Giuseppe Longo

• go to http://www.di.ens.fr/users/longo/ for FULL TEXTS and CV
• DR-CNRS former Professor at Centre Cavaillès, CNRS et Ecole Normale Supérieure de Paris

In 1999, in close collaboration with Jean Petitot and Bernard Teissier, the author of this text set up a scientific project titled Geometry and Cognition (GeoCo) at Ecole Normale Supérieure in Paris (see the “Startup Conference Cycle”, February–April, 1999, in “http://www.di.ens.fr/users/longo/geocogni.html”). This text introduces our project that...

Cet article explore plusieurs questions : tout d’abord, celle du transfert de concepts issus de la physique classique et de la thermodynamique dans le champ de l’économie et de la biologie. Nous montrons que les concepts physiques, tout aussi utiles soient-ils, ne sont pas suffisants pour comprendre l’évolution des organismes vivants et le temps hi...

The most recent tool for acting on the world, the exosomatization of cognitive activities, is often considered an autonomous and objective replacement of knowledge construction. We show the intrinsic limits of the mechanistic myths in AI, from classical to Deep Learning techniques, and its relation to the human construction of sense. Human activiti...

G. Longo. Ces molécules et ces intelligences qui ne meurent pas : comment sortir de ces langages sans sens ni vie, in "Plus d’une discipline : actualité de La vie la mort" (De Michele et al. Cur.), Hermann, 2023. (La-vie-la-mort-pourDerrida_Longo.pdf) Site web de référence : https://www.di.ens.fr/users/longo

Commentary to "The gene: An appraisal" by Keith Baverstock. PBMB, Volume 164, September 2021, Pages 46-62. NOTE: this short and informal commentary constructively criticizes the very interesting approach in the paper by a brief survey of the work that a few of us develop since several years. I will first recall the very pertinent critique of the Mo...

Pair-instability supernovae are theorized supernovae that have not yet been observationally confirmed. They are predicted to exist in low-metallicity environments. Because overall metallicity becomes lower at higher redshifts, deep near-infrared transient surveys probing high-redshift supernovae are suitable to discover pair-instability supernovae....

Pair-instability supernovae are theorized supernovae that have not yet been observationally confirmed. They are predicted to exist in low-metallicity environments. Because overall metallicity becomes lower at higher redshifts, deep near-infrared transient surveys probing high-redshift supernovae are suitable to discover pair-instability supernovae....

Pair-instability supernovae are theorized supernovae that have not yet been observationally confirmed. They are predicted to exist in low-metallicity environments. Because overall metallicity becomes lower at higher redshifts, deep near-infrared transient surveys probing high-redshift supernovae are suitable to discover pair-instability supernovae....

We present FORS2@VLT follow-up photometry of YMCA-1, a recently discovered stellar system located 13\degr~from the Large Magellanic Cloud (LMC) center. The deep color-magnitude diagram (CMD) reveals a well-defined main sequence (MS) and a handful of stars in the post-MS evolutionary phases. We analyse the YMCA-1 CMD by means of the automated isochr...

We present FORS2@VLT follow-up photometry of YMCA-1, a recently discovered stellar system located 13° from the Large Magellanic Cloud (LMC) center. The deep color–magnitude diagram (CMD) reveals a well-defined main sequence (MS) and a handful of stars in the post-MS evolutionary phases. We analyze the YMCA-1 CMD by means of the automated isochrone-...

We report on the discovery of a new diffuse stellar sub-structure protruding for 5 degrees from the North-Eastern rim of the LMC disc. The structure, that we dub North-East Structure (NES), was identified by applying a Gaussian Mixture Model to a sample of strictly selected candidate members of the Magellanic System, extracted from the Gaia EDR3 ca...

2022. Article. The pandemic and the « techno-fix ». Caroline Petit and Giuseppe Longo. Sous presse. Organisms. Journal of biological sciences.

G. Longo, Matematica e senso. Per non divenir macchine, Mimesis, 2022.Plus d'informations sur : https://www.di.ens.fr/users/longo/

Marie Chollat-Namy, Giuseppe Longo. Entropie, Neguentropie et Anti-entropie : le jeu des tensions pour penser le vivant. Invited paper in Entropies, ISTE OpenScience – Published by ISTE Ltd. London, UK, 2022. (ChollatLongo-entropies.pdf).Site web de référence : https://www.di.ens.fr/users/longo/

Giuseppe Longo. Confusing biological twins and atomic clocks. Today’s ecological relevance of Bergson-Einstein debate on time. In "Einstein vs Bergson. An enduring quarrel of time", A. Campo and S. Gozzano, eds, De Gruyter, 2021. (TwinsVScloks.pdf) Site web de référence : https://www.di.ens.fr/users/longo/

We derived surface brightness profiles in the g band for 170 Small Magellanic Cloud (SMC) star clusters (SCs) mainly located in the central region of the galaxy. We provide a set of homogeneous structural parameters obtained by fitting Elson, Fall & Freeman (EFF) and King models. Through a careful analysis of their colour-magnitude diagrams (CMDs)...

We derived surface brightness profiles in the \emph{g} band for 170 Small Magellanic Cloud (SMC) star clusters (SCs) mainly located in the central region of the galaxy. We provide a set of homogeneous structural parameters obtained by fitting Elson, Fall \& Freeman (EFF) and King models. Through a careful analysis of their colour-magnitude diagrams...

We report the possible discovery of a new stellar system (YMCA-1), identified during a search for small scale overdensities in the photometric data of the YMCA survey. The object's projected position lies on the periphery of the Large Magellanic Cloud about $13^\circ$ apart from its center. The most likely interpretation of its color-magnitude diag...

We report the possible discovery of a new stellar system (YMCA-1), identified during a search for small scale overdensities in the photometric data of the YMCA survey. The object’s projected position lies on the periphery of the Large Magellanic Cloud about 13° apart from its center. The most likely interpretation of its color–magnitude diagram, as...

In this chapter, the authors propose the thesis that randomness is unpredictability with respect to an intended theory and measurement. From this point of view, they briefly discuss various forms of randomness that physics, mathematics and computer science have proposed. The authors also discuss biological randomness its peculiar nature and role in...

The positivistic views that dominated the early debate on the foundations of mathematics, at the beginning of the 20th century, survived the “negative results” that have shown the limits of the axiomatic approach since the 1930s. Rigour, abstraction and symbolism have been confused with formalism, based on finite strings of signs, pre-given axioms,...

The iteration of an algorithm, a set of instructions on how to draw a curve – often given as a recursive equation – allows for the generation of remarkable fractals. This chapter shows why art photography brings us closer to biology than the current modeling in homogeneous mathematical spaces, including fractals, in a way that is unlike physics: th...

There is no space in Greek geometry. Symmetries – rotations and translations – provide proof in the finite. And potential infinity (apeiron, without limit, without bounds) is constructed by using extensions and iterations: a segment can be extended with no finite limit in a straight line (the second axiom), eis apeiron. The concept of actual infini...

Nobel Prize winner, Jennifer Doudna, and Samuel Sternberg survey recent advances in a pioneering area of molecular biology. In an accessible and elegant style, the authors present the successes and challenges of a new DNA-modifying technique: CRISPR. They transmit their emotions of discovery, passion for research, and intellectual audacity. While g...

G. Longo. S. Longo. Réinventer le corps et l’espace, in "In difesa dell’umano" (a cura di Boi, Curi, Maffei, Miraglia), 2021: (Longos-ReinventerCorps-espaces.pdf); in italiano: (Longos-ReinventareCorpo-spazio.pdf)

G. Longo. Science in the storm, in "Agnotology, Artificial Intelligence, and Democracy." Philosophy World Democracy Journal. Special issue: " The dusk of theoretical controversies in current sciences.", 2021: (V. Chaix, G. Longo and M. Montévil. Introduction); (G. Longo. Section 4)

Accepted in A&A, 25 pages, 13 figures, 7 tables

Forthcoming large photometric surveys for cosmology require precise and accurate photometric redshift (photo-z) measurements for the success of their main science objectives. However, to date, no method has been able to produce photo-zs at the required accuracy using only the broad-band photometry that those surveys will provide. An assessment of t...

Forthcoming large photometric surveys for cosmology require precise and accurate photometric redshift (photo- z ) measurements for the success of their main science objectives. However, to date, no method has been able to produce photo- z s at the required accuracy using only the broad-band photometry that those surveys will provide. An assessment...

Context. We present the COld STream finder Algorithm (COSTA), a novel algorithm used to search for cold kinematical substructures in the phase space of planetary nebulae (PNe) and globular clusters (GCs) in the halos of massive galaxies and intracluster regions. Aims. The aim of COSTA is to detect small, low-velocity-dispersion streams, such as the...

Context: We present COSTA (COld STream finder Algorithm), a novel algorithm to search for cold kinematical substructures in the phase space of planetary nebulae (PNe) and globular clusters (GCs) in the halo of massive galaxies and intracluster regions. Aims: COSTA aims at detecting small sized, low velocity dispersion streams, as the ones produced...

Through the comparison between two major, long-lasting theoretical frameworks-geocentrism and genocentrism-we discuss the different epistemological role played by metaphors in physics and biology. Throughout its history, physics developed theories and mathematical formalisms, which either do not seem to rely on metaphors at all (as geocentrism) or...

Forthcoming large photometric surveys for cosmology require precise and accurate photometric redshift (photo-z) measurements for the success of their main science objectives. However, to date, no method has been able to produce photo-$z$s at the required accuracy using only the broad-band photometry that those surveys will provide. An assessment of...

Many scientific investigations of photometric galaxy surveys require redshift estimates, whose uncertainty properties are best encapsulated by photometric redshift (photo-z) posterior probability density functions (PDFs). A plethora of photo-z PDF estimation methodologies abound, producing discrepant results with no consensus on a preferred approac...

Turing’s Legacy Today : between Inheritance Appropriation and Resource for the Future. The article describes the particular style of Turing’s articles, distinct from all others by two features : he maintains an imaginary dialogue with his reader and at same time identifies himself with the object he describes in the various domains he deals with, m...

Symmetries play a major role in physics, in particular since the work by E. Noether and H. Weyl in the first half of last century. Herein, we briefly review their role by recalling how symmetry changes allow to conceptually move from classical to relativistic and quantum physics. We then introduce our ongoing theoretical analysis in biology and sho...

Astronomy has entered the multi-messenger data era and Machine Learning has found widespread use in a large variety of applications. The exploitation of synoptic (multi-band and multi-epoch) surveys, like LSST (Large Synoptic Survey Telescope), requires an extensive use of automatic methods for data processing and interpretation. With data volumes...

Relic galaxies are thought to be the progenitors of high-redshift red nuggets that for some reason missed the channels of size growth and evolved passively and undisturbed since the first star formation burst (at $z>2$). These local ultracompact old galaxies are unique laboratories for studying the star formation processes at high redshift and thus...

Relic galaxies are thought to be the progenitors of high-redshift red nuggets that for some reason missed the channels of size growth and evolved passively and undisturbed since the first star formation burst (at z > 2). These local ultracompact old galaxies are unique laboratories for studying the star formation processes at high redshift and thus...

M. Montévil, B. Stiegler, G. Longo, A. Soto, C. Sonnenschein, ANTHROPOCÈNE, EXOSOMATISATION ET NÉGUENTROPIE, dans B. Stiegler (curat.) "BIFURQUER, Eléments de réponses à Antonio Guterres et Greta Thunberg", PARIS, 2020: (AnthropoceneNeguEntrop.pdf)

The rich blend of theories and experiences that made the history of physics possible still now enlightens the scientific method. We stress the need to learn from this method the force of making its principles explicit, while developing a rich diversity of theories, which are often incompatible. Unity is preserved by common founding principles and t...

We propose a reflection on the construction of scientific knowledge and in so doing an image of this knowledge. This will allow us to develop a comparative analysis of some of the main principles underpinning the constitution of the different sciences. We will highlight the role of critical thought in science, or even “negative results,” which pose...

The modern theories of information opened to way to extraordinary new tools for communication and knowledge construction. When identified instead with the world (DNA is a complete information carrier and a program for ontogenesis, atomic particles and planets exchange information …), a new form of scientism affects knowledge and trust in science. V...

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This text will first discuss the great and productive “linguistic turn” that originated in Logic, at the end of the nineteenth century. After Turing’s work on the Logical Computing Machine (1936–1950) and Shannon’s theory (1948), Brillouin attributed information content to Maxwell’s demon’s action (1956), with a scientific invention and, in my opin...

Many scientific investigations of photometric galaxy surveys require redshift estimates, whose uncertainty properties are best encapsulated by photometric redshift (photo-z) posterior probability density functions (PDFs). A plethora of photo-z PDF estimation methodologies abound, producing discrepant results with no consensus on a preferred approac...

The rich blend of theories and experiences that made the history of physics possible still now enlightens the scientific method. We stress the need to learn from this method the force of making its principles explicit, while developing a rich diversity of theories, which are often incompatible. Unity is preserved by common founding principles and t...

RÉSUMÉ. Le riche débat grec et médiéval sur la nature de l’infini, en puissance et en acte, trouve une synthèse et une réponse dans l’invention, en Italie et à la Renaissance, de la perspective géométrique. Dès le milieu du XIVe siècle, des peintres-théologiens donneront à l’infini en acte de Dieu sa première forme symbolique : la ligne ou le point...

Article traduit du français

Giuseppe Longo. Space and Time in the Foundations of Mathematics, or some challenges in the interactions with other sciences. Invited lecture, First AMS/SMF meeting, Lyon, July, 2001 (space-time.pdf); (version française reduite: Intellectica, 2003/1-2, n. 36-37, (espace-temps.pdf))Revised for the Handbook of the Mathematics of the Arts and Sciences...

Giuseppe Longo. Le jeu difficile entre rigueur et sens. Dans La rigueur (T. Paul et al. eds.), Spartacus IDH, 2020 (jeu-rigueur-sens.pdf) (English extended and revised version with E. Blanchard: From axiomatic systems to the Dogmatic gene and beyond. In Foundations of Mathematics and Theoretical Biology (E. Fimmel, A. Rodin, eds.), Special issue of...

The reflections on the nature of time in Relativity Theory will be hinted in reference to the new bridges recently proposed by Connes and by Rovelli's "perspectival" approach, two major steps towards a unification of quantum, thermodynamical and relativistic times. The so called "time of philosophers", a time of the cognizing ego, from Saint August...

The reflections on the nature of time in Relativity Theory will be hinted in reference to the new bridges recently proposed by Connes and by Rovelli's "perspectival" approach, two major steps towards a unification of quantum, thermodynamical and relativistic times. The so called "time of philosophers", a time of the cognizing ego, from Saint August...

Science constructs tools for knowledge and, occasionally, this bold enterprise may let a few believe in the “completeness” of a given theoretical frames: as for these phenomena, we can predict, derive, compute ... everything. Yet, negative results, often based on the very tools proposed by the scientific approaches, set the limits to knowledge cons...

Giuseppe Longo. How Future Depends on Past Histories and Rare Events in Systems of Life, Foundations of Science, (DOI), 23 (3):443-474, 2018 (biolog-observ-history-future.pdf) (Révision en français dans La liberté de l’improbable (Berthoz, Ossola cur.), Collège de France, décembre 2016 : bio-evol-histoire-et-futur.pdf; tradotto in italiano per Stud...

This short paper is meant to be an introduction to the ‘Letter to Alan Turing’ that follows it. It summarizes some basic ideas in information theory and very informally hints at their mathematical properties. In order to introduce Turing’s two main theoretical contributions, in Theory of Computation and in Morphogenesis (an analysis of the dynamics...

This text will first discuss the great and productive "linguistic turn" that originated in Logic, at the end of the XIX century. After Turing's work on the Logical Computing Machine (1936-1950) and Shannon's theory (1948), Brillouin attributed information content to Maxwell's demon's action (1956), with a scientific invention and, in my opinion, a...

This text will first discuss the great and productive "linguistic turn" that originated in Logic, at the end of the XIX century. After Turing's work on the Logical Computing Machine (1936-1950) and Shannon's theory (1948), Brillouin attributed information content to Maxwell's demon's action (1956), with a scientific invention and, in my opinion, a...

Collection : Human Perspectives in Health Sciences and Technology

The present work will illustrate the study case of a patient who came to our attention upon arriving in the emergency room after a road accident, showing a type III B G.A. open fracture of the distal tibia with acute loss of the talus and the distal tibia comminution. In case of a severe articular tibia-tarsic surface impairment with associated com...

The dependence on history of both present and future dynamics of life is a common intuition in biology and in humanities. Historicity will be understood in terms of changes of the space of possibilities (or of “phase space”) as well as by the role of diversity in life’s structural stability and of rare events in history formation. We hint to a rigo...

Interview with Giuseppe Longo by Paolo Bartolini, extended and translated by M.R. Doyle and S. Savic

Theorizing and measuring radically change in physics when using discrete vs. continuous mathematical spaces. We first recall that, in the 20 th century, discrete structures were brought into the limelight by Quantum and Information Theories. In these theories, the reference to discrete observables and parameters and to digital information is far fr...

Biology is a field in which variation has a fundamental theoretical role. Faced with the diversity of the living and faced with the internal heterogeneity of organisms, the human mind can sometimes seem a bit powerless. The contemporary possibility of developing immense digital databases, collaboratively, therefore appears as a major opportunity. T...

This chapter briefly presents and describes the three main principles that the group proposes for a theory of organisms, namely: the default state, proliferation with variation and motility, the principle of variation and the principle of organization. It is crucial to critique the philosophical and theoretical position on which the biological rese...

Some authors assert that the analysis of huge databases could replace the scientifc method. On the contrary, we argue that the best way to make these new technologies bear fruits is to frame them with theories concerning the phenomena of interest. Such theories hint to the observable that should be taken into account and the mathematical structures...

In this paper, following the technical approach to biological time, rhythms and retention/protention in Longo and Montévil (Perspectives on organisms: Biological time, symmetries and singularities. Springer, Berlin, 2014), we develop a philosophical frame for the proposed dimensions and mathematical structure of biological time, as a working exampl...

Dear Alan, It is with great joy that I have accepted the invitation to write you a personal letter. Even in your scientifc writings your presence as a person is very strong, which is unusual for a mathematician ... I shall try to offer my own readings of some of your fundamental texts, placing them in relation to others that were equally revolution...

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The main methodological connection between programming language theory and category theory is the fact that both theories are essentially “theories of functions.” A crucial point, though, is that the categorical notion of morphism generalizes the set-theoretical description of function in a very broad sense, which provides a unified understanding o...

In the last decade, astronomers have found a new type of supernova called `superluminous supernovae' (SLSNe) due to their high peak luminosity and long light-curves. These hydrogen-free explosions (SLSNe-I) can be seen to z~4 and therefore, offer the possibility of probing the distant Universe. We aim to investigate the possibility of detecting SLS...

This short text summarizes the work in biology proposed in our book, Perspectives on Organisms, where we analyse the unity proper to organisms by looking at it from different viewpoints. We discuss the theoretical roles of biological time, complexity, theoretical symmetries, singularities and critical transitions. We explicitly borrow from the conc...

This short text summarizes the work in biology proposed in our book, Perspectives on Organisms, where we analyse the unity proper to organisms by looking at it from different viewpoints. We discuss the theoretical roles of biological time, complexity, theoretical symmetries, singularities and critical transitions. We explicitly borrow from the conc...

We present a machine-learning photometric redshift analysis of the Kilo-Degree Survey Data Release 3, using two neural-network based techniques: ANNz2 and MLPQNA. Despite limited coverage of spectroscopic training sets, these ML codes provide photo-zs of quality comparable to, if not better than, those from the BPZ code, at least up to zphot<0.9 an...

The human attempts to access, measure and organize physical phenomena have led to a manifold construction of mathematical and physical spaces. We will survey the evolution of geometries from Euclid to the Algebraic Geometry of the 20th century. The role of Persian/Arabic Algebra in this transition and its Western symbolic development is emphasized....

The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope. It aims to image 1500 square degrees in four filters (ugri). The core science driver is mapping the large-scale matter distribution in the Universe, using weak lensing shear and photometric redshift measurements. Furth...

The role of continua has been clear since antiquity in the mathematical approaches to physics, while discrete manifolds were brought to the limelight mostly by Quantum and Information Theories, in the XX century. We first recall how theorizing and measuring radically change in physics when using discrete vs. continuous mathematical manifolds. It wi...

Computer simulations brought remarkable novelties to knowledge construction. In this chapter, we first distinguish between mathematical modeling, computer implementations of these models and purely computational approaches. In all three cases, different answers are provided to the questions the observer may have concerning the processes under inves...

Certains auteurs affirment que l'analyse des grandes bases de données pourrait remplacer la méthode scientifique. A contrario, nous argumentons que la bonne manière de faire fructifier ces nouveautés techniques est de les encadrer théoriquement. En biologie, en particulier, il nous semble urgent de développer une théorie des organismes.

Les organismes, qu'ils soient uni ou multi-cellulaires, sont des agents capables de créer leurs propres normes ; ils articulent continuellement leur capacité à créer de la nouveauté et de la stabilité, c'est-à-dire qu'ils combinent plasticité et robustesse. Ici, nous présentons et articulons brièvement les trois principes proposés récemment pour un...

This focused issue of Progress in Biophysics and Molecular Biology is entitled "From the century of the genome to the century of the organism: New theoretical approaches." It was developed during Ana M. Soto’s tenure as Blaise Pascal Chair of Biology 2013-15 at the Ecole Normale Superieure (ENS, Paris, France). Giuseppe Longo was the Pascal Chair h...