The Science of Discworld Revised Edition

ceremonies, in which A Royal Personage or The President pulls a big lever or pushes a big button to ‘start’ some vast monument to technology – which has been running for days behind the scenes. When Queen Elizabeth II opened Calder Hall, the first British nuclear power station, this is just what went on – big meter and all.
    However, it’s a bit early for Quantum, and most of us have forgotten Calder Hall completely. In any case there’s a more urgent matter to dispose of. This is the relation between science and magic. Let’s start with science.
    Human interest in the nature of the universe, and our place within it, goes back a long, long way. Early humanoids living on the African savannahs, for instance, can hardly have failed to notice that at night the sky was full of bright spots of light. At what stage in their evolution they first began to wonder what those lights were is a mystery, but by the time they had evolved enough intelligence to poke sticks into edible animals and to use fire, it is unlikely that they could stare at the night sky without wondering what the devil it was
for
(and, given humanity’s traditional obsessions, whether it involved sex in some way). The Moon was certainly impressive – it was big, bright, and
changed shape
.
    Creatures lower on the evolutionary ladder were certainly aware of the Moon. Take the turtle, for instance – about as Discwordly a beast as you can get. When today’s turtles crawl up the beach to lay their eggs and bury them in the sand, they somehow choose their timing so that when the eggs hatch, the baby turtles can scramble towards the sea by aiming at the Moon. We know this because the lights of modern buildings confuse them. This behaviour is remarkable, and it’s not at all satisfactory to put it down to ‘instinct’ and pretend that’s an answer. What
is
instinct? How does it work? How did it arise? A scientist wants plausible answers to such questions, not just an excuse to stop thinking about them. Presumably the baby turtles’ moonseeking tendencies, and their mothers’ uncanny sense of timing, evolved together. Turtles that just happened, by accident, to lay their eggs at just the right time for them to hatch when the Moon would be to seawards of their burial site,
and
whose babies just happened to head towards the bright lights, got more of the next generation back to sea than those that didn’t. All that was needed to establish these tendencies as a universal feature of turtle-hood was some way to pass them on to the next generation, which is where genes come in. Those turtles that stumbled on a workable navigational strategy, and could pass that strategy on to their offspring by way of their genes, did better than the others. And so they prospered, and outcompeted the others, so that soon the only turtles around were the ones that could navigate by the Moon.
    Does Great A’Tuin, the turtle that holds up the elephants that hold up the Disc, swim through the depths of space in search of a distant light? Perhaps. According to
The Light Fantastic
, ‘Philosophers have debated for years about where Great A’Tuin might be going, and have often said how worried they are that they might never find out. They’re due to find out in about two months. And then they’re
really
going to worry …’ For, like its earthbound counterpart, Great A’Tuin is in reproductive mode, in this case going to its own hatching ground to watch the emergence. That story ends with it swimming off into the cool depths of space, orbited by eight baby turtles (who appear to have gone off on their own, and perhaps even now support very small Discworlds) …
    The interesting thing about the terrestrial turtlish trickery is that at no stage is it necessary for the animals to be conscious that their timing is geared to the Moon’s motion, or even that the Moon exists. However, the trick won’t work unless the baby turtles
notice
the Moon, so we deduce that they did. But we can’t deduce the existence of some turtle astronomer who wondered about the Moon’s puzzling changes of shape.
    When a particular bunch of social-climbing monkeys arrived on the scene, however, they began to ask such questions. The better the monkeys got at
answering
those questions, the more baffling the universe became; knowledge increases ignorance. The message they got was:
Up There is very different from Down Here
.
    They didn’t know that Down Here was a pretty good place for