The “Poet of Physics” Carlo Rovelli on Cosmic Equality

Ahead of the publication of his latest book, published by Penguin and out tomorrow, the physicist and philosopher speaks to AnOther about quantum mechanics, certainty and the reflections that tie our existence together

“Physics is overrated” might seem like an unlikely statement to find in a science book written by one of the most eminent physicists in the world, but then not every science book is written by Carlo Rovelli. For more than a decade now, the Verona-born Rovelli’s skill for deploying and elucidating radical, perception-changing propositions like this in a series of accessible publications has enabled him to become one of the few recognisable faces in his field to mainstream audiences.

Trying to summarise the remarkable ideas in his new book On the Equality of All Things: Physics and Philosophy does Rovelli a deep injustice but, in short, the physicist uses the text to detail how his “relational” take on quantum mechanics might help us best understand reality. He states that we should “give up on the idea of an ultimate foundation” and instead see the world as being “woven by relations: made up of intertwining perspectives – which can only be described from within”. Ultimately, he says, seeing everything through this partial viewpoint should lead us to recognise the titular equality of all things. As you might have guessed, the text throws up some philosophical questions in the process.

While Rovelli has always had an eye on the human implications of science and scientific progress, his book’s genesis came via a stint spent guest lecturing in Princeton University’s Department of Philosophy towards the close of 2024. Its six chapters are presented as “lessons” encapsulating a distinct but linked aspect of his research and thoughts. The result is a treatise that feels entirely liberating and brings its readers closer to the world around them. The poetic streak Rovelli is celebrated for is fully apparent through its pages, simultaneously enriching and contextualising the complex scientific ideas contained within. AnOther caught up with Rovelli to explore some of the book’s ideas.

SEC: Congratulations on the new book, Carlo. In many ways it feels like a lot of your previous thought and writing has been leading up to this work and, through the way it interweaves philosophy and science, it feels especially important. Is it fair to state that this text could only come at this point in your life and career?

CR: Yes, very much so. It is a sort of “end of career book”. My scientific research has focused on quantum gravity – and since gravity determines the geometry of space and time, this is the same as understanding the quantum properties of space and the quantum properties of time. Questioning the nature of space and time as we have previously thought them is something that forces a serious conceptual investigation: What do we actually mean by space? What do we actually mean by time? What is it to observe something in space and time, or to be in space and time? The technical, mathematical and empirical work gets interwoven with all sorts of conceptual issues and raises philosophical questions, including, “what am I actually doing when I do science?” The physics of the last century, quantum physics, and the discoveries by Einstein have opened a colossal rethink of reality. I believe that this rethinking is not over yet, and my book aims to be a step in this. It is the arrival point of a life of thinking about all this.

SEC: How would you outline the basic premise of – and the ideas you discuss within – Equality?

CR: There are various threads in the book. One is my effort to take down some misunderstandings about the nature of science. Good science is one of the instruments we have to understand ourselves and the world. It is a formidable tool, but a humble one: it does not give a picture of an ultimate reality, or a fundamental truth. At its best, it does the opposite: it shows that the very idea of an ultimate reality and absolute truth are just bad ideas. What we can have is just partial perspectives and partial knowledge. Precious, but always partial.

The Enlightenment dream that Reason could give us a clear and complete understanding of the world seen in full clarity from the outside, is only a dream. Reality is far too complex for that – and we are part of it – so our knowledge and reason itself are nothing else than limited components of the network of relations that make up reality. We only look at the world from within. What is astonishing is that the strongest blow to the idea of an accessible and objective description of the world has come from the science that seemed most close to objectivity: physics. The discovery of quantum phenomena has questioned our entire metaphysics.

“We do not need certainty in life. It is the other way around: certainty is what blocks us from learning” – Carlo Rovelli

SEC: The ideas you discuss in the book propose something that feels truly radical – to the layperson at least – that we are to abandon any sense of the universe and our existence resting on any kind of fundamental certainties or foundation. How would you suggest the average reader start comprehending this?

CR: Is it so strange? If we think for a moment, we realise that there are many things we know with great confidence, but nothing of which we are completely totally certain. When my dad was young he thought his name was Franco, as everybody was calling him that, until he got his first official ID and found out his name was Giulio. We can be wrong even about our own name. We do not need certainty in life. It is the other way around: certainty is what blocks us from learning. 

SEC: Tell us about the idea of relationality.

 CR: The striking discovery of quantum mechanics is that all the properties we attribute to things, like an apple being red rather than yellow, or a stone being here rather than there, are not really properties of the apple or the stone, but properties relative to something else – for instance, us. This means that a stone can be here with respect to me – I see it to be here – but with respect to something else the stone might not have any position at all and be, as we say in the jargon of the trade, in a “quantum superposition” of different positions. This is how nature appears to work. Properties are always relations. Not necessarily relative to a human: a stone can have a property relative to another stone, and not relative to an apple. This deep relationality is the grammar of nature. Nature is a network of perspectives that reflect one another.

“Our partial truths, our changing convictions, our own moral values, and openness to change are essential for guiding our lives, and are more than enough for me. Life is light” – Carlo Rovelli

SEC: You’re not overly precious or protective of physics as a field – in a few places in the book you are mischievously flippant about it – and you seem to perpetually look to consolidate different disciplines to best understand the world around us. Do your fellow physicists share this pragmatic approach, or are they typically more protective of the field?

CR: Physicists, like all humans, including philosophers, come in wide varieties. You can find all positions among physicists, and scientists in general. But I do think that there is a general misunderstanding about the presumptions of physics. Look, on the one hand I believe that my bicycle diligently obeys the equations of particle physics. But, if my bicycle breaks and I ask a friend in particle physics to fix it, I am an idiot. I must ask a mechanic, who, generally, knows nothing of particle physics. So, the fact that my bike obeys certain equations is totally irrelevant when it comes to fixing it, or using it, for that matter. If this is true for my bike, it is very much more so for almost everything in nature.

Fundamental physics is widely useless, even if everything obeys its equations. We need other kinds of concepts, knowledge, and experience for dealing with reality, obviously. There is no contradiction between physics, chemistry, biology, anthropology, psychology, economics, and our personal, emotional, spiritual, existential reactions to the world. These are just different perspectives on the same reality – good for capturing different aspects of it. Each teaches us something very useful. We thought physics taught us that there is a very objective description of everything, but it actually tells us the opposite. We better understand the word with the full complexity of our thinking, not with just one tool. 

SEC: There is footage of the noted physicist Richard Feynman talking about how his scientific knowledge changes the way he sees the world around him – he uses the example of looking at a flower. Does the deep understanding of reality that physics gives you have a profound effect on your day-to-day life and how you approach things?

 CR: My daily life is probably more designed by the intersection of the other identities of mine. I am a hand-moving Italian, I carry traces of the legacy of a flower-sun youth, and I am a bit of a trouble-maker from a political past. I have lived in many different countries, picking up habits from here and there, and I love reading, so I’m at the crossroads of all sorts of cultural influences. But maybe it’s also true that giving up the anxiety of longing for certainty and for finding the ultimate foundations of things has given me an immense sense of liberation and serenity. I do not know any ultimate truth, and I feel so much better thinking that this is perfectly OK. Our partial truths, our changing convictions, our own moral values, and openness to change are essential for guiding our lives, and are more than enough for me. Life is light.

On the Equality of All Things: Physics and Philosophy is published by Penguin on 15 September