This is a poetic book of one of the most monumental questions in Physics. In clear and easy to follow language – and just one equation which Rovelli has the good grace to apologise for and explain the necessity of – he explains how time might well not flow in one direction or indeed in a straight line.
Time really is relative – not just the difference between the top of a mountain (slower) and sea-level, and the difference between moving and standing still (slower), but also what happens when you get in the vicinity of a black hole.
He confers with Aristotle and Newton and he absolutely loves Einstein (natch) but he also draws in Lewis Carroll, the Mahabharata, Proust – could hardly not, to be honest – and Shakespeare; he wonders where time comes from; declares that the world is made of events, not things; and that in the end it all comes down to entropy: “a thermodynamic quantity representing the unavailability of a system’s thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.” Basically that heat / energy cannot move from the colder to the warmer, or “backwards” through the system – all the while recognising that at least part of the problem is our inability to express ourselves properly, exactly – thus our understanding is all complicated by our linguistic inadequacy.
I dropped A-level Physics…because…well…frankly…just because, but I enjoyed this enormously. The book ends with a description of listening to a violin playing Beethoven:
“…We are suspended, holding our breath, feeling mysteriously that this must be the source of meaning. That this is the source of time. / Then the song fades and ceases… And it is fine like this. We can close our eyes, rest. This all seems fair and beautiful to me. This is time.“