QM Interpretations: Popularity & Desirability

[dm4b]

I didn't want to hijack somebody else's thread, so thought I would start a new one for this.

There are several interpretations/formulations of QM: Copenhagen, TSQM, MWI, and others.

Which one currently has the most favor within the physics community? Why

Which one currently has the least favor within the physics community? Why

And, lastly, is it still true that they all leave something to be desired?

Thanks!

 

[unusualname]

There can be only one.

Copenhagen is like Ramirez (Sean Connery)
Consistent Histories is like Connor (Christopher Lambert)

MWI is like the badass Kurgan (Clancy Brown)
De Broglie Bohm is like Tony the Hotdog Vendor (Damian Leake)

http://www.imdb.com/title/tt0091203/fullcredits#cast

The sequels don't really tie in well with how I think the ultimate interpretation will emerge, but remember, there can be only one

 

[dm4b]

There can be only one.

Agreed, but how are we going to tell which one is ultimately correct?

For example, as the founders of TSQM state, there is no way to "prove" it over the regular formulation of QM (at least as far as we currently know).

In my mind the two couldn't be more drastically different in their conceptual foundatons, (and ramifications) either. (Well, MWI is pretty far out there too!)

 

[Gordon Watson]

I didn't want to hijack somebody else's thread, so thought I would start a new one for this.

There are several interpretations/formulations of QM: Copenhagen, TSQM, MWI, and others.

Which one currently has the most favor within the physics community? Why

Which one currently has the least favor within the physics community? Why

And, lastly, is it still true that they all leave something to be desired?

Thanks!

..

From my discussions with "quantum engineers": I'd say SUAC has most favor; underpinned by their local realistic beliefs, and thus interpreted that way. Anything non-local has least favor.

Speaking personally: Any interpretation that's not clearly "locally causal and realistic" leaves that to be achieved, imho. The underlined phrase is a personal requirement of mine. (And of Einstein too?)

So (for what its worth), I have my own interpretation: LRQ (Local Realistique Quantenmechanik).

PS: Avoiding abstractions, LRQ is based on empirical data (re spin-entanglement) unknown to the founding-fathers.
..

 

[tom.stoer]

There is no reason why nature (and that includes quantum mechanics) should respect "commons sense". So interpretations of QM based on "common sense" are like the Ptolemaic system and geocentrism.

 

[billschnieder]

There is no reason why nature (and that includes quantum mechanics) should respect "commons sense". So interpretations of QM based on "common sense" are like the Ptolemaic system and geocentrism.

Once you toss "common sense" and "logic" out the window, you have rid yourself of the only tool you had to verify your sanity. So rather than accept something which "makes no sense", question it UNTIL it "makes sense". If it can not be made to "make sense" then it is "non-sense".

QM currently makes sense to me simply as an alternative to "probability theory" for making predictions based on prior information. Therefore my favorite interpretation is the empiricist interpretation.

 

[jtbell]

In physics, what ultimately counts is verifying a theory via experiment. Verifying your sanity is optional.

 

[billschnieder]

In physics, what ultimately counts is verifying a theory via experiment. Verifying your sanity is optional.

The scientific method which you use to verify the theory via experiment is soundly grounded in logic and therefore common sense. If a theory allows a hypothesis to be simultaneously true and false, no amount of experimentation will verify the theory.

 

[eaglelake]

Once you toss "common sense" and "logic" out the window, you have rid yourself of the only tool you had to verify your sanity. So rather than accept something which "makes no sense", question it UNTIL it "makes sense". If it can not be made to "make sense" then it is "non-sense".

Quantum mechanics is not the same as classical physics. In fact it is radically different. Unfortunately, your "common sense" is really "classical sense" and your "logic" is "classical logic". What you are saying is that quantum events should behave like classical events. We know this is not true. You will drive yourself crazy if you keep trying to make it so.
Best wishes

 

[jfy4]

The scientific method which you use to very the theory via experiment is soundly grounded in logic and therefore common sense. If a theory allows a hypothesis to be simultaneously true and false, no amount of experimentation will verify the theory.

I'm being a little pedantic here but I want to make sure this is clear. The scientific method is an extremely well accepted logical fallacy. The scientific method says:

"If the theory is true, then this should happen. The 'this' happened, so the theory is true."

This is called affirming the consequent, and is a blatant deductive logical fallacy. However, one does gain inductive evidence from this procedure that is very logical. If a theory can pass multiple different tests of its conclusions then it qualifies as a good theory.

EDIT:

As for some major achievements, how about the KLT relations? If strings "don't exist", why did that work?

Think about what it means for something to "exist" anyway. How do we know particles "exist"? We don't, in fact we have no idea what these particles "really" are. Maybe these particles are actually tiny vibrating apples made of energy - we don't care. We just come up with a model that attempts to make correct calculations, up to a particular accuracy. If the model works, its constituents are said to "exist". This is what we're doing with string theory in ads/cft. If those calculations lead to something correct, there you have it, strings "exist". Whether or not you'll see them in an experiment, and whether or not our universe is AdS.

I have not met the person who posted this, however I was a little put off by this statement too, as a prime example as what not to get sucked into.

A theory predicting a single phenomenon and that prediction coming true, truly does little for the theory. It must be shown that it can explain and predict a wide variety of phenomna, like all prominent theories of today's standard model do. Statements like ..."This is what we're doing with string theory in ads/cft. If those calculations lead to something correct, there you have it, strings "exist"." are a little too forward. Although to be fair, in a wider view, string theory more going for it.

 

[Matterwave]

I wouldn't say the Scientific Method is a logical fallacy, because it does not make the claim (at least, it shouldn't): "If theory T is true, a (b,c,d,etc) happens. A happened, therefore theory T is true".

The statement that the scientific method makes is:

"If theory T is true, then a,b,c,d,etc., happens." "A happened, therefore theory T is not proven false", "B happened, therefore theory T is not proven false",...etc.

Or

"If theory T is true, then a,b,c,d,etc., happens." "A does not happen, therefore theory T is false."

(Of course, we can interchange "happens" with "does not happen")

These are not logical fallacies.

 

[jfy4]

I wouldn't say the Scientific Method is a logical fallacy, because it does not make the claim (at least, it shouldn't): "If theory T is true, a (b,c,d,etc) happens. A happened, therefore theory T is true".

The statement that the scientific method makes is:

"If theory T is true, then a,b,c,d,etc., happens." "A happened, therefore theory T is not proven false", "B happened, therefore theory T is not proven false",...etc.

Or

"If theory T is true, then a,b,c,d,etc., happens." "A does not happen, therefore theory T is false."

(Of course, we can interchange "happens" with "does not happen")

These are not logical fallacies.

Well the later one is certainly not a logical fallacy, and as far as the first, it isn't either, but I've never seen it taught that way...

I imagine after many attempts to view the Higgs boson at the LHC, many times where it is not observed, and then the one time it is, that there will be some champagne bottles being brought out :tongue: But nothing of what you wrote is a logical fallacy, I'm just not sure if it is what most scientists have as the idea of the scientific method.

On that note, not the thread for the topic, sorry for the digression.

 

[Matterwave]

I think it is often taught that theories cannot be "proved", but only "verified" over and over by experiment. I think that statement is equivalent to mine in much simpler terms. =]

 

[billschnieder]

Unfortunately, your "common sense" is really "classical sense" and your "logic" is "classical logic".

False. Logic is universal. Logic is the formalization of the rules of consistent reasoning by rational beings. If you are willing to suggest that "quantum logic" is "non-sense" and/or inconsistent and/or irrational go ahead.

What you are saying is that quantum events should behave like classical events. We know this is not true. You will drive yourself crazy if you keep trying to make it so.
Best wishes

Don't get ahead of yourself as nothing of the sort was remotely implied in my post. All I'm saying is that just because we don't understand how something "makes sense", it does not mean we never will, and it definitely does not mean we have to eliminate "common sense". It simply means we have to ask the right questions, to get the right answers. Then it will make sense.

To be willing to accept something which we believe will never make sense is a crime, with a swift and certain intellectual death penalty.

In any case, to bring this back on topic, the empiricist interpretation of QM states that QM, like probability theory is an epistemological theory not an ontologic one.

 

[tom.stoer]

False. Logic is universal. Logic is the formalization of the rules of consistent reasoning by rational beings. If you are willing to suggest that "quantum logic" is "non-sense" and/or inconsistent and/or irrational go ahead.

As you may know there are different logical systems. It is by no means clear that quantum mechanics should respect classical (= bivalent, Boolean) logic.

http://en.wikipedia.org/wiki/Classical_logic
http://en.wikipedia.org/wiki/Non-classical_logic

The Kochen–Specker theorem tells us that quantum logic for a system of "true-false observables" is beyond classical logics as it is impossible for a narbitrary set of such observables to assign definite true and false values. Therefore interpreting the quantum world with classical logics may be wrong.

http://en.wikipedia.org/wiki/Kochen–Specker_theorem

And of course "common sense" is not only about logics but about "objects", "reality" etc. Attempts to interpret quantum mechanics in terms of classical entities is reasonable in the classical limit, but there is no reason why it should succeed in the quantum regime.

In any case, to bring this back on topic, the empiricist interpretation of QM states that QM, like probability theory is an epistemological theory not an ontologic one.

I think that pure epistemology is like Feynman's "shut up and calculate". I doesn't explain anything - and I wouldn't call that an interpretation at all.

Of course for 99% of all physicists and their work this positivistic position is fine, but in order to make progress in science questions like "why?" are required. They have been asked by all great physicists (Newton, Einstein, Bohr, Heisenberg) but went out of fashion for some decades.

 

[f95toli]

I think that pure epistemology is like Feynman's "shut up and calculate". I doesn't explain anything - and I wouldn't call that an interpretation at all.

Of course for 99% of all physicists and their work this positivistic position is fine, but in order to make progress in science questions like "why?" are required. They have been asked by all great physicists (Newton, Einstein, Bohr, Heisenberg) but went out of fashion for some decades.

I am not sure I agree that I agree that science needs to be able to answer questions about "why?" something happens, I am quite happy if we can answer "how?" questions, i.e. predict the outcome of experiments.

However, the main reason why the vast majority of all physicists (including myself) who work with QM on a daily basis (especially its "weird" implications, like quantum computing etc) tend to side with the "no interpretation at all" camp (which is essentially Feynman's position) is that if one believes that the "definition" of a scientific theory is that it is something that can be falsified using an experiment , it also follows that the debate about various interpretations is essentially a non-scientific one; until there is a way there is now way to perform an experiment to see which one is correct it has more to do with philosophy than physics (which is why it is a debate largely confined to internet forums and some rather obscure journals)

Note that this does not meant that we are not interested in topics that are related to interpretations (tests of local realism, Bell inequalities etc), but then only as long as one can perform an experiment (I e.g. worked on Macroscopic Quantum Tunnelling as PhD student, which is part of the Legget "program").

 

[dm4b]

Note that this does not meant that we are not interested in topics that are related to interpretations (tests of local realism, Bell inequalities etc), but then only as long as one can perform an experiment

Are you saying you are only interested in it to the extent that you can perform an experiment?

It's just that the stronger the interest you have in something (all along), the quicker you'll probably think of a way to test it via experiment, wouldn't you think?

 

[dm4b]

After reading through these posts it sounds like there are some interpretations I wasn't familar with.

Anybody know of a good resource where one can read up on all the current interpretations? Thanks!

 

[f95toli]

It's just that the stronger the interest you have in something (all along), the quicker you'll probably think of a way to test it via experiment, wouldn't you think?

Possibly. But the problem is that all "popular" interpretations predict exactly the same outcome for experiments, this is why they are known as interpretations as opposed to new theories. It is of course to some extent unavoidable since (more or less) everyone agrees that the math is correct (but people can't agree what the formulas "mean") and the math is what we use to predict the outcome of experiments.
Even Bohmian mechanics which is conceptually very different to more "traditional" QM predicts the exactly the same physics.

Hence, in order to for a interpretation to be falsifiable, someone needs to stick his/herr neck out and predict an outcome of an experiment that does NOT agree with standard "shut up and calculate" QM...

 

[yoda jedi]

Logic

LOGIC is the essence of existence.

QM, like probability theory is an epistemological theory not an ontologic one.

very, very probable.
(Psi-Epistemic models).



.

 

[dm4b]

Possibly. But the problem is that all "popular" interpretations predict exactly the same outcome for experiments, this is why they are known as interpretations as opposed to new theories. It is of course to some extent unavoidable since (more or less) everyone agrees that the math is correct (but people can't agree what the formulas "mean") and the math is what we use to predict the outcome of experiments.
Even Bohmian mechanics which is conceptually very different to more "traditional" QM predicts the exactly the same physics.

Hence, in order to for a interpretation to be falsifiable, someone needs to stick his/herr neck out and predict an outcome of an experiment that does NOT agree with standard "shut up and calculate" QM...

Agreed.

This actually seems to be an increasing challenge in physics as time goes on. Which interpretation of QM is correct? Is Spacetime curvature real? Etc.

These issues seem to be popping up at an increasing rate and offer no way to experimentally verify what's "real", and what's not. Well, at least not within our current understanding.

Than you have areas that are increasingly difficult to empirically verify. Extra compactified spatial dimensions of String Theory. Or, the Strings themselves. Multiverse. Etc.

So, the only problem I see is, if we start seeing more and more of this and increasingly claim it just falls within the realm of philosophy, we'll start throwing out everything "physical" within our theories, and retain only the math.

This might be fine for some, but I personally feel it could be the start of a disturbing trend with potentially troubling consequences for the field. I guess only time will tell.

 

[yoda jedi]

interpretations predict exactly the same outcome for experiments

not so fast, CSl models differs, others models too.




.

 

[eaglelake]

False. Logic is universal. Logic is the formalization of the rules of consistent reasoning by rational beings. If you are willing to suggest that "quantum logic" is "non-sense" and/or inconsistent and/or irrational go ahead.

Don't get ahead of yourself as nothing of the sort was remotely implied in my post. All I'm saying is that just because we don't understand how something "makes sense", it does not mean we never will, and it definitely does not mean we have to eliminate "common sense". It simply means we have to ask the right questions, to get the right answers. Then it will make sense.

To be willing to accept something which we believe will never make sense is a crime, with a swift and certain intellectual death penalty.

In any case, to bring this back on topic, the empiricist interpretation of QM states that QM, like probability theory is an epistemological theory not an ontologic one.

Give us an example where quantum mechanics is nonsense.

 

[tom.stoer]

However, the main reason why the vast majority of all physicists ... tend to side with the "no interpretation at all" camp (which is essentially Feynman's position) is that if one believes that the "definition" of a scientific theory is that it is something that can be falsified using an experiment , it also follows that the debate about various interpretations is essentially a non-scientific one

The problem is that if you narrow your context (as you do in posititivism) you can of course say that questions outside this context are ill-posed. But this does not affect the questions themselves but the context itself.

Feynmans position is OK for all practical purposes (fapp) in QM, but it does not allow us to ask conceptual and ontological questions. Fact is that all physicists agree that there isa world, a kind of reality, e.g. my house, my living room, my car, ... which exists independently. As soon as you agree on reality it is natural to ask ontological questions which automatically generate this quantum interpretation problem.

If you restrict yourself to non-ontological questions you don't need any interpretation at all. But there is not only progress in science due to calculations but due to these ontological questions as well; read the papers, debates and books of Planck, Einstein, Bohr, Heisenberg, Pauli, Schrödinger, deBroglie, Weizsäcker, Bohm, Deutsch, Wheeler, Penrose, ...; science would not be the same w/o their ideas of thinking which are partially far beyond positivism.

 

[dm4b]

But there is not only progress in science due to calculations but due to these ontological questions as well; read the papers, debates and books of Planck, Einstein, Bohr, Heisenberg, Pauli, Schrödinger, deBroglie, Weizsäcker, Bohm, Deutsch, Wheeler, Penrose, ...; science would not be the same w/o their ideas of thinking which are partially far beyond positivism.

Agreed. These days, I think we are far too quick to throw out, or ignore, ideas along these lines.

If you want to see something WAY beyond positivism read Pauli's correspondence with Carl Jung, or Schrodinger's mystical ramblings, or any of Bohm's books, amongst others. These guys definitely weren't shy when it came down to getting "philosophical".

 

[A. Neumaier]

Quantum mechanics is not the same as classical physics. In fact it is radically different. Unfortunately, your "common sense" is really "classical sense" and your "logic" is "classical logic". What you are saying is that quantum events should behave like classical events. We know this is not true.

Don't make quantum mechanics unnnecessarily weird!

All quantum physics obeys classical logic. We use it to think about quantuym mechanics, to infer correctly implications of quantum mechanics, to prove theorems about it. The so-called ''quantum logic'' is completely useless for any of these tasks, except for some extremely simple experiments.

 

[A. Neumaier]

After reading through these posts it sounds like there are some interpretations I wasn't familar with.

Anybody know of a good resource where one can read up on all the current interpretations? Thanks!

SUAC = shut up and calculate

Stanford Encyclopedia of Philosophy:
http://plato.stanford.edu/entries/qm/
(and links there at the bottom to ''Related entries'')

Wikipedia
http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics

The same interpretation usually also has many variants...

 

[dm4b]

SUAC = shut up and calculate

Stanford Encyclopedia of Philosophy:
http://plato.stanford.edu/entries/qm/
(and links there at the bottom to ''Related entries'')

Wikipedia
http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics

The same interpretation usually also has many variants...

Thanks ANeumaier! Looks there were several I wasn't familar with!