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Physical Metaphysics and Theorem-Providing Philosophy: The Case of Particles in Relativistic Quantum Field Theory

A presentation by
Chrysovalantis Stergiou
School of Liberal Arts and Sciences

When: Monday, February 26, 15:00–15:50

Where: Faculty Lounge

Organized by: Faculty Research Seminars 2017-18 Series

Chrysovalantis Stergiou
Philosophy and Classics

BSc, University of Athens; MA, PhD University of Athens

Chrysovalantis Stergiou is member of the Department of History, Philosophy and the Ancient World. He currently teaches philosophy of science, introduction to logic, rationalism and empiricism and other philosophy courses.

His research interests include the foundations and philosophical aspects of contemporary physics, scientific realism and general philosophy of science. He participated in a research program on causality and locality in quantum field theory in the National Technical University of Athens (2005-2008). Also, he has delivered talks in important international conferences (European Philosophy of Science Association Conferences 2007, 2009, 2011), 15th Congress of Logic, Methodology, and Philosophy of Science (Helsinki 2015), as well as national conferences (1st, 2nd, 3rd and 4th Hellenic Conference in Philosophy of Science, 2010, 2012). He was a Post-doctoral Researcher in the National Technical University of Athens and a Research Collaborator of the project Aspects and Prospects of Realism in the Philosophy of Science and Mathematics (funded by the European Union) (2012-2015).

Some of his publications are: “Two Comments on the Common Cause Principle in Algebraic Quantum Field Theory”. In de Regt, H. et. al. (eds.), EPSA Philosophy of Science: Amsterdam 2009, Springer; “The Debate on Scientific Realism”. In Baltas,. A., Stergiopoulos, K., (eds.) Philosophy and Sciences in the Twentieth Century, Herakleion: Cretan University Press (2013) pp. 421-466 (In Greek); “On Particle Phenomenology without Particle Ontology: How much local is almost local” (with A. Arageorgis) Foundations of Physics 43 (8):969-977 (2013); Explaining Correlations by Partitions. Foundations of Physics 45 (12):1599-1612 (2015).


In this talk I attempt to explore two important aspects of modern philosophy of science. On the one hand, I discuss the general idea of a scientifically informed metaphysics; an up-to-date way to talk about existence, existents and their properties with special reference to scientific theories. On the other hand, I examine a methodological issue, the idea of theorem-proving philosophy: how to argue philosophically by means of mathematical theorems. The discussion is based on my paper (with A. Arageorgis): “On Particle Phenomenology without Particle Ontology: How Much Local Is Almost Local?” Foundations of Physics 43 (8):969-977 (2013). In this paper, we argue that the measurements local particle detections are supposed to simulate probe radically holistic aspects of relativistic quantum fields. We prove that in an axiomatic (Haag-Araki) quantum field theory on Minkowski spacetime, formulated in a Hilbert space , there is no positive observable, with norm less than or equal to 1, satisfying the conditions: (1) the expectation value of in the vacuum state is zero, (2) there is at least one vector state in in which the expectation value of is different from zero, and (3) there exists at least one spacetime region such that the non-selective measurement of leaves the expectation values of all observables in the local algebra of that region unaltered regardless of the state the system is in. The result reveals a tension between intuitions regarding localization and intuitions regarding causality: to save “particle phenomena” in the absence of particle ontology, one has to feign “particle” detectors with “good” properties as to locality but “bad” behavior as to causality.