[Athena] Semaine de philosophie de la physique (déc. CEA Orme des merisiers)

[Jean-François PICARD <jean-francois.picard AT mouchez.cnrs.fr>]

De : "GRINBAUM Alexei" <alexei.grinbaum AT cea.fr>

Projet "Fondements de la physique en région parisienne"

 

Semaine de philosophie de la physique, 14-18 décembre 2009

Programme

14 décembre au LARSIM (CEA-Orme des Merisiers, bât. 774, salle 50)
14h15 Richard Healey (University of Arizona) "What's Wrong with 'Measurement'?"

15 décembre au LARSIM (CEA-Orme des Merisiers, bât. 774, salle 50)
11h Harvey Brown (Oxford University) "Boltzmann's H-theorem and the birth of statistical mechanics"
14h30 Giovanni Valente (LARSIM) "Will someone say exactly what Lanford's theorem proves?"

17 décembre à l'ENS (Salle des Actes, 45 rue d'Ulm, Paris 5e)
17h Harvey Brown (Oxford University) "Why do rods contract in motion?"
18h30 Richard Healey (University of Arizona) "Physics and the Search for Ultimate Building Blocks"

18 décembre à l'IHPST (13 rue du Four, Paris 6e)
15h Mathias Frisch (University of Maryland) "Principle or constructive relativity"
16h30 Angelo Cei (University of Leeds) "Lorentzian Pedagogy. A reflection on the debate on constructive relativity"


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Résumés / Abstracts

18 décembre 2009, 16h30, IHPST
Angelo Cei (University of Leeds) "Lorentzian Pedagogy. A reflection on the debate on constructive relativity"
In the recent debate, generated by Harvey Brown's Physical Relativity, about the constructive interpretation of Special Relativity several couples of concepts have been considered, discussed and ascribed to the various contributors. The most significant are the opposition between constructive and principle theories and the distinction kinematics dynamics. I will seek to explore this debate from the perspective of the different models of the relation between laws, symmetries and geometry that constructivists and defenders of the orthodoxy endorse. I argue such relation is ultimately associated with different conceptions of what is to be explained in Natural science and what explanatory results are achieved in Special Relativity.

18 décembre 2009, 15h00, IHPST
Mathias Frisch (University of Maryland) "Principle or constructive relativity"
Appealing to Albert Einstein’s distinction between principle- and constructive theories, Harvey Brown has argued for an interpretation of the theory of relativity as a dynamic and constructive theory. Brown’s view has been forcefully challenged by Michel Janssen and in this paper I investigate their dispute. I argue that there is less of a disagreement between the two positions than it appears initially and that Brown’s view presents less of a departure from orthodoxy than it may seem. I suggest that the appearance of a stark disagreement is at least partially due to the fact that both Brown and Janssen try to frame their respective views in terms of Einstein’s distinction. Appealing to a slightly different distinction between types of theory drawn H. A. Lorentz, I argue that Einstein’s distinction represents a false dichotomy. Once we locate Brown’s and Janssen’s positions within Lorentz’s broader framework, their disagreement becomes one concerning the role of modal and nomic constraints in scientific explanation, rather than a disagreement about the explanatory adequacy of principle- or constructive theories.

17 décembre 2009, 18h30, ENS, salle des Actes
Richard Healey (University of Arizona) "Physics and the Search for Ultimate Building Blocks"
From Democritean atoms to the quarks and leptons of the Standard Model the scientific search for ultimate building blocks of matter has been remarkably successful. The quest continues, with the search for the Higgs boson, supersymmetric partners, and WIMPs or other hypothetical constituents of dark matter. I shall offer a perspective on modern physics from which its achievements do not show that matter is composed of elementary particles or other ultimate building blocks. While a roughly Democritean metaphysics has served science well, the success of physics in the past century shows it can get along without it.

17 décembre 2009, 17h, ENS, salle des Actes
Harvey Brown (Oxford University) "Why do rods contract in motion?"
Einstein's special theory of relativity predicts, correctly, that rigid bodies contract when in motion, (though Einstein was not the first to predict it). But what is the explanation of this phenomenon? Einstein increasingly disliked his original explanation, based on the relativity principle and the light postulate. What should take its place?

15 décembre 2009, 14h30, LARSIM
Giovanni Valente (LARSIM) "Will someone say exactly what Lanford's Theorem proves?"
Boltzmann's equation is an outstanding result in the kinetic theory of gases, which Bolztmann derived from his celebrated H-theorem. Despite its long-standing legacy, the status of the latter had long remained an open issue. More than twenty years after its formulation, Culverwell inaugurated the famous debate in Nature with a provocative question: “Will anyone say exactly what the H-theorem proves?”. As a reaction to Loschmidt’s reversibility objection, Boltzmann formulated what later became known as statistical mechanics. Yet, the problem of giving a counterpart of Boltzmann’s results in such a new framework was left unsolved. As Uffink (2008) suggested, a theorem by Lanford (1975, 1976) would represent the only available candidate for a statistical version of H-theorem. However, this is proven for an extremely short time-length. Moreover, it relies on a set of probabilistic assumptions, whose status ought to be clarified. So, one may well ask: “Will anyone say exactly what Lanford’s theorem proves?”. In this talk we argue that Lanford’s result does provide a statistical H-theorem. It also shows that, under precise conditions, Boltzmann equation can be derived from Hamiltonian mechanics. Remarkably, no time-asymmetric ingredient would need to be added. Finally, we discuss a strategy to extend Lanford’s theorem to arbitrary time.

15 décembre 2009, 11h, LARSIM
Harvey Brown (Oxford University) "Boltzmann's H-theorem and the birth of statistical mechanics"
Boltzmann's 1872 H-theorem was a glorious failure: the Loschmidt-Culverwell (reversibility) and Zermelo (recurrence) objections clearly showed something was wrong with it, but it led to the birth of statistical mechanics. This talk concentrates on historical and conceptual aspects of the theorem and its discontents. On the historical side, the radical nature of the critique by Poincaré and Zermelo is exposed, and Boltzmann's response to it is discussed. On the conceptual side, the nature of the theorem is examined and the relative strengths of the main objections assessed. Several old and modern misconceptions about the H-theorem are clarified.

14 décembre 2009, 14h15, LARSIM
Richard Healey (University of Arizona) "What's Wrong with 'Measurement'?"
In his brilliant article “Against ‘Measurement”, John Bell famously argued that ‘the word has had such a damaging effect on the discussion, that …it should now be banned altogether in quantum mechanics.” But in the beginning was the word, and the word is still with us. Indeed, David Mermin responded “In Praise of ‘Measurement’ that “within the field of quantum computer science the concept of measurement is precisely defined, unproblematic, and forms the foundation of the entire subject”, a verdict reaffirmed by the development of measurement-based quantum computation. Bell’s arguments deserve a more direct response: I shall try to give one.