Terry Pratchett - The Science of Discworld I

There are tentative plans to send out a probe to Europa, land it, and drill down to see what's there. The technical problems are for­midable, the ice layer is at least ten miles (16 km) thick, and the operation would have to be carried out very carefully so as not to disturb or destroy the very thing we're hoping to find: Europan organisms. Less invasively, it would be possible to look for tell-tale molecules of life in Europa's thin atmosphere, and plans are afoot to do this too. Nobody expects to find Europan antelopes, or even fishes, but it would be surprising if Europa's water-based chemistry, apparently an ocean a hundred miles (160 km) deep, has not pro­duced life. Almost certainly there are sub-oceanic 'volcanoes' where very hot sulphurous water is vented through the ocean floor. These provide a marvellous opportunity for complicated chemistry, much like the chemistry that started life on Earth.

The least controversial possibility would be an array of simple bacteria-like chemical systems forming towers around the hot vents, much as Earthly bacteria do in the Baltic sea. More complicated creatures like amoebas and parameciums would be a pleasant sur­prise; anything beyond that, such as multicellular organisms, would be a bonus. Don't expect plants, there's not enough light that far from the sun, even if it could filter down through the layers of ice. Europan life would have to be powered by chemical energy, as it is around Earth's underwater volcanic vents. Don't expect Europan lifeforms to look like the ones round our vents, though: they will have evolved in a different chemical environment.

PONDER OPENED HIS EYES and looked up into a face out of time. A mug of tea was thrust towards him. It had a banana stuck in it. 'Ah ... Librarian,' said Ponder weakly, taking the cup. He drank, stabbing himself harmlessly in the left eye. The Librarian thought that practically everything could be improved by the addition of soft fruit, but apart from that he was a kindly soul, always ready with a helping hand and a banana [23] A magical accident had once turned the University's Librarian into an orangutan, a state which he enjoyed sufficiently to threaten, with simple and graphic gestures, anyone who suggested turning him back. The wizards noticed no difference now. An orangutan seemed such a natural shape for a librarian. .

The wizards had put Ponder to sleep on a bench in the store­room. Dusty items of magical gear were stacked from floor to ceiling. Most of it was broken, and all of it was covered in dust.

Ponder sat up and yawned.

'What time is it?'

'Ook.'

'Gosh, that late?'

As the warm clouds of sleep ebbed, it dawned on Ponder that he had left the Project entirely in the hands of the senior faculty. The Librarian was impressed at how long the door kept swinging.

Most of the main laboratory was empty, except for the pool of light around the Project.

The Dean's voice said, 'Mappin Winterley ... that's a nice name?'

'Shutup.'

'Owen Houseworthy?'

'Shutup.'

'William.'

'Shut up, Dean. That's not funny. It never was funny.' This was the voice of the Archchancellor.

'Just as you say, Gertrude.'

Ponder advanced towards the glowing Project.

'Ah, Ponder,' said the Senior Wrangler, stepping in front of it hurriedly. 'Good to see you looking so…'

'You've been ... doing things, haven't you,' said Ponder, trying to see around him.

'I'msure everything can be mended,' said the Lecturer in Recent Runes.

'And it's still nearly circular,' said the Dean, 'Just ask Charlie Grinder here. His name's definitely not Mustrum Ridcully, I know that.'

'I'm warning you, Dean...'

'What have you done?'

Ponder looked at his globe. It was certainly warmer now, and also rather less globular. There were livid red wounds across one side, and the other hemisphere was mainly one big fiery crater. It was spinning gently, wobbling as it did so.

'We've saved most of the bits,' said the Senior Wrangler, watch­ing him hopefully

'What did you do?'

'We were only trying to be helpful,' said the Dean. 'Gertrude here suggested we make a sun, and...'

'Dean?' said Ridcully

'Yes, Archchancellor?'

'I would just like to point out, Dean, that it was not a very funny joke to begin with. It was a pathetic attempt, Dean, at dragging a sad laugh out of a simple figure of speech. Only four-year-olds and people with a serious humour deficiency keep on and on about it. I just wanted to bring this out into the open, Dean, calmly and in a spirit of reconciliation, for your own good, in the hope that you may be made well. We are all here for you, although I can't imagine what you are here for.' Ridcully turned to the horrified Ponder. 'We made a sun...'

‘...some suns...' muttered the Dean.

‘...some suns, yes, but ... well, this "falling in circles" business is very difficult, isn't it? Very hard to get the hang of.'

'You crashed a sun into my world?' said Ponder.

'Some suns,' said Ridcully.

'Mine bounced off,' said the Dean.

'And created this rather embarrassingly large hole here,' said the Archchancellor. 'And incidentally knocked a huge lump out of the place.'

'But at least bits of my sun burned for a long time,' said the Dean.

'Yes, but inside the world. That doesn't count.' Ridcully sighed. 'Yet your machine, Mister Stibbons, says a sun sixty miles across won't work. And that's ridiculous.'

Ponder stared hollow-eyed at his world, wobbling around like a crippled duck.

'There's no narrativium,' he said dully. 'It doesn't know what size a sun should be.'

'Ook,' said the Librarian.

'Oh dear,' said Ridcully. 'Who let him in here?'

The Librarian was informally banned from the High Energy Magic building, owing to his inherent tendency to check on what things were by tasting them. This worked very well in the Library, where taste had become a precision reference system, but was less useful in a room occasionally containing bus bars throbbing with several thousand thaums. The ban was informal, of course, because anyone capable of pulling the dooknob right through an oak door can obviously go where he likes.

The orangutan knuckled over to the dome and tasted it. The wizards tensed as delicate black fingers twiddled the knobs of the omniscope, bringing into focus the furnace that had exploded yes­terday. It was a tiny point of light now, surrounded by coruscating streamers of glowing gas.

The focus moved in to the glowing ember.

'Still too big,' said Ridcully. 'Nice try, old chap.'

The Librarian turned towards him, the light of the explosion moving across his face, and Ponder held his breath.

It came out in a rush. 'Someone give me a light!'

The globes on his desk rolled off and bounced on the floor as he tried to grab one. He held it as the Senior Wrangler obligingly lit a match, and waggled it this way and that. 'It'll work!' 'Jolly good!' said Ridcully. 'What will?'

'Days and nights!' said Ponder. 'Seasons, too, if we do it right! Well done, sir! I'm not sure about the wobble, but you might have got it just right!'

'That's the kind of thing we do,' said Ridcully, beaming. 'We're the chaps for getting things right, sure enough. What things did we get right this time?'

'The spin!'

'That was my sun that did that,' the Dean pointed out, smugly.

Ponder was almost dancing. And then, suddenly, he looked grave.

'But it all depends on fooling people down there,' he said. 'And there isn't anyone down there ,.. HEX?'

There was a mechanical rattle as HEX paid attention.