This is the fourth book in Stephen Baxter and Terry Pratchett’s Long Earth series, so I’m warning you, if you want to get into it, read The Long Earth and that book’s other sequels before getting into this one. The essential premise of the series is that mankind has figured out how to ‘step’ into parallel Earths, which leads into all sorts of trouble.
Imagine what would happen to civilization if people figured out how to pop around the multiverse, and forget whatever you imagined because what Pratchett and Baxter worked out makes sense. A person can step into one universe at a time, the universes being organised into linear sequences that are frequently compared to pearls on necklaces. However, stepping is exhausting, it makes some people vomit and is completely impossible for an unlucky minority. Large segments of Earth’s population run off to live as interdimensional hunter-gatherers, leaving the rest struggling to run a depleted planet. The authors invent several evolutionary cousins for humanity, who got into stepping long before homo sapiens. They’re called trolls and elves, neatly evoking fantasy in science fiction.
The Long Utopia has two main plot threads. The first concerns the ambiguously sinister activities of The Next, typically patronising posthumans who are almost certainly up to no good. The second involves a parallel Earth whose days are getting shorter, and there are these silver beetle aliens pottering about. It also deals with stepping in the nineteenth century, a subplot I found enjoyable even though it didn’t really contribute to the climax. I’m assuming it’ll become more relevant in later books.
What I liked about The Long Utopia was that it was Lobsang’s book. His backstory is complicated, basically he’s a global AI who as soon as he was activated pleaded for human rights by claiming to be the reincarnation of a Tibetan mechanic. Lobsang begun the series as a Pratchett-y twist on Hal from 2001: Space Odyssey, as well as some of the other AIs in Baxter books like the ones with Greek names in the Time Odyssey series, but in The Long Utopia he gets some lovely character development. Taking the form of a robot indistinguishable from a human, he goes to live as a pioneer on the beautiful Earth with the shrinking days.
I recommend this book, but only on the condition that the three other books in Long Earth series are read first. More broadly, it’s enjoyable for fans of both authors, as well as people who like Douglas Adams and the more speculative, optimistic brand of sci-fi.