A recent review of this book on Goodreads contains the sentence “That’s beautiful, even if I don’t quite fully understand it.” I can’t help but suspect this attitude underlies many of the positive reviews. Rovelli is eloquent throughout, but after the first few chapters, his level of clarity seems to me to drop substantially.
In those early chapters, one of Rovelli’s objectives is to disabuse us of the notion that “the present” exists in any absolute sense:
"What is happening ‘now' in a distant place? Imagine, for example, that your sister has gone to Proxima b, the recently discovered planet that orbits a star at approximately four light-years’ distance from us. What is your sister doing now on Proxima b? The only correct answer is that the question makes no sense. It is like asking 'What is here, in Beijing?' when we are in Venice. It makes no sense because if I use the word ‘here' in Venice, I am referring to a place in Venice, not in Beijing.”
He gives a lucid and satisfying explanation of this, and goes on to describe a way of looking at time as a network of events in which each one has a past and future but there is no global ordering of all the events.
Shortly thereafter, though, we speed through a diagram of wobbly light-cones arranged in a temporal loop, and I find myself wishing for more concrete examples to illustrate exactly what this implies. Several other ideas in the book come across hazily. Rovelli does not want us to believe we live in a “block universe” where everything is static and unchanging, but I could have benefited from more explanation of how (and why) else to conceptualize the present-less network of events he describes. There is a lot of intriguing discussion about the meaning of entropy, but the conclusions he suggests regarding the nature of time are difficult to follow or evaluate.
This book is probably not a good way to get a grasp on the subject matter, though it’s thought-provoking and sometimes moving.
"I am not this momentary mass of flesh reclined on the sofa typing the letter a on my laptop; I am my thoughts full of the traces of the phrases that I am writing; I am my mother’s caresses, and the serene kindness with which my father calmly guided me; I am my adolescent travels; I am what my reading has deposited in layers in my mind; I am my loves, my moments of despair, my friendships, what I’ve written, what I’ve heard; the faces engraved on my memory. I am, above all, the one who a minute ago made a cup of tea for himself. The one who a moment ago typed the word “memory” into his computer. The one who just composed the sentence that I am now completing. If all this disappeared, would I still exist? I am this long, ongoing novel. My life consists of it."