The Science of Discworld II - The Globe tsod-2 Read online

  When Mind evolved on Earth, a kind of narrativium evolved alongside it. Unlike the Discworld variety of narrativium, which on the Disc is just as real as iron or copper or praseodymium, our variety is purely mental. It is an imperative, but the imperative has not been reified into a thing.

  However, we have the sort of mind that respond to imperatives, and to many other non-things.

  And so it feels to us as if our universe runs on narrativium.

  There is a curious resonance here, and 'resonance' is definitely the word. Physicists tell a story about how carbon forms in the universe. In certain stars there is a particular nuclear reaction, a

  'resonance' between nearby energy levels, which gives nature a stepping-stone from lighter elements to carbon. Without that resonance, so the story goes, carbon could not have formed.

  Now, the laws of physics as we currently understand them involve several 'fundamental constants', such as the speed of light, Planck's constant in quantum theory, and the charge on an electron. These numbers determine the quantitative implications of the physical laws, but any choice of constants sets up a potential universe. The way that a universe behaves depends on the actual numbers that are used in its laws. As it happens, carbon is an essential constituent of all known life. All of which leads up to a clever little story called the Anthropic Principle: that it's silly for us to ask why we live in a universe whose physical constants make that nuclear resonance possible - because if we didn't, there'd be no carbon, hence no us to ask about it.

  The story of the carbon resonance can be found in many science books, because it creates a powerful impression of hidden order in the universe, and it seems to explain so much. But if we look a little more closely at this story, we find that it is a beautiful illustration of the seductive power of a compelling but false narrative. When a story seems to hang together, even consciously self-critical scientists can fail to ask the question that makes it fall apart.

  Here's how the story goes. Carbon is created in red giant stars by a rather delicate process of nuclear synthesis, called the triple-alpha process. This involves the fusion of three helium nuclei[8]. A helium nucleus contains two protons and two neutrons. If you fuse three helium nuclei together, you get six protons and six neutrons. That, as it happens, is a carbon nucleus.

  All very well, but the odds on such a triple collision occurring inside a star are very small.

  Collisions of two helium nuclei are much more common, though still relatively rare. It is extremely rare for a third helium nucleus to crash into two that are just colliding. It's like paint- balls and wizards. Every so often, a paintball will go splat! against a wizard. But you wouldn't bet a lot of money on a second paintball hitting him at the exact same moment. This means that the synthesis of carbon has to take place in a series of steps rather than all at once, and the obvious way is for two helium nuclei to fuse, and then for a third helium nucleus to fuse with the result.

  The first step is easy, and the resulting nucleus has four protons and four neutrons: this is one form of the element beryllium. However, the lifetime of this particular form of beryllium is only

  1016 seconds, which gives that third helium nucleus a very small target to aim at. The chance of hitting this target is incredibly small, and it turns out that the universe hasn't existed long enough for even a tiny fraction of its carbon to have been made in this way. So triple collisions are out, and carbon remains a puzzle.

  Unless ... there is a loophole in the argument. And indeed there is. The fusion of beryllium with helium, leading to carbon, would occur much more rapidly, yielding a lot more carbon in a much shorter time, if the energy of carbon just happens to be close to the combined energies of beryllium and helium. This kind of near-equality of energies is called a resonance. In the 1950s Fred Hoyle insisted that carbon has to come from somewhere, and predicted that there must therefore exist a resonant state of the carbon atom. It had to have a very specific energy, which he calculated must be about 7.6 MeV[9].

  Within a decade, it was discovered that there is a state with energy 7.6549 MeV. Unfortunately, it turns out that the combined energies of beryllium and helium are about 4 per cent higher than this. In nuclear physics, that's a huge error.

  Oops.

  Ah, but, miraculously, that apparent discrepancy is just what we want. Why? Because the additional energy imparted by the temperatures found in a red giant star is exactly what's needed to change the combined energy of beryllium and helium nuclei by that missing 4 per cent.

  Wow.

  It's a wonderful story, and it rightly earned Hoyle huge numbers of scientific brownie-points.

  And it makes our existence look rather delicate. If the fundamental constants of the universe are changed, then so is that vital 7.6549. So it is tempting to conclude that our universe's constants are fine-tuned for carbon, making it very special indeed. An it is equally tempting to conclude that the reason for that fine-tuning is to ensure that complex life turns up. Hoyle didn't do that, but many other scientists have given into these temptations.

  Sounds good: what's wrong? The physicist Victor Stenger calls this kind of argument

  'cosmythology'. Another physicist, Craig Hogan has put his finger on one of the weak points.

  The argument treats the temperature of the red giant and that 4 per cent discrepancy in energy levels as if they were independent. That is, it assumes that you can change the fundamental constants of physics without changing the way a red giant works. However, that's obvious nonsense. Hogan points out that 'the structure of stars includes a built-in thermostat that automatically adjusts the temperature to just the value needed to make the reaction go at the correct rate'. It's rather like being amazed that the temperature in a fire is just right to burn wood, when in fact that temperature is caused by the chemical reaction that burns the wood. This kind of failure to examine the interconnectedness of natural phenomena is a typical, and quite common, error in anthropic reasoning.

  In the human world, what counts is not carbon, but narrativium. And in that context we wish to state a new kind of anthropic principle. It so happens that we live in a universe whose physical constants are just right for carbon-based brains to evolve to the point at which they create narrativium, much as a star creates carbon. And the narrativium does crazy things, like putting machines on the Moon. Indeed, if carbon did not (yet) exist, then any narrativium-based lifeform could find some way to manufacture it, by telling itself a really gripping story about the need for carbon. So causality in this universe is irredeemably weird. Physicists like to put it all down to the fundamental constants, but it's more likely an example of Murphy's law.

  But that's another story.

  The more we think about narrative in human affairs, the more we see that our world revolves around the power of story. We build our minds by telling stories. Newspapers select news according to its value as a story, not according to how intrinsically important it is. 'England loses cricket match to Australia' is a story (though not a very surprising one) and it goes on the front page. 'Doctors think that they may have improved the diagnosis of liver disease by 1 per cent' is not a story, even though most science works like that (and in years to come, depending on the state of your liver, you might think it's a rather more important story than a cricket match).

  'Scientist claims cure for cancer' is a story, though, even if the supposed cure is nonsense. So are

  'spiritualist medium claims a cure for cancer', and 'Secret code predictions hidden in the Bible', more's the pity.

  As we write, there is a furore over a small group of people who are proposing to clone a human being. It's a major story, but very few newspapers are reporting the most likely result of this attempt, which will be abject failure. It took 277 failures, many rather nasty, before Dolly the Sheep was cloned, and she has now been found to have serious genetic defects, poor lamb.

  Trying to clone a human may indeed be unethical, but that's not the best reason for objecting to this misguided and f
oolish attempt. The best reason is that it won't work, because nobody yet knows how to overcome numerous technical obstacles; moreover, if by some stroke of

  (mis)fortune it did happen to work, any child produced would have serious defects. Producing such a child, now that is unethical.

  Making 'carbon copies' of human beings, which is the usual basis of the newspapers' story about the ethics, is beside the point. That's not what cloning does, anyway. Dolly the Sheep was not genetically identical to her mother, though she came close. Even if she had been, she would still have been a different sheep, moulded by different experiences. For that matter, the same would be true even if she was genetically identical to her mother. For the same reason, cloning a dead child will not bring that child back to life. Much of the media discussion of the ethics of cloning, like much of the public understanding of science, is vaguely stirred through with science fiction.

  In this arena, as in so many, the power of the story outweighs any questions about the real factual basis.

  Human beings do not just tell stories, or just listen to them. The are more like Granny Weatherwax, who is aware of the power of stories on Discworld, and refuses to be trapped by the story's narrativium. Instead, she uses the power of story to mould events according to her own wishes. Roundworld priests, politicians, scientists, teachers and journalists have learned to use the power of story to get their messages across to the public, and to manipulate or persuade people to behave in particular ways. The 'scientific method' is a defense mechanism against that kind of manipulation. It tells you not to believe things because you want them to be true. The proper scientific response to any new discovery or theory, especially your own, is to look for ways to disprove it. That is, to try to find a different story that explains the same things.

  The anthropologists got it wrong when they named our species Homo sapiens ('wise man'). In any case it's an arrogant and bigheaded thin to say, wisdom being one of our least evident features. In reality, w are Pan narrans, the storytelling chimpanzee.

  At this point, the structure of The Science of Discworld 2: The Globe becomes very self- referential. You will need to bear that in mind as we proceed. The book is itself a story - no - two intertwined stories One, the odd-numbered chapters, is a Discworld fantasy. The other -the even-numbered chapters, is a story of the science of the Mind (metaphysical again). The two are closely related, designed to fit together like foot and glove[10]; the science story is presented as a series of Very Large Footnotes to the fantasy story.

  So far, so good ... but it gets more complicated. When you read a Discworld story, you play a curious mental game. You react as if the story is true, as if Discworld actually exists, as if Rincewind and the Luggage are real, and Roundworld is but a fragment of a long-forgotten dream. (Please stop interrupting, Rincewind, we know it's different from your point of view. Yes, of course we're the ones that don't exist, we're bundles of rules whose consequences take place only inside a small globe on a dusty shelf in Unseen University. Yes, we do appreciate that, and will you please shut up?) Sorry about that.

  People have become very good at playing this game, and we will exploit that by setting Earth and Discworld on the same narrative level, so that each illuminates the other. In the first book, The Science of Discworld, the Discworld defined what is real. That's why reality makes such good sense. Roundworld is a magical construct, designed to keep the magic out, and that's why it makes no sense at all (to wizards, at least). In this sequel Earth acquires inhabitants, the inhabitants acquire minds, and minds do strange things. They bring narrativium to a story-less universe.

  A computer can do a billion sums in the blink of a keystroke and get them all right, but it couldn't pretend to be a cowardly wizard if one walked up to it and thumped it on the memory cache. In contrast, we can think ourselves inside the mind of a cowardly wizard with ease, or recognize someone else when they're acting the part of one, but we're completely lost when it comes to doing several million simple sums a second. Even though, to someone not of this universe, that might appear to be a simpler task.

  That's because we run on narrativium, and computers don't.

  3. JOURNEY INTO L-SPACE

  It was three hours later, in the cool of Unseen University. Not much had changed in the High Energy Magic building, except that a screen had been set up to show the output of Ponder's iconograph projector.

  T don't see why you need it,' said Rincewind. 'There's only the two of us.'

  'Ook,' agreed the Librarian. He was annoyed at having been woken from a doze in his library. It had been a very gentle awakening, sine no one wakes up a 300 lb orangutan roughly (twice, at least) but he was still annoyed.

  "The Archchancellor says that we've got to be more organized about these things,' said Ponder.

  'He says it's no use just shouting out "Hey, I've got a great idea!" These things have got to be presented properly. Are you ready?'

  The very small imp that ran the projector raised a tiny thumb.

  'Very well,' said Ponder. 'First slide. This is the Roundworld as it currently—'

  'It's the wrong way up,' said Rincewind.

  Ponder looked at the image.

  'It's a ball,' he snarled. 'It's floating in space. How can it be the wrong way up?'

  'That crinkly continent should be at the top.'

  'Very well!' snapped Ponder. 'Imp, turn it around. Right? Satisfied?'

  'It's the right way up but now it's the wrong way arou—' Rincewind began.

  There was a thwack as Ponder's pointer stick smacked into the screen. 'This is the Roundworld!'

  he snapped. 'As it exists at present! A world covered in ice! But time on Roundworld is subordinate to time in the real world! All times in Roundworld are accessible to us, in the same way that all pages in a book, though consecutive, are accessible to us! I have ascertained that the Faculty are on Roundworld but not in what appears to be the present time! They are several hundred million years in the past! Which is, from our point of view, perfectly capable of also being the present! I don't know how they got there! It should not be physically possible! Hex has located them! We have to assume that they can't get back the way they came! However -next slide please!'

  Click!

  'It's the same one,' said Rincewind. 'But now it's sideways—'

  'A globe has no sideways!' said Ponder. There was a tinkle of breaking glass from the direction of the projector, and some very small cursing.

  'I just thought you wanted to do it properly,' murmured Rincewind. Anyway, this is going to be about L-space, isn't it? I know it is. You know it is.'

  'Yes, but I don't say that yet! I've got another dozen slides to come!' gasped Ponder. 'And a flow chart!'

  'But it is, isn't it,' said Rincewind wearily. I mean, they say they've found other wizards. That means libraries. That means you can get there through L-space.'

  I was going to say that's how we can get there,' said Ponder.

  Yes, I know,' said Rincewind. 'That's why I thought I'd take the opportunity of saying "you" at this early juncture.'

  'How can there be wizards on Roundworld?' said Ponder. 'When we know magic doesn't work there?'

  'Search me,' said Rincewind. 'Ridcully did say they're useless.'

  'And why can't the faculty come back by themselves? They were able to send the bottle! That must have used magic, surely?'

  'Why not just go and ask them?' said Rincewind.

  'You mean by homing in on the distinctive biothaumic signature of a group of wizards?'

  'Well, I was thinking of waiting until something dreadful happened and you going to have a look in the wreckage,' said Rincewind. 'Bui the other stuff would probably work.'

  "The omniscope locates them in approximately the 40,002,730,907th century,' said Ponder, staring at the globe. 'I can't get an image. But if we can find a way to the nearest library—'

  'Ook!' said the Librarian. And then he ooked some more. He ooked at length, with an occasional eek. Once he thumped hi
s fist on the table. He didn't need to thump the table a second time.

  There wasn't, at that point, much in the way of table left to thump.

  'He says only very senior librarians can use L-space,' said Rincewind, as the Librarian folded his arms. 'He was quite emphatic. He says it's not to be treated like some kind of magic funfair ride.'

  'But it's an order from the Archchancellor!' said Ponder. 'There isn't any other way to get there!'

  The Librarian looked a little uncertain at that. Rincewind knew why. It was hard to be an orangutan in Unseen University, and the only way the Librarian had been able to deal with it was by acknowledging Mustrum Ridcully as the alpha male, even though the Archchancellor seldom climbed up to a high place on the rooftops and called mournfully over the city at dawn. This meant that, unlike the other wizards, he found it very hard to shrug off an archchancelloric command. It was a direct, fang-revealing, chest-beating challenge. Rincewind had an idea.

  'If we put the globe in the Library,' he said to the ape, 'then that would mean that even though you are travelling in L-space you would not be taking Mr. Stibbons anywhere outside the Library. I mean, the globe would be inside the library, so even though you'd wind up in the globe, you really wouldn't have travelled very far at all. A few feet, maybe. The globe's only infinite on the inside, after all.'

  'Well, Rincewind, I am impressed,' said Ponder, while the Librarian looked perplexed. 'I'd always thought of you as rather stupid, but that was a remarkable piece of verbal reasoning. If we put the globe down right on the Librarian's desk, say, then the whole journey would take place inside the library, right?'

  'Exactly,' said Rincewind, who was prepared to overlook 'rather stupid' in view of this unexpected praise.

  And it's perfectly safe in the library, after all ...'

  'Big thick walls. Very safe place,' Rincewind agreed.

  'So, put like that, no harm will come to us,' said Ponder.

  'There you go with the "us" again,' said Rincewind, backing away.