Seven Brief Lessons on Physics

by Carlo Rovelli

science shows us how to better understand the world, but it also reveals to us just how vast is the extent of what is still not known.

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.

Albert was reading Kant and attending occasional lectures at the University of Pavia: for pleasure, without being registered there or having to think about exams. It is thus that serious scientists are made.

There are absolute masterpieces that move us intensely: Mozart’s Requiem, Homer’s Odyssey, the Sistine Chapel, King Lear. To fully appreciate their brilliance may require a long apprenticeship, but the reward is sheer beauty—and not only this, but the opening of our eyes to a new perspective upon the world. Einstein’s jewel, the general theory of relativity, is a masterpiece of this order.

Undistracted by schooling, one studies best during vacations.

Every so often I would raise my eyes from the book and look at the glittering sea: it seemed to me that I was actually seeing the curvature of space and time imagined by Einstein. As if by magic: as if a friend were whispering into my ear an extraordinary hidden truth, suddenly raising the veil of reality to disclose a simpler, deeper order.

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.

an extraordinary idea occurred to him, a stroke of pure genius: the gravitational field is not diffused through space; the gravitational field is that space itself. This is the idea of the general theory of relativity. Newton’s “space,” through which things move, and the “gravitational field” are one and the same thing.

A momentous simplification of the world: space is no longer something distinct from matter—it is one of the “material” components of the world. An entity that undulates, flexes, curves, twists.

a glimpse of reality, a little less veiled than our blurred and banal everyday view of it. A reality that seems to be made of the same stuff that our dreams are made of, but that is nevertheless more real than our clouded, quotidian dreaming.

The two pillars of twentieth-century physics—general relativity, of which I spoke in the first lesson, and quantum mechanics, which I’m dealing with here—could not be more different from each other. 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 (the computer on which I write, for example), but more than a century after its birth it remains shrouded in mystery and incomprehensibility.

Genius hesitates.