There are three different levels of reality in this novel: On the one hand it is the story of Terje Huus, a Norwegian mathematician undergoing a midlife crisis. That part of the story is presented through diary entries that include an extra-marital affair he has along with his attempts to write a book about the famous mathematician Bernhard Riemann. That is framed at a higher level by the story of his family who has found his diary after his disappearance. And, within all of that, there is the story of Riemann himself, focusing more on his personal life than on his mathematical research. The three levels are tied together in an interesting way by the titular imaginary number *i*. Riemann's research into the distribution of primes involves complex numbers, there is a sense in which the woman with whom Huus has an affair is like this number in that they *should* not exist and yet they do, and finally the family is skeptical of what is written in the diary thinking that it may well be the product of Huus' *imagination*. Another connection is that both Huus and Riemann suffered from depression. Norwegian Fields Medal winner Atle Selberg also makes an appearance in the novel.
I learned about this book from Peter Hertz who told me about the German translation by Günther Frauenlob that was published in 2007. (Danke sehr, Peter!) The title for the German version was changed to *Die Riemannsche Vermutung* ("The Riemann Hypothesis"), presumably to emphasize the connection to the famous German mathematician.
Disclaimer: I have not actually read this book (and since I am not fluent in either Norwegian or German, I wouldn't get much out of it if I did). So, all of the information above was put together from the bits I could learn about it from a thorough internet search along with the information provided by Peter Hertz. I apologize if any of it is mistaken or misleading. If you have actually read this work of mathematical fiction, please write to let me know! |