The Long Mars

Terry Pratchett and Stephen Baxter

Baxter and Pratchett’s latest collaboration begins as a catastrophic eruption of the Yellowstone supervolcano forcibly accelerates emigration from our Earth to the thousands of ‘stepwise’ duplicates explored in the previous books.

But, as the title suggests, another new frontier has opened up too; conditions on some alternate Earths make space launches much easier, and Mars turns out to have stepwise duplicates of its own.

Unlike Earth’s, these are mostly dry and lifeless... but not always.

Meanwhile on Earth, contact with other dimensions is breeding fundamental changes into humanity.

In many ways, this continues the Long Earth sequence in accustomed form; the established sense of wonder and inventiveness are still present and correct. But the exposition sometimes seems clumsier than in the first two books, and some choices are puzzling: a reference to Daedalus is explained, where those to Eugene Cernan and Tom Swift are not.

Ultimately, its worldbuilding is its appeal.