By: Carlo Rovelli
My Take
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My Favorite 10 Highlights
- Note the wonderful initial “It seems to me…,” which recalls the “I think . . .” with which Darwin introduces in his notebooks the great idea that species evolve, or the “hesitation” spoken of by Faraday when introducing for the first time the revolutionary idea of magnetic fields. Genius hesitates. (Page 15)
Note: The smartest people don’t jump to conclusions - Why are precisely these elements listed there, and why does the periodic table have this particular structure, with these periods, and with the elements having these specific properties? The answer is that each element corresponds to one solution of the main equation of quantum mechanics. The whole of chemistry emerges from a single equation. (Page 17)
- There are therefore in the universe thousands of billions of billions of billions of planets such as Earth. (Page 28)
- The force that “glues” quarks inside protons and neutrons is generated by particles that physicists, with little sense of the ridiculous, call “gluons.”
Electrons, quarks, photons, and gluons are the components of everything that sways in the space around us. They are the “elementary particles” studied in particle physics. (Page 32) 5. The effort to synthesize has in the past been rewarded with great strides forward in our understanding of the world. Newton discovered universal gravity by combining Galileo’s parabolas with the ellipses of Kepler. Maxwell found the equations of electromagnetism by combining the theories of electricity and of magnetism. Einstein discovered relativity by way of resolving an apparent conflict between electromagnetism and mechanics. A physicist is only too happy when he finds a conflict of this kind between successful theories: it’s an extraordinary opportunity. (Page 41)
Note: Many discoveries were found at the intersection of two disciplines
- General relativity has taught us that space is not an inert box but rather something dynamic: a kind of immense, mobile snail shell in which we are contained—one that can be compressed and twisted. Quantum mechanics, on the other hand, has taught us that every field of this kind is “made of quanta” and has a fine, granular structure. It immediately follows that physical space is also “made of quanta.”
The central result of loop quantum gravity is indeed that space is not continuous, that it is not infinitely divisible but made up of grains, or “atoms of space…”
They are called “loops,” or rings, because they are linked to one another, forming a network of relations that weaves the texture of space, like the rings of a finely woven, immense chain mail. (Page 43)
7. This is why we observe black holes remaining the same for long periods of time: a black hole is a rebounding star seen in extreme slow motion. (Page 47)
8. The difference between past and future exists only when there is heat. The fundamental phenomenon that distinguishes the future from the past is the fact that heat passes from things that are hotter to things that are colder.
So, again, why, as time goes by, does heat pass from hot things to cold and not the other way around?
The reason was discovered by Boltzmann and is surprisingly simple: it is sheer chance. (Page 53)
9. When his great Italian friend Michele Besso died, Einstein wrote a moving letter to Michele’s sister: “Michele has left this strange world a little before me. This means nothing. People like us, who believe in physics, know that the distinction made between past, present and future is nothing more than a persistent, stubborn illusion.” (Page 60)
10. The heat of black holes is like the Rosetta stone of physics, written in a combination of three languages— quantum, gravitational, and thermodynamic—still awaiting decipherment in order to reveal the true nature of time. (Page 64)
Note: Great writing