Terry Pratchett - The Science of Discworld I

Most of us don't think like scientists. We think like the wizards of Discworld. Everything in the past was leading inevitably to Now, which is the important time.

While the news that the Earth is a small planet in a dull part of the universe has caught on in recent centuries, it's only in the last few decades that the words 'the Earth' have come to mean, for a sig­nificant proportion of any society, 'the planet' rather than 'the soil'. We watch the fireworks as great balls of ice plummet into the atmosphere of a nearby planet and, although any one of them would have seriously troubled the Earth, the event was just that: a firework display. As one old lady told a news reporter, 'that sort of thing happens in Outer Space'. But we're in Outer Space, too, and it might pay us to get good at it.

The dinosaurs were not, as suggested in Jurassic Park, 'selected for extinction', they were clobbered by a very large rock, and/or its after-effects. Rocks don't think.

The dinosaurs were in fact doing very well, and had merely neg­lected to develop three-mile thick armour plating. They may even have evolved something that we'd recognize as 'early civilization'; we shouldn't underestimate how much the surface of the planet can change in 65 million years. But rocks don't care, either.

But even if the rock had missed, there were other rocks. And if they had missed too, then we should be aware that the planet has other, home-grown means of disposal.

Evidence is emerging that suggests that other extinctions were caused by 'natural' but catastrophic changes in the planet's atmos­phere. A case is being made that indicates that the very existence of life on Earth will, periodically, trip a catastrophe.

Rocks don't mind.

This will probably not happen tomorrow. But, one day, it will. And then Rincewind's kaleidoscope is shaken up for a new pretty pattern.

Eden and Camelot, the wondrous garden-worlds of myth and legend, are here now. This is about as good as it ever gets. Mostly, it's a lot worse. And it won't stay like this for very long.

There are, perhaps, choices. We could leave. We've dealt with that. Considerable optimism is required. But there might be other small blue planets out there ... By definition, though, Earthlike worlds will have life on them. That's why they'll be Earthlike. And the trouble is that the more Earthlike it is, the more troublesome it would be. Don't worry about the laser-wielding monsters, you can talk to them, if only about lasers. The real problem is more likely to be something very, very small. In the morning you get a rash. In the afternoon, your legs explode [53] This is probably another lie. Alien microbes are unlikely to find us edible. So are alien tigers, although they might do us quite a lot of damage in finding out. But certainly an alien world will have a whole host of nasty surprises, if we are not very careful. We can't tell you what they'll be. They'll be a surprise. .

The other 'choice' is to stay. We may be lucky, we tend to be. But we won't be lucky forever. The average life of a species is about five million years. Depending on how you define humanity, we may already be close to the average.

A useful project, and one that's much cheaper to achieve, is to leave a note to the next occupiers, even if it is only to say 'We Were Here'. It may be of interest to a future species that even if they are, alone in space, they're not alone in Time.

We may already have left our marker. It depends on how long things will really last on the Moon, and if, in a hundred million years, anyone else feels it necessary to go there. If they do, they may find the abandoned descent stages of the Apollo Moon landers. And they'll wonder what a 'Richard M. Nixon' was.

How much luckier are the inhabitants of Discworld. They know they live on a world made for people. With a large hungry turtle, not to mention the four elephants, interstellar debris becomes lunch rather than catastrophe. Large-scale extinction has more to do with magical interference than random rocks or built-in fluctu­ations; it may have the same effect, but at least there is someone to blame.

Unfortunately, it does reduce the scope for asking interesting questions. Most of them have already been answered. Certainty rules. Mustrum Ridcully is not the kind of person who would tol­erate an Uncertainty Principle, after all.

Back in Roundworld, there is perhaps one point worth making.

Just suppose there is nothing else. Arguments about intelligent life on other worlds have always been highly biased by the desires of those doing the arguing that there should be intelligent life on other worlds, and we three are among them. But the argument is a house of cards with no card on the bottom. We know of life on one world. Everything else is guesswork and naked statistics. Life may be so common through the universe that even the atmosphere of Jupiter is alive with Jovian gasbags and every cometary nucleus is home to colonies of microscopic blobuies. Or there may be nothing alive at all, anywhere else but here.

Perhaps intelligent life arose before humanity, and perhaps it will again when humanity's span has become a rather complex layer in the strata. We can't tell. Time does not simply, as the hymn says, bear all its sons away, it can easily see the disappearance of the entire continent on which they stood.

In short, in a universe a billion Grandfathers long and a trillion Grandfathers wide, there may be just a few hundred thousand years on one planet where a species worried about something other than sex, survival, and the next meal.

This is our Discworld. In its little cup of spacetime, humanity has invented gods [54] We apologize to any real gods. , philosophies, ethical systems, politics, an unfeasible number of ice-cream flavours and even more esoteric things like 'natural justice' and 'boredom'. Should it matter to us if tigers are made extinct and the last orangutan dies in a zoo? After all, blind forces have repeatedly erased species that were probably more beautiful and worthy.

But we feel it does matter, because humans invented the concept of things 'mattering'. We feel we ought to be brighter than a mile of incandescent rock and a continent-sized glacier. Humans seem to have created, independently, in many pkces and at various times, a Make-a-Real-Human-Being Kit, which begins with prohibitions about killing and theft and incest and is now groping towards our responsibilities to a natural world in which, despite its ability to hurt us mightily, we nevertheless have a godlike power [55] Unfortunately, huge malicious destructive force is a god-like power. .

We advance arguments about saving rainforests because 'there may be undiscovered cancer cures in there', but this is because extelligence wants to save rainforests and the cancer-cure argument might convince the bean-counters and the fearful. It might have a real basis in fact, too, but the real reason is that we feel that a world with tigers and orangutans and rainforests and even small unobtru­sive snails in it is a more healthy and interesting world for humans (and, of course, the tigers and orangutans and snails) and that a world without them would be dangerous territory. In other words, trusting the instincts that up until now have generally seen us through, we think that Tigers Are Nice (or, at least, Tigers Are Nice In Moderation And At A Safe Distance).

It's a circular argument, but in our little round human world we've managed to live on circular arguments for millennia. And who else is going to argue with us?

RINCEWIND WALKED VERY GINGERLY towards his office, the globe of the project held carefully in his hands.