The Hydrogen Sonata

The Hydrogen Sonata is a science fiction novel by the Scottish writer Iain M. Banks, set in his Culture universe. The hardcover edition was released on 4 October 2012 in the United Kingdom and on 9 October in the United States, and its publication marked twenty-five years since the first Culture novel.

The book's nominal errand is musical: a musician has been invited to perform a piece called the Hydrogen Sonata, which is so difficult that it cannot be played by a human being. Around that journey, a civilisation called the Gzilt is preparing to leave the physical universe, and a small group of people who know something about its founding want the truth told before it goes, which puts the musician and the ship in the middle of a political dispute.

Banks writes the Culture novels as space opera with a strong interest in how a very advanced society conducts itself, and this is one of the later volumes. Its ship's avatar and artificial intelligences are major characters rather than background.