Old Tom

This book is very strong (and interesting if you like that sort of thing) on philosophy and poetic language, but fails to explain its main thesis. Rovelli seems to be saying that that relations are the primary stuff of physics. But relations must be between things (he calls these objects) which he refers to as nodes. The objects can change with the observer as does time in special relativity. The relations are describable by what he calls ‘relative information’. I presume this is what most call mutual information but I am not sure, because there is nowhere, (absolutely nowhere!!) where any technical example is explained using his relative information. There is a hand-waving discussion about an interference experiment due to Anton Zeilinger, but none on how this or more general systems are best described by relative information. If you want to understand Rovelli’s idea of ‘Relative Quantum Mechanics’ you won’t find it in this self-indulgent book.