Book Review: Reality is not what it seems – The Journey to Quantum Gravity, by Carlo Rovelli
This is a clever and interesting book, but if you struggled with A Brief History of Time, I don’t think this book is for you. Rovelli’s style is at points florid and pretentious, though this may be a feature of the translation. He first reviews the science of Ancient Greece, before proceeding through Newton and Einstein. After discussing quantum mechanics, it’s on to the fundamental purpose of this book: how to resolve the approaches of general relativity and quantum mechanics in describing the universe. They are both experimentally verified to very high standards, yet are incompatible. Rovelli makes the argument (for me, not wholly convincingly) that time does not exist as a fundamental entity; like temperature, or “up” and “down”, it is a property that emerges at a macroscopic layer.
There were some new discoveries for me in this book: Rovelli’s explanation that spacetime is the field of gravity (rather than that the field of gravity permeates spacetime) is good, and goes beyond many popular science books which simply explain that gravity is “different” when it comes to unifying the fundamental forces. Yet, there is a missed opportunity here: the presented self-referential nature of spacetime and gravity ought to trigger the word “Gödel”, but it doesn’t, possibly because of a fear that would cause the end of physics, just as it might have been feared to cause the end of mathematics. One would also expect some mention of quantum entanglement, and this is also missing, although in the chapter on information the concept rears its head, unspoken, and again the opportunity is left untaken. Overall I am left with the feeling that this is a good and useful book, but that given its depth it nevertheless has some unexpected limitations.