Free The Science of Discworld IV by Ian Stewart & Jack Cohen Terry Pratchett

Anyway, once the feline disruption was taken care of, Newton discovered that white light from the Sun splits into colours, and optics was born.
    This kind of experiment is a cinch for things like light, which can be confined to a laboratory (if the cat complies). If you want to discover the nature of the universe, however, it’s not so easy. You can’t put the universe on a laboratory bench, and you can’t step outside it to observe its form, or go back in time to see how it began. The wizards can do, and have already done, all of these things; however, neither the scientists nor the theologians of Roundworld are likely to accept that the Dean of Unseen University kicked it all off by poking his finger in.
    Instead, human-centred thinkers on Roundworld tend to go for human-level explanations like emperors and elephants, scaled up to superhuman levels to become gods and world-bearers. Most human civilisations have a creation myth – often several, not always compatible. Universe-centred thinkers have to fall back on scientific inference, and test the resulting theories indirectly. Their cosmological scenarios have often fared little better than most creation myths. Some look remarkably similar: compare the Big Bang to Genesis.However, scientific cosmologists do try to prove themselves wrong, and keep looking for weaknesses in their theories even when observations seem to confirm that they’re right. Typically, after about twenty years of increasingly good supporting evidence, these theories start to unravel as the observations become more sophisticated: see chapter 18 .
    Our ancestors needed to rationalise the things they observed in the natural world, and creation myths played a significant role. It can therefore be argued that they helped to bring about today’s science and technology, because they long ago drew humanity’s attention to the big questions, and held out hope of answering them. So it’s worth examining the similarities and differences between the creation stories of different cultures – especially when it comes to world-bearing elephants and space-faring turtles. Along with a third common world-bearing creature, the giant snake.
    The world turtle (cosmic turtle, divine turtle, world-bearing turtle) can be found in the myths of the Chinese, Hindus and various tribes of native North Americans, in particular the Lenape (or Delaware Indians) and the Iroquois.
    Around 1680 Jasper Danckaerts, a member of a Protestant sect known as Labadists, travelled to America to found a community, and he recorded a Lenape myth of a world turtle in
Journal Of A Voyage To New York In 1679-80
. We paraphrase the story from a 1974 article by Jay Miller. fn2 At first, all was water. Then the Great Turtle emerged, mud on its back became the Earth, and a great tree grew. As it rose skywards, one twig became a man; then it bent to touch the Earth and another twig became a woman. All humans descended from these two. Miller adds: ‘my … conversations with the Delaware indicate that life and the Earth would have been impossible without the turtle supporting the world.’
    According to the Iroquois creation story, immortal Sky People lived on a floating island before the Earth existed. When one of the women discovered that she was going to have twins, her husband lost his temper and pulled up a tree at the island’s centre, the tree being their source of light at a time when the Sun did not exist. The woman looked into the hole thus created, and far below she saw the ocean that covered the Earth. Her husband pushed her into the hole, and she fell. Two birds caught her, and tried to get mud from the ocean floor to make land for her to live on. Finally Little Toad brought up mud, which was spread on the back of Big Turtle. The mud grew until it turned into North America. Then the woman gave birth. One son, Sapling, was kind, and filled the world with all good things; the other, Flint, ruined much of his brother’s work and created