Book review: The Long Earth

Terry Pratchett only seems to have got more prolific in recent years; The Long Earth, which he co-writes with Stephen Baxter, is the first in a planned new fantasy series that plays on the ever-popular theme of parallel universes. But where quantum theory sees every decision spin off into a different reality, so that infinite universes exist with tiny differences, The Long Earth is a multiverse where our Earth - here called the Datum Earth - is the only one that's inhabited, by humans at least. And the multiple other Earths stretch out to a notional East and West. A few years into the future, blueprints for a mysterious device are posted on the internet, and the result is a "Stepper," a machine that allows people to move along by one Earth at a time. Faced with a seemingly infinite number of fresh new planets just as the original one's resources are starting to run out, humanity's instinct is to colonise.

The main thrust of the novel follows Joshua, a young man born between worlds who's acquired a natural affinity for stepping as a result, and his journey with Lobsang, a disembodied entity who claims to be a reincarnated Tibetan, but may in fact be a computer program that's become sentient. They travel West through the Long Earth, partly to research the different realities but partly to be the first to travel millions of steps away from the Datum. There's a few plotlines running through their journey but largely this is a scene-setting novel that builds up the writers' fictional universe, and given how little hard plot it has I found it very entertaining. Beyond things like the design of the Stepper device (it requires a potato to work) there's little of the comic side of Pratchett, but instead there's an interesting central relationship between the loner Joshua and the rather smugly omnipotent Lobsang.