Beyond Weird - Philip Ball *****

It would be easy to think 'Surely we don't need another book on quantum physics.' There are loads of them. Anyone should be happy with The Quantum Age on applications and the basics, Cracking Quantum Physics for an illustrated introduction or In Search of Schrödinger's Cat for classic history of science coverage. Don't be fooled, though - because in Beyond Weird, Philip Ball has done something rare in my experience until Quantum Sense and Nonsense came along. It makes an attempt not to describe quantum physics, but to explain why it is the way it is.

Historically this has rarely happened. It's true that physicists have come up with various interpretations of quantum physics, but these are designed as technical mechanisms to bridge the gap between theory and the world as we see it, rather than explanations that would make sense to the ordinary reader.

Ball does not ignore the interpretations, though he clearly isn't happy with any of them. He seems to come closest to the Copenhagen interpretation - but points out how frustrating this is because it really just says 'We can't know anything really, but hey, the numbers work.' He is most scathing about the many worlds interpretation, though he does seem to have sympathy for some aspects of Bohm's version.

That isn't the main content of this book, though, which refers to, say, Immanuel Kant almost as much as it does to Heisenberg or Schrödinger. Somewhat disconcertingly, Dirac isn't mentioned at all, which underlines how much this isn't an introduction to the essentials of quantum theory. For that matter we never hear anything about quantum field theory. Instead there's an awful lot of trying to find ways to get the brain around something that appears weird, even though Ball is at pains to point at that it isn't weird at all. It's what nature is - it's just that our viewpoint of how nature behaves is misled by the special case that is macro-sized objects.

There is a lot to like here. It really got me thinking about what quantum physics involves, and Ball's assertions that it's primarily about interaction with the environment and about information (even if John Bell said  'information' should be a banned word in quantum mechanics) make a lot of sense, though I think more could have been done to emphasise that, just like waves and particles, the concept of 'information' here itself is likely to be more of a model than the reality.

However, Beyond Weird can also be a little frustrating to read. Initially, this is because Ball seems determined to go into aggressive 'You think this is true? Well, it's NOT!' mode. This is even emphasised in the subtitle. Even when the tone settles down, there is a lot of dancing around in the text, partly because it's difficult to use words to do what Ball is doing without getting in a bit of a tangle. So if you've just persuaded us, for example, that light or matter really isn't made of particles, you then it seems odd to refer to a 'quantum particle.'

It doesn't help that this is a topic where there is anything but a consensus. Ask three physicists what they think about quantum interpretations and you'll get three different answers. But it was instructive to hear of some of the thinking since the 1990s, which is where most quantum texts run out of steam.

As a book it's both frustrating - it can feel very woffly - and fascinating in equal measures. But I'm really glad I've read it and I recommend it to anyone who has already picked up the basics on quantum physics and wants to take more of an immersive dive into the philosophy that underlies it. It's broader and more readable than Quantum Sense and Nonsense, which probably makes it the best of its kind at the moment.

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Review by Martin O'Brien