I'm not sure what to make of Vlatko Vedral's Decoding Reality: the universe as quantum information. This problem is mine, not the author's. Quantum theory is hard and my understanding of even this well-written pop science version of it is hazy.

Why, you might be wondering, am I reviewing a physics book here anyway? The reason is that Prof Vedral pitches information as the key to a Grand Unified Theory of absolutely everything, the economy and society as well as the universe. In this, he joins Hans Christian von Baeyer, another physicist whose book Information, The New Language of Science, was published in 2003. So there's something going on in the world of quantum physics if two leading scientists have tried to popularise this idea. And I have a hunch it might be related to another book I never understood properly either, Nicholas Georgescu-Roegen's The Entropy Law and the Economic Process, which considers the implications of thermodynamics for economics. An impenetrable book on an important subject.

Back to Decoding Reality. The first line of argument in the book is that information processing is a physical process. Whether it takes place in a brain or a computer, the laws of classical physics and – in later chapters – quantum physics must apply. This is why computers get hot and why thinking uses calories. The first and second laws of thermodynamics apply – the first says energy can't be created out of nothing, and the second (the entropy law) says the conversion occurs with less than perfect efficiency so that the degree of disorder increases. Over time energy will be dissipated to the environment, but in the short term we can control the rate at which this occurs. This creation of order out of disorder is information processing. “The higher the entropy of a system, the more information it carries.”

After a whiz through classical physics, Vedral applies the idea that everything can be understood as information processing to specific disciplines including evolutionary science and economics. The economics chapter is a bit disappointing. There's a bit of network theory, 'small worlds' models, Zipf's law and Schelling's segregation model, all of which are covered in more detail by other authors eg Philip Ball or Paul Ormerod. I also lost the plot here on what this had to do with thermodynamics, although Vedral concludes that entropy quantifies the degree of social connectedness or complexity of an economy.

Then part 2 turns to quantum physics and it only gets harder. The argument in this part is that the universe itself should be thought of as engaged in quantum information processing. Information, not energy, is the fundamental concept. Bits are the building blocks of the universe.

Because of quantum uncertainty – which means that a particle can be in more than one state simultaneously, before it is measured either directly by an observer or indirectly by contact with its environment – we are taken to the conclusion that information processing is not a solitary or internal activity. Instead, “The informational content of anything does not reside in the object itself, but is a relational property of the object in connection with the rest of the universe.”

Vedral's ultimate conclusions are that the universe and our entire reality is made up of information. We process and compress the information to generate our view of reality; that in turn affects the reality. The ends with a quotation from the Tao Te Ching, whose final lines rather effectively sum up my state of mind at the end of this: “Darkness within darkness/The gate to all mystery.” I'm sure there are profoundly important messages in this book, but the laws of thermodynamics no doubt mean my brain would probably spontaneously combust were I to get close to understanding them.

The author himself has a go at explaining the book – much better than I can – here and there was a very positive review in The New Scientist  by Seth Lloyd. He says: “By turns irreverent, erudite and funny, Decoding Reality is – by the standard of books that require their readers to know what a logarithm is – a ripping good read.
” So there you have it – baffling but fun.