like this – in fact, sufficiently advanced physics is indistinguishable from magic).
Oklo tells us that the fundamental constants have not changed during the last two billion years – about half the age of the Earth and ten per cent of that of the universe. The key to the argument is a particular combination of fundamental constants, known as the ‘fine structure constant’.fn4 Its value is very close to 1/137 (and a lot of ink was devoted to explanations of that whole number 137, at least until more accurate measurements put its value at 137.036). The advantage of the fine structure constant is that its value does not depend on the chosen units of measurement – unlike say, the speed of light, which gives a different number if you express it in miles per second or kilometres per second. The Russian physicist Alexander Shlyakhter analysed the different chemicals in the Oklo reactor’s ‘nuclear waste’, and worked out what the value of the fine structure constant must have been two billion years ago when the reactor was running. The result was the same as today’s value to within a few parts in ten million.
In late 1998, though, a team of astronomers led by John Webb made a very accurate study of the light emitted by extremely distant, but very bright, bodies called quasars. They found subtle changes in certain features of that light, called spectral lines, which are related to the vibrations of various types of atom. In effect, what they seem to have discovered is that many billion years ago – much further back than the Oklo reactor – atoms didn’t vibrate at quite the same rate as they do today. In very old gas clouds from the early universe, the fine structure constant differs from today’s value by one part in 50,000. That’s a huge amount by the standards of this particular area of physics. As far as anyone can tell, this unexpected result is not due to experimental error. A theory suggested in 1994 by Thibault Damour and Alexander Polyakov does indicate a possible variation in the fine structure constant, but only one-ten thousandth as large as that found by Webb’s team.
In 2001 another team led by John Webb analysed the absorption of light from distant quasars by clouds of interstellar gas, and announced that the fine structure constant has increased by one hundred thousandth since the Big Bang. This result, if true, implies that the gravitational, weak nuclear, and strong nuclear forces have all changed over time. The work is being checked for possible systematic errors, which might produce the same observations.
It’s all a bit of a puzzle, and most theorists sensibly prefer to hedge their bets and wait for further research. But it could be a straw in the wind: perhaps we will soon have to accept that the laws of physics were subtly different in the distant reaches of time and space. Not turtle-shaped, perhaps, but… different.
fn1 Or at least, less radioactive. We can but hope.
fn2 He was the victim of a magical accident, which he rather enjoyed. But you know this.
fn3 They say that every formula halves the sales of a popular science book. This is rubbish – if it was true, then The Emperor’s New Mind by Roger Penrose would have sold one-eighth of a copy, whereas its actual sales were in the hundreds of thousands. However, just in case there is some truth to the myth, we have adopted this way of describing the formula to double our potential sales. You all know which formula we mean. You can find it written out in symbols on page 118 of Stephen Hawking’s A Brief History of Time – so if the myth is right, he could have sold twice as many copies, which is a mindboggling thought.
fn4 The fine structure constant is defined to be the square of the charge of an electron, divided by 2 times Planck’s constant times the speed of light times the permittivity of the vacuum (as a handy lie, the last term might be thought as ‘the way it reacts to an electric charge’). Thank you.
IT DID NOT take long for the faculty to put its collective finger on the philosophical nub of the problem, vis-à-vis the complete destruction of everything.
‘If no one will know if it happens, then in a very real sense it wouldn’t have happened,’ said the Lecturer in Recent Runes. His bedroom was on one of the colder sides of the university.
‘Certainly we wouldn’t get the blame,’ said the Dean, ‘even if it did.’
‘As a matter of fact,’ Ponder went on, emboldened by the wizards’ relaxed approach, ‘there is some theoretical evidence to suggest that it could not possibly happen, due to the non-temporal nature of the thaumic component.’
‘Say again?’ said Ridcully.
‘A malfunction would not result in an explosion exactly, sir,’ said Ponder. ‘Nor, as far as I can work out, would it result in things ceasing to exist from the present onwards. They would cease to have existed at all, because of the multidirectional collapse of the thaumic field. But since we are here, sir, we must be living in a universe where things did not go wrong.’
‘Ah, I know this one,’ said Ridcully. ‘This is because of quantum, isn’t it? And there’s some usses in some universe next door where it did go wrong, and the poor devils got blown up?’
‘Yes, sir. Or, rather, no. They didn’t get blown up because the device the other Ponder Stibbons would have built would have gone wrong, and so … he didn’t exist not to build it. That’s the theory, anyway.’
‘I’m glad that’s sorted out, then,’ said the Senior Wrangler briskly. ‘We’re here because we’re here. And since we’re here, we might as well be warm.’
‘Then we seem to be in agreement,’ said Ridcully. ‘Mr Stibbons, you may start this infernal engine.’ He nodded towards the red lever on the plinth.
‘I was rather assuming you would do the honours, Archchancellor,’ said Ponder, bowing. ‘All you need to do is pull the lever. That will, ahem, release the interlock, allowing the flux to enter the exchanger, where a simple octiron reaction will turn the magic into heat and warm up the water in the boiler.’
‘So it really is just a big kettle?’ said the Dean.
‘In a manner of speaking, yes,’ said Ponder, trying to keep his face straight.
Ridcully grasped the lever.
‘Perhaps you would care to say a few words, sir?’ said Ponder.
‘Yes.’ Ridcully looked thoughtful for a moment, and then brightened up. ‘Let’s get this over quickly, and have lunch.’
There was a smattering of applause. He pulled the lever. The hand on a dial on the wall moved off zero.
‘Well, we’re not blown up after all,’ said the Senior Wrangler. ‘What are the numbers on the wall for, Stibbons?’
‘Oh, er … they’re … they’re to tell you what number it’s got to,’ said Ponder.
‘Oh. I see.‘ The Senior Wrangler grasped the lapels of his robe. ‘Duck with green peas today, gentlemen, I believe,’ he said, in a far more interested tone of voice. ‘Well done, Mr Stibbons.’
The wizards ambled off in the apparently slow yet deceptively fast way of wizards heading towards food.