To say that I’m a fan of Terry Pratchett’s Discworld is an understatement. Among the humorous fantasy writers, Terry Pratchett has pride of place. At his right and left hand are Douglas Adams in sheer satiric glory, and Neil Gaiman, whose humour shades into great darkness.

Pratchett’s Discworld is imagined in the prologue to the first book, The Colour of Magic:

In a distant and secondhand set of dimensions, in an astral plane that was never meant to fly, the curling star-mists waver and part…

See…

Great A’Tuin the turtle comes, swimming slowly through the interstellar gulf, hydrogen frost on his ponderous limbs, his huge and ancient shell pocked with meteor craters. Through sea-sized eyes that are crusted with rheum and asteroid dust He stares fixedly at the Destination.

In a brain bigger than a city, with geological slowness, He thinks only of the Weight.

Most of the weight is of course accounted for by Berilia, Tubul, Great T’Phon and Jerakeen, the four giant elephants upon whose broad and star-tanned shoulders the Disc of the World rests, garlanded by the long waterfall at its vast circumference and domed by the baby-blue vault of Heaven.

I don’t know the effect these words had on you when you first read them, but for me they were a temenos, the threshold between my chair and the faërie woods beyond the hedge, the invisible bridge from now to myth. The prologue was a magic ring, a desperate wish, an open wardrobe door.

In the paperback reprint of The Colour of Magic, Terry Pratchett talks about how Discworld came into being:

If I had a penny for every time someone asked me where I got the idea of the Discworld, I’d have—hang on a moment—£4.67.

Anyway, the answer is that it was lying around and didn’t look as though it belonged to anyone.

The world rides through space on the back of a turtle. It’s one of the great ancient myths, found wherever men and turtles were gathered together; the four elephants were an Indo-European sophistication. The idea has been lying in the lumber rooms of legend for centuries. All I had to do was grab it and run away before the alarms went off.

I actually bumped into this idea—save the elephants—in a legendary lumber room of my childhood, though I can`t remember where exactly. I kind of think it was a book on finance I found lying around the house. I was a strange child.

In any case, the author—who I’m now sure was a self-made millionaire kind of guru—talked about a book signing event where one of his fans brought of up the idea of a flat world. “It sits on the back of a giant turtle,” she declared. The author, who I imagine has a square jaw, asked her what the turtle was sitting upon. “Another turtle,” she said. “And beneath that?” he persisted. The woman considered the question, as if it had never occurred to her before. Finally, she looked up brightly at the self-help guru. “It’s turtles all the way down,” she said brightly.

The “all the way down” stuck with me. The Great A’Tuin floats in a pre-Ptolomaic space, so we don’t have to question what the turtle sits on. There are more important questions, like the turtle’s sex.

But if we look at A’Tuin not just in space but in time, there are important questions. According to The Colour of Magic, there are differing theories:

There was, for example, the theory that A’Tuin had come from nowhere and would continue at a uniform crawl, or steady gait, into nowhere, for all time. This theory was popular among academics.

An alternative, favored by those of a religious persuasion, was that A’Tuin was crawling from the Birthplace to the Time of Mating, as were all the stars in the sky which were, obviously, also carried by giant turtles. When they arrived they would briefly and passionately mate, for the first and only time, and from that fiery union new turtles would be born to carry a new pattern of worlds. This was known as the Big Bang hypothesis.

Brilliant.

And it demonstrates my own hunch that the Big Bang Theory of the beginning of our own universe is really a religious idea. The theory presumes a beginning, after all, where something shifts. Off becomes on. Inactivity becomes activity. Potential energy becomes kinetic energy. The inert moves. It is a creation narrative, since some force must act upon matter in a cause and effect universe. If we claim to be a cause and effect universe, then there must be an ultimate Cause. If we aren’t a cause and effect universe, we can’t say anything about science and history at all.

The other option, the theory “popular among academics,” claims that there is no need for an ultimate Cause. Some say the Big Bang is triggered internally, meaning that the first event in a cause and effect universe had no cause. This seems to me like special pleading, that the rules apply only as long as we are comfortable with them.

For others, the Big Bang is just the nearest or most recent manifestation of a multiverse in flux. “No,” they say, “the Big Bang was caused by some activity in another or previous universe.” When we encounter this idea, even if our jaws are not Hollywood level and we haven’t made  millions as a self-help guru, we need to ask the theorist: “What caused that universe?” There is only one of two answers. 1) That the other universe—one with no hint of evidence, we might remember—is uncaused. We are back again to special pleading. 2) That the other universe was caused by still another universe. When asked how that one began, the answer will be the same. Like the woman at the book signing, these people think, “It’s turtles all the way down.”

No, it doesn’t work. As long as this is a cause and effect universe, there needs to be an ultimate Cause. We are left with one of two realities. Either we must wait until quantum physics or some future scientific endeavour proves that this is not a cause and effect universe. How this happens without cause and effect reasoning, I cannot predict. It is a movement beyond any human experience thus far. In that sense it is a matter of faith and hope. It is a yet a religious idea.

Or we must remember our Aristotle and our Thomas Aquinas, imagining that there may actually be wisdom in a pre-digital age. Thomas reasoned that when we see an arrow moving past, we must suspect an archer. To use a colleague’s illustration, nature is like train cars on a track moving up a mountain. We have these billions of years of evolutionary movements lined up along space-time. These fingers on the keyboard, the exchange of CO₂ in my lungs, the words that come into my brain seemingly unbidden—these are just the nearest things in our evolutionary history. We are in movement, and each of these effects is a cause.

Think now of the train. Imagine that the engine is hidden in the clouds higher up the mountain. We may ask why the last car is moving, and may rightly answer that the car in front of it is pulling it. And this answer applies to the car in front of it, and so on. But we cannot go on forever. Somewhere in the distance is the First Car, the First Cause. So it is with the universe. Time and size can never change what is the most basic reality of the universe.

I don’t know how the great scholars of Discworld would deal with this thought experiment, but the turtle argument always has stuck with me. Unfortunately, the self-help guru never taught me how to become a millionaire. But he did tell me to check under argumentative rocks—or beneath the turtle, so to speak. A beautiful and exciting idea, the multiverse is only one more turtle in the stack. And so is the idea that the Big Bang theory “began it all.”