Six Impossible Things - John Gribbin *****

On first handling John Gribbin's book, it's impossible not to think of Carlo Rovelli's Seven Brief Lessons in Physics - both are very slim, elegant hardbacks with a numbered set of items within - yet Six Impossible Things is a far, far better book than its predecessor. Where Seven Brief Lessons uses purple prose and vagueness in what feels like a scientific taster menu, Gribbin gives us a feast of precision and clarity, with a phenomenal amount of information for such a compact space. It's a TARDIS of popular science books, and I loved it.

Like rather a lot of titles lately (notably Philip Ball's excellent Beyond Weird), what Gribbin is taking on is not the detail of quantum physics itself - although he does manage to get across its essence in two 'fits' (named after the sections of Hunting of the Snark - Gribbin includes Lewis Carroll's epic poem in his recommended reading, though it's such a shame that the superb version annotated by Martin Gardiner is out of print). Instead, the focus here is the interpretation of quantum theory - the attempts to theorise about what is 'really' going on underneath the so-successful mathematics.

Different interpretations make up the 'six impossible things', which Gribbin poetically describes as the 'quanta of solace' in his subtitle. He covers the Copenhagen interpretation, pilot waves, many worlds, decoherence, the ensemble interpretation and the 'timeless' transactional interpretation. Each is dealt with in just a few pages, accompanied by some excellent full-page illustrations of key players, and I was extremely impressed by the way that Gribbin manages to encapsulate what are sometimes very complex ideas in an approachable fashion. This could well be the best piece of writing this grand master of British popular science has ever produced, condensing as it does many years of pondering the nature of quantum physics into a compact form.

Inevitably, there were one or two moments when even Gribbin managed to potentially lose the reader (though this was far less the case than with Rovelli). In his section on decoherence, it's pretty much assumed that the reader knows what coherence means (in a physics sense), which probably is an assumption too far. And there are a couple of examples of leaps of logic brought on by the compactness. Notably, at one point in the ensemble interpretation section, Gribbin comments 'In an infinite universe, there would be infinitely many copies of you...' - that's quite a big leap. I can certainly envisage plenty of types of infinite universe which don't have infinite sets of copies of everyone in them.

Early on, Gribbin says that he will offer an 'agnostic overview of some of the main interpretations' and that 'I have my own views on their relative merits, which I hope I shall not reveal.' I think he succeeds in this. It's clear he's no Copenhagen enthusiast, but where from previous interactions I assumed there would be a many worlds bias lying beneath the apparent fair dealing, I found at least two of the other interpretations to come across more acceptably, given his words.

Sadly, I suspect Six Impossible Things won't be such a big seller as Rovelli's book - but it deserves to be.

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Review by Brian Clegg