[PhilPhys] FW: seminaires LARSIM philosophie/fondements de la physique

[GRINBAUM Alexei]

Séminaires LARSIM <http://iramis.cea.fr/Phocea/Vie_des_labos/Ast/ast_visu.php?id_ast=761>  en décembre 2010

 

10 décembre à 11h au LARSIM (CEA-Orme des Merisiers, bât. 774, salle 50)

Miklos Rédei (LSE) "Is algebraic relativistic quantum field theory causally complete?"

 

15 décembre à 11h au LARSIM (CEA-Orme des Merisiers, bât. 774, salle 50)

Huw Price (University of Sydney) "New Slant on the EPR-Bell Experiment"

 

16 décembre à 17h à l'ENS (45 rue d'Ulm Paris 5e), salle des Actes

Jos Uffink (Université d'Utrecht) "Entropy, Entanglement and Utility"

 

4 et 18 décembre: séminaire Poincaré sur le temps <http://www.bourbaphy.fr/temps.pdf>  

 

Conférences du 18 décembre à l'IHP:

14h Huw Price "Time's Arrow and Eddington's Challenge"

15h Jos Uffink "Time Arrow and Lanford's Theorem"

 

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Résumés / Abstracts

 

10 décembre 2010, 11h, LARSIM, salle 50

Miklos Rédei (LSE) "Is algebraic relativistic quantum field theory causally complete?"

A probabilistic theory is called causally complete if it provides a causal explanation of all the correlations it predicts. The causal explanation can be of two sorts: in terms of a causal connection between the correlated entities, or in terms of a so-called common cause of the correlation. The talk defines first the notion of common cause and causal completeness in classical probability spaces and reviews some results on the problem of causal completeness of classical probability theories. This is followed by recalling results showing that Algebraic Quantum Field Theory (AQFT) predicts correlations between projections in algebras localized in spacelike separated spacetime regions. Since a causal link between spacelike separated entities is prohibited, an explanation of these correlations should be given in terms of suitably localized common causes. The talk defines three notions of localized common causes in AQFT and raises the question of whether the axioms of AQFT entail the existence of such localized common causes. It is shown that weakly localized common causes exist under certain assumptions but it remains open whether more strongly localized common causes exist.

 

15 décembre 2010, 11h, LARSIM, salle 50

Huw Price (University of Sydney) "New Slant on the EPR-Bell Experiment"

The best case for thinking that quantum mechanics is nonlocal rests on Bell's Theorem, and later results of the same kind. However, the correlations characteristic of EPR-Bell (EPRB) experiments also arise in familiar cases elsewhere in QM, where the two measurements involved are timelike rather than spacelike separated; and in which the correlations are usually assumed to have a local causal explanation, requiring no action-at-a-distance. It is interesting to ask how this is possible, in the light of Bell's Theorem. We investigate this question, and present two options. Either (i) the new cases are nonlocal, too, in which case action-at-a-distance is more widespread in QM than has previously been appreciated (and does not depend on entanglement, as usually construed); or (ii) the means of avoiding action-at-a-distance in the new cases extends in a natural way to EPRB, removing action-at-a-distance in these cases, too. There is a third option, viz., that the new cases are strongly disanalogous to EPRB. But this option requires an argument, so far missing, that the physical world breaks the symmetries which otherwise support the analogy. In the absence of such an argument, the orthodox combination of views -- action-at-a-distance in EPRB, but local causality in its timelike analogue -- is less well established than it is usually assumed to be.

 

16 décembre 2010, 17h, ENS, salle des Actes

Jos Uffink (Universite d'Utrecht) "Entropy, Entanglement and Utility"

This talk explores a formal analogy between the study of entanglement in quantum theory, entropy in classical thermodynamics, and utility in decision theory. Roughly speaking, I will argue that in all three cases, the mathematical problem arises of finding and characterizing those functions that respect a given pre-ordering relation, subject to certain auxilliary conditions. Moreover, theorems have been obtained in these three separate areas that might be applied to them in common. It is my main purpose to draw attention to these, and argue how they might be useful in thermodynamics and quantum theory.

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