Seven Brief Lessons on Physics


This book was written by Carlo Rovelli for people who know little of modern science, as noted by the author. But I found it to be a great read. Throughout this book, much of its content reminds us how little we know of physics and the universe in general, and in some sense even less of ourselves.

The first six lessons are about the revolutions in physics during the 20th and 21st centuries, both the discoveries and more so the unknowns, including: Albert Einstein’s general theory of relativity (the most beautiful of theories), quantum mechanics, the architecture of the cosmos, elementary particles, quantum gravity, and the sixth lesson on probability, time and the heat of black holes.

In his youth Albert Einstein spent a year loafing aimlessly. You don’t get anywhere by not “wasting” time – something, unfortunately, that the parents of teenagers tend frequently to forget.

We are so terribly overloaded with interruptions in the form of emails, tweets, messages, meetings and so on. Without a great chunk of time wondering in the misty forest of our deep thoughts, it is impossible to be creative either in science, engineering, literature or art. I came to the realisation some years ago that to stop responding to trivialities is merely negligent of trivialities, but to not protect one’s solitude and high quality thinking time is irresponsible to oneself and the universe that brings us to our existence.

In contrasting general relativity and quantum mechanics, the author wrote beautifully:

Both theories teach us that the fine structure of nature is more subtle than it appears. But general relativity is a compact gem: conceived by a single mind, that of Albert Einstein, it’s a simple and coherent vision of gravity, space and time. Quantum mechanics, or “quantum theory”, on the other hand, has gained unequaled experimental success and led to applications that have transformed our everyday lives, but more than a century after its birth it remains shrouded in mystery and incomprehensibility.

The books piled up on my desk could not agree with the author more on this. These books, to be revealed in upcoming articles, are all related to quantum physics and its pioneers.

In the third lesson about the cosmos, the author drew a few pictures to show how the cosmos has been conceptualised and how that has evolved, in other word, the journey between visions. I like this particular passage:

Before experiments, measurements, mathematics, and rigorous deductions, science is above all about visions. Science begins with a vision. Scientific thought is fed by the capacity to “see” things differently than they have previously been seen.

The fourth lesson on elementary particles, the components of everything that sways in the space around us (as the author puts it): electrons, quarks, photons, and gluons. To share some of the author’s poetic writing:

The nature of these particles, and the way they move, is described by quantum mechanics…They disappear and reappear according to the strange law of quantum mechanics, where everything that exists is never stable and is nothing but a jump from one interaction to another. Even if we observe a small, empty region of space in which there are no atoms, we still detect a minute swarming of these particles. There is no such thing as a real void, one that is completely empty. Just as the calmest sea looked at closely sways and trembles, however slightly, so the fields that form the world are subject to minute fluctuations, and it is possible to imagine its basic particles having brief and ephemeral existences, continually created and destroyed by these movements. This is the world described by quantum mechanics and particle theory. We have arrived very far from the mechanical world of Newton, where minute, cold stones eternally wandered on long, precise trajectories in geometrically immutable spaces. Quantum mechanics and experiments with particles have taught us that the world is a continuous, restless swarming of things, a continuous coming to light and disappearance of ephemeral entities. A set of vibrations, as in the switched-on hippie world of the 1960s. A world of happenings, not of things.

One note about the Standard Model is worth bearing in mind for future reference, and is probably widely applicable:

Perhaps on closer inspection it is not the model that lacks elegance. Perhaps it is we who have not yet learned to look at it from just the right point of view, one that would reveal its hidden simplicity.

In lesson on quantum gravity, the author concluded the chapter with:

Physics opens windows through which we see far into the distance. What we see does not cease to astonish us. We realise that we are full of prejudices and that our intuitive image of the world is partial, parochial, inadequate. Earth is not flat; it is not stationary. The world continues to change before our eyes as we gradually see it more extensively and more clearly. If we try to put together what we have learned in the twentieth century about the physical world, the clues point toward something profoundly different from our instinctive understanding of matter, space and time. Loop quantum gravity is an attempt to decipher these clues and to look a little farther into the distance.

The last lesson is about ourselves, how it is possible to think about our existence in the light of the strange world described by physics. This is my favorite chapter of the book, for its most thought provoking nature. It seems to me that the chapter on ourselves conveys more of the author’s own thinking and view than any other chapters. We perceive and interact with the world around us. We have emotions, thoughts, characteristics and physical actions. But what is our role in this world depicted by the physics?

If the world is a swarm of ephemeral quanta of space and matter, a great jigsaw puzzle of space and elementary particles, then what are we? Do we also consist only of quanta and particles? If so, then from where do we get that sense of individual existence and unique selfhood to which we can all testify? And what then are our values, our dreams, our emotions, our individual knowledges? What are we, in this boundless and glowing world?

I hardly knew how to breathe while reading this paragraph. I had to read it again and again to rebalance and restore my mental and physical agility. True that the author noted that he could not imagine attempting to answer these questions either in this book. Ask questions nevertheless!

We, human beings, are first and foremost the subjects who do the observing of this world, the collective makers of the photograph of reality that I have tried to compose. We are nodes in a network of exchanges through which we pass images, tools, information, and knowledge.

The images that we construct of the universe live within us, in the space of our thoughts. Between these images – between what we can reconstruct and understand with our limited means – and the reality of which we are part, there exist countless filters: our ignorance, the limitations of our senses and of our intelligence. The very same conditions that our nature as subjects, and particular subjects, imposes upon experience.

All things are continually interacting with one another, and in doing so each bears the traces of that with which it has interacted: and in this sense all things continuously exchange information about one another.

There is not an “I” and “the neurons in my brain”. They are the same thing. An individual is a process: complex, tightly integrated.

Our appetite for life is voracious, our thirst for life insatiable. – Lucretius

It is part of our nature to love and to be honest. It is part of our nature to long to know more and to continue to learn. Our knowledge of the world continues to grow.

The book ends with this image:

Here, on the edge of what we know, in contact with the ocean of the unknown, shines the mystery and the beauty of the world. And it’s breathtaking.