Chapters 27 to 52
Final part
The "Long Earth" is a (possibly infinite) series of parallel worlds that are similar to Earth, which can be reached by using an inexpensive device called a "Stepper" – designs for which are one day posted online suddenly allowing humanity to explore worlds "East" and "West" of "Datum Earth". The worlds are mostly familiar, though others differ in greater and greater details, but all share one similarity: on none are there, or have there ever been, Homo sapiens – although the same cannot be said of earlier hominid species, especially Homo habilis.
The book deals primarily with the journey of Joshua Valienté (a natural "Stepper") and Lobsang, who claims to be a Tibetan motorcycle repairman reincarnated as an artificial intelligence. The two chart a course to learn as much as possible about the parallel worlds, travelling millions of steps away from the original Earth. They encounter evidence of other humanoid species (referred to as trolls and elves); of human settlers who learned their gifts early – including Sally Linsay, daughter of the inventor of the stepper, who joins them on their expedition; and of an extinct race of bipedal dinosaur descendants. They also encounter warning signs of a great danger, millions of worlds away from Earth, causing catastrophe as it moves. The book also deals with the effects of the explosion of available space on the people of Datum Earth and the new colonies and political movements that are spreading throughout the Long Earth.
