The Long Cosmos is easily the best book in the whole Long Earth saga.
The premise of the series is that in the near future, people learn how to step into parallel Earths. None of these other worlds have humans on them, although they do have exotic new hominids with fantasy names like elves and trolls. This moves the focus away from speculating about historical what-ifs and onto encounters with bizarre animals, geography and the impact that all this extra space has on humanity. The Long Earth series is what you’d get if you mixed Sliders with David Attenborough. Lots of dramatic stuff went down in the previous four books, including Yellowstone erupting, an expedition across parallel Marses, the emergence of a typically patronising posthuman subspecies and an alien invasion of an alternate Earth, but the Long Cosmos tops them all with an interstellar message instructing mankind how to build a computer the size of a continent.
Speculative fiction that about travelling usually ends up presenting a series of increasingly cool and mind-blowing ideas. The one from The Long Cosmos that really stuck with me was the gigantic forest, with trees the size of skyscrapers supported by helium. Their reproduction strategy involves spreading seeds when they inevitably explode during bushfires. I also amazed by the sentient islands that sampled life while moving between worlds, and that ridiculously large computer.
The Long Cosmos felt more coherent and less disjointed than the previous books in the series. I can’t explain why I feel this way. Maybe it was because the plotlines felt more related, and came to a satisfactory conclusion?
What really intrigues me about the Long Earth series are the pop culture references. Two of the main protagonists watch the Blues Brothers, the Tim Allen comedy Galaxy Quest is mentioned far more often then you’d expect, and the interstellar signal plot draws from Contact. There’s also a nun who really, really likes Jim Steinman. At first I though there were so many of these references because this would’ve been the first time in a long while Pratchett could directly invoke them , without forcing them into a fantasy context. But after reading another Baxter book, where a cyborg remembers Cloudy with the Chance of Meatballs as a beloved childhood classic, I’m thinking he was also responsible. Either way, I need to see Galaxy Quest.
The Long Cosmos’ genre means that it feels more like a Baxter book than a Pratchett one, although there is a fair bit of whimsy about. And I really don’t think it would make much sense without reading the rest of the series. Look at it this way – if you’re a fan of these authors and you’ve never heard of the Long Earth before, today’s your lucky day.