The Hydrogen Sonata

The Hydrogen Sonata is the ninth novel in the Culture series by Iain M. Banks. It is set in the civilization of the Gzilt, which is on the verge of ‘subliming’—that is, departing the physical universe to become immortal beings of pure energy. As the big day approaches, one question still niggles: what was the origin of the Gzilt’s suspiciously well-informed ‘Book of Truth’? ( Genuine religious inspiration or hoax by ancient meddling aliens? )