Seven Brief Lessons on Physics by Carlo Rovelli
My rating: 5 of 5 stars

"Ever since we discovered that Earth is round and turns like a mad spinning-top, we have understood that reality is not as it appears to us: every time we glimpse a new aspect of it, it is a deeply emotional experience. Another veil has fallen."

In Preface, the author of Seven Brief Lessons on Physics, Carlo Rovelli, a renowned theoretical physicist and a philosopher of science, addresses his book to "those who know little or nothing about modern science." Although I am an applied mathematician, an engineer, and have even taught a course on mechanics (a classical part of physics), I know very little - really next to nothing - about modern physics. I have learned a lot from that tiny book (total of 81 pages!) and I absolutely love Dr. Rovelli's amazing way of making some basic tenets of contemporary physics almost understandable by amateurs like myself. This is the best popular science writing I have ever read!

The first lesson deals with "the most beautiful of theories" - Einstein's general theory of relativity. We read wonderful passages like

"[...] the gravitational field is not diffused through space; the gravitational field is that spaceitself."

We then read about curvature of space and that "it isn't only space that curves; time does too." The second lesson focuses on quantum mechanics, which in layman's terms posits that energy is discrete rather than continuous. And it is here that to my delight (and likely to screams of horror of many people) randomness and probability appear! Dr. Rovelli states at the end of the chapter that the equations of quantum mechanics and their consequences "remain mysterious," and suggests an idea that "reality [of the physical world] is only interaction." So cool!

I am omitting two next chapters in my summary, Architecture of the Cosmos and Particles (with its Standard Model, confirmed experimentally in 2013 yet still considered unsatisfactory). The Fifth Lesson focuses on the contradictions between the current form of the two main theories of physics - general relativity and quantum mechanics - and on the current efforts of physicists to combine the two theories. One such effort is the loop quantum gravity theory and Dr. Rovelli, in extreme modesty, neglects to write that he is one of the founders (if not the main founder - that I do not know) of the theory.

Naturally, the lesson titled Probability, Time, and the Heat of Black Holes, is my favorite! Even a mention of the word "probability" makes my heart beat faster and here it becomes a central mechanism of physics. Dr. Rovelli writes

"This bringing of probability to the heart of physics, and using it to explain the bases of the dynamics of heat, was initially considered to be absurd."

And what about the following stunning passage:

"[...] the intimate connection between time and heat. There is a detectable difference between the past and the future only when there is the flow of heat. Heat is linked to probability; and probability in turn is linked to the fact that our interactions with the rest of the world do not register the fine details of reality."

Finally, in the lesson called In Closing, the author writes about "ourselves" - us, the humans. He dwells on the nature of consciousness and the issue of free will. In a passage that unfortunately becomes more and more relevant with each passing year he points out the "incomprehension and distrust of science shown by a significant part of our contemporary culture." He also offers a sobering prediction that "our species will not last long" and alludes to the damage that the species keeps doing.

A beautifully written book about Very Difficult Things.

Five stars.


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