Speaker: Adam Caulton (Cambridge) Wednesday 15th May 2013 Ludwigstr.31 Room E021 Time: 4 to 6 pm Title: Individuating so-called "indistinguishable" quantum systems Abstract: In this talk I investigate and build on recent heterodox proposals by Zanardi and others about the idea of a natural decomposition of an assembly. I argue that so-called "indistinguishable" quantum systems may, in fact, be individuated---that is, picked out uniquely by some (permutation-invariant) description---and may in some cases be ascribed non-trivial reduced density operators. This heterodox account has several interesting consequences, that I will outline. First, it entails that the received opinion within the quantum philosophy literature, that bosons and fermions are always indiscernible, at least by their monadic properties (a view shared even by Muller, Saunders and Seevinck), is mistaken. Second, the account prompts a revision of the notion of entanglement in cases where permutation-invariance is imposed. More specifically: non-separability of the joint state is no longer sufficient for that state's being entangled. This revision happily coincides with recent proposals by Ghirardi, Marinatto and Weber. Third, arbitrariness in the individuating description suggests that a quantum analogue of David Lewis's counterpart theory is an appropriate metaphysics for such systems. _______________________________________________ philphysmunich mailing list philphysmunich@lists.lrz.de https://lists.lrz.de/mailman/listinfo/philphysmunich