'And the best thing is,' said Ridcully, to Rincewind's back, 'that although we are sending you to a place of immense danger where no living thing could possibly survive, you will not, in so many words, actually be there. Won't that be nice?'
Rincewind hesitated.
'How many words?'
'It'll be like being in a ... story,' said the Archchancellor. 'Or ... or a dream, as far as I can understand it. Mister Stibbons! Come and explain!'
'Oh, hello, Rincewind,' said Ponder, stepping out of the mist and wiping his hands on a rag. 'Twelve spells HEX has amalgamated for this! It's an amazing piece of thaumaturgical engineering! Do come and see!'
There are creatures which have evolved to live in coral reefs and simply could not survive in the rough, tooth-filled wastes of the open sea. They continue to exist by lurking among the dangerous tentacles of the sea anemone or around the lips of the giant clam and other perilous crevices shunned by all sensible fish.
A university is very much like a coral reef. It provides calm waters and food particles for delicate yet marvellously constructed organisms that could not possibly survive in the pounding surf of reality, where people ask questions like 'Is what you do of any use?' and other nonsense.
In fact Rincewind in his association with UU had survived dangers that would have stripped a hero to the bone, but he nevertheless believed, despite all the evidence to the contrary, that he was safe in the university. He would do anything to stay on the roll.
At the moment this involved looking at some sort of skeletal armour made out of smoke while Ponder Stibbons gabbled incomprehensible words in his ear. As far as he could understand it, the thing put all your senses somewhere else when you stayed here. So far, that sounded quite acceptable, since it had always seemed to Rincewind that if you had to go a long way away it'd be nice to stay at home while you did it, but people seemed a little unclear about where pain fitted in.
'We'll send you, that is, your senses, somewhere,' said Ridcully.
'Where?' said Rincewind.
'Somewhere amazing,' said Ponder. 'We just want you to tell us what you see. And then we'll bring you back.'
'At what point will things go wrong?' said Rincewind.
'Nothing can possibly go wrong.'
'Oh,' Rincewind sighed. There was no point in arguing with a statement like that. 'Could I have some breakfast first?'
'Of course, dear fellow,' said Ridcully, patting him on the back. 'Have a hearty meal!'
'Yes, I thought that'd probably be the case,' said Rincewind gloomily.
When he'd been taken away, under escort by the Dean and a couple of college porters, the wizards clustered around the project.
'We've found a suitably large "sun", sir,' said Ponder, taking care to annunciate the inverted commas. 'We're moving the world now,'
'A very suspicious idea, this,' said the Archchancellor. 'Suns go around. We see it happen every day. It's not some kind of optical illusion. This is a bit of a house of cards we're building here.'
'It's the only one available, sir.'
'I mean, things fall down because they're heavy, you see? The thing that causes them to fall down because they're heavy is, in fact, the fact that they're heavy. 'Heavy' means inclined to fall down. And, while you can call me Mr Silly...'
'Oh, I wouldn't do that, sir,' Ponder said, glad that Ridcully couldn't see his face.
‘...I somehow feel that a crust of rock floating around on a ball of red-hot iron should not be thought of as "solid ground".'
'I think, sir, that this universe has a whole parcel of rules that take the place of narrativium,' said Ponder. 'It's ... sort of ... copying us, as you so perspicaciously pointed out the other day. It's making the only kind of suns that can work in it, and the only worlds that can exist if you don't have chelonium.'
'Even so ... going around a sun ,.. that's the sort of thing the Omnian priests used to teach, you know. Mankind is so insignificant that we just float around on some speck, and all that superstitious stuff. You know they used to persecute people for saying the turtle existed? And any fool can see it exists.'
'Yes, sir It certainly does.'
There were problems, of course
'Are you sure it's the right sort of sun?' said Ridcully.
'You told HEX to find one that was "nice and yellow, nice and dull, and not likely to go off bang", sir,' said Ponder. 'It seems to be a pretty average one for this universe.'
'Even so ... tens of millions of miles ... that's a long way away for our world.'
'Yes, sir. But we tried some experimental worlds close to and they fell in, and we tried one a bit further out and that's baked like a biscuit, and there's one ... well, it's a bit of an armpit, really. The students have got quite good at making different sorts. Er ... we're calling them planets.'
'A planet, Stibbons, is a lump of rock a mere few hundred yards across which gives the night sky a little, oh, I don't know, what's the word, a little je ne sais quoi'
'These will work, sir, and we've such a lot of them. As I said, sir, I've come to agree with your theory that, within the Project, matter is trying to do all by itself what in the real world is done by purpose, probably conveyed via narrativium.'
'Was that my theory?' said Ridcully.
'Oh, yes, sir,' said Ponder, who was learning the particular survival skills of the academic reef.
'It sounds rather a parody to me, but I dare say we will understand the joke in time. Ah, here comes our explorer. 'Morning, Professor,' said Ridcully. 'Are you ready?'
'No,' said Rincewind.
'It's very simple,' said Ponder, leading the reluctant traveller across the floor. 'You can think of this assemblage of spells as a suit of very, very good armour. Things will flicker , and then you'll be ... somewhere else. Except you'll really be here, you see? But everything you see will be somewhere else. Absolutely nothing will hurt you because HEX will buffer all extreme sensations and you'll simply received a gentle analogue of them. If it's freezing you'll feel rather chilly, if it's boiling you'll feel a little hot. If a mountain falls on you it'll be a bit of a knock. Time where you're going is moving very fast but HEX can slow it down while you are there, HEX says that he can probably exert small amounts of force within the Project, so you will be able to lift and push things, although it will feel as though you're wearing very large gloves. But this should not be required because all we want you to do to start with ... Professor ... is tell us what you see.'
Rincewind looked at the suit. It was, being largely make up of spells under HEX's control, shimmery and insubstantial. Light reflected off it in odd ways. The helmet was far too large and completely covered the face.
'I have three ... no, four ... no, five questions,' he said.
'Yes?'
'Can I resign?'
'No.'
'Do I have to understand anything you just told me?'
'No.'
'Are there any monsters where I'm being sent?'
'No.'
'Are you sure?' 'Yes.'
'Are you totally positive about that?'
'Yes.'
'I've just thought of another question,' said Rincewind.
'Fire away.'
'Are you really sure?'
'Yes!' snapped Ponder 'And even if there were any monsters, it wouldn't matter.'
'It'd matter to me.'
'No it wouldn't! I have explained! If some huge toothed beast came galloping towards you, it'd have no effect on you at all.'
'Another question?'
'Yes?'
'Is there a toilet in this suit?'
'No.'
'Because there will be if a huge toothed beast comes galloping towards me.'
'In that case, you just say the word and you can come back and use the privy down the hall,' said Ponder. 'Now, stop worrying, please. These gentlemen will help you, er, insert yourself into the thing, and we'll begin ...'
The Archchancellor wandered up as the reluctant professor
was enveloped in the glittering, not-quite-there stuff.
'A thought occurs, Ponder,' he said.
'Yes, sir?'
'I suppose there's no chance that there is life anywhere in the Project?'
Ponder looked at him in frank astonishment.
'Absolutely not, sir! It can't happen. Simple matter is obeying a few rather odd rules. That's probably enough to get things ... spinning and exploding and so on, but there's no possibility that they could cause anything so complex as...'
'The Bursar, for example?'
'Not even the Bursar, sir.'
'He's not very complicated, though. If only we could find a parrot that was good at sums, we could pension the old chap off.'
'No, sir. There's nothing like the Bursar. Not even an ant or a blade of grass. You might as well try to tune a piano by throwing rocks at it. Life does not turn up out of nowhere, sir. Life is a lot more than just rocks moving in circles. The one thing we're not going to run into is monsters.'
Two minutes later Rincewind blinked and found, when he opened his eyes, that they were somewhere else. There was a rather grainy redness in front of them, and he felt rather warm.
'I don't think it's working,' he said.
'You should be seeing a landscape,' said Ponder, in his ear.
'It's all just red.'
There was the sound of distant whispering. Then the voice said, 'Sorry. The aim wasn't very good. Wait a moment and we'll soon have you out of that volcanic vent.'
In the HEM Ponder took the ear trumpet away from his ear. The other wizards heard it sizzling, as if a very angry insect was trapped therein.
'Curious language,' he said, in mild surprise, 'well, let's raise him somewhat and let time move on a little ...'
He put the trumpet to his ear and listened.
'He says it's pissing down,' he announced.
18. AIR AND WATER
IT'S CERTAINLY A SURPRISE that the rigid rules of physics permit anything as flexible as life, and the wizards can hardly be blamed for not anticipating the possibility that living creatures might come into being on the barren rocks of Roundworld. But Down Here is not as different from Up There as it seems. Before we can talk about life, though, we need to deal with a few more features of our home planet: atmosphere and oceans. Without them, life as we know it could not have arisen; without life as we know it, our oceans and atmosphere would be distinctly different. The story of the Earth's atmosphere is inextricably intertwined with that of its oceans. Indeed, the oceans can reasonably be viewed as just a rather damp, dense layer of the atmosphere. The oceans and the atmosphere evolved together, exerting strong influences on each other, and even today such an 'obviously' atmospheric phenomenon as weather turns out to be closely related to what happens in the oceans. One of the main recent breakthroughs in weather prediction has been to incorporate the oceans' ability to absorb, transport, and give off heat and moisture. To some extent, the same point can be made about the solid regions of the Earth, which also co-evolved with the air and the seas, and also interact with them. But the link between oceans and atmosphere is stronger.
The Earth and its atmosphere condensed together out of the primal gascloud that gave rise to the Sun and to the solar system. As a rough rule of thumb, the denser materials sank to the bottom of the condensing clump of matter that we now inhabit, and the lighter ones floated to the top. Of course there was, and still is, a lot more going on than that, so the Earth is not just a series of concentric shells of lighter and lighter matter, but the general distribution of solids, liquids, and gases makes sense if you think about it that way. And so, as the molten rocks of Earth began to cool and solidify, the nascent planet found itself already enveloped in a primordial atmosphere.
It was almost certainly very different from the atmosphere today, which is a mixture of gases, the main ones being the elements nitrogen, oxygen and the inert gas argon, and the compounds carbon dioxide and water (in the form of vapour). The primordial atmosphere also differed considerably from the gas cloud out of which it condensed, it wasn't just a representative sample of what was around. There are several reasons for this. One is that a solid planet and a gas cloud retain different gases. Another is that a solid planet can generate gases, by chemical or even nuclear reactions, or by other physical processes, which can escape from its interior into its atmosphere.
The early cloud was rich in hydrogen and helium, the lightest of elements. The speed with which a molecule moves becomes slower as the molecule gets heavier, a molecule with one hundred times the mass moves at about one-tenth the speed. Anything that moves faster than the Earth's escape velocity, about 7 miles per second (11 km/sec), can overcome the planet's gravity and disappear into space. Molecules in the atmosphere whose molecular weight, what you get by adding up the atomic weights of the component atoms -is less than about 10 should therefore disappear into the void. Hydrogen has molecular weight 2, helium 4, so neither of these otherwise abundant gases should be expected to hang around. The most abundant molecules in the primal gas cloud, with molecular weight greater than 10, are methane, ammonia, water, and neon. This is similar to what we find today on the gas giants Jupiter, Saturn, Uranus, and Neptune, except that they are more massive, so have a greater escape velocity, and can retain lighter gases such as hydrogen and helium as well. We can't be certain that the Earth of 4 billion years ago possessed a methane-ammonia atmosphere, because we don't know exactly how the primal gas cloud condensed, but it is clear that if the ancient Earth ever possessed such an atmosphere, it lost nearly all of it. Today there is little methane or ammonia, and what there is has a biological origin.
Shortly after the Earth was formed, the atmosphere contained very little oxygen. Around 2 billion years ago, the proportion of oxygen in the atmosphere increased to about 5%. The most likely cause of this change, though perhaps not the only one, was the evolution of photosynthesis. At some stage, probably around 2 billion years ago, bacteria in the oceans evolved the trick of using the energy of sunlight to turn water and carbon dioxide into sugar and oxygen. Plants use the same trick today, and they use the same molecules as one of the early bacteria did: chlorophyll. Animals proceed in pretty much the opposite direction: they power themselves by using oxygen to burn food, producing carbon dioxide instead of using it up. Those early photosynthesizing bacteria used the sugar for energy, and multiplied rapidly, but to them the oxygen was just a form of toxic waste, which bubbled up into the atmosphere. The oxygen level then stayed roughly constant until about 600 million years ago, when it underwent a rapid increase to the current level of 21%.
The amount of oxygen in today's atmosphere is far greater than could ever be sustained without the influence of living creatures, which not only produce oxygen in huge quantities but use it up again, in particular locking it up in carbon dioxide. It is startling how far 'out of balance' the atmosphere is, compared to what would happen if life were suddenly removed and only inorganic chemical processes could act. The amount of oxygen in the atmosphere is dynamic, it can change on a timescale that by geological standards is extremely rapid, a matter of centuries rather than millions of years. For example, if some disaster occurred which killed off all the plants but left all the animals, then the proportion of oxygen would halve in about 500 years, to the level on mountain peaks in the Andes today. The same goes for the scenario of 'nuclear winter' introduced by Carl Sagan, in which clouds of dust thrown into the atmosphere by a nuclear war stop most of the sunlight from reaching the ground. In this case, plants may still eke out some kind of existence, but they don't photosynthesize: they do use oxygen, though, and so do the microorganisms that break down dead plants.
The same screening effect could also occur if there were unusual numbers of active volcanoes, or if a big meteorite or comet hit the Earth. When comet Shoemaker-Levy 9 hit Jupiter in 1994, the impact was equivalent to half a million hydrogen bombs.
The 'budget' of income and expenditure for oxygen, and the associated b
ut distinct budget for carbon, is still not understood. This is an enormously important question because it is vital background to the debate about global warming. Human activities, such as electrical power plants, industry, use of cars, or simply going about one's usual business and breathing while one does so, generate carbon dioxide. Carbon dioxide is a 'greenhouse gas' which traps incoming sunlight like the glass of a greenhouse. So if we produce too much carbon dioxide, the planet should warm up. This would have undesirable consequences, ranging from floods in low-lying regions such as Bangladesh to big changes in the geographical ranges of insects, which could inflict serious damage on crops. The question is: do these human activities actually increase the Earth's carbon dioxide, or does the planet compensate in some way? The answer makes the difference between imposing major restrictions on how people in developed (and developing) countries live their lives, and letting them continue along their current paths. The current consensus is that there are clear, though subtle, signs that human activities do increase the carbon dioxide levels, which is why major international treaties have been signed to reduce carbon dioxide output. (Actually taking that action, rather than just promising to do so, may prove to be a different matter altogether.)
The difficulties involved in being sure are many. We don't have good records of past levels of carbon dioxide, so we lack a suitable 'benchmark' against which to assess today's levels, although we're beginning to get a clearer picture thanks to ice cores drilled up from the Arctic and Antarctic, which contain trapped samples of ancient atmospheres. If 'global warming' is under way, it need not show up as an increase in temperature anyway (so the name is a bit silly). What it shows up as is climatic disturbance. So even though the six warmest summers in Britain this century have all occurred in the nineties, we can't simply conclude that 'it's getting warmer', and hence that global warming is a fact. The global climate varies wildly anyway, what would it be doing if we weren't here?
A project known as Biosphere II attempted to sort out the basic science of oxygen/carbon transactions in the global ecosystem by setting up a 'closed' ecology, a system with no inputs, beyond sunlight, and no outputs whatsoever. In form it was like a gigantic futuristic garden centre, with plants, insects, birds, mammals, and people living inside it. The idea was to keep the ecology working by choosing a design in which everything was recycled.
The Science of Discworld I tsod-1 Page 15