The Science of Discworld Revised Edition

project
can’t
help being affected by this world. Piles of sand try to look like mountains. Men try to act like gods. Little things so often appear to look like big things made smaller. Our new universe, gentlemen, will do its crippled best to look like ours. We should not be surprised to see things that look hauntingly familiar. But not as good, obviously.’
    The inner eye of H EX gazed at a vast cloud of mind. H EX couldn’t think of a better word. It didn’t
technically
exist yet, but H EX could sense the shape. It had hints of many things – of tradition, of libraries, of rumour …
    There had to
be
a better word. H EX tried again.
    On Discworld, words had real power. They had to be dealt with carefully.
    What lay ahead had the
shape
of intelligence, but only in the same way that a sun had the shape of something living out its brief life in a puddle of ditchwater.
    Ah …
ex
telligence would do for now.
    H EX decided to devote part of its time to investigating this interesting thing. It wanted to find out how it had developed, what kept it going … and why, particularly, a small but annoying part of it seemed to believe that if everyone sent five dollars to the six names at the top of the list, everyone would become immensely rich.
    1 Of which there were quite a number, given H EX ’s unusual construction. In addition to AND, OR and their combinations and variants, H EX could call up MAYBE, PERHAPS, SUPPOSE and WHY . H EX could think the unthinkable quite easily.

EIGHT
WE ARE STARDUST
(or at least we went to Woodstock)

    ‘IRON’S IRON.’ BUT is it? Or is iron made from other things?
    According to Empedocles, an ancient Greek, everything in the universe was a combination of four ingredients: earth, air, fire, and water. Set light to a stick and it burns (showing that it contains fire), gives off smoke (showing that it contains air), exudes bubbly liquids (showing that it contains water), and leaves a dirty heap of ash behind (showing that it contains earth). As a theory, it was a bit too simple-minded to survive for long – a couple of thousand years at best. Things moved more slowly in those days, and Europe, at least, was more interested in making sure that the peasants didn’t get above their station and copying out bits of the Bible by hand in as laborious and colourful a manner as possible.
    The main technological invention to come out of the Middle Ages was a better horse collar.
    Empedocles’s theory was a distinct advance on its predecessors. Thales, Heraclitus, and Anaximenes all agreed that everything was made from just
one
basic ‘principle’, or element – but they disagreed completely about what it was. Thales reckoned it was water, Heraclitus preferred fire, and Anaximenes was willing to bet the farm on air. Empedocles was a wishy-washy synthesist who thought
everyone
had a valid point of view: if alive today he would definitely wear a bad tie.
    The one good idea that emerged from all this was that ‘elementary’ constituents of matter should be characterized by having simple, reliable properties. Earth was dirty, air was invisible, fire burned, and water was wet.
    Aside from the superior horse collar, the medieval period did act as a breeding ground for what eventually turned into chemistry. For centuries the nascent science known as alchemy had flourished; people had discovered that some strange things happen when you mix substances together and heat them, or pour acid over them, or dissolve them in water and wait. You could get funny smells, bangs, bubbles, and liquids that changed colour. Whatever the universe was made of, you could clearly convert some of it into something else if you knew the right trick. Maybe a better word is ‘spell’, for alchemy was akin to magic – lots of special recipes and rituals, many of which actually
worked
, but no theory about how it all fitted together. The big goals of alchemy were spells – recipes – for things like the Elixir of Life, which would make you live forever, and How to Turn Lead Into Gold, which would give you lots of money to finance your immortal lifestyle. Towards the end of the Middle Ages, alchemists had been messing about for so long that they got quite good at it, and they started to notice things that didn’t fit the Greeks’ theory of four elements. So they introduced extra ones, like salt and sulphur, because these substances also had simple, reliable properties, different from being dirty, invisible, burning,