THE LONG COSMOS

Final installment of the series (The Long Utopia, 2015, etc.) wherein Earth is one of an indefinite sequence of worlds occupying the same space but separated by some higher dimension (one can almost hear Pratchett murmur, “Nobody knew for certain, but it was probably quantum”).

This Long Earth, discovered by people with a natural ability to step between worlds, was opened to everybody by means of a simple device. The only constraints are that most people suffer debilitating nausea with repeated steps and that it’s impossible to carry iron from world to world. Also, there are no other humans anywhere, though there are sapient beings—singing, gorillalike trolls, belligerent, doglike beagles, and so forth. By the year 2070, airships equipped with rapid-step devices ply the trade and passenger routes between worlds. Far from the original, or Datum, Earth (devastated by a vast volcanic explosion and partially abandoned), the post-human Next, who generally hold ordinary humanity in contempt, pick up a radio signal from the center of the galaxy—a signal that somehow resonates with the trolls and other nonhumans and whose message is simple yet devastating: “Join us.” Embedded in the message are instructions for constructing a huge artificial intelligence, but to build it the Next will need the cooperation and active assistance of all the industrialized worlds. Elsewhere, readers will be reacquainted with familiar parties such as Joshua Valienté, one of the original natural steppers, Lobsang, the ubiquitous AI who invisibly runs things, and retired churchman Nelson Azikiwe. Once again, the purpose is less to tell a story than to discover and explore, in both physical and philosophical senses, an infinite landscape of infinite possibilities. And series fans seem OK with the less-than-compelling narrative and not-especially-engaging characters.

Scientist Baxter’s naturally rather pedantic and dispassionate tone needed more of the warmth and wit of the late fantasist Pratchett (who died in 2015).