The Long Earth

As an experienced Pratchett reader (I have ALL of his books), I am used to surrendering all idea of science-based interpretation of the universe, for a joyous confusion of mythology, magic and outrageous invention.

With Stephen Baxter, however, one is generally given a hard, logical, physics-based universe, even if sometimes the way in which things work is incomprehensibly vague (think: the Manifold series, where very mysterious things happen, but then play out in a hard physics universe).

It was a little strange, therefore, that these two worlds should marry - and that the central premise of the story, the device that allows people to Step sideways across the infinite series of parallel Earths, should involve some electronics, and... a potato? Really?

OK, once you get past that Pratchettism - and it is never explained properly - everything develops as it should in a Baxter universe, and a logical progression of events follows the inevitable sideways diffusion of humanity, along the line of Earths.

Assuming, of course, that you buy into an independent AI who claims to be the reincarnation of a Tibetan motorcycle mechanic, and that mysteriously, iron doesn't seem to be able to travel sideways - which would seem to be paying homage to faery myths, in an otherwise very uncompromising physics-based universe.

But that's part of the charm of this strange and wonderful juxtaposition of talents B-)