Tuesday, 28 March 2006
Gauging Deutsch-Hayden:  
A new theory meets a familiar argument
Chris Timpson, University of Leeds
12:05 pm, 817R Cathedral of Learning

Abstract:  Deutsch and Hayden (2000) have proposed an alternative formulation of quantum mechanics which, they claim, is completely local.  Following some conceptual tidying (Timpson 2005) it can be seen that there is an interesting and important sense in which their claim is true.  But this benefit does not come for free:  I shall argue that their theory faces a dilemma formally identical to that familiar from discussion of gauge theories and in particular of the Aharanov-Bohm effect (1959). Namely, locality is achieved at the expense of introducing underdetermination and indeterminism into the theory, while attempts to remove these features by treating gauge equivalent states as one and the same physical state returns one to a nonlocal theory. Thus in the Deutsch and Hayden case, just as much as in the electromagnetism case, we are left with one of two options: avoid nonlocality by embracing underdetermination and indeterminism or reject these latter and accept nonlocality.  The general consensus in the electromagnetism case is that the second option is preferable. So too, I shall suggest, when one considers the Deutsch-Hayden approach.

(joint work with David Wallace)

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