München 2019 – scientific programme

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AGPhil: Arbeitsgruppe Philosophie der Physik

AGPhil 7: Philosophy of Cosmology VII

AGPhil 7.3: Invited Talk

Wednesday, March 20, 2019, 17:45–18:30, HS 10

Q.E.D., QED — •Chris Smeenk and Adam Koberinski — Western University, Canada

Quantum electrodynamics is often regarded as the most well-tested theory ever, due to incredibly high precisions tests such as the measurement of the anomalous magnetic moment of the electron. This talk proposes a different understanding the evidence in favor of QED. Regarding it as confirmed by a series of predictions does not adequately reflect the strength of the case in favor of QED, nor do they correctly capture the logic of theory testing. High precision tests of QED presuppose that the theory is correct in order to describe the experiments. This raises two concerns. The first regards whether this involves circular reasoning. The main issue has been whether any discrepancies that are uncovered with increasing precision can be accounted for with more detailed physical models. For example, low energy experiments with pure QED systems have, surprisingly, reached a level of precision such that other Standard Model interactions have to be taken into account. Studies of different systems have allowed for consistent independent determinations of the fine structure constant. Second, is this use of QED compatible with acknowledging that it is only an effective field theory? We will argue that the reasoning involved in treating these experiments only depends on QED providing an accurate description within a limited domain.