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-17 novembre 2003, 9h30-12h30, salle de l'AX (Association des Anciens Elèves de l'Ecole Polytechnique, 5 rue Descartes, 75005 Paris) [Organisation Alexei Grinbaum]

Carlo Rovelli (Université d'Aix-Marseille et Université de Rome)

"Relational Quantum Mechanics"

The debate on what precisely quantum theory is telling us about the world is raising again increasing interest. The meaning of the theory is uncontroversial as far as the theory is applied to microsystems interacting with classical macrosystems. But opinions diverge sharply about how, or even whether, the theory describes all physical systems. I present some considerations on this issue, and a tentative point of view. I argue that if we trust the empirical adequacy of the theory, we are lead to conclude that all contingent properties of a physical system can only be interpreted as relative to another physical system, interacting with the first. The theory deals with the information about future interactions that can be gathered, in principle, from past interactions. Information from different systems can be compared, but does not allow us to hypostatize that systems have an absolute state, nor that physical events have absolute reality. I suggest that the discovery of this physical limitation is the lesson from experimental microphysics which is coded in the formalism of quantum theory.

Michel Bitbol (CREA/CNRS, Paris)

"Réponse sur la mécanique quantique relationnelle"

L'interprétation relationnelle de la mécanique quantique de Carlo Rovelli a des points communs à la fois avec la lecture de Bohr et avec l'interprétation des états relatifs d'Everett. On montre cependant qu'elle leur est aussi symétriquement opposée, car elle va plus loin que chacune d'entre elles dans la dénonciation de certains "absolus" ou "reifications" présupposés par la théorie physique. La mécanique quantique relationnelle de Rovelli n'est cependant pas elle-même exempte de toute absolutisation: elle absolutise implicitement le "point de vue des points de vue" à partir duquel elle décrit le réseau de relations entre systèmes physiques supposés définir les états quantiques.


-8 décembre 2003, 14h-17h, salle de l'AX (Association des Anciens Elèves de l'Ecole Polytechnique, 5 rue Descartes, 75005 Paris). [Organisation Alexei Grinbaum]

Christopher Fuchs (Bell Laboratories, Lucent Technologies et Dublin Institute of Technology)

"What is the Difference between a Quantum Observer and a Weatherman?"

Not much. But where there is a difference, there lies quantum theory's most direct statement about properties of the world all by itself (i.e., the world without observers or weathermen). In this talk, I will try to make sense of the last two sentences.


Philippe Grangier (Institut d'optique, Orsay)

"Contextual objectivity : an experimentalist's view on the foundations of
quantum mechanics"

Abstract :
An attempt is made to formulate quantum mechanics (QM) in physical rather than in mathematical terms. It is argued that the appropriate conceptual framework for QM is "contextual objectivity", which includes an objective definition of the quantum state. This point of view sheds new light on topics such as the reduction postulate and the quantum measurement process.


-14 Janvier 2004, 9h30-17h30, Amphithéâtre Stourdzé, entrée 25, rue de la montagne Sainte-Geneviève

JOURNEE "Ontologie et objectivité en physique quantique"


-5 mars 2004, 18h00, CREA salle 315 , entrée 25, rue de la montagne Sainte-Geneviève

Christian de Ronde (Center Leo Apostel, Brussels, Belgium )

"Historical Development of the Modal Interpretations: Monism and Relationalism".


Modal interpretations have been developed since the early '70 by a growing group of physicists and philosophers as a way out of the measurement problem. It is a no collapse interpretation in which properties are assigned to systems. From this characteristic it steams its realistic flavor.
I will present a review of the historical development of modal interpretations analyzing some of its main characteristics and specifically the ontology which derives from each interpretation. In this historical development several no-go theorems play a significant role as a road sign towards a perspectival version of the modal interpretation (Bene and Dieks 2002). I will end my seminar with a study of this perspectival interpretation and its possible development.


-5 Avril 2004, 17h00, CREA salle 315 , entrée 25, rue de la montagne Sainte-Geneviève [Organisation Alexei Grinbaum]

Andrei Khrennikov (International Center for Mathematical Modeling in Physics and Cognitive Sciences, University of Vaxjo, Sweden)

"Contextual approach to quantum mechanics and the theory of the fundamental prespace"


We constructed a Hilbert space representation of a contextual Kolmogorov model. This representation is based on two fundamental observables -- in the standard quantum model these are the position and momentum observables. This representation has all distinguishing features of the quantum model. In particular, Kolmogorov random variables are represented by noncommuting operators. However, our representation is not standard model with hidden variables. In particular, this is not a reduction of the quantum model to the classical one. In our model both classical and quantum spaces are very rough images of PRESPACE. We cannot say so much about algebraic and topological structure of prespace, since we operate only with probabilistic pictures of this space.


A. Yu. Khrennikov, Representation of the Kolmogorov model having all distinguishing features of quantum probabilistic model. {Phys. Lett. A}, {bf 316}, 279-296 (2003).

A. Yu. Khrennikov, Interference of probabilities and number field structure of quantum models. {Annalen der Physik,} {bf 12}, N. 10, 575-585 (2003).


-16 Juin 2004, 9h30-17h30, Amphithéâtre A, Bâtiment Joffre, 1. Entrée par le 25, rue de la Montagne Sainte-Geneviève

JOURNEE "Science et subjectivité"