A brief return to the theme of mathematics in literature: I can’t resist sharing what is, by a long way, the silliest piece of fictional mathematics I have ever come across. It comes in “The Girl Who Played With Fire,” by the late Stieg Larsson, translated (not very well) by someone called Reg Keeling. Here is a little piece of advice for any author who wants to incorporate mathematics into a novel. If you don’t want what you write to be risibly unrealistic, it is not enough to read popular science books: you must also run what you write past a mathematician.
And here is the passage in question.
Salander began her advance towards the house, moving in a circle through the woods. She had gone about a hundred and fifty metres when suddenly she stopped in mid-stride.
In the margin of his copy of Arithmetica, Pierre de Fermat had jotted the words I have a truly marvellous demonstration of this proposition which this margin is too narrow to contain.
The square had been converted to a cube, and mathematicians had spent centuries looking for the answer to Fermat’s riddle. By the time Andrew Wiles solved the puzzle in the 1990s, he had been at it for ten years using the world’s most advanced computer programme.
And all of a sudden she understood. The answer was so disarmingly simple. A game with numbers that lined up and then fell into place in a simple formula that was most similar to a rebus.
Fermat had no computer, of course, and Wiles’s solution was based on mathematics that had not been invented when Fermat formulated his theorem. Fermat would never have been able to produce the proof that Wiles had presented. Fermat’s solution was quite different.
She was so stunned that she had to sit down on a tree stump. She gazed straight ahead as she checked the equation.
So that’s what he meant. No wonder mathematicians were tearing out their hair.
Then she giggled.
A philosopher would have had a better chance of solving this riddle.
She wished she could have known Fermat.
He was a cocky devil.
After a while she stood up and continued her approach through the trees. She kept the barn between her and the house.
Needless to say Salander is entirely self-taught at mathematics. More surprisingly and cringeworthily, she has been seriously interested in it for only about a year. I was initially puzzled by what would have made the author think that Wiles used “the world’s most advanced computer programme” but I now have a theory that could perhaps explain this: he might have read a popular account of the proof that said that it used extremely advanced mathematical machinery, and, literary genius that he was, failed to spot that the word “machinery” was a metaphor. I can’t decide whether that is my favourite detail, or whether it is the superfluous brackets round the equation (not to mention the fact that that case has been known since Euler).
It is hard to believe that anyone can match this passage. However, it does seem to be quite common for novelists to make fools of themselves in this way, and past experience on this blog suggests that I am usually wrong when I make a universal claim about literary depictions of mathematics (which in this case is the claim that nothing is as silly as the passage that I have just quoted). I have to admit that my amusement is mixed with just a hint of annoyance — by writing a post about it I am getting it off my chest.