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Well, the Heisenberg uncertainty relations basically tell you physical observables form a noncommutative algebra.

When you look beyond your past experience you're likely to encounter things that are counter-intuitive. "Counter-intuitive" is a statement about your intuition, not about the phenomena.

The real problem is not quantum behaviour, but the "classical limit". I think decoherence and consistent histories go a long way towards solving that.

Can the last politician to go out the revolving door please turn the lights off?

by Migeru (migeru at eurotrib dot com) on Thu Jul 26th, 2007 at 02:56:39 AM EST
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Is the "classical limit" the same problem as the measurmement problem, where the disctinction between determenistic wave evolution and a "mesurement" is not clear? Bell says that that Bohm's model (a particle riding a wave) solves this issue, but then "non-local" interpretations are weird.

Above that, is objectivity of the "real world" is now clear?

by das monde on Thu Jul 26th, 2007 at 10:53:02 AM EST
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IMHO the measurement problem stems from von Neumann's introduction of a "collapse of the wavefunction" axiom in his (1931?) Mathematical Foundations of Quantum Mechanics. Personally, I go for Everett's "relative state" formulation. But that has ontological problems.

Bohm's model works for spinless, newtonian particles. I am not aware of a workable generalisation of Bohm's "pilot wave" formulation to quantum fields, variable unmbers of particles, or particles with spin or internal degrees of freedom.

The "classical limit" is related, but not the same, as the measurement problem. It is related because we describe "measurement" in terms of macroscopic objects. Imagining that von Neumann's "collapse" applies to any interaction that one might call a "measurement" leads to the quantum zeno paradox. But the quantum zeno paradox assumes that interactions are instantaneous, which is unphysical.

The fact is, every single counterintuitive or paradoxical prediction of quantum mechanics that has been tested experimentally has been confirmed, so when I say above that a particular interpretation on quantum mechanics has "ontological problems" I have to wonder whether it's not Ontology that has experimental problems.

Can the last politician to go out the revolving door please turn the lights off?

by Migeru (migeru at eurotrib dot com) on Thu Jul 26th, 2007 at 11:07:28 AM EST
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What issue is Bohm's model "solving", by the way? It gives exactly the same experimental predictions as "ordinary" quantum mechanics. So the issue is not actually empirically motivated.

Can the last politician to go out the revolving door please turn the lights off?
by Migeru (migeru at eurotrib dot com) on Thu Jul 26th, 2007 at 11:09:26 AM EST
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I agree, the issue must be to feed ontology, or intuition. Thank for discussion!
by das monde on Fri Jul 27th, 2007 at 05:37:04 AM EST
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