Antti Värtö's Reviews > Ajan luonne

Rovelli explains the evolution of our concept of time starting from the common-sense meaning of the word, through the mistaken Newtonian idea of absolute time, to the Einsteinean insights about the relativity of time and how there is no common "present" or "now" in the universe, and beyond. Indeed, the tentative equations about quantum gravity have no such thing as "time" in them, which means that time is not a fundamental part of the universe. Time, as such, doesn't really exist. Only macroscopic objects such as humans, who must follow the laws of thermodynamics, can perceive the rise of entropy - and percieve that as "time".

This book had some good insights, like the ideas about why the universe was in minimum-entropy state when it was born: if you shuffle a deck of cards, it will get further and further away from it's starting order, so it's entropy increases. But this is true regardless of the initial order of the cards! If the deck is large enough, if we percieve the starting order as meaningful, the deck will always be less meaningful after we shuffle it. But the "meaningfulness" of the starting order is only a matter of viewpoint: it feels meaningful to us, since this whole event gave birth to the universe that gave birth to us, but from another viewpoint it was just an event, and the cards are not in any way "less" or "more" ordered now than in the beginning. That was very interesting, food for thought for a long while.

Rovelli also manages to explain Special and General Relativity pretty lucidly, which is no mean feat. I've seen many other writers stumble there.

I wasn't a fan of his writing style, though. Rovelli too often sounds annoyingly paternalistic. For instance, when he talked about thermodynamics, he actually wrote: "Dear reader, I'm sorry, I had to include this one equation in this book". As if his readers are ignoramuses who will throw away a book in disgust if it includes *shudder* EQUATIONS! The horror!