Physics and its poetry

My mind thirsts for knowledge, and it seeks out the new and unexplored. For this reason I've spent my Saturday afternoon so far sitting in my favorite local bookstore devouring a short, tidy volume called Seven Brief Lessons on Physics by an Italian physicist named Carlo Rovelli. 

I like to think physicists would be heartened to know that the humanities lovers among us secretly hunger for a layman's introduction to the sciences, even if we appreciate it all the more when the profound theorems are packaged in poetics.

So I loved it. I was even moved by it. And I couldn't resist noting down, as I sometimes do, the sections that most delighted me. For anyone who identifies, wistfully, as someone who's "not a science person" but harbors some closeted curiosities like me, here are some shimmering excerpts:

On the Heisenberg uncertainty principle:

"Heisenberg imagined that electrons do not always exist. They only exist when someone or something watches them, or better, when they are interacting with something else. They materialize in a place, with a calculable probability, when colliding with something else. The 'quantum leaps' from one orbit to another are the only means they have of being 'real': an electron is a set of jumps from one interaction to another. When nothing disturbs it, it is not in any precise place. It is not in a 'place' at all.

It's as if God had not designed reality with a line that was heavily scored but just dotted it with a faint outline."

On the dynamic, interactive nature of reality:

"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 space. 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."

On the question of heat—and of time:

"Why does heat go from hot things to cold things and not vice versa? It is a crucial question because it relates to the nature of time. In every case in which heat exchange does not occur, or when the heat exchanged is negligible, we see that the future behaves exactly like the past. For example, for the motion of the planets of the solar system heat is almost irrelevant, and in fact this same motion could equally take place in reverse without any law of physics being infringed. As soon as there is heat, however, the future is different from the past. While there is no friction, for instance, a pendulum can swing forever. If we filmed it and ran the film in reverse, we would see movement hat is completely possible. But if there is friction, then the pendulum heats its supports slightly, loses energy, and slows down. Friction produces heat. And immediately we are able to distinguish the future (toward which the pendulum slows) from the past. We have never seen a pendulum start swinging from a stationary position, with its movement initiated by the energy obtained by absorbing heat from its supports. 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.

Boltzmann's idea is subtle and brings into play the idea of probability. Heat does not move from hot things to cold things due to an absolute law: it does so only with a large degree of probability. The reason for this is that it is statistically more probable that a quickly moving atom of the hot substance collides with a cold one and leaves it a little of its energy, rather than vice versa. Energy is conserved in the collisions but tends to get distributed in more or less equal parts when there are many collisions. In this way the temperature of objects in contact with each other tends to equalize. It is not impossible for a hot body to become hotter through contact with a colder one: it is just extremely improbable."

And finally:

"There are frontiers where we are learning, and our desire for knowledge burns. They are in the most minute reaches of the fabric of space, at the origins of the cosmos, in the nature of time, in the phenomenon of black holes, and in the workings of our own thought processes. 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."