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they also took a keen interest in what those lights in the sky
did
. They knew that the Moon was round – a sphere rather than a flat disc They probably knew that the Earth was round, too, because it cast a rounded shadow on the Moon during lunar eclipses. They knew that the year was about 365¼ days long. They even knew about the ‘precession of the equinoxes’, a cyclic variation that completes one cycle every 26,000 years. They made these discoveries by keeping careful records of how the Moon and the planets moved across the sky. Babylonian astronomical records from 500 BC survive to this day.
    From such beginnings, an alternative explanation of the universe came into being. It didn’t involve gods, at least directly, so it didn’t find much favour with the priestly class. Some of their descendants are still trying to stamp it out, even today. The traditional priesthoods (who then and now often included some very intelligent people) eventually worked out an accommodation with this godless way of thinking, but it’s still not popular with postmodernists, creationists, tabloid astrologers and others who prefer the answers you can make up for yourself at home.
    The current name for what has variously been called ‘heresy’ and ‘natural philosophy’ is, of course, ‘science’.
    Science has developed a very strange view of the universe. It thinks that the universe runs on
rules
. Rules that never get broken. Rules that leave little room for the whims of gods.
    This emphasis on rules presents science with a daunting task. It has to explain how a lot of flaming gas and rocks Up There, obeying simple rules like ‘big things attract small things, and while small things also attract big things they don’t do it strongly enough so as you’d notice’, can have any chance whatsoever of giving rise to Down Here. Down Here, rigid obedience to rules seems notably absent. One day you go out hunting and catch a dozen gazelles; next day a lion catches
you
. Down Here the most evident rule seems to be ‘There are no rules’, apart perhaps from the one that could be expressed scientifically as ‘Excreta Occurs’. As the Harvard Law of Animal Behaviour puts it: ‘Experimental animals, under carefully controlled laboratory conditions, do what they damned well please.’ Not only animals: every golfer knows that something as simple as a hard, bouncy sphere with a pattern of tiny dots on it never does what it’s supposed to do. And as for the weather …
    Science has now divided into two big areas: the life sciences, which tell us about living creatures, and the physical sciences, which tell us about everything else. Historically, ‘divides’ is definitely the word – the scientific styles of these two big divisions have about as much in common as chalk and cheese. Indeed, chalk is a rock and so clearly belongs to the geological sciences, whereas cheese, formed by bacterial action on the bodily fluids of cows, belongs to the biological sciences. Both divisions are definitely science, with the same emphasis on the role of experiments in testing theories, but their habitual thought patterns run along different lines.
    At least, until now.
    As the third millennium approaches, more and more aspects of science are straddling the disciplines. Chalk, for instance, is more than just a rock: it is the remains of shells and skeletons of millions of tiny ocean-living creatures. And making cheese relies on chemistry and sensor technology as much as it does on the biology of grass and cows.
    The original reason for this major bifurcation in science was a strong perception that life and non-life are extremely different. Non-life is simple and follows mathematical rules; life is complex and follows no rules whatsoever. As we said, Down Here looks very different from Up There.
    However, the more we pursue the implications of mathematical rules, the more flexible a rule-based universe begins to seem. Conversely, the more we understand