Berlin 2012 – wissenschaftliches Programm

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AGPhil: Arbeitsgruppe Philosophie der Physik

AGPhil 2: "Condensed Metaphysics" II: Specific Models

AGPhil 2.2: Hauptvortrag

Montag, 26. März 2012, 15:15–16:00, E 020

How Do Quasi-Particles Exist? — •Brigitte Falkenburg — Institut für Philosophie und Politikwissenschaft, Fakultät 14, TU Dortmund, D-44221 Dortmund

Quasi-particles emerge in solids. In the context of the debate on scientific realism, their concept is puzzling. Quasi-particles are fake entities rather than physical particles. But they can be used as markers etc. in crystals. Hence, it is possible to use them as technologcal tools,even though in a certain sense they do not exist. It has been argued that for this reason they counter Ian Hacking's reality criterion, "If you can spray them, they exist." However, this line of reasoning misses the crucial point that quasi-particles are real collective effects of the constituents of a solid. In order to spell out the way in which they indeed exist, their particle properties are discussed in detail. It is instructive to compare their particle properties with those of ubatomic matter constituents, on the one hand, and the field quanta of a quantum field, on the other hand. All these particle properties are weaker than the classical particle properties. Their discussion sheds light on the way in which quantum phenomena in general exist, and on the specific way in which quasi-particles exist.