army1987 comments on Ask an experimental physicist - Less Wrong

35 Post author: RolfAndreassen 08 June 2012 11:43PM

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Comment author: [deleted] 11 June 2012 05:44:53PM *  1 point [-]

I wouldn't call it “orthodox”, but see this:

In addition to these formal axioms one needs a rudimentary interpretation relating the formal part to experiments. The following minimal interpretation seems to be universally accepted.

MI. Upon measuring at times t_l (l=1,...,n) a vector X of observables with commuting components, for a large collection of independent identical (particular) systems closed for times t<t_l, all in the same state rho_0 = lim_{t to t_l from below} rho(t) (one calls such systems identically prepared), the measurement results are statistically consistent with independent realizations of a random vector X with measure as defined in axiom A5.

Note that MI is no longer a formal statement since it neither defines what 'measuring' is, nor what 'measurement results' are and what 'statistically consistent' or 'independent identical system' means. Thus MI has no mathematical meaning - it is not an axiom, but already part of the interpretation of formal quantum mechanics.

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The lack of precision in statement MI is on purpose, since it allows the statement to be agreeable to everyone in its vagueness; different philosophical schools can easily fill it with their own understanding of the terms in a way consistent with the remainder.

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MI is what every interpretation I know of assumes (and has to assume) at least implicitly in order to make contact with experiments. Indeed, all interpretations I know of assume much more, but they differ a lot in what they assume beyond MI.

Everything beyond MI seems to be controversial. In particular, already what constitutes a measurement of X is controversial. (E.g., reading a pointer, different readers may get marginally different results. What is the true pointer reading?)