The Order of Time

Carlo Rovelli has the brilliance of Stephen Hawking and Albert Einstein and the communicative skills of Carl Sagan. Otherwise he is an Italian theoretical physicist that specializes in quantum gravity and is a proponent, if not quite an advocate, of loop theory. Beyond that he is a philosopher with a heart for ancient poetry and love. And he brings all of it to bear in this delightful book about time, which, in the end, is life, and everything, including the context in which it unfolds. It would be in error to suggest that time doesn’t exist, but it would be equally in error to suggest that time is as simple as the continuum we record with our clocks. What I like most about the book is the fact that Rovelli recognizes that philosophy and science, if not two sides of the same coin, are cousins. He refers to Proust, which few scientists do, and suggests that while reason is among the best tools available for interpreting our “collective delirium,” it is “only an instrument, a pincer.” The science and the prose are very accessible. You will, however, have to be willing to think abstractly, a skill that in our wired, binary world seems to be greatly dissipating. And he is the first scientist I have read in a while who takes time to explain why the problem is sometimes not the science itself, but the limitations of language. Language is a human construction and has not kept up with our scientific revelation. Which is why theoretical physicists sometimes seem to be speaking another language. If only there was another language that was constructed in the world as we know it today, our communication would be so much easier and our knowledge would expand more rapidly. It would be impossible to summarize the knowledge contained in this book. You really have to read it. Here is a start, however: “The world is not a collection of things, it is a collection of events.” If you can comprehend that the rest is largely additional perspective. And if the idea that universal time doesn’t exist in any absolute sense seems a stretch, consider Rovelli’s simple explanation (I’m paraphrasing): People never used to worry about clocks. They worried about the cycle of sunshine and darkness. But that cycle is different in every single village, town, and city on the planet. The cycle varies both east to west and north to south. And back when we used to spend our lives in our little village we didn’t care. But then the scientists and engineers invented trains to take us from one village to the next. And people needed to know when the train left their village. But how can you develop a timetable when every village has its own time? You can’t. But, at the same time, it’s not quite practical to say that the whole world has just one time. Farmers don’t care what the sun is doing in London. They care what it’s doing on their farm. (China actually has no time zones by edict. The entire country is on Beijing time and there are significant practical limitations.) The solution was the time zone, and it’s a compromise. Time zones are a construct and practical in the local sense, but highly inaccurate when talking about the universe. In the language of theoretical physics, they don’t exist. Eastern philosophers believe that reality is not knowable. It is real, but is made up of an infinite number of variables. We can only comprehend or think about a handful at a time. A tree is real. I can touch it and smell it. But it is not entirely knowable because there are too many variables (e.g. altitude, climate, soil, etc.) that define each tree for me to know them all. Time is the same way. Time is real but it is not knowable. Throw in the limitations of language and it begins to look like an illusion. To his great credit, Rovelli admits that there is much we don’t know. Think of a Seurat painting that has been blacked out. We have exposed a few, perhaps 10% (my number), of the original dots of pigment. It’s a lot, but we’re still guessing as to what the underlying picture is. And that’s pretty exciting. The key to our understanding to date, however, is the second law of thermodynamics which states that entropy can never decrease. It’s critical to our understanding of time, as Rovelli explains. Personally I’m not convinced it’s inviolate. Perhaps we just haven’t uncovered enough dots of pigment yet. If entropy could work both ways it would explain a lot, but attraction does not equal fact. (Entropy obviously has a big role in causality, of course. Bidirectional entropy would be a huge boost for inductive reason.) It’s a short book and even if you get through a small amount of it you will learn a lot. Beyond writing in an accessible way, Rovelli comes off as very personable. The perfect person to sit down and share a cup of coffee with. If only he had the time. (Sorry) A marvelous book that I highly recommend.

Rovelli is a physicist, but in this book he comes across as more of a philosopher, taking on the meanings of "here", "now", and even death and life. I was hoping for more of the physics of time and how it factors into the equations that describe the world we live in. Could time be fundamental and determine the "speed" of causality and light? Not even a hint of this from Rovelli. Maybe time is simply too difficult to understand and, therefore, not included in our physics. However the physics of time was addressed only in the first couple of chapters, in which he noted that time is a factor in only one equation of classical physics, and none in quantum physics. How can this be -- that time is not a factor in the physics of our world and universe when we live with it every day? In fact, Rovelli essentially dismisses time altogether. He says," Perhaps the [human] emotion of time is precisely what time IS for us. I don't think there is much more than this to be understood." Wow! In this respect, I was a bit disappointed in the book, although it is well written and easy to read. Lots of deep-thought philosophy, and references to ancient and contemporary philosophers. There was only one simple equation (although there were equations in the footnotes), not even Einstein's famous equation, although many mentions of Einstein himself. I would recommend this book to anyone who wants a philosophical approach to the meaning of time, but very little of the theoretical physics of time, even though the author is a theoretical physicist, working on the elusive topic of quantum gravity.

I started by reading reality is not what it seems, and I have read almost every book by this author in the last month now lol this book is very captivating, it will have you questioning human perspective in general.

The Order of Time is a brilliant book on quantum physics explained in a simple and beautiful way. Professor Rovelli not only guides us through a complex theme that is quantum, as he quotes poetry that is somehow related with the concepts of the book. The main subject, as the title indicates, is time. How time behaves, what is time, how it affects us, how we perceive it, ultimately, how it affects reality. Some of the most interesting points that Professor Rovelli brings up are: • The relativity of time towards a body mass: how time passes differently in the mountains or at sea level. Basically time passes faster in the mountains and slower at sea level, because the sea is closer to the Earth’s nucleo. • The relativity of time towards movement: how time passes faster for a clock that is placed in a specific spot in comparison to a clock that is being moved around. • How the world is made of events and not of things, made of something that occurs and not of objects or the shape a thing have at a specific time. • Why present is relative and it only exists on Earth. • Our perception of time and reality, past and future, and how these are not a straight line. • How language affects our perception of time, past and future and, consequently, our difficulty to approach its relativity. • What entropy actually means in terms of time/reality/energy and its importance. It really is a very clarifying book with an interesting light on the subject. Professor Rovelli is not only an outstanding physicist, as he has the soul of a poet and he is able to connect with the reader from the first line. For all these reasons, The Order of Time was one of the most brilliant books I’ve ever read. I highly recommend it to anyone who wishes to understand more about who and what we are as human beings experiencing life on Earth in this form and why time is an undeniably huge part of it.

Il libro è scritto in modo che anche una persona non specializzata in fisiatra possa comprenderlo. Uno sguardo affascinante al tempo come lo conosciamo.

Carlo has a way with words. Amazing book: Interesting and easy to follow.

One of those books that changes the perspective about life and the whole of Cosmos. Although some parts are little bit technical for me, overall the flow of the book is smooth. A must read and deserves to be read again and again.

Narrativa fluida e claríssima. Rovelli aborda temas sofisticados com maestria e simplicidade. Deixa claro o que é visão pessoal e consenso acadêmico. Leitura de qualidade para leigos e especialistas.

20世紀の大きな思想変革として「相対化」があげられる。神や絶対正義が理性によって否定され、その理性の創り出す世界観も相対性理論や量子理論、不完全性定理によって相対化された。そのなかで依然として確固とした地位を保っているかに見えた「時間」はどうなのか？スリリングな知的刺激と視覚の広がりを与えてくれる。平易な英語で読みやすい。