The Science of Discworld II Read Free Page A

of safety and a long-term chance of a decent pint.
    The Discworld wizards never found out who the builders of the space elevator on Roundworld were. We know that they were us , the descendants of those apes, who’d brought sex and mucking about to high levels of sophistication. The wizards missed that bit, although, to be fair, the Earth had been in existence for over four billion years, and apes and humans were present only for a tiny percentage of that time. If the entire history of the universe were compressed to one day, we would have been present for the final 20 seconds.
    Quite a lot of interesting things happened on Roundworld while the wizards were skipping ahead, and now, in this present book, the wizards are going to find out what those things were. And of coursethey’re going to interfere, and inadvertently create the world we live in today, just as their interference in the Roundworld Project inadvertently created our entire universe. It has to work like that, doesn’t it?
    That’s how the story goes.
    Seen from outside, as it sits in Rincewind’s office, the entire human universe is a small sphere. Large quantities of magic went into its manufacture and, paradoxically, into maintaining its most interesting feature. Which is this: Roundworld is the only place on Discworld where magic does not work. A strong magical field protects it from the thaumic energies that surge around it. Inside Roundworld, things don’t happen because people want them to or because they make a good narrative: they happen because the rules of the universe, the so-called ‘laws of nature’, make them happen.
    At least, that was a reasonable way to describe things … until human beings evolved. At that point, something very strange happened to Roundworld. It began, in various ways, to resemble Discworld. The apes acquired minds, and their minds started to interfere with the normal running of the universe. Things started to happen because human minds wanted them to. Suddenly the laws of nature, which up to that point had been blind, mindless rules, were infused with purpose and intention. Things started to happen for a reason, and among these things that happened was reasoning itself. Yet this dramatic change took place without the slightest violation of the same rules that had, up to that point, made the universe a place without purpose. Which, on the level of the rules, it still is.
    This seems like a paradox. The main content of our scientific commentary, interleaved between successive episodes of a Discworld story, will be to resolve that paradox: how did Mind (capital ‘M’ for ‘metaphysical’) come into being on this planet? How did a Mindless universe ‘make up its own Mind’? How can we reconcile human free will (or its semblance) with the inevitability of natural law? What is the relation between the ‘inner world’ of the mind and the allegedly objective ‘outer world’ of physical reality?
    The philosopher René Descartes argued that the mind must be built from some special kind of material – ‘mind-stuff’ that was differentfrom ordinary matter, indeed undetectable using ordinary matter. Mind was an invisible spiritual essence that animated otherwise unthinking matter. It was a nice idea, because it explained at a stroke why Mind is so strange, and for a long time it was the conventional view. Nevertheless, today this concept of ‘Cartesian duality’ has fallen out of favour. Nowadays only cosmologists and particle physicists are allowed to invent new kinds of matter when they want to explain why their theories totally fail to match observed reality. When cosmologists find that galaxies are rotating at the wrong speeds in the wrong places, they don’t throw away their theories of gravitation. They invent ‘cold dark matter’ to fill in the missing 90 per cent of the mass of the universe. If any other scientists did that