The Long Cosmos by Terry Pratchett and Stephen Baxter Doubleday 4/5 stars And so here it is, the last new work we’ll ever have from Terry Pratchett , barring a box of undiscovered treasure somewhere. The Long Cosmos is the conclusion of his collaborative series with Stephen Baxter, about the Long Earth, a universe in which a possibly infinite number of parallel worlds exist and you can simply “step” from one to another. The arc of the series had long been mapped out, after the pair decided at a dinner party in 2010 to work on an abandoned SF storyline of Pratchett’s. Baxter notes in the introduction that, short on time, Pratchett worked on what material he could (including devising a marvellous floating wood), and that Baxter finished the series as they’d both planned it. Fantastic fantasy: Terry Pratchett fans queue to buy ‘extraordinary’ final Discworld book In normal alternate universes, one generally expects a Hitler or two, or an eastern empire. But in the Long Earth books, the worlds are more or less completely empty, and look more or less exactly like ours – possibly a little greener, possibly with a slightly different variation of elephant evolution. Travelling between the worlds requires a device called a stepper, unless you’re unusual, like Joshua Valienté. In the first of the novels, he makes a journey up into the “high megs”– millions of worlds away, in the company of a robot/human/divine entity called Lobsang – in a beautiful airship; the effects of this journey are still being felt four books later. If it is pulse-racing narrative you’re after, you should know that the Long Earth books are not so much stories as travelogues. New worlds are intricately described – the corn fields, the ice belts – and there is jeopardy, but never anything terribly concerning, even when nuclear war wipes out half the Datum (the name given to the original Earth). Fans love them for their gently immersive properties: it is extremely relaxing to travel so many worlds from home in a luxury airship, “stepping” with every turn of the page. The Long Cosmos doesn’t meddle with this template: journeys are made, quite slowly; strange creatures emerge and vanish; things that were lost are found again. Even the more horrific aspects, such as the lollipop heads – humanoids with brains so enormous that they are literally spilling out of their skulls – turn out to be more or less benign. The charm of these books lies in the way they weave the worlds together: they’re not funny, and nor are they designed to be, unless you find trolls who say “hoo” intrinsically hilarious. For The Long Cosmos specifically, a good working knowledge of the film version of Carl Sagan’s Contact is useful, as the book often plays out as a homage, while long-term fans will be excited to learn that as well as going east and west, we finally step north. Not all our questions are answered, but Baxter’s scientific grounding will make you dwell once more on that chilling quantum idea that to exist is to be observed, as well as on more quotidian reflections about what is important in life – your family, your childhood and the connections you make. If you’ve been following the series from the beginning, the last chapter will make you cry, all on its own. And that’s before you have to think about the fact that there will, now, be no more Pratchett books, and all that we have lost.