¡°Can a biologist fix a radio?¡± is one of the questions posed in this relatively short volume by London-born Paul Davies, director of the Beyond Centre for Fundamental Concepts in Science at Arizona State University. The answer is: ¡°No, but this tells you something important about biology.¡±

The book takes as its starting point a series of lectures titled What is Life? that quantum mechanics pioneer Erwin Schr?dinger delivered at Trinity College Dublin in 1943. Davies summarises the studies that he considers have a place in answering that question, in fields including cosmology, quantum mechanics, chemistry, medicine, biology in its many proliferating aspects, philosophy, information theory and the search for extraterrestrial life. The result is a dizzying tour de force, which mostly reports fairly on the many highly contentious matters discussed.

The original demon of Davies¡¯ title was invented by Scottish physicist James Clerk Maxwell in 1867, who wanted to explode the hallowed second law of thermodynamics. Maxwell knew that in any enclosed volume of a gas, some of the molecules move slowly, some faster and a few very quickly indeed. He therefore proposed a tube in which a robot (the demon) placed in the middle could gradually confine the slower, colder molecules in one half and the faster, hotter molecules in the other half, by judicious operation of a shutter. This separation allows mechanical work to be done without expenditure of energy (trust me) and so breaches the second law.

Davies cites a range of what he calls biological demons ¨C real-life exemplifications of Maxwell¡¯s creation. Chemicals such as kinesin, sometimes called molecular ratchets, are the best parallels. These convert heat energy into movement and use this to carry important cargoes from the periphery of a cell to its centre. Other examples highlight the sorting or differentiating ability of the particular ¡°demon¡±. Olfactory receptors tell us that molecule A smells very different to molecule B, even though A and B have nearly identical chemical structures. Davies, however, courts serious controversy when he suggests that demons in the genome of an organism might enable it to pass on to its offspring characteristics acquired only during its lifetime. He is therefore sympathetic to the idea that genetic mutation may not be entirely random, thus questioning a central tenet of Darwin¡¯s theory of evolution.

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A major theme of the book is the organisation of information in biological systems. Davies argues that, while chemistry represents the hardware of life, information is its software. The book¡¯s subtitle refers to how ¡°webs of information are solving the mystery of life¡±, but it presents little evidence that we are nearing an answer to that conundrum.

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In 1995, Davies accepted the Templeton Prize, awarded for ¡°making an exceptional contribution to affirming life¡¯s spiritual dimension¡±. Here he is supportive of the idea that the universe is constructed to be sympathetic to the creation of life and seems to regard almost as unworthy the reductionist position that to understand life and its origin we need only the mundane, known rules of physics and chemistry. Perhaps his God has principal software developer as a significant part of her job description.

Richard Joyner is emeritus professor of chemistry at Nottingham Trent University.

The Demon in the Machine: How Hidden Webs of Information Are Solving the Mystery of Life
By Paul Davies
Allen Lane, 272pp, ?20.00
ISBN 9780241309599
31 January 2019