Timpson, C. (2009). What would a consistent instrumentalism about quantum mechanics be? Or, why Wigner's friendly after all.. Perimeter Institute for Theoretical Physics. https://pirsa.org/09090029
MLA
Timpson, Christopher. What would a consistent instrumentalism about quantum mechanics be? Or, why Wigner's friendly after all.. Perimeter Institute for Theoretical Physics, Sep. 25, 2009, https://pirsa.org/09090029
BibTex
@misc{ scivideos_PIRSA:09090029,
doi = {10.48660/09090029},
url = {https://pirsa.org/09090029},
author = {Timpson, Christopher},
keywords = {Quantum Foundations},
language = {en},
title = {What would a consistent instrumentalism about quantum mechanics be? Or, why Wigner{\textquoteright}s friendly after all.},
publisher = {Perimeter Institute for Theoretical Physics},
year = {2009},
month = {sep},
note = {PIRSA:09090029 see, \url{https://scivideos.org/pirsa/09090029}}
}
Instrumentalism about the quantum state is the view that this mathematical object does not serve to represent a component of (non-directly observable) reality, but is rather a device solely for making predictions about the results of experiments. One honest way to be such an instrumentalist is a) to take an ensemble view (= frequentism about quantum probabilities), whereby the state represents predictions for measurement results on ensembles of systems, but not individual systems and b) to assign some specific level for the quantum/classical cut. But what happens if one drops (b), or (a), or both, as some have been inclined to? Can one achieve a consistent view then? A major worry is illustrated by the Wigner's friend scenario: it looks as if it should make a measurable difference where one puts the cut, so how can it be consistent to slide it around (as, e.g., Bohr was wont to)? I'll discuss two main cases: that of Asher Peres' book, which adopts (a) but drops (b); and that of the quantum Bayesians Caves, Fuchs and Shack, which drops both. A view of Peres' sort can I, think, be made consistent, though may look a little strained; the quantum Bayesians' can too, though there are some subtleties (which I shall discuss) about how one should handle Wigner's friend.