A Week In Books: The appliance of science

Our Midsummer night's frenzy began at 12, as bookshops flung open their doors (and tills) to sell Harry Potter and the Order of the Phoenix. We have under our belts three centuries of Enlightenment, scientific reason, and creeping secularisation. At the end of all that, magical yarns about a pocket warlock unite the British in breathless expectation. Did Newton and Darwin think and toil in vain?

Complaints about the Potter cult seem as otiose as passing judgment on the wind or tide. It, like them, will shift or fade. In the meantime, this week we devote three pages to some of the most attractive new work in popular science. Next Wednesday, the Aventis Prize will honour the year's highest achievements in the genre. The Aventis runs parallel competitions for adult and young readers' titles. So it would be pleasing if a few of the kids who will besiege bookstores for Harry this weekend could also leave with a work from the junior shortlist.

Even grown-up Pottermaniacs should take a look at the adult Aventis selection. Because there is, I suspect, a not-so-occult affinity between the way that pop-sci books and supernatural fables operate. Both, after all, start with the big, baffling questions about origins and destinies, and seek to answer them with stories that at once entrance and explain. Both exploit our lingering need for narratives of wonder and surprise. The canniest science writers know how to turn a craving for magical tales to logical ends.

Two Aventis contenders leap into the distant reaches of astrophysics, where mathematics mutates into something like mysticism. Robert Kirshner's The Extravagant Universe (Princeton) advances the fledgling science of the "dark energy" that invisibly propels our cosmos. Stephen Webb's Where is Everybody? (Copernicus) revisits the conundrum of extraterrestrial life, and the reluctance of aliens to show up in the flesh (or goo, or pulses, or pixels ... ). Meanwhile, Steven Pinker's The Blank Slate (Penguin) probes all our anxieties about the clash between genetic legacy and the freedom to choose and change - a favourite Rowling topic.

It's another Aventis shortlistee, however, that comes nearest to the narrative domain of fairy-tale and fantasy. Mark Buchanan's Small World: uncovering nature's hidden networks (Phoenix paperback; £7.99) aims to fuse our ingrained alertness to coincidence and connection with the new science of networks and complexity. Here, maths really does mate with magic. Buchanan beguiles us with fresh theories to explain our "small world" instinct for the links that can make sense of huge, intricate systems, in society and nature. Stanley Milgram's famous notion of a maximum "six degrees of separation" between people turns out to boast a mathematical basis. Buchanan also shows that tiny causes, once networked, may lead to vast effects - as in the seemingly magical idea of the "tipping point". Patterns of coincidence - the trigger for so much superstitious belief - emerge as no coincidence at all.

Like so much pop science rooted in an all-powerful Big Idea, Small World depends on a one-size-fits-all model of reasoning. This can infuriate with its glibness as much as it appeals with its fluency. The Big Idea works, literally, like a charm: it opens every door and dispels every obstacle. As a result, you wouldn't want to trust Buchanan on politics or economics, any more than you would the arguments of Professors Snape or McGonagall. Modern science may offer an antidote to magical storytelling. But strong science writing still rests, remarkably often, on its old, dark arts.