CARLO ROVELLI
The author of Seven Brief Lessons on Physics (2014), The Order of Time (2017) and most recently, Helgoland (2021), Italian theoretical physicist Carlo Rovelli is a marked outlier in a landscape of “big ideas” popular science that too often attempts to answer life’s great questions by coating the obvious in pseudo-profundity. Rovelli is less interested in grand narratives that seek to explain everything through a string of counterintuitive insights than he is in acquainting his audience with the most confounding mysteries of his field with clarity and poetry. He discussed quantum mechanics, thinking across disciplines and finding comfort in uncertainty with Masoud Golsorkhi.
Interview by Masoud GolsorkhiPortrait by Christopher Wahl
Masoud Golsorkhi You’ve been described as the person in whom physics has found its poet. Why did you start writing in a literary style for a wide audience?
Carlo Rovelli I never decided to write in a literary style, I just decided to write. There was a shift quite late in my life when I started writing for the larger public, though. It was not a decision, but came about by chance a little bit. I was teaching the history of science and taking notes on the Greek philosopher Anaximander; I passed along my notes to my friends, who said I should publish a book. After much hesitation, I decided to put all my notes together and that became my first book, Anaximander. Then I started writing newspaper articles, because somebody listened to my conference and asked if I would write it down. I’m infinitely curious and my interests are large.
MG Your parallel work as an author generates its own momentum. Did you ever at any point think, “This is too much, I need to go and be a physicist?”
CR I’ve claimed that time is not what we think, but sometimes time is what we think and we struggle with it. I definitely have to juggle. I’m not writing right now because I’m doing science, but they’re not completely separate operations either, because writing these books has been a way to bring together ideas from scientific works of myself and others. Writing forces us to look for coherence and better understand the bigger picture. I think there’s been a reciprocal influence between my technical work and my popular work.
MG What was the starting point with this particular book, Helgoland, about quantum mechanics? It’s a very difficult subject about which many have struggled to write.
CR A good part of my professional life is making sense of the quantum revolution. My key job is to work on quantum gravity, to apply quantum mechanics to spacetime. I started writing technically about the nature of quantum mechanics back in the 1990s, and some of the ideas in the book come from that writing. After The Order of Time, I decided not to write anything for a while. But then I said, OK, if I write something, there’s only one topic that deserves it, which is quantum physics, because that’s the real mystery and the real revolution, the deepest revolution in modern physics. The book is a way to tell that story, but it’s also a way to articulate my own thinking about quantum mechanics. It’s addressed to the larger public, but it’s also a contribution to the scientific debate going on around quantum mechanics.
MG When you talk about the various historical figures whose work you’ve built upon in the book, you give a real sense of the personal and subjective nature of their enquiries. For example, when you discuss Schrödinger’s cat, you’re ambiguous as to whether he really meant to set it up as a way of refuting quantum mechanics or if it was just mischievous wordplay. I wondered if that was a problem for you, because you’re deploying the language of non-specialists to talk about something that’s normally expressed using a very different set of tools.
CR I think that science seen from a distance is an abstract enterprise that works in a rational way, but seen from nearby, it’s a completely different story. It’s people, with their personalities, who come up with concepts and ideas and experiments. The imprint of who they are and the way they think about the science they do is enormous. I’m not saying that this takes away the objectivity of science. A great photographer shows us something that is real, it’s out there in the world but the photograph is the photographer, it’s his view of the world. This happens with science, too. When I study a problem, I often go back to the sources, something you always do in humanities but rarely do in science, because in the sources you see the way scientists think. Once you see that, you then start to see the cracks, the things you could do differently and the things you might learn from that. Doing science is also engaging in a sort of one-to-one conversation. Schrödinger’s cat itself was an outcome of a conversation he had with Einstein, and when I reference his concept, I feel as if I’m debating with him. Science is not clean, especially on the boundary between what we know and we don’t know. With equations, you can describe the world and it works very, very well. But how did you get there? The equations are not themselves transparent; they have to do with our concepts, which often cloud them with meaning.
MG It seems that with this book you demonstrate the complete absence of direct certainties. Is that a source of regret or joy?
CR Joy, absolutely. I think that the idea of certainty is one of the most devastating and useless ideas ever produced in the history of culture. If you really pose the question about what we know with total certainty, the answer is nothing. Dozens of philosophers have clarified that. The problem is not certainty, the problem is getting a reliable picture of the world that we can believe in and that we can work with. Giving up certainty is extremely liberating. Knowledge is not just what we know about the world with absolute certainty, but what we know with an extremely credible level of certainty. To a large extent, the work of science is to dig out what’s wrong in our knowledge and make it better. In everything we know, there is something wrong somewhere. For me, there is a sense of lightness and life in the ambiguity that will always remain in our description of the world.
MG In that sense, do you see quantum mechanics as just another chapter in our understanding of the physical world? Do you anticipate there to be something beyond it that will make it appear as limited as Newtonian physics looks now?
CR This is a really good question. This is technically debated in the field. The real answer is that I don’t know. If you look at things from a distance, you can ask why we should expect to have arrived at a final picture of mechanics. However, it’s also true that there is no hint whatsoever today of any mistake in quantum mechanics. So trying to change quantum mechanics seems to me at present not a very promising enterprise. Nothing has ever come out wrong for quantum mechanics since it was invented – and unlike the other theories, we don’t have a hint of where it could go wrong.
MG There’s no sense of its edges?
CR Exactly. With general relativity, Einstein’s theory, for instance, we see its edges very, very well. We know that there are singularities inside black holes, we know that it disregards quantum mechanics and we know that it doesn’t work at the Big Bang. So the theory is fantastic, but you see very clearly where it goes wrong; it then makes sense to try to change it. With quantum mechanics, however, we don’t see those edges.
MG At a talk I saw you give in London, you were extremely patient taking questions from a group of audience members who seemed to have some kind of fixation with the pyramids. You were very generous, but do you worry about the way that ideas from real, serious physics can enter into conspiracy theories and other forms of fiction?
CR Unfortunately, quantum mechanics is the source of a lot of nonsense. I find it stupid, but even more than that, I find it dangerous because of things like quantum medicine. I seriously think that the law should come in here. Everybody can heal themselves the way they want, but people cannot sell fake ideas that lead other people to lose a life because they have trusted some doctors who should not be trusted. Quantum mechanics has medical applications, but we are not quantum things and our brain is not a quantum thing that can be healed with quantum mechanics.
MG It’s good to welcome fiction into our lives, but there also has to be a point where we stop it.
CR That’s a great way of putting it. In politics, we need to imagine a world that is not this one. We need to think about how things might be different. So we need imagination constantly; we need to dream. At the same time, we have to be very careful, because imagination can be horrendous and misleading. You can think that you can walk on air and then come down and kill yourself. It’s a delicate boundary, how much we allow ourselves to dream and how much we take this dream seriously. Within science it is similar: without wild speculation you go nowhere, but there is a lot of wild speculation that indeed does go nowhere. In theoretical physics right now, the balance is toward excessive speculation. It’s not true that physicists don’t have enough imagination; they have too much. I think they waste a lot of energy running after theories that have shown little reason to be considered reliable.
MG You end the book with the poem from Shakespeare’s The Tempest. The book is named after the island where Werner Heisenberg first intuited quantum mechanics. Shakespeare’s play also takes place on an island. There’s also the stormy island that adorns the book’s cover. Is that a coincidence? Could you unpack the associations for you there?
CR It was not a coincidence. I didn’t make the connection explicit because I was hoping at least some of my readers would see the relation, so thank you for noticing! The aspect of The Tempest that I always appreciated, before studying quantum mechanics even, is the sense of different levels of reality that Shakespeare so beautifully plays with. I included that poem not just to put an arbitrary literary quotation there, but to evoke the dissolution of a strong, single sense of reality. This idea was present in Shakespeare’s Renaissance but resisted by later European culture. I think an awareness of the complexity of reality, of the different levels of reality, is now returning, and not just in physics. What captured me about that piece is that the complexity doesn’t come with a sense of fear or horror, but a sense of lightness. It’s not bad to lose a piece of our certitude. It can be liberating. ◉