What is your favored interpretation of quantum mechanics?

[wuliheron]

I pick "Shut up and calculate!" I'm more in agreement with Nabuco, don't sweat the small stuff like metaphysics. QM works marvelously while metaphysics is as useless as a politician. If you can't accept that all I can suggest is get over it!

I would guess that even when we combine relativity and qm there will still be at least two uniquely useful ways of interpreting the theory. Personally I'm rooting for noncommutative fractal geometry and utter chaos. They seem to be about as perfectly opposite as it gets, yet, leave lots of room for every conceivable interpretation.

 

[Aeroflech]

Sorry for the gravedig, but there's something that I need to say.

jambaugh, you say that any QM needs to be freed of the 'expectations' of a classical theory.

I assert we need to stop keeping the S.S. Quantum Cruiser tied to the classical home dock. Cast off the "canonical quantization of a classical model" ropes and see what she can discover when allowed to sail past the horizon.

However, from what I've heard of the Copenhagen Interpretation(CI), I don't think that it truly does that. The reason I think this is that CI asserts that measurement apparati/observer is classical. This necessitates a line between quantum and classical behaviour. This line (I've heard it being called the Heisenberg cut) has been the cause of much grief over QM, with such ill-defined concepts such as macroscopicity and consciousness being proposed as the location of the cut. Also, CI, while of great use in calculating what happens in quantum systems, implies that QM is incomplete, because CI explicitly denies the universality of QM.

 

[jambaugh]

Sorry for the gravedig, but there's something that I need to say.

jambaugh, you say that any QM needs to be freed of the 'expectations' of a classical theory.

However, from what I've heard of the Copenhagen Interpretation(CI), I don't think that it truly does that. The reason I think this is that CI asserts that measurement apparati/observer is classical. This necessitates a line between quantum and classical behaviour. This line (I've heard it being called the Heisenberg cut) has been the cause of much grief over QM, with such ill-defined concepts such as macroscopicity and consciousness being proposed as the location of the cut. Also, CI, while of great use in calculating what happens in quantum systems, implies that QM is incomplete, because CI explicitly denies the universality of QM.

This cut is a cut in description not in the actuality. We don't need to write our theorems or record our data on "quantum paper" (or rather we don't need to take the paper's quantum nature into account).

In the CI quantum theory is "quantum complete" in that it is a maximal description. You must distinguish ontological completeness which classical theory claims (and is its failing) with empirical completeness which quantum theory under CI (or any other "interpretation") claims. Indeed it is the fact that all "interpretations" of QM are indistinguishable empirically which shows that as a matter of science "interpertation" is a theological question. CI is the most "atheistic".

None of this invalidates my point which is one about heuristics and not about interpretation. In our attempts to generate new/better theories we follow the old route of quantizing a classical description of a system. Naturally we historically converted the older classical descriptions to quantum ones as we moved into the new paradigm. But I think we've just about gone as far as we can there and its time to lay down that habit and think in terms of generating quantum theories and classicalizing them to see whether they correspond to the current remaining purely classical ones e.g. gravity.

This has essentially already been done in the quantum field theories of gauge forces in the standard model. There was never a classical treatment of the strong and weak interactions beyond some rough square well nuclear models. And yet the heuristic was still followed in the formulation. The standard model gauge theories were constructed first as classical gauge fields and quantized. Though the classical model wasn't taken seriously the same old formula was followed. It was of course very successful in so far as it went...however...

I assert that the problem with field theories in general and similarly with string theories is that they begin with a classical space-time description and preserve it throughout. String/brane theory abstracts this a bit with its multidimensional manifolds in a fixed higher dimensional spaces but its still fundamentally a quantization scheme applied to an underlying classical model.

The actuality of it is that the universe is fundamentally quantum. At some scales a classical descripiton is sufficient and we may easily explain how quantum systems may in the large scale, with restrictions on observables, behave classically. But there is no reason to suppose that there exists out there a classical model of some imagined universe which via a quantization scheme will generate the correct description of ours. Even if such is true it doesn't seem to be the most efficient way to go about it.

And this isn't a purely academic point. The decision on what research to fund is crucial and if the channeling of funds into a single branch motivates researchers to give up alternatives then we'd better be consicous of which avenues are dead ends and which are more direct paths to the better theory.

 

[metaethics]

Many Worlds Interpretation

Some proponents of MWI hold that other worlds except the actual world had better be understood as merely "possible worlds" or possibilities rather than real, parallel worlds. If MWI is read this way, it is not metaphysically queer at all. Are there any problems with this (revised) "Many Worlds Interpretation"? Please let me know. Thanks.

 

[Lord Ping]

Some proponents of MWI hold that other worlds except the actual world had better be understood as merely "possible worlds" or possibilities rather than real, parallel worlds. If MWI is read this way, it is not metaphysically queer at all. Are there any problems with this (revised) "Many Worlds Interpretation"? Please let me know. Thanks.

If anything this is even more metaphysically bizarre. The "worlds" in MWI are severely constrained. Normally philosophers take anything not logically impossible to be possible. But MWI cannot do this. For example, it is not logically impossible for the laws of quantum mechanics to be completely wrong!

So your interpretation needs to justify the constraints placed on possibility in these constrained-possible-worlds, explain their ontology (Do we imagine them? Do they really exist in some non-physical realm?), and explain why one of these constrained-possible-worlds is actualised while the others are not.