Photography: Huw Spanner
Your new book, Helgoland,1Published by Allen Lane on 25 March 2021 begins with a vivid account of the development of quantum theory in 1925 by Werner Heisenberg, a young man whose mind was intensely focused on the fundamental questions of physics. You yourself when you were young were more interested in reading literature, taking LSD and pursuing revolutionary politics. How did that young man develop into the man you are today? Did you grow out of the preoccupations of your youth?
I never felt I did. There was a sense at the end of the Seventies, at least in [Italy], that our strong desire to change the world together was not going anywhere and there is nothing we can do. There was disappointment with the failure of the revolution. And that coincided with the moment I fell in love with science.
But falling in love with science for me was contiguous to the fascination with discovery and change that had driven my adolescence. I read books on quantum mechanics and general relativity in the same spirit in which I had been travelling the world and enlarging my horizons.
It’s often said that as we get older our take on life becomes more serene. Maybe your deep understanding of the physical world today has made things such as politics seem less momentous?
It has become less a source of anguish. Growing older, I definitely have found much more serenity with respect to the Sturm und Drang of my youth. I smile much more at things that once made me angry.
But I don’t think that the concerns of our life are empty, not at all. I continue to have the same worries and desires and dreams as always.
Let me tell you something very personal: I behave – in public. Quite often, I don’t say what I really think, because I think that people are not going to accept it when my views are too radical
Theoretical physics has often involved extraordinary feats of imagination. Did your experience of taking ‘mind-expanding’ drugs as a young man help you to grasp the bizarreness of reality?
The answer is: No and yes. Obviously, you don’t write good physics papers after smoking pot or dropping acid – no way. There’s nothing I learnt directly from those kinds of experiences that went into my physics. But it certainly helped me to be more flexible in my thoughts and see things in different ways. It was a period of growth for me – it did not last long, but it made me what I am.
In the book, you mention Erwin Schrödinger’s highly unorthodox private life. Why do we expect artists to be Bohemian and transgressive, but not scientists? So often scientists tell us that reality is not at all what we think, but when it comes to questions of ‘What ought…?’ rather than ‘What is…?’ they are quite conventionally moralistic.
You ask nice questions! I see what you’re saying and it’s true that there is a morality, this ‘ought to’, which is common. I wonder if it is more a recent characterisation of scientists. But there have been many scientists who had a persona similar to artists – Schrödinger’s not unique. There are all sorts of scientists. If you look just at the inventors of quantum mechanics, they were profoundly different from one another: Max Born seems from a different planet to Schrödinger and Heisenberg – and Paul Dirac is completely different again. So, there’s a great variety. And of course public image and private life do not always match.
Look, let me tell you something very personal: I behave – in public. Quite often, I don’t say what I really think, because I think that people are not going to accept it when my views are too radical. All through my life I have felt like this, a little bit disconnected from the common views.
Things have changed with the success of my popular books, and this was a surprise to me.2In particular, Seven Brief Lessons on Physics has been translated into 41 languages and has sold well over a million copies since it was first published in Italian in 2014. I realised that there are many people who think like me.
I know you have talked of feeling that you were an outsider growing up in Verona…
My family was not from Verona, which is not a particularly open-minded or worldly town, and I always perceived myself as not being fully accepted. Most people just didn’t like the way I looked: my hair, my way of dressing…
One of the things I liked when I went into the science world was that it was so relaxed about such things. I remember arriving at Imperial College London [in 1986] and being surprised to see a man in a shirt and tie discussing physics with a young man with very long hair and torn jeans and they were absolutely cool to talk to each other. But even in science I have felt always a little bit like an outsider – I had not been a nerd focused on science, I did not come from a powerful scientific clan. It has been my fortune, because it has given me a lot of freedom. I never felt obliged to respect the common views.
You describe quantum mechanics as ‘nonsensical’. Is the theory simply a way to frame questions, or does it describe something that actually exists?
The big surprise of the last three centuries has been the spectacular harmony between the different branches of science. It’s not that scientists have searched for unity, it’s that they’ve found it
In a sense you are going straight to the main question [about quantum theory], because, I think, everything turns around this. [Niels] Bohr [used to say] it’s not about nature, it’s about what we know about nature, what we can say about nature. This is a huge distinction in a sense. My answer would be: Does it really make a difference? Of course we think that there is a world out there – we’re sure there is, to the extent [that] we are sure about things – and we try to understand how it works; [but] we can never really distinguish, it seems to me, our conceptualisation of the world from the world itself. That’s what the world is: what we think it is. Somehow to distinguish the two is a mistake.
What is also a mistake is to think that our theories exhaust what is out there. I mean, we know that they are incomplete approximations. They’re partial, perspectival.
Do you expect that at some point something will supersede quantum physics, just as it has superseded Newtonian physics?
Of course, nobody knows. Why should we think that we are at the end of our discoveries? But just as quantum physics surprised the science community by subverting the previous way of thinking, which was much more clear-cut and solid, so it keeps surprising the scientific community by being, so far, always exactly right. Even today, many of my colleagues take it for granted that quantum mechanics will prove to be wrong at some point and will have to be corrected somehow; but for a hundred years it has been right in every single detail. The surprise is always that it’s right.
You say that your objective in your own research is to reconcile general relativity and quantum mechanics. Why should they be reconcilable?
There is no a priori reason why they should, but the big surprise of the last three centuries, from Newton on, has been the spectacular harmony between the different branches of science. There is an incredible coherence. It’s not that scientists have searched for unity, it’s that they’ve found it. Of course, each science has its own language, its own way of thinking; but the connection between chemistry and physics, for example, has been miraculous. The fact that in physics we have two descriptions of the world, general relativity and quantum mechanics, which are so apparently incoherent seems to be screaming that there is still something else to understand. So many of the great advances in physics in the past worked exactly this way: there was one piece of knowledge of the world that worked well and another piece of knowledge that worked well, but they seemed to be saying very different things. But then it turned out that they were just two sides of the same coin.
I don’t believe that we know that the world is coherent, but historically searching for coherence has been a path of discovery. So, I see the discrepancy between quantum mechanics and general relativity not so much as a problem as an opportunity.
The apparent nonsense of quantum theory was famously sent up by the thought experiment of ‘Schrödinger’s cat’.3Quantum theory proposes that the properties of subatomic particles are indeterminate unless and until they are actually observed. In 1935, Schrödinger imagined a cat shut in a steel box with a small flask of hydrocyanic acid that would be shattered by a device triggered by the discharge of a single electron. According to one interpretation of the theory, until an observer opened the box the cat would logically have to be both dead and alive simultaneously. (In your book, you humanely substitute a sleeping draught for the original poison.) Is there a mystery so profound that it points to a fundamental flaw in our understanding? Or is some tweak to our model of reality going to resolve it?
I think it’s something quite substantial. All attempts to make sense of quantum phenomena require us to believe something extraordinary. For instance, one idea that has become popular in recent years is that the cat [in my version] is both asleep and awake and when you look at it you see only one state because you yourself become two, in two different universes. This is coherent but you say, ‘Come on! Really?’ Because in the end you get innumerable universes. Many philosophers at Oxford are in love with this explanation – and they’re extremely intelligent people – but if that’s the solution, we don’t have a solution in my opinion.
Your preferred explanation is that the material world is essentially ‘relational’: that the physical properties of things are not intrinsic to them, as we’ve always assumed, but emerge from their relation to other things. When you and I see a colourful butterfly, say, we may describe it in similar terms but see different things.
Yes. Potentially, we see different things. It is a non-trivial fact that we agree so much – I mean, we see the same world and we constantly confirm to one another that we see the same world. But quantum physics is the discovery that the agreement is not perfect. If you go into minute detail, there is a difference in how things are with respect to you and with respect to me, and this difference is irreducible.
Is that a difference in how they are or how we perceive them?
There is no ‘are’ except with respect to someone. There is no colour period. There is a colour with respect to you and there is a colour with respect to me. There is an agreement between them, but if we go in this small, we find it is not perfect.
So, colour is an interpretation?
No, this is not about subjectivity. Physical properties are relational. They are relative to any other physical object. For instance, the Moon has a velocity with respect to the Earth, a different velocity with respect to the Sun and a different velocity still with respect to our galaxy; but this is not because the Sun ‘interprets’ the Moon differently, it’s just that velocity pertains to two objects, not one. It’s a property of the ensemble, if you want.
Why do you and I seem to agree on the colour of the butterfly? Is it that we each kind of adjust our perception so that they concur?
That’s almost a metaphor for the way societies work, isn’t it? We all have our own take on life but we have a shared language to describe it.
Yes, exactly so. We understand how things work in this way in the social sphere, but in physics we were saying: ‘No, no, no, once you go down to [the nano level of] particles, you don’t need these complications. Things are much easier down there. There’s just one position, one velocity for each particle period.’ Quantum physics has discovered [that] you need to think in terms of interaction all the way down to as far as we know.
Your thesis reminded me of the Southern African concept of Ubuntu4An abbreviation of the isiZulu expression Umuntu ngumuntu ngabantu, which is sometimes translated ‘A person is a person through other persons.’ and, given your political background, I can see why it appeals to you.
A lot of us imagine, I think, that great scientific truths are simply ‘out there’, waiting to be discovered, and all it takes is for some genius – a Galileo, a Darwin, an Einstein – with the imaginative reach to grasp them. However, as you say, every attempt to make sense of quantum phenomena ‘requires us to believe something extraordinary’.
There’s a lot of emotional involvement in research. It should not be overstated, but scientists constantly mix their own feelings with a rational search for how to describe the world
I wonder whether different physicists are attracted to different hypotheses because those hypotheses appeal to them personally…
Yes, I think so. I don’t think that scientific thinking is well understood. I mean, when you discover something, there is a strong sense that you’re just opening a box and seeing something that was inside; and there is an element of that, no doubt, but things are more complicated. There is no clear truth ‘out there’ – we’re just organising a complexity of phenomena in ways that make sense to us and allow us to anticipate nature.
There’s a lot of creative work in building a vision of the world that works, which involves individuals of genius but is also a big collective enterprise. What emerges is a powerful new way of thinking that is built by a variety of people; and the science built by different people is different, and the science that attracts different people is different – no doubt. In a difficult problem like making sense of quantum theory, different people are attracted to different tentative solutions depending on their culture, their personality… I’m reading Brian Greene’s latest book5Until the End of Time: Mind, matter, and our search for meaning in an evolving universe (Allen Lane, 2020). Greene was interviewed for High Profiles in March 2020. and he says that in his youth what really fascinated him in science was that there was certainty and solidity. For me, it was exactly the opposite: I was attracted to science because it is always in motion, things change, rules are broken. And then I think: He likes string theory, I prefer loop quantum gravity.6Essentially, these are rival attempts to explain gravity in the same terms as the other three fundamental forces of nature. The former proposes that subatomic particles are made of even more fundamental components, which are more like vibrating strings. The latter proposes that space-time itself is not smooth and continuous but granular. There is a difference in what attracts us that certainly then becomes a difference in the way we think about nature.
And thanks for mentioning Ubuntu. After I’d written the book, I thought: Maybe I should have looked into that more. It is an attractive notion.
In 1999, the physicist Paul Davies told us: ‘I want to see life emerging as part of a natural process. I particularly want to feel that we live in a universe that is inherently bio-friendly.’7bit.ly/22Vj028 It seems strange that a leading scientist talks about what he wants the universe to be. Surely, science is objective and the personal preferences of scientists are immaterial?
I see the point very well. Let me give you another example. Roger Penrose,8Interviewed for High Profiles in November 1999 who just got the Nobel Prize, is investigating the possibility of the universe being recycled in another Big Bang. If you hear him talking about it, even talking seriously, what he says is: ‘Come on! If this doesn’t happen, it means that in the future [it will end in] a sort of death, and I don’t want that.’
What has it to do with what anyone wants? So, yes. It also reminds me of the famous exchange between Einstein and Bohr when Einstein says, ‘God does not play dice’ and Bohr says: ‘Stop telling God what to do!’
To some extent, this is just language – it’s a way of saying ‘I find this plausible’ or ‘I don’t find this plausible.’ Still, there’s a lot of emotional involvement in research. It should not be overstated, but it’s true that scientists constantly mix their own feelings with a rational search for how to describe the world. After all, to find something one must have a good motivation, no?
I noticed that sometimes in Helgoland the word ‘nature’ is given a capital N and sometimes not.
One of the messages I keep going back to in my books is that there are things we don’t know. So what? We are mortals, we are finite, and we can do very well – or very badly, sometimes – just as we are
My copy editor complained about that. They said, ‘Come on, we should have all lower-case.’ I said: No, sometimes it’s definitely capitalised, because it’s almost personified, it’s almost synonymous with ‘God’, as it was for [the early Enlightenment thinker] Spinoza – the ensemble of everything, which has its own ways and we are just amazed by it and in awe of it. Or her – ‘Nature’ in Italian is always ‘she’. At other times, it would make no sense to capitalise it.
What do you mean by ‘nature’?
I laugh, because I’ve never been asked that question but it’s one I have always expected and I don’t know how to answer it. You know, words have clouds of significance and what is interesting about them is that they don’t mean exactly one thing; there is something evocative about them. One of the main trends in modern philosophy is naturalism, the vague idea that everything is just nature and can be studied scientifically. [More specifically], it is the idea that we are part of nature, we are not outside it. To be a naturalist is to view ourselves, our psychology and our culture, as part of a much larger set of affairs, and [to believe that] we can understand, at least in part, the way it all works coherently.
I guess I’m more comfortable with ‘nature’ than ‘Nature’, which seems to be a way to avoid using the word ‘God’.
Very good point – but ‘God’ is another word that means everything and its opposite. Everybody has their own understanding of what God is. The notion is so flexible that it always surprises me that so many people seem to agree that they’re talking about the same thing. ‘Nature’ with a capital N, at least for me, is strongly related to the fact that we have emotional relations with whatever happens around us. Nature is not just the ensemble of things and laws and processes, it is also a source of marvel, of mystery, of fascination. I think that in science there’s a strong emotional drive towards whatever is outside us, and ‘Nature’ is a little bit an expression of that.
And that, I think, is good. Ultimately, what drives us is always emotion. Rationality is what we use to organise things, but the drive is emotional.
Do you wonder why nature is as it is?
I don’t think that questions like this are good questions. Of course there are things we don’t know, and to me the right attitude is: Just accept our ignorance. That’s one of the main arguments, for me, for not believing in God. It’s an answer to a question to which I think we can simply say: We don’t know.
And that’s also true of nature. For instance, we seem to be very good at describing nature using mathematical equations – beautiful equations that work spectacularly well. Are they the answer to all the questions our minds are capable of producing? Of course not. Why these equations, not others? Perhaps such questions are meaningless – or perhaps they have some meaning, we just don’t know.
In either case, good. We can live accepting our ignorance – that’s one of the main messages I keep going back to in my books. There are things we don’t know. So what? I mean, we are mortals, we are finite, and we can do very well – or very badly, sometimes – just as we are.
Do you think that at some point we will reach our cognitive limits?
Look, six million years ago we had common ancestors with chimpanzees. At some point, our brain developed a bit better [than theirs], but we are still enormously limited. It’s clear that there are things we just don’t get.
However, so far we have done pretty well in unravelling things that were not understood before. Can we understand a little bit more? I would say probably we can – and that’s what science is about, I think. It’s not [about] understanding the ultimate nature of things, but understanding a little bit more, a little bit more, a little bit more.
We haven’t got to our limits yet – we’re still understanding new things every day – but it doesn’t mean that it goes on forever, obviously.
Popular science likes to speak of certainty –
Yeah! I try to do the opposite. I think that the notion of certainty is dangerous, and sometimes even devastating, because it’s a fact of life that we never have absolute certainty. We can be easily deceived, we can make mistakes, we can have wrong impressions or wrong data – and for sure we are full of wrong prejudices.
If you cling to certainty, the moment you realise that you don’t have certainty you feel lost and then you fall into the desperation of nihilism, of ‘Nothing is certain, so nothing is worthwhile’ and ‘I don’t know anything.’ But this reaction is silly. I mean, even if they are not certain, there are plenty of things we know reliably. And that’s how we live.
The second mistake is even worse: because we [crave] certainty, we defend our own positions with our teeth and with our soul. I think that this fear of uncertainty has generated a lot of wrong philosophy and, morally, led to a lot of evil. A lot of philosophy looks for something that is certain, a fixed point, whether it’s God, it’s matter, it’s experience, it’s reason, you name it – some bottom line on which to anchor everything. And certainty is also what moves people to go to war, because they’re convinced that they’re right – on both sides, of course.
You refer in Helgoland to ‘the great laws of nature, from which nothing can escape’. Do these merely describe how the world works or do they dictate how it works?
It’s the first, definitely. At least in the way I view these things.
In fact, ‘law’ is a very bad term. These are just the regularities that we see in the world, that allow us to predict what happens next – again, not with total certainty but with good reliability. Almost all the ‘laws’ of nature are violated somewhere. Obviously, they don’t constrain anything. I have just finished writing a technical manual for students on general relativity, and I don’t think I have used the word ‘law’ once.
Why is it that, as the material world turns out to be less and less like the vast machine that Newton supposed it was, scientists are not just astonished that nevertheless it behaves in such a totally regular and predictable way? Even where it is unpredictable, it is consistently unpredictable.
It’s a very good question. It does astonish me. Yeah, it does.
I think my sincere answer is that there are plenty of things that we don’t know. We don’t have the final answers to these questions. We don’t even know if [we’re asking] the right questions. I find none of the attempts to put everything in order metaphysically convincing.
You invoke the ancient Buddhist philosopher Nāgārjuna, who ‘teaches the serenity, the lightness and the shining beauty of the world: we are nothing but images of images. Reality, including our selves, is nothing but a thin and fragile veil, beyond which … there is nothing.’
I feel that a perception of the world in which we are just what we are in the moment has helped me to concentrate on the fact that what has value for me is what is here now
Does such a perception of reality fundamentally influence how you yourself think and live?
Yes, it does. It does. My reflections about quantum mechanics and general relativity and my reflections about my own life have never been very separate.
Give me a practical example.
Well, it changes my attitude towards death. I mean, if you have this understanding of yourself not as a single entity but as an ensemble of processes, it’s much easier to be serene about death. In everyday life, we all have the same concerns, we all get angry if something breaks or whatever; but I do feel that a perception of the world in which we are just what we are in the moment has helped me to concentrate on the fact that what has value for me is what is here now. Which doesn’t mean that I don’t have concerns about the future, of course – for me, for others – but I have them here now.
Does quantum theory give us any insight into what life is? I’ve sat next to both of my parents as they have died, and one moment something is going on and a moment later it isn’t. In many ways, most of those cells are still active biochemically – hair and nails grow for days and weeks – but something has gone. Do you leave such questions to the biologists?
No, I… I’ve been asking this question throughout my life, over and over again. I’m not anguished by it – it’s more curiosity. To some extent, what makes the question so hard to answer is that the moment of death is so sudden, so clear-cut: it seems to separate two things so unbelievably different before and after. And it’s not just one thing that happens in the moment of death; there’s a lot of different processes that stop.
I do believe that life is a very complicated process. Subjectivity is a complex phenomenon – but I see no reason why it should be different from other complicated phenomena in the universe. Quantum physics makes the difference between brute matter and consciousness a little bit less dramatic. If we think [in terms of] the old physics, it seems strange that little particles bouncing around make me dream and think; but if we think that the best way of understanding physics is in terms of how things manifest themselves, one to the other – so, relative properties, not absolute properties – we’re perhaps a little bit closer to an understanding of matter that might be coherent with an understanding of us.
Are we then hyper-complex machines?
It depends what you mean by ‘machine’. We are certainly a bunch of bouncing atoms [but] we are also nodes in a society, we are also receiving, elaborating and transmitting ideas, we are also lovers and loved ones, we are also intense emotions, we are also dreamers. I do not see the contradiction between these different aspects of ourselves. My small house in Verona is just a pile of bricks but is also the keeper of my past and my soul. Where is the contradiction? Nature is far more complicated than we think. Nature is incredibly complicated: its processes are so, so vast and complex – not just in biology [but] even in a star, a galaxy, an atom – and we only understand pieces of it. And this, again, goes back to naturalism: that we are just one of the many beautiful, strange phenomena that happen in nature.
So many scientists talk of ‘beauty’ and ‘awe’ in relation to nature, but surely the way nature makes us feel, while it may say something about us and our psychology, says nothing at all about nature? Another lifeform as intelligent as us, if it existed, might have no sense of beauty or awe at all, or might even find nature ugly.
I think you’re totally right, a hundred per cent. There is no beauty in nature: the beauty is in the eyes of the beholder, obviously. The beauty of the equations makes no sense at all in terms of nature itself. If there is any way of making sense of it, it’s through a complicated story about us, not about nature. But let me just make one [further point]. Think about classical music: there are people who love it and others who are completely deaf to it. So, where is the beauty? It is not in the sequence of sounds themselves and not in the people, either, but [in] the possible relation that can be established between the two.
So, I think what the scientists are saying – and I say the same thing – is simply: ‘Look, there is something to be discovered here if you want.’ It’s not about nature itself, you’re right; it’s about the reaction we can have to nature.
Which, by the way, is what I would like religious people to tell me. Instead of trying to explain to me that there is a God out there, I like it when they tell me: ‘Look, there is something happening in me in relation to something, and that’s something you might share.’
|Published by Allen Lane on 25 March 2021
|In particular, Seven Brief Lessons on Physics has been translated into 41 languages and has sold well over a million copies since it was first published in Italian in 2014.
|Quantum theory proposes that the properties of subatomic particles are indeterminate unless and until they are actually observed. In 1935, Schrödinger imagined a cat shut in a steel box with a small flask of hydrocyanic acid that would be shattered by a device triggered by the discharge of a single electron. According to one interpretation of the theory, until an observer opened the box the cat would logically have to be both dead and alive simultaneously.
|An abbreviation of the isiZulu expression Umuntu ngumuntu ngabantu, which is sometimes translated ‘A person is a person through other persons.’
|Until the End of Time: Mind, matter, and our search for meaning in an evolving universe (Allen Lane, 2020). Greene was interviewed for High Profiles in March 2020.
|Essentially, these are rival attempts to explain gravity in the same terms as the other three fundamental forces of nature. The former proposes that subatomic particles are made of even more fundamental components, which are more like vibrating strings. The latter proposes that space-time itself is not smooth and continuous but granular.
|Interviewed for High Profiles in November 1999
Carlo Rovelli was born in 1956 in Verona, where he was educated at Italy’s oldest high school, the Liceo ‘Scipione Maffei’.
He became involved with the leftist free radio stations Radio Alice in Bologna and Radio Anguana in Verona (which he co-founded), and was charged but not prosecuted for ‘crimes of opinion’ in Bologna Marzo 1977: Fatti nostri, a book on the ‘Movement of 1977’ which he co-authored with three others.
He read physics at Bologna University – taking time out after his first year to hitchhike around North America – and left with a master’s degree in 1981. He obtained his doctorate at Padua University in 1986.
After further research in theoretical physics at Imperial College London and Sapienza University in Rome, he secured a fellowship at Yale in 1987. In 1989, he worked at Syracuse University in New York as a visiting fellow and at the International School for Advanced Studies (Sissa) in Trieste.
In 1990, he joined the faculty of Pittsburgh University, becoming a professor in 1999. In 1998–9, he was also director of research at the Centre for Theoretical Physics at Luminy in Marseille.
Since 2000, he has been professor of theoretical physics at the University of the Mediterranean (in 2006 becoming a professeur de classe exceptionnelle). The university was incorporated into Aix-Marseille University in 2012.
He has had nearly 300 scientific articles published in international journals, as well as two monographs: Quantum Gravity (2004) and, with Francesca Vidotto, Covariant Loop Quantum Gravity (2014). He is, besides, the author of six books aimed at a wider readership: The First Scientist: Anaximander and his legacy (2011); Seven Brief Lessons on Physics (2014); Reality Is Not What It Seems: The journey to quantum gravity (2014), which shared that year’s Merck Literary Prize and in 2015 won the Galileo Literary Prize among others; The Order of Time (2017), which won the 2019 Duc de Villars Prize; and There Are Places in the World Where Rules Are Less Important than Kindness (2020). Helgoland was published in Italian in 2020 and in English on 25 March 2021.
He writes for several Italian newspapers, including the Corriere della Sera, Il Sole 24 Ore and La Repubblica.
He is a senior member of the University Institute of France and a member of the International Academy of Philosophy of Science, an honorary professor at Beijing Normal University and a distinguished visiting research chair at the Perimeter Institute in Canada. He sits on many editorial and advisory boards.
He received the triennial Basilis C Xanthopoulos International Award from the International Society for General Relativity and Gravitation in 1995, and won the FQXi ‘community prize’ in 2009 (and a FQXi second prize in 2013) and the Larderello Prize and the Alassio Prize for Cultural Information in 2015. He has an honorary doctorate from the National University of General San Martín (Unsam) in Argentina.
In 2019, the magazine Foreign Policy listed him among the year’s 100 most influential ‘global thinkers’.
He has no children.
Up-to-date as at 1 April 2021