But even if the rock had missed, there were other rocks. And if they had missed too, then we should be aware that the planet has other, home-grown means of disposal.
Evidence is emerging that suggests that other extinctions were caused by 'natural' but catastrophic changes in the planet's atmosphere. A case is being made that indicates that the very existence of life on Earth will, periodically, trip a catastrophe.
Rocks don't mind.
This will probably not happen tomorrow. But, one day, it will. And then Rincewind's kaleidoscope is shaken up for a new pretty pattern.
Eden and Camelot, the wondrous garden-worlds of myth and legend, are here now. This is about as good as it ever gets. Mostly, it's a lot worse. And it won't stay like this for very long.
There are, perhaps, choices. We could leave. We've dealt with that. Considerable optimism is required. But there might be other small blue planets out there ... By definition, though, Earthlike worlds will have life on them. That's why they'll be Earthlike. And the trouble is that the more Earthlike it is, the more troublesome it would be. Don't worry about the laser-wielding monsters, you can talk to them, if only about lasers. The real problem is more likely to be something very, very small. In the morning you get a rash. In the afternoon, your legs explode[53].
The other 'choice' is to stay. We may be lucky, we tend to be. But we won't be lucky forever. The average life of a species is about five million years. Depending on how you define humanity, we may already be close to the average.
A useful project, and one that's much cheaper to achieve, is to leave a note to the next occupiers, even if it is only to say 'We Were Here'. It may be of interest to a future species that even if they are, alone in space, they're not alone in Time.
We may already have left our marker. It depends on how long things will really last on the Moon, and if, in a hundred million years, anyone else feels it necessary to go there. If they do, they may find the abandoned descent stages of the Apollo Moon landers. And they'll wonder what a 'Richard M. Nixon' was.
How much luckier are the inhabitants of Discworld. They know they live on a world made for people. With a large hungry turtle, not to mention the four elephants, interstellar debris becomes lunch rather than catastrophe. Large-scale extinction has more to do with magical interference than random rocks or built-in fluctuations; it may have the same effect, but at least there is someone to blame.
Unfortunately, it does reduce the scope for asking interesting questions. Most of them have already been answered. Certainty rules. Mustrum Ridcully is not the kind of person who would tolerate an Uncertainty Principle, after all.
Back in Roundworld, there is perhaps one point worth making.
Just suppose there is nothing else. Arguments about intelligent life on other worlds have always been highly biased by the desires of those doing the arguing that there should be intelligent life on other worlds, and we three are among them. But the argument is a house of cards with no card on the bottom. We know of life on one world. Everything else is guesswork and naked statistics. Life may be so common through the universe that even the atmosphere of Jupiter is alive with Jovian gasbags and every cometary nucleus is home to colonies of microscopic blobuies. Or there may be nothing alive at all, anywhere else but here.
Perhaps intelligent life arose before humanity, and perhaps it will again when humanity's span has become a rather complex layer in the strata. We can't tell. Time does not simply, as the hymn says, bear all its sons away, it can easily see the disappearance of the entire continent on which they stood.
In short, in a universe a billion Grandfathers long and a trillion Grandfathers wide, there may be just a few hundred thousand years on one planet where a species worried about something other than sex, survival, and the next meal.
This is our Discworld. In its little cup of spacetime, humanity has invented gods[54], philosophies, ethical systems, politics, an unfeasible number of ice-cream flavours and even more esoteric things like 'natural justice' and 'boredom'. Should it matter to us if tigers are made extinct and the last orangutan dies in a zoo? After all, blind forces have repeatedly erased species that were probably more beautiful and worthy.
But we feel it does matter, because humans invented the concept of things 'mattering'. We feel we ought to be brighter than a mile of incandescent rock and a continent-sized glacier. Humans seem to have created, independently, in many pkces and at various times, a Make-a-Real-Human-Being Kit, which begins with prohibitions about killing and theft and incest and is now groping towards our responsibilities to a natural world in which, despite its ability to hurt us mightily, we nevertheless have a godlike power[55].
We advance arguments about saving rainforests because 'there may be undiscovered cancer cures in there', but this is because extelligence wants to save rainforests and the cancer-cure argument might convince the bean-counters and the fearful. It might have a real basis in fact, too, but the real reason is that we feel that a world with tigers and orangutans and rainforests and even small unobtrusive snails in it is a more healthy and interesting world for humans (and, of course, the tigers and orangutans and snails) and that a world without them would be dangerous territory. In other words, trusting the instincts that up until now have generally seen us through, we think that Tigers Are Nice (or, at least, Tigers Are Nice In Moderation And At A Safe Distance).
It's a circular argument, but in our little round human world we've managed to live on circular arguments for millennia. And who else is going to argue with us?
45. AS ABOVE, SO BELOW
RINCEWIND WALKED VERY GINGERLY towards his office, the globe of the project held carefully in his hands.
He would have expected an entire universe to be heavier, but this one seemed on the light side. It was probably all that space.
The Archchancellor had explained at length to him that although he would be called the Egregious Professor of Cruel and Unusual Geography, this was only because that was cheaper than repainting the title on the door. He was not entitled to wages, or to teach, or express any opinions on anything, or order anyone around, or wear any special robes, or publish anything. But he could turn up for meals, provided he ate quietly.
To Rincewind, it sounded like heaven.
The Bursar appeared right in front of him. One moment there was an empty corridor, the next moment there was a bemused wizard.
They collided. The sphere went up in the air, turning gently.
Rincewind rebounded from the Bursar, looked up at the ball curving through the air, flung himself forward and down with rib-scraping force and caught it a few inches from the stone floor.
'Rincewind! Don't tell him who he is!'
Rincewind rolled over, clasping the little universe, and looked back along the passage. Ridcully and the other wizards were advancing slowly and cautiously. Ponder Stibbons was waving a spoonful of jelly invitingly.
Rincewind glanced up the Bursar, who was looking perplexed.
'But he's the Bursar, isn't he?' he said.
The Bursar smiled, looked puzzled for a moment, and vanished with a 'pop'.
'Seven seconds!' shouted Ponder, dropping the spoon and pulling out a notebook. 'That'll put him in ... yes, the laundry room!'
The wizards hurried off, except for the Senior Wrangler, who was rolling a cigarette.
'What happened to the Bursar?' said Rincewind, getting to his feet.
'Oh, young Stibbons reckons he's caught Uncertainty,' said the Senior Wrangler, licking the paper. 'As soon as his body remembers what it's called it forgets where it's supposed to be.' He stuck the bent and wretched cylinder in his mouth and fumbled for his matches. 'Just another day at Unseen University, really.'
He wandered off, coughing.
Rincewind carried the sphere though the maze of dank passages and into his office, where he cleared a space for it on a shelf.
The ice age had cleared up. He wondered what was happening down there, what gastropod or mammal or lizard wa
s even now winding up its elastic ready to propel itself towards the crown of the world. Soon, without a doubt, some creature would suddenly develop an unnecessarily large brain and be forced to do things with it. And it'd look around and probably declare how marvellous it was that the universe had been built to bring forward the inevitable development of creature-kind.
Boy, was it in for a shock ...
'Okay, you can come out,' he said. 'They've lost interest.'
The Librarian was hiding behind a chair. The orangutan took university discipline seriously, even though he was capable of clapping someone on both ears and forcing his brain down his nose.
'They're busy trying to catch the Bursar right now,' said Rincewind. 'Anyway, I'm sure it couldn't have been the apes. No offence, but they didn't look the right sort to me.'
'Ook!'
'It was probably something out of the sea somewhere. I'm sure we didn't see most of what was going on.'
Rincewind huffed on the surface of the globe, and polished it with his sleeve. 'What's recursion?' he said.
The Librarian gave a very expansive shrug.
'It looks okay to me,' said Rincewind. 'I wondered if it was some sort of disease ...'
He slapped the Librarian on the back, raising a cloud of dust. 'Come on, let's go and help them hunt ...'
The door shut. Their footsteps died away.
The world spun in its little universe, about a foot across on the outside, infinitely large on the inside.
Behind it, stars floated away in the blackness. Here and there they congregated in great swirling masses, spinning about some unimaginable drain. Sometimes these drifted together, passing through one another like ghosts and parting in a trailing veil of stars.
Young stars grew in luminous cradles. Dead stars rolled in the glowing shrouds of their death.
Infinity unfolded. Walls of glittering swept past, revealing fresh fields of stars ...
... where, sailing through the endless night, made of hot gas and dust but recognizable nevertheless, was a turtle.
As above, so below.
Примечания
1
In a manner of speaking. They happen because things obey the rules of the universe. A rock has no detectable opinion about gravity.
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2
Like the denizens of any Roundworld university, they have unlimited time for research, unlimited funds and no worries about tenure. They are also hy 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.
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3
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.
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4
Or at least, less radioactive. We can but hope.
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5
He was the victim of a magical accident, which he rather enjoyed. But you know this.
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6
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.
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7
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.
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8
As yet unmeasured, but believed to be faster than light owing to its ability to move so quickly out of light's way.
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9
Actually you can eat salt. But nobody outside Discworld goes to a restaurant to order a basalt balti.
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10
As humans, we have invented lots of useful kinds of lie. As well as lies-to-children ('as much as they can understand') there are lies-to-bosses ('as much as they need to know') lies-to-patients ('they won't worry about what they don't know') and, for all sorts of reasons, lies-to-ourselves. Lies-to-children is simply a prevalent and necessary kind of lie. Universities are very familiar with bright, qualified school-leavers who arrive and then go into shock on finding that biology or physics isn't quite what they've been taught so far. ‘Yes, but you needed to understand that,’ they are told, ‘so that now we can tell you why it isn't exactly true’. Discworld teachers know this, and use it to demonstrate why universites are truly storehouses of knowledge: students arrive from school confident that they know very nearly everything, and they leave years later certain that they know practically nothing. Where did the knowledge go in the meantime? Into the university, of course, where it is carefully dried and stored.
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11
'What You Get Is What You're Given And It's No Good Whining.'
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12
Not while these are still in the polar bear.
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13
This figure replaces the previously favoured value of about 20 billion years. Recently lots of scientists collectively decided it should be 15 billion instead. (For a while some stars seemed to be older than the universe, but the age of those stars has also been downsized.) In other circumstances they might well have settled for 20 billion. If this worries you, substitute the term 'a very long time'.
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14
Indeed, impeccable Discworld thinking is that no matter how big the universe grows, it's always the same size.
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15
Of which there were quite a number, given HEX's unusual construction. In addition to AND, OR and their, combinations and variants, HEX could call up MAYBE, PERHAPS, SUPPOSE and WHY. HEX could think the unthinkable quite easily.
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16
Silicon might also be able to do this, but nowhere near as readily; if you want other exotic lifeforms you have to start thinking in terms of organized vortices in the upper reaches of a sun, weird quantum assemblages in interstellar plasma, or completely implausible creatures based on non-material concepts such as information, thought, or narrativium. DNA is a different matter entirely: you could surely base lifeforms on other carbon-rich molecules. We can do it now, in laboratories, with minor variants of DNA.
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17
Ask Mummy or Daddy if you have no idea what we're talking about.
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18
There also ought to be 'Population III' stars, older than Population II and consisting entirely of hydrogen and helium. These would explain the occurence of some heavy elements in Population II. However, nobody has ever found a Population III star. This may be because they were short-lived. Or, a more recent theory: very soon after the Big Bang there were heavy elements around, even before any stars formed. So when the first stars condensed, they already were Population II. This contradicts what we say in the main text - lies-to-children, of course.
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19
&nb
sp; 'Most civilizations' is admittedly not the same as 'most people'. 'Most people' through the history of the planet have not needed to concern themselves with what shape the world is, provided it supports, somewhere, the next meal.
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20
This rule does require some special assumptions, such as the chronic and irreversible stupidity of humanity.
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21
As Nanny Ogg always says, 'He's just a big softy.'
The Science of Discworld I tsod-1 Page 35