Feel like brushing up on physics? Carlo Rovelli is here to help

At one point in my youth, my father thought I was spending too much time reading and unceremoniously instructed me to go outside and do something. According to family legend, I went out the front door with a book, sat under a tree, and resumed reading. Lately I’ve been indulging my reading hunger with books on a couple of subjects that have fascinated me since childhood: aircraft carriers and physics. Geoff Dyer’s account of a visit to a carrier, which I read last week, came out in 2014; my take on it can be found on Goodreads. Carlo Rovelli’s Seven Brief Lessons on Physics is almost new, having been published in March, and so I’ll reproduce here, with perhaps an edit or two, the thoughts I posted on Goodreads. Incidentally, Rovelli feels the same temptation to go outdoors with a book. His chapter on relativity includes a recollection of sitting on a beach in Calabria, supposedly vacationing, but irresistibly reading instead.

Seven Brief Lessons coverScience might be described as the project by which we try to understand the world, but it has advanced far enough that understanding science is itself a challenge. Carlo Rovelli is a scientist (one of many, fortunately) who appears to believe that little good will come of leaving ordinary citizens to figure it out on their own, so he has undertaken to speak directly to the public about his chosen field, which is physics. The result is Seven Brief Lessons on Physics, first published as a series of articles for the Italian newspaper Il Sole 24 Hore, now expanded, translated into English by Simon Carnell and Erica Segre, and offered as a standalone book. It’s a slender volume, only 86 pages including the index, and Rovelli’s text is the very definition of elegance: graceful, tasteful, precise, neat, simple.

His seven lessons address:

  • Einstein’s general theory of relativity—the physics of the very big
  • quantum mechanics—the physics of the very small
  • the architecture of the cosmos—how we’ve come to know our planet’s place within our solar system, which is situated within our galaxy, which joins numberless others within the immensity of spacetime
  • our current model of elementary particles and what’s wrong with it
  • quantum gravity—attempts to combine general relativity and quantum mechanics
  • probability, time, and heat—in other words, thermodynamics (the only chapter I found a bit fuzzy)
  • ourselves—as he puts it in the preface, “how it is possible to think about our existence in the light of the strange world described by physics”

It’s hard for me to assess how well Rovelli’s book will serve uninitiated readers, but my impression is that they’ll come away with a sense of what all these potentially forbidding terms mean—only a sense, but that’s something. I value the book because it offers something for the informed reader as well. What follows are a few remarks, not intended as a full-fledged review.

Rovelli has his tastes and his tendencies. He doubts supersymmetry and favors loop quantum gravity; the latter is unsurprising, since he’s one of the theory’s creators. No one will be misled by his presentation of either, because he makes clear that the questions remain open. Unlike many writers on science, who (perhaps admonished by publishers) fear that every equation loses readers, Rovelli presents exactly one, which pertains to general relativity.* After warning that “you will almost certainly not be able to decipher it,” he adds, “Perhaps anyone reading this will still be able to appreciate its wonderful simplicity.” He’s right—it’s only a few characters long, and we gain something by seeing it. What a profound expression this must be!

In his discussion of particles, Rovelli writes, “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.” This is evocative, marvelously suggestive; I’m probably not the only reader who will be led to think of Buddhism—such comparisons were all the rage some years ago. But it’s also quite specific, a summing-up of much that Rovelli has already presented. That it occurs only 33 pages in will tell you how succinct his book is.

In his final chapter, a good deal later—that is, only 36 pages later—Rovelli makes an important distinction, which is worth quoting at length:

When we talk about the big bang or the fabric of space, what we are doing is not a continuation of the free and fantastic stories that humans have told nightly around campfires for hundreds of thousands of years. It is the continuation of something else: of the gaze of those same men in the first light of day looking at tracks left by antelope in the dust of the savannah—scrutinizing and [deducing] from the details of reality in order to pursue something that we can’t see directly but can follow the traces of. In the awareness that we can always be wrong, and therefore ready at any moment to change direction if a new track appears; but knowing also that if we are good enough we will get it right and will find what we are seeking. This is the nature of science.

The confusion between these two diverse human activities—inventing stories and following traces in order to find something—is the origin of the incomprehension and distrust of science shown by a significant part of our contemporary culture. The separation is a subtle one: the antelope hunted at dawn is not far removed from the antelope deity in that night’s storytelling.

The border is porous. Myths nourish science, and science nourishes myth. But the value of knowledge remains. If we find the antelope, we can eat.

(In brackets, I’ve corrected what I feel sure is a typo.) In speaking of “free and fantastic stories,” Rovelli may give too little credit to myths. One reason they satisfy us, when they do, is that they give us a kind of understanding. That Hypnos (sleep) and Thanatos (death) were twin brothers in the Greek pantheon makes sense, doesn’t it? The Buddhist idea of dependent arising doesn’t reflect something we can directly see around us, any more than the quantum-mechanical fizz can be seen, but both reflect our sense of transience, as the Christian notion of original sin may address our fallibility. Perhaps we should say it’s a matter of different uses. Regardless, Rovelli is right to stress that myths and science are different. Might a few of the book’s readers learn something from this? I hope so.

To use the word more broadly, one can say that, in a sense, the physical theories presented here are stories. We’ve been telling this kind of story for a long time, changing and elaborating and discarding as we go. It happens that I’ve been, so to speak, watching this channel since childhood, so I’ve heard these stories before, seen how they’ve developed. They have a thrill and a beauty and a strangeness to them that always gets me. Rovelli tells them well.

*The equation Rovelli gives is

Rab – ½Rgab = Tab

That’s a simplified form of the Einstein field equations. A knowledgeable acquaintance explained, “It is very common in relativity to use measurement units in which the fundamental physics constants equal 1, as Rovelli does here.” [Updated 7/16/16]


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