Hi all, Next Friday, our visitor Antoine (Choups) Soulas will talk about “A solution to the preferred-basis problem based on the WAY theorem”. See below for the abstract. The talk will take place on Friday at 14:00 in HIT E41.1. Best, Ladina %%%%%%%% Title: A solution to the preferred-basis problem based on the WAY theorem Abstract: The preferred-basis problem is an issue that arises in several fields of quantum foundations: decoherence theory (including its later developments like quantum Darwinism), consistent histories, the quantum-to-classical transition, as well as in some discussions about the measurement problem and the interpretation of QM. From a “3rd person perspective”, it can be formulated as follows: given the laws of physics, in which bases do systems preferably entangle and therefore mutually decohere? That is: about which observables does information accurately flow between systems? Equivalently, from a “1st person perspective”, it amounts to understand which measurements can actually be performed, while the vast majority of bases in the Hilbert space can not be probed in practice (e.g. Wigner’s unfeasible measurement on his friend). While a variety of models already exist, they remain arguably insufficient: lack of either universality or physical meaning, unrealistic Hamiltonians, circularity, diverging conclusions… In this talk, we propose a general solution to the preferred-basis problem which merely assumes the existence of a global symmetry, relying on the Wigner-Araki-Yanase (WAY) theorem and some basics of quantum reference frames. We further discuss the implications of this result for the quantum-to-classical transition.