After reading this great interview with Terry Pratchett I decided to go back and finish this post I was writing about *The Long Earth*, Pratchett's recent collaboration with Stephen Baxter. Obviously, spoilers spoilers.
Basic setting summary: In The Long Earth, someone releases schematics on the internet for an easy to build box with a switch. When the switch is pressed, the user can travel either 'east' or 'west' through infinite parallel Earths, with the near Earths being very similar to the original 'datum' earth (but lacking in people) with weirder and wilder creatures waiting in the far off Earths. One of the fun things about reading collaborations between well-known authors is trying to break down who introduced what elements. Sometimes you can pick up the voices, but in cases like the Long Earth tracking the lineage of the ideas involved is illuminating. While based on an old idea of Pratchett's, the threads of it have appeared in a few previous Baxter books (which is probably why the project is such a good fit.)
In Baxter's Origin, the world is changed by the appearance of the Red Moon (which replaces the boring grey one). The Red Moon travels from parallel earth to parallel earth, opening up portals and picking up and depositing creatures from world to world. Through this, it picked up humanity's predecessors at various points in history and deposited them on other earths, where they evolve in different and similar ways, aquatic apes, puritans with tails, super-intelligent gorillas who hug the surface of their gigantic and windswept Earth. So the idea that there are places beside our own where humanity's cousins (in The Long Earth's case Trolls and Elves) developed in their own strange ways is a familiar one.
That Trolls are largely peaceful creatures who make people feel better by singing while Elves are intelligent, malicious hunters where some species farm others for their brains fits into the Pratchett rebellion against Tolkien regarding elves (from Lords and Ladies):
Elves are wonderful. They provoke wonder.Elves are marvellous. They cause marvels.Elves are fantastic. They create fantasies.Elves are glamorous. They project glamour.Elves are enchanting. They weave enchantment.Elves are terrific. They beget terror.The thing about words is that meanings can twist just like a snake, and if you want to find snakes look for them behind words that have changed their meaning.No one ever said elves are nice.Elves are bad.
The Long Earth is also an example of, for lack of a better term, "Democratic Science Fiction" - where an extraordinary change is put in the hands of every person. What's a world like where everyone has superpowers? When anyone can travel in time? When anyone can get a potato and a switch, and step into another earth? This is ground Baxter has visited before in a previous collaboration with Arthur C. Clark in The Light Of Other Days, where the invention of wormhole technology allows anyone to view any location, anywhere in history - effectively abolishing privacy.
Lobsang is an interesting element, a sentient computer that claims to be the reincarnated soul of a Tibetan car mechanic. Someone obscure being reincarnated as a computer feels like a classic Pratchett footnote joke (and there has been a 'Lobsang' in the Discworld-verse) , but it's tempered and kept in line with a sci-fi universe by the heavy hinting that Lobsang is just pretending to be reincarnated to have a better claim to have personhood rights. To make an end of paragraph habit, Baxter's collaboration with Clarke in the Time Odyssey series also featured AI's with recognised rights.
You might guess from how often I've referred back to his previous books that this story 'feels' more like Baxter than Pratchett but his sensibilities are clearly there if you look. I wouldn't say it's either of their greatest works, but it's a perfectly enjoyable read that plays with its world in a way that I'm not sure would have come naturally to either of them on their own.