The grand theme of this book is music. I cannot think of much SF I've read where this was the case, or even a big factor: The three Crystal Singer books by Anne McCaffrey and a short story by James Blish, the latter being good and the former being OK.

Robinson, on typically ambitious form, takes us on a tour of the solar system alongside the protagonist, a composer who develops a grand vision of how music and physics relate to each other at a fundamental level and creates music that gives people transcendant visions in response to hearing it. Now, music is sound and sound is a wave and waves have been studied by physicists for centuries and, of course, music can have a powerful and pretty direct effect on our emotional state, so there is some reality behind the ideas presented. I think that's all Robinson really wants to say; music is powerful and that power is mysterious in that, fundamentally, it's just a superposition of waves. He drops some hints that the Baroque composers are his personal inspiration. This is no surprise as there is supposed to be a correlation between high mathematical talent and liking the Baroque period in general and J.S. Bach particularly.

It's an interesting book, with a thriller plot-thread running through it to drive the narrative along but, surprisingly, the characters seem quite thin. This is odd because usually Robinson's great strength is characterisation, so much so that he can make it a fault by spending too much effort on it at the expense of slow pacing. No slow pace here. There is also very little in the way of ecological protection as a theme, which is again unusual for Robinson. His obsessions with Mars in general and Olympus Mons (the solar-system's biggest volcano) specifically are all present and correct, however.

The protagonist's visions of the nature of reality reminded me of a similar thing in [b:Galileo's Dream|6391377|Galileo's Dream|Kim Stanley Robinson|http://photo.goodreads.com/books/1303142224s/6391377.jpg|6579805], where it is done better. It would be tempting to say Robinson has improved as a writer in the intervening time but my experience is that his books have been a pretty random hit-or-miss collection with no obvious trend. This one sits firmly in the middle, neither the most perfect nor the most ambitious and not the weakest by some distance, either.

If you are a Robinson fan already, I can recommend this one; if you have never read any, I would recommend starting elsewhere, e.g. [b:Antarctica|41126|Antarctica|Kim Stanley Robinson|http://photo.goodreads.com/books/1320509406s/41126.jpg|3011567].