When Physics World published a list of the five biggest unanswered questions in physics earlier this year in its 25th anniversary special issue, "What is consciousness?" was not on it. The reason for its exclusion seemed, at the time, straightforward: although the nature of consciousness is one of the toughest conundrums of modern science, it is not one that is commonly associated with physics. Biology and neuroscience, yes. Philosophy, certainly. Perhaps even art or poetry. But not, for the most part, physics.
In his book Physics in Mind: a Quantum View of the Brain, author Werner Loewenstein sets out to convince readers otherwise, and thereby "sink into oblivion" the idea that "biology is biology, and physics is physics, and never the twain shall meet". The result is, in the words of our reviewer Seth Lloyd "an intellectual rollercoaster ride" that takes in ideas about the nature of time, evolution, electrochemical signalling, information theory and, ultimately, quantum computing – a burgeoning field that Loewenstein believes may hold vital clues to the problem of consciousness.