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Nithep Seminar: Prof. Barbra Drossel: Contextual wave function collapse: Steps of a measurement process
August 5, 2019 @ 3:00 pm - 4:00 pm
Abstract: This talk presents a theoretical treatment of the measurement
process that takes into account all the steps between the initial arrival of the
particle at the detector and the final pointer deflection. By using methods from the
respectively relevant fields of physics, it becomes clear that only the first step,
the initial creation of a linear superposition, follows unitary time evolution. All the
later steps involve classical elements, elements from statistical physics, and
nonlinearities. I will argue that the coupling to the internal heat bath of the
detector puts an end to unitary time evolution, since a heat bath cannot be
described by a many-particle wave function. This is because its state is specified
only to limited number of bits (as implemented in the Boltzmann formula for
entropy), and because its microstate cannot be controlled even in principle.
Overall, while our approach benefits a lot from the Copenhagen interpretation,
from decoherence theory, and from collapse models, it goes a step further by
taking into account top-down influences from the classical and thermal
environments in order to identify where the ‘collapse’ happens.
Reference: B. Drossel and G. Ellis, New J. Physics 20 (2018)