The story is very well crafted, from its opening drama that motivates the physicist character's interest in avoiding the moral dilemmas he suffers due to Everett's "Many Universes" interpretation of quantum physics, to the careful detail to the math and physics, and finally through to the emotionally satisfying ending. In reality, it is much more a story about physics than about math, but it is such a nice story that I've decided to include it here even though it only has bits of math in it.

So, let's focus for a moment on the math, even though it is mostly irrelevant to the story. The two main characters are a male physicist and female mathematician who meet as undergraduates in a complex analysis class. There is a description of them working together, and we see how "the Cauchy-Riemann Equations" later becomes a romantic code word for them after years as a married couple that there is something serious they need to discuss.

It is nice to see a female mathematician character who is so realistic and well grounded. She is described as being a talented mathematician and the chair of her department, but we don't really get to see any of her work and she plays a relatively small role in the main storyline.

There are two other ways in which mathematics, at least tangentially, shows up in this story. Much of the story is about quantum computing. Certainly, there is a lot of mathematics in quantum computing. Some of the most significant results in the field were developed by mathematician Peter Shor, and I know lots of mathematicians working on quantum computing. However, these mathematical aspects are not explicitly discussed in the story. Instead, the focus is on this idea that a quantum computer could be forced to remain in a classical state through frequent forced "wave collapse".

Also, perhaps as an indication of how carefully Egan thinks out his fantastical stories, he includes a discussion of mathematician Roger Penrose's theory that the brain makes use of quantum superposition. Although he doesn't specifically mention this reason anywhere in the story, I imagine that Egan recognized that Penrose's theory -- if it were true -- would prevent the ADAI ("Autonomously Developing Artificial Intelligence") in the story from being able to think in the same way that actual humans do. And so he has a subplot in which the physicist takes part in a psychology experiment that disproves Penrose's hypothesis.

Since I'm focusing on the math and tangentially the physics, I'm not addressing the emotional side of the story here. There is an emotional story -- runaway children, marital tensions, kidnapping and rape -- all well told and worth the read.

The story was originally published in Interzone #176, February 2002, but I am pleased to announce that Egan has posted the story on his website and so it is now available for free. (Just click on the title above or the link below to get to it.)