Possibility that all current interpretations of QM are wrong

[joegibs]

Is there a possibility that none of the current interpretations of QM are right?
Or is the current interpretations all that there will be on the table?

 

[Orodruin]

Is there a possibility that none of the current interpretations of QM are right?

Of course.

 

[mfb]

It is not even clear if "right" is a meaningful classification.

It is possible that new interpretations will be developed in the future.

 

[joegibs]

It is not even clear if "right" is a meaningful classification.

It is possible that new interpretations will be developed in the future.

Do you think that an interpretation as follows could be possible in the future?
The wave function is objectively real (no hidden variables). There is wave function collapse but it doesn't happen instantaneously, it's a physical process that occurs at sublight speed. And it is a local theory. Is this a possible future interpretation?

 

[mfb]

Quite sure that is ruled out by Bell tests.

 

[joegibs]

Quite sure that is ruled out by Bell tests.

Which part?

 

[Nugatory]

Which part?

We have https://arxiv.org/abs/1303.0614 which shows that if collapse of a Bell state is a physical process, it's not one that propagates at sublight speeds. And of course the (too many to list here) observed violations of Bell's inequality show that no theory in which the wave function is objectively real can be local.

 

[joegibs]

We have https://arxiv.org/abs/1303.0614 which shows that if collapse of a Bell state is a physical process, it's not one that propagates at sublight speeds. And of course the (too many to list here) observed violations of Bell's inequality show that no theory in which the wave function is objectively real can be local.

Is it possible that it really does propagate faster than light? Is it possible that relativity is incomplete?

 

[mfb]

Would be surprising. Everything faster than light in one reference frame is backwards in time in other reference frames. There is no indication that any reference frame would be special, and violating causality unnecessary would be odd as well.

 

[bohm2]

Do you think that an interpretation as follows could be possible in the future?
The wave function is objectively real (no hidden variables). There is wave function collapse but it doesn't happen instantaneously, it's a physical process that occurs at sublight speed. And it is a local theory. Is this a possible future interpretation?

Retrocausal interpretations would meet these criteria. Such models are consistent with Special Relativity and restore locality to nonrelativisitc quantum mechanics. They also restore time-symmetry to microphysics. See:

A live alternative to quantum spooks
https://arxiv.org/pdf/1510.06712.pdf

 

[durant35]

Would be surprising. Everything faster than light in one reference frame is backwards in time in other reference frames. There is no indication that any reference frame would be special, and violating causality unnecessary would be odd as well.

MWI suffers from similar flaws when combined with SR

https://www.physicsforums.com/threads/mwi-and-special-relativity.412608/

 

[Zafa Pi]

Is it possible that it really does propagate faster than light? Is it possible that relativity is incomplete?

The type of FTL phenomena that accounts for the correlations in distant measurements (no matter/energy or information transfer) doesn't appear to be in conflict with relativity.

 

[LeandroMdO]

Certain minimalistic interpretations (Ballentine's ensemble interpretation, Original Copenhagen etc) don't claim anything more than the axioms of quantum mechanics themselves do, so they'll never be "wrong" unless quantum mechanics itself is wrong.

 

[Vanadium 50]

First, by definition all interpretations make the same predictions. If they make different predictions, they are different theories.

A consequence of that is that there is no scientific way to say which is right and which is wrong. To take an example from E&M, is the method of images a right or wrong interpretation?

Next, it looks a lot like the OP is proposing personal theories. We don't discuss them on PF.

 

[mfb]

MWI suffers from similar flaws when combined with SR

https://www.physicsforums.com/threads/mwi-and-special-relativity.412608/

It is different. For MWI you don't have to agree when worlds split, different observers can have different conclusions without issue. If you assume a physical collapse process, you have to define when it happens.

 

[durant35]

It is different. For MWI you don't have to agree when worlds split, different observers can have different conclusions without issue. If you assume a physical collapse process, you have to define when it happens.

But if you assume some type of cloning of worlds while branching, it still sounds confusing. So you would say that there are absolutely no issues when combining MWI and SR?

 

[mfb]

But if you assume some type of cloning of worlds while branching, it still sounds confusing. So you would say that there are absolutely no issues when combining MWI and SR?

I don't see where. MWI is local, all the experiments don't depend on what is happening at spacelike separation. If you look at coincidence counts later it does matter, but comparing those results happens at lightlike or timelike distances. Every observer can assume that branching happens according to their reference frame, because there is no need to agree on a time-ordering of the processes.

If wave function collapse is an actual and observer-independent process, then it has to have some time-ordering.

 

[Karolus]

Established that in my opinion, to quote Feynman, no one understands quantum mechanics, I believe that among the "different interpretations", the Copenhagen interpretation "Orthodox" is the most consistent. Although it has elements of ambiguity, the Copenhagen interpretation seems to me the most coherent and more representative of the experimental data. Furthermore it is the most "practical", in order use of the calculations. For example, in the interpretation MW, where are the "other worlds"? There are experimental evidence for the existence of them? It is more simple, in terms of the calculations, thinking that the function of wave collapses, rather, that continue in another space, or the world or universe that is. I'm not saying that the MWI is "wrong." But a quantum physicist, has some practical benefit to use for practical purposes (ie calculation) this interpretation?

 

[vanhees71]

One has to specify what's meant by "Copenhagen interpretation". There are plenty of flavors. I can only accept Copenhagen flavors which do not assume an instantaneous collapse. The only interpretation that's consistent for me is the minimal statistical interpretation (also known as "ensemble interpretation"). It just takes the formalism, including the Born rule, i.e., it gives the usual probabilistic meaning to the quantum state, and that's how experiments are indeed done, i.e., one prepares a lot of equally prepared quantum systems (ensembles) and analyses the outcome of measurements statistically.

 

[dkotschessaa]

Is there a possibility that none of the current interpretations of QM are right?
Or is the current interpretations all that there will be on the table?

All scientific theories have a possibility of being wrong.

 

[DrChinese]

All scientific theories have a possibility of being wrong.

If you judge theories by their utility, then no single theory is best in all respects. You could say they are all wrong, if what you are looking for is the "final" and "correct" theory of something. The best we can hope for is a "better" theory for some specified scope of behavior.

 

[Karolus]

all in all, you could say, reversing the original question of the thread, that all interpretations of QM are right...

 

[newjerseyrunner]

Are interpretations even useful for anything other than theorizing about GUT? Whether you believe that pilot waves are pushing particles around, or if the particle takes all paths at once and collapses, does it matter in the slightest if the math describes what we see?

 

[Nugatory]

Are interpretations even useful for anything other than theorizing about GUT?

It's not clear that they're useful even for that purpose.

 

[bhobba]

It's not clear that they're useful even for that purpose.

I don't think they are useful for that.

IMHO their usefulness is in elucidating exactly what the formalism does or does not imply.

Thanks
Bill

 

[Zafa Pi]

We have https://arxiv.org/abs/1303.0614 which shows that if collapse of a Bell state is a physical process, it's not one that propagates at sublight speeds. And of course the (too many to list here) observed violations of Bell's inequality show that no theory in which the wave function is objectively real can be local.

So if you look at Price, he says in Q2 that in MWI the wave function is objectively real, and in Q12 that MWI is local.
Blaylock also says the same, but goes on to say that MWI is nonCFD.
What do you make of this?

 

[Elias1960]

Do you think that an interpretation as follows could be possible in the future?
The wave function is objectively real (no hidden variables). There is wave function collapse but it doesn't happen instantaneously, it's a physical process that occurs at sublight speed. And it is a local theory. Is this a possible future interpretation?

This construction would fit into the general scheme of an Einstein-local realistic theory as used in Bell's theorem, thus, would forbid violations of the Bell inequalities. Thus, it would not be a QM interpretation.

 

[vanhees71]

and it would be "wrong" given the empirical facts about the violation of Bell's inequalities and the "accurateness" of the quantum predictions ;-).

 

[Elias1960]

So if you look at Price, he says in Q2 that in MWI the wave function is objectively real, and in Q12 that MWI is local.
Blaylock also says the same, but goes on to say that MWI is nonCFD.
What do you make of this?

I personally make out of this that MWI is pseudoscience. Nothing in this interpretation is well-defined, it makes not even sense to talk about probabilities, but they nonetheless "prove" that their "probabilities" follow the Born rule, and, as usual in inconsistent theories, one can derive everything. Sorry, I could not resist.

 

[mfb]

MWI is the interpretation you necessarily get if you take the equations of quantum mechanics and don't add any magic. It is the most well-defined interpretation.

 

[Demystifier]

MWI is the interpretation you necessarily get if you take the equations of quantum mechanics and don't add any magic. It is the most well-defined interpretation.

It's the most well defined intrinsically, as an interpretation of the Schrodinger equation itself. But when it comes to extrinsic interpretation, namely to interpretation of the experimental observations in terms of those equations, MWI has serious problems.

 

[DarMM]

MWI is the interpretation you necessarily get if you take the equations of quantum mechanics and don't add any magic. It is the most well-defined interpretation.

You also have to take the wavefunction as representing a real wave and you have a lack of clarity with the Born rule. This can be sorted out, but MWI after sorting out the Born rule has very similar ambiguities to other interpretations.

 

[mfb]

But when it comes to extrinsic interpretation, namely to interpretation of the experimental observations in terms of those equations, MWI has serious problems.

I see that differently, but this has been discussed a lot already and I don't want to start yet another iteration of that discussion.

 

[DarMM]

I see that differently, but this has been discussed a lot already and I don't want to start yet another iteration of that discussion.

If at some point you want to discuss it, it would be interesting to hear as even most MWI authors don't see it that way. They see getting experimental observations out as requiring a lot of additional structure with the details unresolved.

 

[Elias1960]

MWI is the interpretation you necessarily get if you take the equations of quantum mechanics and don't add any magic. It is the most well-defined interpretation.

I disagree. You have to add a lot of magic. And the equations of quantum mechanics are simply ignored.

From the Schroedinger equation follows, last but not least, a continuity equation for $\rho(q)=|\psi(q)|^2$. According to MWI, this is a continuity equation for something which does not exist.

 

[mfb]

If at some point you want to discuss it, it would be interesting to hear as even most MWI authors don't see it that way. They see getting experimental observations out as requiring a lot of additional structure with the details unresolved.

No, my point was that we discussed it way too often already. One of many threads.

According to MWI, this is a continuity equation for something which does not exist.

Of course it exists! It's the reason to care about the squared amplitude and therefore a critical element of hypothesis testing, see above.

But as I said: I'm not interested in yet another iteration of these discussions, this will be my last post on MWI here.

 

[kith]

No, my point was that we discussed it way too often already. One of many threads.

I just reread part of this thread and FWIW I'm still interested in understanding your position. Now that @DarMM has noticed it, I'm actually hoping that he uses his magic powers and translates it like he did with the thermal interpretation. ;-)

 

[entropy1]

Do you think that an interpretation as follows could be possible in the future?
The wave function is objectively real (no hidden variables). There is wave function collapse but it doesn't happen instantaneously, it's a physical process that occurs at sublight speed. And it is a local theory. Is this a possible future interpretation?

If I am correct, the worlds in MWI are orthogonal, so if a certain measurement yields A, B and C for worlds, and for sake of argument you end up in world B, then that may subjectively be seen as a collapse (into world B).

 

[physika]

Is there a possibility that none of the current interpretations of QM are right?

Yes.

or perhaps one is correct.

Collapse Models
has different predictions, so it can be tested.

 

[Elias1960]

If I am correct, the worlds in MWI are orthogonal, so ...

If MWI worlds are orthogonal, this would require an additional structure which nobody has proposed yet.
So, let's simply denote the set of all those orthogonal worlds with Q, and a particular world with $q \in Q$. Just a denotation. Then, the most general wave function would be a $\mathbb{C}$-valued function on Q. So, there would be a preferred base, namely the configuration space base Q.

But a main selling point of MWI is their claim that they don't need any additional structure, they simply take QT as it is. Different from evil dBB, which prefers Q.

 

[PeterDonis]

If MWI worlds are orthogonal, this would require an additional structure which nobody has proposed yet.

No, it wouldn't. It just requires that the different terms in the entangled wave function that describes the system + observer + environment after measurement are orthogonal. In practice this won't be exactly true, but it will be true to a very good approximation once decoherence has happened.

 

[Elias1960]

No, it wouldn't. It just requires that the different terms in the entangled wave function that describes the system + observer + environment after measurement are orthogonal.

And how does one split the wave function if one has nothing but the wave function, without any additional structure?

Instead of defining such a structure in precise terms, MWI uses handwaving verbal descriptions and refer to particular situations where things are obvious, like Schroedinger's cat. Of course, for Schroedinger's cat it does not matter if you use configuration space or phase space, the dead and the living cat will be (approximately) orthogonal.

But this is not what a reasonably well-defined interpretation should provide. Once one claims to have no additional structure, one should not use verbal handwaving about Schroedinger cats to define those worlds but use precise well-defined fundamental structures.

 

[vanhees71]

The physical predictions of QM are interpretation independent.

If you have alternative models, which make different predictions than standard QM you have physically different theory, which can be tested against QM, and then an appropriate experiment must decide about which theory is the better one.

 

[PeterDonis]

how does one split the wave function

MWI doesn't "split" the wave function. Everything in the MWI is unitary and preserves information; there is no "splitting".

 

[Elias1960]

MWI doesn't "split" the wave function. Everything in the MWI is unitary and preserves information; there is no "splitting".

What are, in this case, those "different terms in the entangled wave function that describes the system + observer + environment after measurement"? IMHO there are no such "different terms" without some structure which makes them different, and without some well-defined operation which splits the wave function into such "different terms".

(My main objection against MWI is that it is not a well-defined interpretation at all. It is diffuse handwaving using imprecise notions which seem plausible only in some particular situations. If one asks for clarification of the meaning of these notions, one never gets precise answers.)

 

[PeterDonis]

What are, in this case, those "different terms in the entangled wave function that describes the system + observer + environment after measurement"?

The terms that come from the interaction Hamiltonian that entangles the system + observer + environment. In the simplest case, where we don't include a separate environment, say the system is a qubit in the z-spin up state and the measurement is a Stern-Gerlach measurement in the x direction. Then the initial state is a product state of the qubit z-spin up (written in the spin-x basis since that's what we're going to measure) and the observer's "waiting to observe result" state. So we have (ignoring normalization):

$$
\Psi_\text{before} = \left( | + \rangle + | - \rangle \right) | \text{waiting to observe result} \rangle
$$

After the measurement, the qubit's state is now entangled with the observer's state, so we have:

$$
\Psi_\text{after} = | + \rangle | \text{observed x spin up} \rangle + | - \rangle | \text{observed x spin down} \rangle
$$

Showing that the unitary evolution induced by the interaction Hamiltonian takes us from $\Psi_\text{before}$ to $\Psi_\text{after}$ is straightforward given the definition of a Stern-Gerlach measurement in the x direction.

 

[kith]

What are, in this case, those "different terms in the entangled wave function that describes the system + observer + environment after measurement"? IMHO there are no such "different terms" without some structure which makes them different, and without some well-defined operation which splits the wave function into such "different terms".

I would put it like this: In the MWI, the fundamental ontological object is the universal wavefunction / state. Whether the "different terms" are there or not, isn't a property of the wavefunction or of the Hilbert space but depends on how (or whether) the Hilbert space is divided into subspaces. This is something which the observer does in order to describe his experiments.

So in a sense, it is the observer who puts the many worlds into the MWI. They aren't inherently present or well-defined in the universal wavefunction and the Hilbert space.