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Friday, November 9, 2012

Reading List: The Long Earth

Pratchett, Terry and Stephen Baxter. The Long Earth. New York: HarperCollins, 2012. ISBN 978-0-06-206775-3.
Terry Pratchett is my favourite author of satirical fantasy and Stephen Baxter is near the top of my list of contemporary hard science fiction writers, so I expected this collaboration to be outstanding. It is.

Larry Niven's Ringworld created a breathtakingly large arena for story telling, not spread among the stars but all reachable, at least in principle, just by walking. This novel expands the stage many orders of magnitude beyond that, and creates a universe in which any number of future stories may be told. The basic premise is that the multiple worlds interpretation of quantum mechanics literally exists (to be technical, Max Tegmark's Level III parallel universes), and that some humans possess a native ability to step from one universe to the next. The stepper arrives at the same location on Earth, at the same local time (there is apparently a universal clock like that assumed in quantum theory), but on a branch where the history of the Earth has diverged due to contingent events in the past. Adjacent universes tend to be alike, but the further one steps the more they differ from the original, or Datum Earth.

The one huge difference between Datum Earth and all of the others is that, as far as is known, humans evolved only on the Datum. Nobody knows why this is—perhaps there was some event in the chain of causality that produced modern humans which was so improbable it happened only once in what may be an infinite number of parallel Earths.

The ability to step was extremely rare, genetically transmitted, and often discovered only when an individual was in peril and stepped to an adjacent Earth as the ultimate flight response. All of this changed on Step Day, when Willis Linsay, a physicist in Madison, Wisconsin, posted on the Internet plans for a “stepper” which could be assembled from parts readily available from Radio Shack, plus a potato. (Although entirely solid state, it did include a tuber.) A rocker switch marked “WEST — OFF — EAST” was on the top, and when activated moved the holder of the box to an adjacent universe in the specified notional direction.

Suddenly people all over the Earth began cobbling together steppers of their own and departing for adjacent Earths. Since all of these Earths were devoid of humans (apart from those who stepped there from the Datum), they were in a state of nature, including all of those dangerous wild beasts that humans had eradicated from their world of origin. Joshua Valienté, a natural stepper, distinguishes himself by rescuing children from the Madison area who used their steppers and were so bewildered they did not know how to get back.

This brings Joshua to the attention of the shadowy Black Corporation, who recruits him (with a bit of blackmail) to explore the far reaches of the Long Earth: worlds a million or more steps from the Datum. His companion on the voyage is Lobsang, who may or may not have been a Tibetan motorcycle repairman, now instantiated in a distributed computer network, taking on physical forms ranging from a drinks machine, a humanoid, and an airship. As they explore, they encounter hominid species they call “trolls” and “elves”, which they theorise are natural steppers which evolved on the Datum and then migrated outward along the Long Earth without ever developing human-level intelligence (perhaps due to lack of selective pressure, since they could always escape competition by stepping away). But, as Joshua and Lobsang explore the Western frontier, they find a migration of trolls and elves toward the East. What are they fleeing, or what is attracting them in that direction? They also encounter human communities on the frontier, both homesteaders from the Datum and natural steppers who have established themselves on other worlds.

Spoiler warning: Plot and/or ending details follow.  
The concept of stepping to adjacent universes is one of those plot devices that, while opening up a huge scope for fiction, also, like the Star Trek transporter, threatens to torpedo drama. If you can escape peril simply by stepping away to another universe, how can characters be placed in difficult circumstances? In Star Trek, there always has to be some reason (“danged pesky polaron particles!”) why the transporter can't be used to beam the away team out of danger. Here, the authors appear to simply ignore the problem. In chapter 30, Joshua is attacked by elves riding giant hogs and barely escapes with his life. But, being a natural stepper, he could simply step away and wait for Lobsang to find him in an adjacent Earth. But he doesn't, and there is no explanation of why he didn't.
Spoilers end here.  

I enjoyed this book immensely, but that may be in part because I've been thinking about multiverse navigation for many years, albeit in a different context and without the potato. This is a somewhat strange superposition of fantasy and hard science fiction (which is what you'd expect, given the authors), and your estimation of it, like any measurement in quantum mechanics, will depend upon the criteria you're measuring. I note that the reviews on Amazon have a strikingly flat distribution in stars assigned—this is rare; usually a book will have a cluster at the top or bottom, or for controversial books a bimodal distribution depending upon the reader's own predisposition. I have no idea if you'll like this book, but I did. And I want a stepper.

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