Major: Physics

Field: Theoretical physics

Carlo Rovelli is an Italian theoretical physicist and writer who has worked in Italy, the United States and, since 2000, in France. He works mainly in the field of quantum gravity and is a founder of loop quantum gravity theory. He has also worked in the history and philosophy of science. He collaborates with several Italian newspapers, including the cultural supplements of the Corriere della Sera, Il Sole 24 Ore and La Repubblica.

His popular science book, Seven Brief Lessons on Physics, was originally published in Italian in 2014. It has been translated into 41 languages and has sold over a million copies worldwide. In 2019, he was included by Foreign Policy magazine in a list of 100 most influential global thinkers.

**Present positions**

– Professeur de classe exceptionnelle, Department of Physics, Aix-Marseille University.

– Adjunct Professor, Department of Philosophy, University of Western Ontario.

– Distinguished Visiting Research Chair, Perimeter Institute.

**Honorary positions**

– Universidad de San Martin, Buenos Aires, Argentina, Laurea Honoris Causa.

– Beijing Normal University, Beijing, China, Honorary Professor.

– Institut Universitaire de France, Senior Member.

– Acad´emie Internationale de Philosophie des Sciences, Membre Titulaire.

– Accademia di Agricultura Scienze e Lettere di Verona, Honorary Member.

– Accademia Galileana, Member.

– Department of History and Philosophy of Science, Pittsburgh University, Aliated Professor.

– Citt`a di Condofuri, Honorary citizen.

– Fondazione, Orchestra Federico II di Svevia, membro del Comitato d’Onore.

**Education**

1970-1975 Liceo Maffei, Verona Classical studies

1975-1981 Universita di Bologna Laurea in Fisica (with honors)

1983-1986 Universita di Padova Dottorato di Ricerca (Ph.D.) in Physics

**Professional Employment**

2006-pres Universite de la Mediterranee Professeur de classe exceptionnelle

2000-2006 Universite de la Mediterranee Professeur (1ere classe)

1999-2000 Pittsburgh University Full Professor

1998-1999 CPT Luminy Directeur de Recherche

1994-1999 Pittsburgh University Associate Professor

1990-1994 Pittsburgh University Assistant Professor

1989 Sissa, Trieste Post-Doctoral position

1989 Syracuse University Visiting Fellow

1987 Yale University Post-doctoral Fellowship

1987-1988 Universita di Roma INFN Post-doctoral position

1986 Imperial College London Visiting position

Main Contributions

Loop quantum gravity

In 1988, Rovelli, Lee Smolin and Abhay Ashtekar introduced a theory of quantum gravity called loop quantum gravity. In 1995, Rovelli and Smolin obtained a basis of states of quantum gravity, labelled by Penrose's spin networks, and using this basis they were able to show that the theory predicts that area and volume are quantized. This result indicates the existence of a discrete structure of space on a very small scale. In 1997, Rovelli and Michael Reisenberger introduced a "sum over surfaces" formulation of the theory, which has since evolved into the currently covariant "spinfoam" version of loop quantum gravity. In 2008, in collaboration with Jonathan Engle and Roberto Pereira, he has introduced the spin foam vertex amplitude which is the basis of the current definition of the loop quantum gravity covariant dynamics. Loop theory is today considered a candidate for a quantum theory of gravity. It finds applications in quantum cosmology, spinfoam cosmology and quantum black hole physics.

Physics without time

In his 2004 book, Quantum Gravity, Rovelli developed a formulation of classical and quantum mechanics that does not make explicit reference to the notion of time. The first step towards a theory of quantum gravity without a time variable is described by Wheeler–DeWitt equation. The timeless formalism is used to describe the world in the regimes where the quantum properties of the gravitational field cannot be disregarded. This is because the quantum fluctuation of spacetime itself makes the notion of time unsuitable for writing physical laws in the conventional form of evolution laws in time.

This position led him to face the following problem: if time is not part of the fundamental theory of the world, then how does time emerge In 1993, in collaboration with Alain Connes, Rovelli proposed a solution to this problem called the thermal time hypothesis. According to this hypothesis, time emerges only in a thermodynamic or statistical context. If this is correct, the flow of time is an illusion, one deriving from the incompleteness of knowledge. Similar conclusions had been reached earlier in the context of nonequilibrium statistical mechanics, in particular in the work of Robert Zwanzig, and in Caldeira-Leggett models used in quantum dissipation.

Relational quantum mechanics

In 1994, Rovelli introduced the relational interpretation of quantum mechanics, based on the idea that the quantum state of a system must always be interpreted relative to another physical system (like the "velocity of an object" is always relative to another object, in classical mechanics). The idea has been developed and analyzed in particular by Bas van Fraassen and by Michel Bitbol. Among other important consequences, it provides a solution of the EPR paradox that does not violate locality. Rovelli has exposed the main idea of relational quantum mechanics in the popular book Helgoland.

Relative information

Rovelli won the second prize in the 2013 FQXi contest "It From Bit or Bit From It?" for his essay about "relative information". His paper, Relative Information at the Foundation of Physics, discusses how "Shannon’s notion of relative information between two physical systems can function as [a] foundation for statistical mechanics and quantum mechanics, without referring to subjectivism or idealism...[This approach can] represent a key missing element in the foundation of the naturalistic picture of the world." In 2017, Rovelli elaborated further upon the subject of relative information, writing that:

In nature, variables are not independent; for instance, in any magnet, the two ends have opposite polarities. Knowing one amounts to knowing the other. So we can say that each end “has information” about the other. There is nothing mental in this; it is just a way of saying that there is a necessary relation between the polarities of the two ends. We say that there is "relative information" between two systems anytime the state of one is constrained by the state of the other. In this precise sense, physical systems may be said to have information about one another, with no need for a mind to play any role. Such "relative information" is ubiquitous in nature: The colour of the light carries information about the object the light has bounced from; a virus has information about the cell it may attach, and neurons have information about one another. Since the world is a knit tangle of interacting events, it teems with relative information. When this information is exploited for survival, extensively elaborated by our brain, and may be coded in a language understood by a community, it becomes mental, and it acquires the semantic weight that we commonly attribute to the notion of information. But the basic ingredient is down there in the physical world: physical correlation between distinct variables. The physical world is not a set of self-absorbed entities that do their selfish things. It is a tightly knitted net of relative information, where everybody’s state reflects somebody else’s state. We understand physical, chemical, biological, social, political, astrophysical, and cosmological systems in terms of these nets of relations, not in terms of individual behaviour. Physical relative information is a powerful basic concept for describing the world. Before “energy,” “matter,” or even “entity.”

**Recognitions, Awards, Honors**

– 2021 Watkin’s Prize.

– Included in the 2019 list of the 100 most influential “Global Thinkers” by Foreign Policy magazine.

– Prix du Duc de Villars 2019 for the book “The Order of Time”.

– First Prize of the 2016 FQXi “Wandering Towards a Goal” Essay Contest for the article “Meaning and Intentionality = Information + Evolution”.

– 2015 Prize “Premio Alassio centolibri per l’informazione scientifica”,

– 2015 Prize “ Premio Larderello” ,

– 2014 Prize “Premio Merk-Serono”,

– 2014 Prize “Pagine di scienza di Rosignano”, for the book “La realt`a non `e come ci appare”,

– 2014 Prize for scientific writing “Premio Galileo”, for the book “La realt`a non `e come ci appare”,

– Second Prize of the 2013 FQXi Essay Contest, for the article ““Relative information at the foundation of physics”.

– Prix du jury du jury du festival d’Astronomie de la Haute Maurienne, for the book “Anaximandre de Millet” 2011.

– Fellow of the International Society of General Relativity and Gravitation, 2010.

– First Prize of the 2009 FQXi “The nature of Time” Community Essay Contest, for the article “Forget Time”.

– 2005 and 2009 Selection by IOP Select for the articles [127] and [151] below.

– Prix du Rayonnement International, Festival des Sciences et des Technologies, 2004.

– Chiamata per chiara fama (Honor nomination) voted by Rome University Physics Dept, 2002.

– Gravity Research Foundation, Second Award 1996, and Honorable mention 1995 and 2002.

– Idoneo al concorso Professore Universitario di Prima Fascia, Universit`a di Lecce, Maggio 2000.

– Aspen Insititute Italia, membro della sezione “Protagonisti italiani nel mondo”.

– Xanthopoulos Award, Triennial International Prize in Relativity, (“for the best relative worldwide under forty”) 1995.

– 1994 Annual Series Lecturer, Pittsburgh Center for Philosophy of Science.

– Chancellor Distinguished Research Award, University of Pittsburgh 1993.

**Books and Articles**

Rovelli has written more than 200 scientific articles published in international journals. He has published two monographs on loop quantum gravity and several popular science books. His book, Seven Brief Lessons on Physics, has been translated into 41 languages.

Scientific books

Quantum Gravity, Cambridge University Press, 2004, ISBN 0-521-83733-2

With Francesca Vidotto, Covariant Loop Quantum Gravity: An Elementary Introduction to Quantum Gravity and Spinfoam Theory, Cambridge University Press, 2014, ISBN 978-1107069626

**Popular books**

Helgoland, Penguin Random House 2021 / Helgoland, Adelphi, 2020.

There Are Places in the World Where Rules Are Less Important Than Kindness, Penguin Random House, 2020 / Ci sono luoghi al mondo dove più che le regole è importante la gentilezza, Solferino, 2020.

The Order of Time, Penguin Random House, 2018 / L'ordine del tempo, Adelphi, 2017.

Reality Is Not What It Seems: The Journey to Quantum Gravity, Penguin Random House, 2016 / La realtà non è come ci appare: La struttura elementare delle cose, Raffaello Cortina Editore, 2014.

Seven Brief Lessons on Physics, Penguin Random House, 2015 / Sette brevi lezioni di fisica, Adelphi, 2014.

The first scientist Anaximander and his legacy, Westholme Publishing, 2011 / Che cos'è la Scienza. La rivoluzione di Anassimandro., Mondadori, 2012.

What is time, what is space? (interview), Di Renzo Editore, 2006 / Che cos'é il tempo, che cos'é lo spazio?, Di Renzo Editore, 2004.

**Main scientific papers**

C Rovelli, L Smolin: "Discreteness of Area and Volume in Quantum Gravity", Nuclear Physics, B442, 593 (1995).

C Rovelli, L Smolin: "Loop space representation for quantum general relativity", Nuclear Physics, B331, 80 (1990).

C Rovelli, L Smolin: "Spin Networks and Quantum Gravity", Physical Review, D53, 5743 (1995).

C Rovelli: "Relational Quantum Mechanics", International Journal of Theoretical Physics 35, 1637 (1996).

C Rovelli "Loop Quantum Gravity", Living Rev.Rel. 1 (1998) 1.

A Connes, C Rovelli, "Von Neumann algebra automorphisms and time-thermodynamics relation in general covariant quantum theories", Classical and Quantum Gravity, 11, 2899 (1994).

M Reisenberger, C Rovelli: "Sum over Surfaces Form of Loop Quantum Gravity", Physical Review D56, 3490 (1997).

C Rovelli "Time In Quantum Gravity: Physics Beyond The Schrodinger Regime", Physical Review D43, 442, (1991).

J Engle, E Livine, R Pereira, C Rovelli, "LQG vertex with finite Immirzi parameter", Nuclear Physics, B799, 136 (2008).

His popular science book, Seven Brief Lessons on Physics, was originally published in Italian in 2014. It has been translated into 41 languages and has sold over a million copies worldwide. In 2019, he was included by Foreign Policy magazine in a list of 100 most influential global thinkers.

– Professeur de classe exceptionnelle, Department of Physics, Aix-Marseille University.

– Adjunct Professor, Department of Philosophy, University of Western Ontario.

– Distinguished Visiting Research Chair, Perimeter Institute.

– Universidad de San Martin, Buenos Aires, Argentina, Laurea Honoris Causa.

– Beijing Normal University, Beijing, China, Honorary Professor.

– Institut Universitaire de France, Senior Member.

– Acad´emie Internationale de Philosophie des Sciences, Membre Titulaire.

– Accademia di Agricultura Scienze e Lettere di Verona, Honorary Member.

– Accademia Galileana, Member.

– Department of History and Philosophy of Science, Pittsburgh University, Aliated Professor.

– Citt`a di Condofuri, Honorary citizen.

– Fondazione, Orchestra Federico II di Svevia, membro del Comitato d’Onore.

1970-1975 Liceo Maffei, Verona Classical studies

1975-1981 Universita di Bologna Laurea in Fisica (with honors)

1983-1986 Universita di Padova Dottorato di Ricerca (Ph.D.) in Physics

2006-pres Universite de la Mediterranee Professeur de classe exceptionnelle

2000-2006 Universite de la Mediterranee Professeur (1ere classe)

1999-2000 Pittsburgh University Full Professor

1998-1999 CPT Luminy Directeur de Recherche

1994-1999 Pittsburgh University Associate Professor

1990-1994 Pittsburgh University Assistant Professor

1989 Sissa, Trieste Post-Doctoral position

1989 Syracuse University Visiting Fellow

1987 Yale University Post-doctoral Fellowship

1987-1988 Universita di Roma INFN Post-doctoral position

1986 Imperial College London Visiting position

Main Contributions

Loop quantum gravity

In 1988, Rovelli, Lee Smolin and Abhay Ashtekar introduced a theory of quantum gravity called loop quantum gravity. In 1995, Rovelli and Smolin obtained a basis of states of quantum gravity, labelled by Penrose's spin networks, and using this basis they were able to show that the theory predicts that area and volume are quantized. This result indicates the existence of a discrete structure of space on a very small scale. In 1997, Rovelli and Michael Reisenberger introduced a "sum over surfaces" formulation of the theory, which has since evolved into the currently covariant "spinfoam" version of loop quantum gravity. In 2008, in collaboration with Jonathan Engle and Roberto Pereira, he has introduced the spin foam vertex amplitude which is the basis of the current definition of the loop quantum gravity covariant dynamics. Loop theory is today considered a candidate for a quantum theory of gravity. It finds applications in quantum cosmology, spinfoam cosmology and quantum black hole physics.

Physics without time

In his 2004 book, Quantum Gravity, Rovelli developed a formulation of classical and quantum mechanics that does not make explicit reference to the notion of time. The first step towards a theory of quantum gravity without a time variable is described by Wheeler–DeWitt equation. The timeless formalism is used to describe the world in the regimes where the quantum properties of the gravitational field cannot be disregarded. This is because the quantum fluctuation of spacetime itself makes the notion of time unsuitable for writing physical laws in the conventional form of evolution laws in time.

This position led him to face the following problem: if time is not part of the fundamental theory of the world, then how does time emerge In 1993, in collaboration with Alain Connes, Rovelli proposed a solution to this problem called the thermal time hypothesis. According to this hypothesis, time emerges only in a thermodynamic or statistical context. If this is correct, the flow of time is an illusion, one deriving from the incompleteness of knowledge. Similar conclusions had been reached earlier in the context of nonequilibrium statistical mechanics, in particular in the work of Robert Zwanzig, and in Caldeira-Leggett models used in quantum dissipation.

Relational quantum mechanics

In 1994, Rovelli introduced the relational interpretation of quantum mechanics, based on the idea that the quantum state of a system must always be interpreted relative to another physical system (like the "velocity of an object" is always relative to another object, in classical mechanics). The idea has been developed and analyzed in particular by Bas van Fraassen and by Michel Bitbol. Among other important consequences, it provides a solution of the EPR paradox that does not violate locality. Rovelli has exposed the main idea of relational quantum mechanics in the popular book Helgoland.

Relative information

Rovelli won the second prize in the 2013 FQXi contest "It From Bit or Bit From It?" for his essay about "relative information". His paper, Relative Information at the Foundation of Physics, discusses how "Shannon’s notion of relative information between two physical systems can function as [a] foundation for statistical mechanics and quantum mechanics, without referring to subjectivism or idealism...[This approach can] represent a key missing element in the foundation of the naturalistic picture of the world." In 2017, Rovelli elaborated further upon the subject of relative information, writing that:

In nature, variables are not independent; for instance, in any magnet, the two ends have opposite polarities. Knowing one amounts to knowing the other. So we can say that each end “has information” about the other. There is nothing mental in this; it is just a way of saying that there is a necessary relation between the polarities of the two ends. We say that there is "relative information" between two systems anytime the state of one is constrained by the state of the other. In this precise sense, physical systems may be said to have information about one another, with no need for a mind to play any role. Such "relative information" is ubiquitous in nature: The colour of the light carries information about the object the light has bounced from; a virus has information about the cell it may attach, and neurons have information about one another. Since the world is a knit tangle of interacting events, it teems with relative information. When this information is exploited for survival, extensively elaborated by our brain, and may be coded in a language understood by a community, it becomes mental, and it acquires the semantic weight that we commonly attribute to the notion of information. But the basic ingredient is down there in the physical world: physical correlation between distinct variables. The physical world is not a set of self-absorbed entities that do their selfish things. It is a tightly knitted net of relative information, where everybody’s state reflects somebody else’s state. We understand physical, chemical, biological, social, political, astrophysical, and cosmological systems in terms of these nets of relations, not in terms of individual behaviour. Physical relative information is a powerful basic concept for describing the world. Before “energy,” “matter,” or even “entity.”

– 2021 Watkin’s Prize.

– Included in the 2019 list of the 100 most influential “Global Thinkers” by Foreign Policy magazine.

– Prix du Duc de Villars 2019 for the book “The Order of Time”.

– First Prize of the 2016 FQXi “Wandering Towards a Goal” Essay Contest for the article “Meaning and Intentionality = Information + Evolution”.

– 2015 Prize “Premio Alassio centolibri per l’informazione scientifica”,

– 2015 Prize “ Premio Larderello” ,

– 2014 Prize “Premio Merk-Serono”,

– 2014 Prize “Pagine di scienza di Rosignano”, for the book “La realt`a non `e come ci appare”,

– 2014 Prize for scientific writing “Premio Galileo”, for the book “La realt`a non `e come ci appare”,

– Second Prize of the 2013 FQXi Essay Contest, for the article ““Relative information at the foundation of physics”.

– Prix du jury du jury du festival d’Astronomie de la Haute Maurienne, for the book “Anaximandre de Millet” 2011.

– Fellow of the International Society of General Relativity and Gravitation, 2010.

– First Prize of the 2009 FQXi “The nature of Time” Community Essay Contest, for the article “Forget Time”.

– 2005 and 2009 Selection by IOP Select for the articles [127] and [151] below.

– Prix du Rayonnement International, Festival des Sciences et des Technologies, 2004.

– Chiamata per chiara fama (Honor nomination) voted by Rome University Physics Dept, 2002.

– Gravity Research Foundation, Second Award 1996, and Honorable mention 1995 and 2002.

– Idoneo al concorso Professore Universitario di Prima Fascia, Universit`a di Lecce, Maggio 2000.

– Aspen Insititute Italia, membro della sezione “Protagonisti italiani nel mondo”.

– Xanthopoulos Award, Triennial International Prize in Relativity, (“for the best relative worldwide under forty”) 1995.

– 1994 Annual Series Lecturer, Pittsburgh Center for Philosophy of Science.

– Chancellor Distinguished Research Award, University of Pittsburgh 1993.

Rovelli has written more than 200 scientific articles published in international journals. He has published two monographs on loop quantum gravity and several popular science books. His book, Seven Brief Lessons on Physics, has been translated into 41 languages.

Scientific books

Quantum Gravity, Cambridge University Press, 2004, ISBN 0-521-83733-2

With Francesca Vidotto, Covariant Loop Quantum Gravity: An Elementary Introduction to Quantum Gravity and Spinfoam Theory, Cambridge University Press, 2014, ISBN 978-1107069626

Helgoland, Penguin Random House 2021 / Helgoland, Adelphi, 2020.

There Are Places in the World Where Rules Are Less Important Than Kindness, Penguin Random House, 2020 / Ci sono luoghi al mondo dove più che le regole è importante la gentilezza, Solferino, 2020.

The Order of Time, Penguin Random House, 2018 / L'ordine del tempo, Adelphi, 2017.

Reality Is Not What It Seems: The Journey to Quantum Gravity, Penguin Random House, 2016 / La realtà non è come ci appare: La struttura elementare delle cose, Raffaello Cortina Editore, 2014.

Seven Brief Lessons on Physics, Penguin Random House, 2015 / Sette brevi lezioni di fisica, Adelphi, 2014.

The first scientist Anaximander and his legacy, Westholme Publishing, 2011 / Che cos'è la Scienza. La rivoluzione di Anassimandro., Mondadori, 2012.

What is time, what is space? (interview), Di Renzo Editore, 2006 / Che cos'é il tempo, che cos'é lo spazio?, Di Renzo Editore, 2004.

C Rovelli, L Smolin: "Discreteness of Area and Volume in Quantum Gravity", Nuclear Physics, B442, 593 (1995).

C Rovelli, L Smolin: "Loop space representation for quantum general relativity", Nuclear Physics, B331, 80 (1990).

C Rovelli, L Smolin: "Spin Networks and Quantum Gravity", Physical Review, D53, 5743 (1995).

C Rovelli: "Relational Quantum Mechanics", International Journal of Theoretical Physics 35, 1637 (1996).

C Rovelli "Loop Quantum Gravity", Living Rev.Rel. 1 (1998) 1.

A Connes, C Rovelli, "Von Neumann algebra automorphisms and time-thermodynamics relation in general covariant quantum theories", Classical and Quantum Gravity, 11, 2899 (1994).

M Reisenberger, C Rovelli: "Sum over Surfaces Form of Loop Quantum Gravity", Physical Review D56, 3490 (1997).

C Rovelli "Time In Quantum Gravity: Physics Beyond The Schrodinger Regime", Physical Review D43, 442, (1991).

J Engle, E Livine, R Pereira, C Rovelli, "LQG vertex with finite Immirzi parameter", Nuclear Physics, B799, 136 (2008).