Re:Why don't more physicists subscribe to pilot wave theory?
by naasking on Sunday December 18, 2016 @10:46AM
(#13206165)
> Pilot Wave posits a bunch of extra crap and derives the Born rule. Regular / MWI QM posits the born rule and skips the extra crap. They're both positing something - but the Born rule is a far simpler claim
Except it's not, because you also have to posit the measurement postulates in orthodox QM. This so-called "extra crap" reproduces the measurement postulates and the Born rule, thus replacing a large set of assumptions with a much smaller set.
Many-Worlds is indeed much simpler than orthodox QM, but it's still not simpler than pilot waves. They are roughly comparable, with many-worlds still having unresolved conceptual difficulties surrounding probabilities, among other issues [1]. Which is more parsimonious between many-worlds and pilot waves is hotly debated among philosophers of science.
> Also: aren't we to the point where measurement makes perfect sense (besides the values of the probabilities, as given by the Born rule), via entanglement between experiment+lab frames, and decoherence of unrelated Degrees of Freedom?
"Measurement now makes perfect sense" is an interpretation-specific claim. Measurement still doesn't make sense in Copenhagen, measurement mostly makes sense in Many-Worlds, modulo some of the difficulties I mentioned earlier [1].
> Also, pilot wave fails badly in relativistic extensions, for the obvious reason that a universe-wide pilot wave function is hard to make covariant.
It's actually pretty trivial if you're willing accept a preferred foliation of space-time, as long as the preferred frame is unobservable. This seems aesthetically unappealing, hence why people perpetuate this myth of "difficulty", but it's not a priori wrong.
Fortunately, a preferred foliation can actually be derived from the wave function itself, which means this foliation exists in every interpretation of QM [2].
This is the kind of surprising result that probably no one would have even bothered looking for, and I think it proves John Bell's position that non-locality is the unresolved problem of QM [3]. Other interpretations just let you paper over it, to our detriment IMO.
Except it's not, because you also have to posit the measurement postulates in orthodox QM. This so-called "extra crap" reproduces the measurement postulates and the Born rule, thus replacing a large set of assumptions with a much smaller set.
Many-Worlds is indeed much simpler than orthodox QM, but it's still not simpler than pilot waves. They are roughly comparable, with many-worlds still having unresolved conceptual difficulties surrounding probabilities, among other issues [1]. Which is more parsimonious between many-worlds and pilot waves is hotly debated among philosophers of science.
> Also: aren't we to the point where measurement makes perfect sense (besides the values of the probabilities, as given by the Born rule), via entanglement between experiment+lab frames, and decoherence of unrelated Degrees of Freedom?
"Measurement now makes perfect sense" is an interpretation-specific claim. Measurement still doesn't make sense in Copenhagen, measurement mostly makes sense in Many-Worlds, modulo some of the difficulties I mentioned earlier [1].
> Also, pilot wave fails badly in relativistic extensions, for the obvious reason that a universe-wide pilot wave function is hard to make covariant.
It's actually pretty trivial if you're willing accept a preferred foliation of space-time, as long as the preferred frame is unobservable. This seems aesthetically unappealing, hence why people perpetuate this myth of "difficulty", but it's not a priori wrong.
Fortunately, a preferred foliation can actually be derived from the wave function itself, which means this foliation exists in every interpretation of QM [2].
This is the kind of surprising result that probably no one would have even bothered looking for, and I think it proves John Bell's position that non-locality is the unresolved problem of QM [3]. Other interpretations just let you paper over it, to our detriment IMO.
[1] https://plato.stanford.edu/entries/qm-manyworlds/#6
[2] https://arxiv.org/abs/1307.1714
[3] John Bell, who was a big fan of pilot waves by the way.