The L-Space Web: Interviews

Interview Conducted by with Terry Pratchett, Ian Stewart and Jack Cohen

Weird Science


Terry Pratchett's Discworld comic-fantasy series needs no introduction. Biologist Jack Cohen and mathematician Ian Stewart have already collaborated on bestselling popular science works like The Collapse of Chaos. Now all three have formed a sinister coven to produce The Science of Discworld, in which the bizarre realities of our own "Roundworld" are shown to make Discworld cosmology seem quite sensible and natural... David Langford talked to the authors for in the learned surroundings of Unseen University Library, under the watchful gaze of its orangutan Librarian.

Librarian: Oook? Good point, but I'm asking the questions today. Where did the idea of The Science of Discworld spring from?

Ian Stewart: I was at a slightly drunken lunch with a publisher and the idea, first suggested in jest, took root in my mind. We got on to it via The Physics of Star Trek, The Science of the X-Files, etc. Myself, I keep wanting to do The Physics of Tolkien's Middle-Earth.

Stewart: I happened to mention knowing Terry Pratchett through SF connections and a personal introduction by Jack at a convention years ago. And slowly an idea emerged ... But not the final idea, right?

Stewart: The publisher's vision at that stage was a Cohen/Stewart book on science with a Pratchett introduction and blessing--but we had other ideas. WE WANTED TERRY ON BOARD AS AN AUTHOR. So we made a big enough mess of the Discworld bits that we sent him as samples that he felt he had no choice but to do them right. Bait accepted, trap sprung...but now it was a very different proposition, more expensive to publish, and we ended up with a different publisher (Ebury).

Jack Cohen: It just seemed to grow naturally from the pub conversations we'd had. It was not easy to sell, as a quite new kind of book. What was it like, tackling this three-way collaboration and making it a real science book as well as a real Discworld story?

Cohen: It was the most fun I've had out of bed for a long time...!

Terry Pratchett: It evolved like this. I'd write a Discworld "story" after some long discussions with Ian and Jack--and a lot of phone calls while it was being written, too.

Stewart: First, we got together and plotted out a skeleton of the structure--a sequential list of scientific topics and a rough story to go with it. Then, interactively on occasion, Terry worked out a more detailed storyline.

Cohen: Terry was going to do 10,000 words, but then got caught by our stance and did three times that!

Librarian: Oook! And then?

Stewart: Jack and I looked over the storyline to see if any topics we wanted to write about were "missing", that is, didn't have a suitable hook in the story. As it happened, there were more than enough hooks. Terry then went full steam ahead on the "short" story, originally intended to be about 12,000 words long, but ending up at 30,000 ... one-third of a Discworld novel. Once Terry was confident that the narrative hung together, Jack and I started on the interspersed science chapters. But Terry still stayed involved, of course?

Pratchett: Originally, I didn't intend to have any real involvement with the rest of the text, on the basis that the universe doesn't actually lean over a scientist's shoulder and tell him how to observe it. In fact you might just recognise some Pratchett spin around the beginning and the end--but I have to say that since Jack and Ian know their SF, we were pretty much all of one mind.

Stewart: Finally, Terry went over the whole thing to smooth transitions, remove inconsistencies, and "scatter fairydust". Jack and I looked at this "final" rewrite, made very tiny changes where we'd got the science slightly out of whack ... and that was it! What aspects of the finished book make you particularly proud?

Cohen: I feel proud of something rather subtle: the stance. We had no idea how it would turn out, it just had to grow into shape. We all three trusted each other to follow a trail if we could pick one up, I think. Just by chance, I had a student here asking about extinctions, so sent Terry a list of the major ones. He had meanwhile begun the Roundworld bit and had one of the wizards being deprecating about the kind of Universe you get, starting with nothing, or even Nothing: "a third of the elements just fall to pieces in no time at all" seemed to me to set the tone.

Stewart: I think we are most proud of the structure--fantasy/fact fusion. We have a genuine, honest-to-gods Discworld story that stands on its own, is fun as always, and fits slap into the mainstream canon. In addition we have a typical Stewart-Cohen pop science book. The two are then very intimately entwined. A Discworld story can always take care of itself, so let's talk about the science chapters. The scenario is that, following certain problems with that mysterious device the High Energy Magic students have been building in Unseen University's squash court, the wizards find themselves studying the arcane physics of a world without magic--our world. By the way, that squash court business seems familiar from past Discworld asides: is it a relief to have used it at last, Terry?

Pratchett: Let's just say the idea was ready and waiting, shall we? And in an unintended masterpiece of timing, Bernard Pearson's limited-edition ceramic Unseen U (now sold out) was just able to include a High Energy Magic building that featured things mentioned in The Science of Discworld.

Cohen: The official map of Unseen U was also modified to include the magical reactor in the squash court... How did you ap proach the science chapters?

Stewart: Instead of the usual "science of ..." potboiler, we have the scenario that there isn't any science on Discworld, so the wizards have to invent some. Then, from our Roundworld viewpoint, we observe them struggling with the same problems that bedevilled Earthly science. What sort of thing is the sun? Is the Earth flat? How does Life get going from inorganic bits and pieces? And you track it in fast-forward all the way from the Big Bang to the first prehumans ...

Stewart: So the wizards struggle through the age-old hangups, and the reader learns alongside them. We also realised that the magical aspects of Discworld illuminate today's earthly science in unexpected ways. For example, the current view of the role of the gene in biology is very close to that of a spell in magic. It does something all right, but you don't really understand how. Right. You take Arthur C. Clarke's much-quoted line "Any sufficiently advanced technology is indistinguishable from magic", and point out that--for most people--computers and TV might as well be magic.

Stewart: So now the initial "There is no science in Discworld" gets turned round to add: "but there is magic in earthly science". So we tackle science on two levels: content (the age of the universe is ...?) and philosophy (how do scientists know things, and in what sense?). My favourite motif was your repeated description of scientific simplifications as "lies-to-children". Will you be lynched for this? By whom, how early and how often?

Stewart: Yes. By (a) Swedes, (b) Literal-minded schoolteachers, (c) Po-faced scientists. How early? As soon as rev iews come out. How oft? Repeatedly and of course most undeservedly!

Cohen: Ian and I were nearly lynched for Lies-to-Children in Abisko, north of the Arctic Circle, by a lot of Swedes who didn't understand the metaphor.

Pratchett: I like the lies-to-children motif, because it underlies the way we run our society and resonates nicely with Discworld. Like the reason for Unseen being a storehouse of knowledge--you arriv e knowing everything and leave realising that you know practically nothing, therefore all the knowledge you had must be stored in the university. But it's like that in "real Science", too. You arrive with your sparkling A-levels all agleam, and the first job of the tutors is to reveal that what you thought was true is only true for a given value of "truth". I did physics and I remember that. With a shudder.

Pratchett: Most of us need just "enough" knowledge of the sciences, and it's delivered to us in metaphors and analogies that bite us in the bum if we think they're the same as the truth. Besides the fun in the book, things get slightly melancholy as Rincewind and colleagues explore prehistoric Earth through magical virtual reality, and it's just one damned mass extinction after another.

Pratchett: One of the things that came out of all this for me was an increasing sense of the frailty of our human-centred environment. Extinction after extinction, catastrophe after catastrophe ... I suppose I've known this ever since I got interested in good sf and popular science, but I felt a definite Cthulhian dread creeping over me towards the end. Cheerfulness still keeps breaking in, though, as the wizards struggle with the problem of things hitting "their" Roundworld.

Pratchett: It seemed to me wizardly logical that, faced with regular extinctions by impact, they'd design a creature entirely built to withstand them, and Jack and I had a long phone call about this ... I'd been wondering who came up with that four-mile-long whelk!

Cohen: For smaller Roundworld life, we have the wizards using Rincewind's famous magical Luggage to trap specimens and bring them back for study.

Stewart: The climax examines the real nature of science, and the extent to which scientists really know anything--and explores the long-term future of humanity in the light of Rincewind's observations of the history of life on Earth over Deep Time. Did you consider having the wizards meet twentieth-century humans, rather than just accidentally teaching apes to use bones as in 2001 (but not quite)?

Pratchett: There was our old friend, Deep Time. As the story developed, we agreed to leave out "human civilisation" from the wizards' experience of the planet because, from their point of view, there wasn't any: from the point of view of Deep Time, we get a walk-on part and then vanish. Can we talk about what happens to humanity offstage, or is that one of the book's little secrets?

Librarian: OOOOK! Too late, the Librarian's spilled the beans. Many thanks, Terry, Ian, Jack and the monk--OUCH!--er, our excellent orangutan friend. Thank you all.

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