Niels Bohr famously insisted on the indispensability of what he termed "classical concepts." In the context of the decoherence program, on the other hand, it has become fashionable to talk about the "dynamical emergence of classicality" from the quantum formalism alone. Does this mean that decoherence challenges Bohr's dictum and signifies a break with the Copenhagen interpretation‐‐‐for example, that classical concepts do not need to be assumed but can be derived? In this talk I will try to shed some light down these murky waters where formalism and philosophy meet. First, I shall clarify the precise type of classicality that we deal with in the decoherence description. Then I will reflect on some of the possible notions of Bohr's classical concepts and discuss different takes on the quantum‐classical problem in Bohr's and Heisenberg's writings. Having thus laid out the different ways one might understand the term "classical" in a quantum context, I will put forward some tentative suggestions for how we may better understand the relation between decoherence‐induced classicality and Bohr's classical concepts

At 17:00 hrs, before the CoQuS colloquium,

there will be a presentation by CoQuS student

Robert Bücker

on „Probing atom correlations by single‐particle‐sensitive imaging”

 Monday, June 7th, 2010

17:30 hrs s.t.