Profound Philosophy of Quantum Physics
June 13th 2013
University of Groningen
N. P. Landsman
(Institute for Mathematics, Astrophysics and Particle Physics, RU)|
Against Emergence: The Case of Spontaneous Symmetry Breaking (slides)
Beginning with Anderson (1972), spontaneous symmetry breaking (SSB) in infinite quantum systems is often put forward as an example of (asymptotic) emergence in physics, since in theory no finite system should display it.
Even the correspondence between theory and reality is at stake here, since numerous real materials show SSB in their ground states, although they are finite.
Thus against what is sometimes called 'Earman's Principle', a genuine physical effect (viz. SSB) seems theoretically recovered only in some idealization (namely the thermodynamic limit), disappearing as soon as the the idealization is removed.
Fortunately, a deeper analysis provides continuity between finite- and infinite-volume descriptions of quantum systems featuring SSB and hence restores Earman's Principle (at least in this particularly threatening case).
To the extent that Emergence opposes Reductionism, the latter is vindicated.
(Faculty of Philosophy, RUG)
In their 1936 paper "the logic of quantum mechanics" Birkhoff and Von Neumann derived a (non-classical!) logic for quantum propositions through an investigation of the structure of the theory. Unfortunately, a pressing question was left unanswered: "what do these quantum propositions express?" In this talk three possible answers will be investigated. The first may be associated with Putnam's quantum realism, and leaves the orthodox quantum logic intact. The second accords more with modal interpretations of quantum mechanics and demands the extension of the orthodox quantum logic into a normal modal algebra or weakly Heyting algebra. The third accords more with a Bohrian instrumentalist interpretation and results in an intuitionistic logic which in turn may be embedded in a classical logic. In short, the logic of quantum mechanics strongly depends on what one considers quantum mechanics to be about.
F. A. Muller
(Faculty of Philosophy, EUR, and Institute for the History and Foundations of Science, Dept. of Physics and Astronomy, UU)
To interpret X is to assign meaning to X. To assign meaning to X we must produce sentences, which hopefully do not contain expressions that stand in the same dire need of interpretation as X does, otherwise we have replaced the problem of interpretation. Hermeneutics is the art, or science, of interpretation. Many things can be interpreted: X can be an obscure or ambiguous expression in the English language, or an event, or a poem, or a novel, or human behaviour, or so forth. Can X be a scientific theory too? The very existence of 'interpretations of quantum mechanics' (QM) suggest an answer in the affirmative. Is QM, then, obscure or ambiguous? If so, how can scientists use QM? If understanding is strongly connected to being able to use in order to save phenomena, as H.W. de Regt and D. Dieks maintain, then physicists understand QM very well. If you understand X very well, you can hardly maintain that X is obscure or ambiguous. Dummett wrote that physicists use QM and impressed by its succes, they believe that QM is true, but their endless debates about the interpretation of QM reveal that they don't understand it. They do understand it and they don't understand it. Mammy, help! What are we doing when we are interpreting QM? Are we engaging in `quantum hermeneutics'? Yours truly will propose a crystal clear and unambiguous answer.
J. B. Uffink
(Department of Philosophy, University of Minnesota)
The concept of entanglement was famously coined in 1935 by Schrödinger to express the curious correlation that can occur between quantum systems. However, this situation was already described by Born in 1926, in a manuscript which is widely misread as presenting his statistical interpretation of the wave function. I will focus on the difference in interpretation that Born and Schrödinger attributed to entangled states, and the crucial point of the non-unique decompositions of certain entangled states. Comparing these interpretation with the 1935 Einstein Podolsky Rosen argument (that triggered Schrödinger's work) and the argument that Einstein wrote in correspondence to Schrödinger that year, I argue that Schrödinger was the only physicist at the time who saw the deep non-classical nature of entanglement.
Chair: J. W. Romeijn