Poll: Interpretations of Quantum Mechanics

In summary: That's beautiful. And... it does look to me like evidence against collapse postulates, in one way or another.Not exactly. It basically just says that collapse is relevant with respect to some "external observer". Same thing happens in Schrodinger's Cat experiment, after all. Cat's observations are considered irrelevant. This is still self-consistent so long as you consider only one observer. And there are actually some advantages of doing it this way. Decoherence, for example, can play a major role, and then it's actually convenient to distinguish between "true" observer, who read the measurements once decoherence took place, and intermediate observer, such as a measurement device

To which interpretation of Quantum Mechanics do you subscribe?

  • Total voters
    43
  • #36
Mark M said:
BTW, I wonder what the people who voted 'Other' had in mind, considering it's winning.

I prefer the local realistic approach of my journal articles http://akhmeteli.org/akh-prepr-ws-ijqi2.pdf and http://akhmeteli.org/wp-content/uploads/2011/08/JMAPAQ528082303_1.pdf and later preprints.

Briefly (and cutting some corners), I start from scalar electrodynamics or spinor electrodynamics, eliminate the (scalar or spinor) matter field, using gauge invariance, and thus obtain nonlinear equations describing independent evolution of the electromagnetic field. It turns out that the resulting theories can be embedded into quantum field theories.
 
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  • #37
Concerning interpretations, I'm usually in a state of superposition (to be frank, I actually don't think very much about it). I'd like to vote "Other", but I can't make myself collapse into a particular one; I haven't found any suitable yet, even though I've tried to. So I guess I keep my superposition and vote "I don't know". Boring, I know... :smile:
 
  • #38
akhmeteli said:
I prefer the local realistic approach of my journal articles http://akhmeteli.org/akh-prepr-ws-ijqi2.pdf and http://akhmeteli.org/wp-content/uploads/2011/08/JMAPAQ528082303_1.pdf and later preprints.

Briefly (and cutting some corners), I start from scalar electrodynamics or spinor electrodynamics, eliminate the (scalar or spinor) matter field, using gauge invariance, and thus obtain nonlinear equations describing independent evolution of the electromagnetic field. It turns out that the resulting theories can be embedded into quantum field theories.

Thanks for sharing, I'll read that right now.

DennisN said:
Concerning interpretations, I'm usually in a state of superposition (to be frank, I actually don't think very much about it). I'd like to vote "Other", but I can't make myself collapse into a particular one; I haven't found any suitable yet, even though I've tried to. So I guess I keep my superposition and vote "I don't know". Boring, I know... :smile:

:smile:
 
  • #39
K^2 said:
By definition, interpretations are part of the same theory. If there is distinction, they are distinct theories.

Under axioms of Quantum Mechanics, Copenhagen and Many-Worlds are interpretations. Id est, indistinguishable. While experiment could exist that would point towards one or another, it would simultaneously disprove Quantum Mechanics, as violation of one of the axioms is prerequisite for a distinction.

The reason I don't find this convincing is because Copenhagen is actually not at all clear about what will happen in every conceivable process. It's sometimes too vague to give an accurate prediction, and this because Copenhagen doesn't handle its distinction between macro and micro well. Note I'm saying that sometimes it is simply silent, where other "interpretations" do make claims. So it's more subtle than "right vs wrong".

The clearest example of this, imo, is how Copenhagen actually doesn't tell you what a measuring apparatus for, say, energy looks like (as in: how it should function).
 
  • #40
akhmeteli said:
I prefer the local realistic approach of my journal articles http://akhmeteli.org/akh-prepr-ws-ijqi2.pdf and http://akhmeteli.org/wp-content/uploads/2011/08/JMAPAQ528082303_1.pdf and later preprints.

Briefly (and cutting some corners), I start from scalar electrodynamics or spinor electrodynamics, eliminate the (scalar or spinor) matter field, using gauge invariance, and thus obtain nonlinear equations describing independent evolution of the electromagnetic field. It turns out that the resulting theories can be embedded into quantum field theories.

I wish I could say that I'm going to read that soon, but I don't have the mathematical background necessary for that :P I'll definitely bookmark it for later, though!

mr. vodka said:
The reason I don't find this convincing is because Copenhagen is actually not at all clear about what will happen in every conceivable process. It's sometimes too vague to give an accurate prediction, and this because Copenhagen doesn't handle its distinction between macro and micro well. Note I'm saying that sometimes it is simply silent, where other "interpretations" do make claims. So it's more subtle than "right vs wrong".

The clearest example of this, imo, is how Copenhagen actually doesn't tell you what a measuring apparatus for, say, energy looks like (as in: how it should function).

I completely agree.

And furthermore, there is a point I forgot to make:
K^2 said:
By definition, interpretations are part of the same theory. If there is distinction, they are distinct theories.
We are arguing 'by definition' here. Yes, in very deed, interpretations are part of the same theory... according to some definitions. But if we dissolve the meaning of our words, maybe we can build a better discussion.

What I mean is that I don't see the interpretations as really simple subjective interpretations of the data available, or not all of them. I think some of them are that, while some others would benefit from being called "metatheories." I don't think that you can say the interpretations are really indistinguishable because, as mr. vodka said, there are things the different "interpretations" say about the world that frequently collide. Exempli gratia, what mr. vodka has said. So yes, I do hold that the different "interpretations" can make novel predictions and add to the theory. We have to agree that the Quantum Theory is not complete, and if any interpretation makes a prediction that is not outright forbidden or ruled out by the parent theory (such as collapse-like postulates, which in spite of being extra and seemingly unphysical are not forbidden by the Theory) but which is forbidden in one or more of the so-called "interpretations", there is no reason why that experimental result should break the parent theory at the same time.
 
  • #41
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  • #42
ParticleGrl said:
Your poll is missing a number of popular interpretations- ensemble/statistical (see Ballentine's book https://www.amazon.com/dp/9810241054/?tag=pfamazon01-20 ),consistent histories (Bob Griffith's fantastic book http://quantum.phys.cmu.edu/CQT/index.html), transactional (Cramer's http://www.npl.washington.edu/npl/int_rep/ti_over/ti_over.html).

I second this. It looks as though there are quite a few people who are choosing "other", but then again, this thread has not been up for that long. Maybe you can try adding other options in order to get a better idea of what people believe. For example, here is another fairly recent poll I found that was pretty comprehensive. And just to give my own input, perhaps you can also add a "shut up and calculate" interpretation, which is essentially not taking a stand on any particular interpretation and focusing on just the maths.

As for myself, I am just recently learning about QM, so I won't contribute (but from what I hear, the Copenhagen interpretation is pretty standard).
 
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  • #43
ParticleGrl said:
Your poll is missing a number of popular interpretations- ensemble/statistical (see Ballentine's book https://www.amazon.com/dp/9810241054/?tag=pfamazon01-20 ),consistent histories (Bob Griffith's fantastic book http://quantum.phys.cmu.edu/CQT/index.html), transactional (Cramer's http://www.npl.washington.edu/npl/int_rep/ti_over/ti_over.html).

Personally, I'm agnostic with leanings towards the ensemble interpretation.

I know, I just made the poll with the names that showed up off the top of my head. Besides, I don't really know many interpretations too well.

lmoh said:
I second this. It looks as though there are quite a few people who are choosing "other", but then again, this thread has not been up for that long. Maybe you can try adding other options in order to get a better idea of what people believe. For example, here is another fairly recent poll I found that was pretty comprehensive. And just to give my own input, perhaps you can also add a "shut up and calculate" interpretation, which is essentially not taking a stand on any particular interpretation and focusing on just the maths.

As for myself, I am just recently learning about QM, so I won't contribute (but from what I hear, the Copenhagen interpretation is pretty standard).

I can't edit a poll, I don't think. Or can I? If so, how?

And yeah, Copenhagen is the "original" one, when no one else had thought of a way to explain the measurements. But nowadays there has been a steady decrease in its popularity with a proportional increase in other interpretations' (with Many Worlds being the leading alternative).
 
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  • #44
But nowadays there has been a steady decrease in its popularity with a proportional increase in other interpretations' (with Many Worlds being the leading alternative).

I'm not sure many worlds is the leading alternative- I think different sub-specialties have different cultures. When I was in grad school, a paper by Deutsch on the origin of probability in many worlds was making the rounds, and pretty much everyone dismissed it as "if you have to do this much work to get predictions, its not worth it."
 
  • #45
ParticleGrl said:
I'm not sure many worlds is the leading alternative- I think different sub-specialties have different cultures. When I was in grad school, a paper by Deutsch on the origin of probability in many worlds was making the rounds, and pretty much everyone dismissed it as "if you have to do this much work to get predictions, its not worth it."

Hm... does any other interpretation explain the origin of probability in Q.M., without just putting it there because it works? I'm pretty sure that's a challenge of Q.M. in general not just MWI.

And I don't know, at least here on this forum MWI is winning (unless by some miracle everyone who voted for 'Other' was thinking of exactly the same interpretation) and I've seen some polls (granted, only one of them was properly scientific) that show that while Copenhagen still leads, second place is comfortably owned by MWI.
 
  • #46
ParticleGrl said:
Your poll is missing a number of popular interpretations- ensemble/statistical (see Ballentine's book https://www.amazon.com/dp/9810241054/?tag=pfamazon01-20 ),consistent histories (Bob Griffith's fantastic book http://quantum.phys.cmu.edu/CQT/index.html), transactional (Cramer's http://www.npl.washington.edu/npl/int_rep/ti_over/ti_over.html).

Personally, I'm agnostic with leanings towards the ensemble interpretation.

Well, Bell's theorem and the experiments based on it have essentially shown that the statistical approach is incorrect. Also, in the SQUID experiment in 2000, an actual superposition was created for a few nanoseconds. See here:

http://www3.amherst.edu/~jrfriedman/Scientific American/scientific-american edited.html

And since Bell showed that there is a definite predictive difference between the standard quantum approaches and the statistical approach, the agnostic position was eliminated.

And I don't know, at least here on this forum MWI is winning (unless by some miracle everyone who voted for 'Other' was thinking of exactly the same interpretation) and I've seen some polls (granted, only one of them was properly scientific) that show that while Copenhagen still leads, second place is comfortably owned by MWI.

Usually it goes Copenhagen, MWI, and then Bohm. But it depends on who is polled, if, for example, you poll a quantum computing conference, MWI usually wins pretty comfortably.
 
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  • #47
Mark M said:
Well, Bell's theorem and the experiments based on it have essentially shown that the statistical approach is incorrect.

Well, that's clearly not true. Bell's theorem rules out classes of hidden variables, it doesn't tell us how to interpret the wavefunction.

Also, macroscopic super-positions might kill GRW/objective collapse stuff, but why would they rule out an ensemble interpretation?

I once read that the quantum-zeno effect was a killer for ensemble interpretations, but I've never looked at the arguments around this.

And since Bell showed that there is a definite predictive difference between the standard quantum approaches and the statistical approach

Please, explain.
 
  • #48
Mark M said:
And since Bell showed that there is a definite predictive difference between the standard quantum approaches and the statistical approach, the agnostic position was eliminated.

Hold it, how does the agnostic position also become eliminated from this?
 
  • #49
Interesting discussion by the way, I've enjoyed reading this thread. I'd like to make some comments here and there, but I have to wait until later (I'm quite too tired to think straight for this kind of discussion at the moment :bugeye:). Btw, James, I don't think you can change the poll, but you could start a new one with more options (e.g. some examples here) later if you'd like to, perhaps?
 
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  • #50
ParticleGrl said:
Well, that's clearly not true. Bell's theorem rules out classes of hidden variables, it doesn't tell us how to interpret the wavefunction.

Also, macroscopic super-positions might kill GRW/objective collapse stuff, but why would they rule out an ensemble interpretation?

I once read that the quantum-zeno effect was a killer for ensemble interpretations, but I've never looked at the arguments around this.
Please, explain.

Maybe I'm misunderstanding. The ensemble approach was Einstein's opinion of QM, correct? If so, it states that wavefunctions are mathematical abstractions that describe particle behavior, but particles do not actually exist within superpositions. Hence, the experiments based on Bell's Theorem showed that quantum entanglement really did involve a superposition prior to measurement. Obviously, if QE involved superpositions, so would the wavefunction.

Also, macroscopic superposition is just that, a superposition. Which contradicts the ensemble interpretation's view that single states do not exist in superpositions. Look at ensemble interpretation under this chart:
http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics#Comparison
Thanks for the reply!
lmoh said:
Hold it, how does the agnostic position also become eliminated from this?

Bell showed that if particles existed in a superposition before prior to measurement, there is an observable difference in comparison to a purely statistical approach. Quoting the textbook An Introduction to Quantum Mechanics by Griffith:

"Until recently, all three positions had their partisians. But in 1964 John Bell astonished the physics community by showing it makes an observable difference if the particle had a precise (but unknown) position prior to measurement. Bell's discovery had essentially eliminated agnosticism as a viable option, and made it an experimental question weather 1 or 2 is the correct choice."
 
  • #51
Perhaps I am misunderstanding what you mean by "agnostic position". Is this another word for the statistical approach or are you referring to another interpretation?
 
  • #52
ParticleGrl said:
I once read that the quantum-zeno effect was a killer for ensemble interpretations,
It's not (at least as of 1991)...

but I've never looked at the arguments around this.
Here are 3 relevant papers:

Itano et al, "Quantum Zeno effect"
Phys. Rev. A 41, 2295 (1990)

Abstract: The quantum Zero effect is the inhibition of transitions between quantum states by frequent measurements of the state. The inhibition arises because the measurement causes a collapse (reduction) of the wave function. If the time between measurements is short enough, the wave function usually collapses back to the initial state. We have observed this effect in an rf transition between two 9Be+ ground-state hyperfine levels. The ions were confined in a Penning trap and laser cooled. Short pulses of light, applied at the same time as the rf field, made the measurements. If an ion was in one state, it scattered a few photons; if it was in the other, it scattered no photons. In the latter case the wave-function collapse was due to a null measurement. Good agreement was found with calculations.

Shortly after, Ballentine published the following refutation of its claims about the effect being due to wave function collapse:

L. E. Ballentine, "Comment on 'Quantum Zeno effect' "
Phys. Rev. A 43, 5165–5167 (1991)

Abstract:The quantum Zeno effect is not a general characteristic of continuous measurements. In a recently reported experiment [Itano et al., Phys. Rev. A 41, 2295 (1990)], the inhibition of atomic excitation and deexcitation is not due to any ‘‘collapse of the wave function,’’ but instead is caused by a very strong perturbation due to the optical pulses and the coupling to the radiation field. The experiment should not be cited as providing empirical evidence in favor of the notion of ‘‘wave-function collapse.’’

Then came the reply of Itano et al, in which they back-peddle away from the belief that the experiment "proves" wave function collapse:

Itano, et al, Reply to ``Comment on `Quantum Zeno effect'''
Phys. Rev. A 43, 5168-5169, (1991)

Abstract:Various interpretations of quantum mechanics are valid insofar as they predict the same experimental results. Some invoke ``wave-function collapse'' and some do not. An interpretation based on the collapse postulate provides a simple explanation for a recent experimental demonstration of the quantum Zeno effect [Itano et al., Phys. Rev. A 41, 2295 (1990)], but other interpretations are also valid.

So the Itano experiment does not kill the ensemble interpretation in favour of collapse. They simply use collapse to give a "simple explanation". (Translation: dumbed-down, don't-ask-inconvenient-questions... )

IMHO, the most important bit in all this is the last sentence of the 1st Itano abstract above:

Good agreement was found with calculations.

One might claim that this therefore supports the SU&C* interpretation, but this option wasn't listed in the poll alternatives of this thread.

[*] Shut Up & Calculate.
 
  • #53
Mark M said:
Maybe I'm misunderstanding. The ensemble approach was Einstein's opinion of QM, correct? If so, it states that wavefunctions are mathematical abstractions that describe particle behavior, but particles do not actually exist within superpositions.

I am referring to the interpretation usually associated with Ballentine and his textbook (which is why I referenced it).
 
  • #54
I voted for 'other' because I don't understand any of the various interpretations of QM well enough to pick one over all the others. It is, however, interesting and fun to consider the various alternative approaches (as far as I'm capable of actually considering them). I really enjoyed the fairly recent exchange between Hurkyl and Ken G on MWI. Demystifier has demystified a lot wrt the dBB interpretation. And I like jambaugh's take on the CI.

Interpreting the Quantum World by Asher Peres
This is an "Essay-Review" of a book with the same title, by Jeffrey Bub (Cambridge University Press, 1997).
Stud. History Philos. Modern Physics 29 (1998) 611
http://arxiv.org/pdf/quant-ph/9711003.pdf

Quantum Theory Needs No "Interpretation" by C. A. Fuchs and Asher Peres
An opinion article published in the March, 2000 Physics Today.
http://www.scribd.com/matheus_corr%C3%AAa_3/d/46812463-Fuchs-Christopher-Quantum-Theory-Needs-No-Interpretation

Quantum Theory: Interpretation Cannot be Avoided by Eric Dennis and Travis Norsen
A response to the Fuchs and Peres Physics Today essay.
http://arxiv.org/pdf/quant-ph/0408178.pdf
 
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  • #55
lmoh said:
Perhaps I am misunderstanding what you mean by "agnostic position". Is this another word for the statistical approach or are you referring to another interpretation?

The agnostic interpretation is the lack of any interpretation. It states there is no difference between orthodox quantum mechanics and the statistical interpretation, so, it is pointless to speak about it. Since Bell showed there is a difference, this position is eliminated.
 
  • #56
Mark M said:
The agnostic interpretation is the lack of any interpretation. It states there is no difference between orthodox quantum mechanics and the statistical interpretation, so, it is pointless to speak about it. Since Bell showed there is a difference, this position is eliminated.

You can still be agnostic about other interpretations though, just not the statistical approach. From what I've read, I got the impression that you think this point is somehow eliminated by eliminating the statistical approach.
 
  • #57
lmoh said:
You can still be agnostic about other interpretations though, just not the statistical approach. From what I've read, I got the impression that you think this point is somehow eliminated by eliminating the statistical approach.

Oh, I was referring to the agnosticism regarding the interpretations that consider the wavefunction to be real, and the statistical interpretation. Obviously, you can still be agnostic about the ones being voted on here.
 
  • #58
DennisN said:
Btw, James, I don't think you can change the poll, but you could start a new one with more options (e.g. some examples here) later if you'd like to, perhaps?

I think I might, but the discussion here is so beautiful it would be sad to see it die with the thread. Unless people kept both threads alive... well, I think I will bet on the last part and make a new thread!

---EDIT:

New thread here!
 
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