Physics of the Impossible – Michio Kaku *****

One of the first books we ever reviewed on www.popularscience.co.uk was The Physics of Star Trek by Lawrence Krauss. There were to be many ‘Physics of…’ and ‘Science of…’ books to follow from different authors, and now Physics of Star Trek seems rather dated. But there’s no need to worry, as Michio Kaku’s Physics of the Impossible brings it all up to date and goes much further, pulling in pretty well every imagining from science fiction. So, yes, we have phasers and transporters, antimatter energy and warp drives… but we also delve into space elevators, time travel, robots, the Death Star and much more.

Kaku, a physics professor at the City University of New York and a popular science broadcaster, doesn’t explicitly set this as ideas from science fiction, though he uses many SF examples in the book. Instead he is looking at degrees of impossibility. Each of the improbable applications of science is classified at one of three levels. Class I impossibilities have no problems with today’s science but present significant engineering challenges. We can’t do them today, but could well be able 100-200 years. Class II impossibilities sit on the edge of our current knowledge of physics. They may be possible in the far future, but getting there would require a big breakthrough. Class III impossibilities actually break the laws of physics. This doesn’t totally rule them out, as our understanding of physics can go through major shifts (Kuhn’s ‘paradigm shifts’), and it could be that we see things sufficiently differently in the future that they could become possible – but for now they are no-nos.

All the way through Kaku has a light, highly approachable style. This is no Brief History of Time – it’s not the sort of book you are going to start on and then give up because it becomes impenetrable. (To be fair, Brief History isn’t really like this, but it has the reputation.) Instead we get superb insights into just why the technology in question needs to be labelled impossible, and what the potential ways around the difficulties are. It is always entertaining and in terms of the sheer volume of content that is fitted in without ever seeming heavy going it’s a tour de force. There are so many examples it’s difficult to pick out favourites, but I liked the way we discover that force fields, seemingly so straightforward in Sci-Fi, would actually be ludicrously complex, while robot fans (and supporters of the Singularity) idea might be shocked at just how difficult it is to produce true artificial intelligence.

No book is absolutely perfect. If I had to pick out issues, there are just two small ones. I do think that there’s a slight tendency to over-simplify. It’s always hugely difficult to describe complex physics like quantum theory in a few lines, and the simplification that is essential to be able to do this occasionally makes a point slightly inaccurate. There’s also a slight oddity in the way time travel is a Class II impossibility, but precognition is Class III impossibility. Unless you are only accepting a parallel worlds interpretation, where time travel means involuntarily moving to alternative universes, then travelling into the past (or even sending a message into the past) implies a form of precognition. There seems to be a consistency issue here.

These are very minor points, though (and the simplification is almost a necessity in a book that has the huge scope of this one). Overall it’s one of my favourite popular science reads in a good while and works wonderfully both as an addition to an existing popular science shelf or as a book to encourage a first toe in the water for someone who has never strayed beyond watching Star Trek or Dr Who before. Recommended.

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Review by Brian Clegg