Your confusion likely stems from the fact that along with Feersum Endjinn and Against a Dark Background, this novel is science fictional but not set in the Culture fictional universe.
AJ: You have a new book out this month, The Algebraist, which is an Iain M. Banks, so presumably science fiction?
IB: It is, yes, but it’s not part of the Culture series. The idea was to write something that wasn’t a Culture novel that Culture fans would enjoy. It was quite complex in terms of details and the back story and so forth, and that held me up for longer than usual. It was always going to be a long book anyway, and it’s actually longer than I intended. It probably could become a trilogy, but for now it’s a standalone novel.
Northings Interview. Iain Banks, A Restless Imagination
For the record, the Algebraist is set in the year 4034AD, several millennia after Earth was contacted by The Culture in that fictional universe.