World Engines: Destroyer

In Stephen Baxter's collaboration with the late Terry Pratchett, he imagined that there were a limitless number of parallel dimensions just a small step away, each with a slightly different version of Earth (although none others of which contained indigenous humans). In his latest novel, World Engines: Destroyer, Baxter has gone back to the idea of parallel dimensions, each with a different Universe but this time he's following the multiverse theory that for each small change, a new divergent reality is created.

Multiverse theory is one that's been around for some time and has become increasingly popular both in popular fiction and science (although the mechanics in both often differ). There might be a Universe the laws of gravity are different, or one where life might be more common than it appears to be in this one. That a dimension is created for each action that takes place is a fascinating one, that there could be an Earth where Hitler was never defeated, or that the spectre of Brexit was never raised. There might even be a Universe where Trump has a modicum of common sense, although that might be stretching things a bit. Personally I'd like to witness a Universe where cats can talk, so they can finally explain their plans for world domination.

It's the 25th century (with no Buck Rogers in sight) and an old character of Baxters (Reid Malenfant) is getting a new lease of life. We last saw Malenfant in Baxter's Manifold series, a trilogy that also takes place in alternate Universes. Here, we see the 21st Century astronaut revived from cryogenic sleep in a universe that is almost, but not quite the same as ours. He has been awakened with a message, his partner Emma Stone (also a resident of the 21st Century) has sent an SOS specifically to him from the small Mars moon of Phobos - a place she was last seen heading to on an urgent NASA mission 14 years prior to Malanfant's cryogenic freeze.

The 450 years have not been kind to planet Earth, the polar icecaps melted a long time ago and climate change has altered the planet significantly. London is mostly underwater and has a tropical climate and people have been forced to live on the bits of land that haven't been covered. The planet is recovering though and there are vast reclaimed forests, while the population of the planet is significantly reduced to that of just a billion people. Advanced technology and caretaker AI help to make sure that no more damage is done. Baxter does a great job of describing this future, which is both plausible and imaginatively drawn. Baxter is also a genius at describing hard-science and this book is no exception. It's clear everything has been carefully researched and considered, while the changes to the different realities seem entirely feasible.

While there is a degree of hard-science explanations (as there are in pretty much every Baxter novel), there isn't enough to cause a disruption to the pace, and it isn't gratuitous. The actual world-building of the 25th Century however takes up a large chunk at the start of the book and it's a while before Malanfant even gets round to going on a mission to find Emma. That's not really his fault, but that of his nurse and the planetary AI, and while I loved this exploration of a possible, plausible 25th Century, it is a sedate beginning.

The book really picks up after they leave Earth however and its a wonderful journey with some big concepts explained in a way that pretty much anyone should be able to understand them. The story is imaginative, bold and completely engrossing, dealing not just with alternate realities but also some great ideas on ancient aliens and the consequences of leaping before you look. It's also clearly the start of something big and Baxter does a great job of leaving you wanting more.

World Engines: Destroyer is one of Baxter's best books yet. It's got his trademark ingenious ideas and hard-science attention to detail, softened by a great cast of characters and an engaging, intriguing story. Big, Bold and Brilliant.