The Long Cosmos

Normally I let the spoiler warnings for these be implicit, but this is the fifth (and final) book in a series, so I’ll go ahead and put it here again, to be clear: spoiler warning.
Good? Good.
So, I was a little bit sad to find that, as I’m writing this, I only have a single post tagged ‘Terry Pratchett’ on here. Which makes sense, I suppose – my love of his writing predates my writing book reviews. A bit of a shame, really, because that would be more than 60 reviews – he was a rather prodigious writer.
Now, I mentioned in my previous Pratchett review that it was his last book. That wasn’t entirely accurate – it was his last Discworld book, but the Long Earth series hadn’t wrapped up yet, either. And for this, he had a coauthor – Stephen Baxter.1 I’m going to drop in a chunk of the foreword, written by Baxter, here:

The books have been published annually, but we worked faster than that; time was not on our side, and Terry had other projects he wanted to pursue. Volumes 1 and 2 of the series were published in 2012 and 2013 respectively. But by August 2013 we had presented our publishers with drafts of the final three volumes of the series, including the present book. We did continue to work on the books subsequently. The last time I saw Terry was in the autumn of 2014, when we worked on, among other things, the ‘big trees’ passages of The Long Cosmos (chapter 39 onwards). It has been my duty to see this book through its editorial and publishing stages.

Having just finished reading the book, I know now what the ‘big trees’ passages he references are, and it makes me happy in a quiet, sad way to know that Pratchett had his hands on those directly. My first experience with Terry Pratchett was the Nomes trilogy.2 I’ve no idea where I got them – it was long enough ago that that memory is entirely gone – but I know that it captured my imagination in a wonderful way. The books were silly and sweet, and the characters even more so. But they didn’t quite capture my interest the way the Discworld books would later. I do distinctly remember how I found my way into that series – the Kindle had just come out, and I really wanted one. While we were on vacation, a family friend who had one offered to let me play around with it to see what I thought.
I’ll interrupt this story to reference the fact that I tend to be reading a lot of books at once – one or two paperbacks, something on my Kindle, and something else in the Kindle app on my phone.3 On this vacation, I hadn’t brought the paperback I was reading, but I remembered the title – Dark Watch. Except I didn’t quite remember the title, and put in Night Watch instead. I’m sure the Kindle Store tried to show me the cover, but low-resolution grayscale images aren’t super helpful, so I wound up downloading the sample of the wrong book.
But hey, never look a gift horse in the mouth – I figured I’d read the sample, it’d work just as well for figuring out if I liked the Kindle or not.
And I did – I’ve mentioned before that the original Kindle was, in my opinion, the Best Kindle, and the fact that when it (sadly) died, I replaced it immediately. When I got mine, the first book I downloaded4 was Night Watch. I finished reading it, and I’ve loved Terry Pratchett ever since then.5
Finding out that he was working on a science fiction series? I was intrigued. I’ve read The Dark Side of the Sun and Strata6 They were both characteristically hilarious, but more importantly, interesting takes on the genre.
The Long Earth series is quite a bit more serious than those, but it’s nothing the less for it. It’s also lacking in those characteristic footnotes, which makes it feel less like a Pratchett work than any of his other stuff, but it’s still deeply fascinating. The world building throughout is marvelous, and the degree to which they extend it is, I think, my favorite thing about the series.
It basically starts off with a single premise: stepping. A device is invented, the blueprints published online for all to see, that allows the user to step, moving from one Earth to another in an apparently-infinite chain of Earths. Only ours, referred to as the Datum Earth, has a human population: the rest are pristine, untouched natural wilds. From there, it’s extended: each of these Earths is something akin to a quantum probability mesh, and the further out from the Datum you go, the stranger things can get. One step away, the only difference is that there’s no industrialization-aftereffects from humanity. Go ten million steps away, and you hit worlds where life as we know it never evolved, and instead there are slime colonies the size of small buildings wandering around. Ten million steps in the other direction, and you can climb a tree five miles high and fight giant lizards in the forest of its canopy.
Of course, this does Bad Things to the governments of the world – who’s going to stick around and work a 9-to-5 when they can hop over a couple worlds and have a hunter-gatherer lifestyle? Who’s going to pay taxes if they live on a homestead ten thousand steps West7 that doesn’t see a dime of government services?
And Pratchett and Baxter play with that – as the series goes on, and by the end it’s spanned nearly 400 years of history,8 you can see the way the United States reacts to the paradigm shift that is stepping. It’s fascinating.
And then you get to Book Three, and explore the Long Mars. Because somewhere along the infinite chain of Earths, there’s one where the asteroid impact that formed the moon hit at a different angle and the Earth never formed. Which is a terrifying way to die – you think you’re going to step normally into another world, but instead find yourself suddenly in interplanetary space. But people are creative, and it’s possible to bring materials with you, so the Long Earth’s equivalent to SpaceX forms up on the world just this side of what becomes known as the Gap. Forget about expensive rockets – just hold onto your spacecraft, and then step right out of the gravity well. Once you’re free-floating, step back, and you’re suddenly in orbit, at about a billionth the energy cost. Space exploration is suddenly a lot easier.
And then a bonus twist on the concept: Mars is Long too, but in a different direction. Sure, it’s still stepping East and West, but a step West from Mars gets you to a different reality than a step West from Earth.
Book four is where things get spooky. (Spoiler warning again, because what I’m talking about now is from closer to the end of that book, rather than early-on reveals as above.)
Given a multiply-infinite series of worlds, certain things become inevitable. Von Neumann machines are one of these – somewhere out there along that infinity, there’s going to be a sentient lifeform. Given that it’s truly infinite, there’s probably going to be an infinite number of those. And at least one of them will have been smart enough to come up with the idea of a von Neumann probe, and dumb enough to actually build it. And then the problem with von Neumann probes shows up, one that we here on our Earth have been dealing with for centuries: self-replicating systems will eventually have a problem. For humans, with our self-replicating cells, we call it cancer. A von Neumann probe system will similarly eventually become cancerous, which makes it a massive threat to the entire galaxy.
And that’s all I’m going to say about The Long Utopia. I’m 1,500 words in, I should probably start talking about the book in the title.
The Long Cosmos takes another spin on that “given an infinite universe, there will be sentient life” thing. With the von Neumann probes, we never actually saw their creators, nor even any evidence that they’re still alive. In The Long Cosmos, though, we get proof of life: a signal that blows SETI’s “Wow!” signal out of the water.
“Join us.”
And that’s all I’m going to say about the story, I think. Suffice it to say it’s in the same vein of the rest of the Long Earth books – a delightful look at a truly large-scale world, and the people who inhabit it. It’s those characters who really make the story, and it’s a nice way to check in with all of them again.
Overall, it’s a wonderful book. Each one gets larger in scale than the last, and that’s what I like about them – it’s such a huge world to play around in, and the underlying concept is simple and understandable. It’s a veritable playground for the imagination.
As with every single other Terry Pratchett book out there, I highly recommend it. Start with the first, of course, but when you’ve read the rest of the series, read this one too.


  1. There’s nothing tagged under his name, as of yet, but I figure I’ll link to it anyways. Might read more of his work in the future, you never know! 
  2. I’ve actually still not read the first one in the series, but once I’m home and have access to my library I might go back and reread the second and third. 
  3. And yes, Amazon’s WhisperSync service does function to keep me in one place in the book if I read it on both devices, but I like this way better. 
  4. Aside from a bunch of free stuff from Project Gutenberg 
  5. And been heavily influenced in how I write – I like to say my use of footnotes has a lot to do with David Foster Wallace, and there’s some of him in there, but it’s a lot closer in style to Sir Terry Pratchett’s. 
  6. And I want to get a copy of Strata for myself, but it’s still hard to get in the United States. Ooh, maybe I’ll find a used book store while I’m abroad… 
  7. As opposed to East – knowing which is which is apparently an instinctive sort of thing for people when they step. 
  8. From the actual start point to the end point, it’s closer to 80 years, but there’s a good bit of prequel-type action in the earlier books.