I "Single-world interpretations.... cannot be self-consistent"

[LeandroMdO]

To get a "single-world" from this, it seems to me that you need a second kind of dynamics (the hidden-variables of Aaronson, or Bohm) that selects one possibility out of the two possible measurement states.

To get many worlds you also need another kind of dynamics that separates the mental states of the observers. The final state is a state in a superposition, not necessarily a state with "many worlds". It must first be proved that the many worlds interpretation is correct before making this assertion.

The main question is this: what kind of models are describable by the mathematics of quantum mechanics? It's clear that there are many-world models that satisfy that property, but it's also clear that there are models with a single world that also do. We can use the flow model, or the Schrödinger model, or any other such hidden variable model to construct either possibility. For that reason, any attempt to argue that either many-world interpretations or single-world interpretations are logically impossible is doomed to fail. More assumptions other than the pure axioms of quantum mechanics are needed to establish this.

 

[LeandroMdO]

I don't think that is a consistent interpretation, in light of Bell's theorem. I think that the video does a pretty good job of explaining why that doesn't work.

Bell's theorem says nothing one way or the other about whether it is logically possible to minimally interpret the quantum state as a generalization of a probability distribution. Certainly it says that it is not possible to do so in a local classical theory, so the correct interpretation is that if the fundamental theory of reality is local it is not classical, and if it is classical it is not local.

In fact, even in a theory with many-worlds this minimal interpretation of the quantum state as a book-keeping device would be correct! The many-worlds ontology would then be an explanation of why the rules work. Copenhagen truly is a minimal interpretation in the sense that every correct interpretation of quantum mechanics must agree with it:
1. Observers construct states (rays in Hilbert spaces), which are defined and evolve according to specific rules.
2. After a "measurement", the observer must update his description of the system to reflect the measurement outcome.

That is it -- whether there is a single world in which measurement outcomes happen, or whether there's a tree of irreversibly branching worlds is not relevant. The only difference in the latter case is that the observer makes an update that is only valid for his branch of the wavefunction. But that's okay, because his brothers will make updates reflecting the other possibilities.

 

[Denis]

Very nice description of the relationship between Bohmian mechanics and Copenhagen. Is that original with you?

Thanks. Yes. But I see it misses one difference, namely that in dBB the wave function is ontological, in CI not. But to reinterpret some really existing object as describing only knowledge about some object is also some sort of getting rid of what we cannot see.

See other posts but the problem with Bell's theorem only exists if you mistakenly (in absolute opposition to CI) reify the wave function. Bell's theorem negates the ANTI-Copenhagen interpretation of the wave function as a model of some physical reality...

No, given that an interpretation which "reifies" the wave function - dBB - has no problem with Bell's theorem.

 

[zonde]

Are you kidding me? Of course they're a part, they're even an essential to explanation. And hence the base root of everything is your definitional primitives. In modern axiomatic mathematics you begin with undefined terms because (pure) mathematics is a conceptual construct. These terms are the foundation and their meaning comes from their use in the structure of the axioms and subsequent definitions.

Your answer is inconsistent with your earlier answer:

Primitive term in definition, not in explanation.

However in science we begin with operational primatives by which we can assert "if you do this then that will always occur."

I disagree. "if you do this then that will always occur" is a prediction and in science we don't start with predictions.

Now you're just being silly. By that argument we should stick with the aether version of Lorentz relativity rather than Einstein's SR?

Do you say that predictions using Lorentz relativity where made and published before SR? I might have hole in my knowledge about historical situation at the time when SR came up, but I won't believe you without proper reference.

Or for that matter, conspiring demons and deities since they "explain" everything and came first in our theories of the world. Chronology is irrelevant to truth or whether something is irrelevant to the truth. Go back to my prior post and try again.

Now you are silly. Since when explanations based on conspiring demons and deities can make equally good predictions about reality as scientific theories?

I'm trying to enlighten you to the need to subdivide your concepts. The change in common terminology happened before I came onto the scene because there are two meanings (in science) to the word interpretation. Let's use whatever words you like but let's both use the same words in the same way.

First concept: What I call an interpretation is...
A system by which we translate the concepts, terms and symbols on paper into actions and observations in the laboratory. The correspondence rules to which you referred. Call this praxic interpretation. (praxic as in pragmatic, as in operational, as in positivistic).

Second concept: What I think you are calling an interpretation...
An ontological model (world picture) of what is going on beyond the praxic interpretation. A hypothesized state of the reality of objects as they are with objective properties as they are. Call this the ontic intepretation. But I call it a ontological model.

[For a reference these praxic vs ontic qualifiers, I got them from David R. Finkelstein, see his book Quantum Relativity.]

Perhaps you don't like my definitions above and you would like to rephrase them. I am after all trying to make a specific point and I may in point of fact be biased in my wording.

"Correspondence rules" is common term in philosophy of science:
https://plato.stanford.edu/entries/structure-scientific-theories/#IntTheStrPerSynVie

Suggest what you like but can you not agree that the Orthodox CI is fundamentally different in nature from say Bohm's Pilot waves and Everetts MW in that it is a praxic interpretation* while these others are ontic interpetations. *(praxic interpretation plus a stronger assertion that we should refrain from any ontic interpretations hence its conflict with these others.)

CI says that there is no deeper reality of individual members of quantum system ensembles than that given by wave function i.e. there are no hidden variables. I see this claim ontic enough to disagree with you. In contrast minimal statistical (ensemble) interpretation remains agnostic about existence of hidden variables so this is the one I would consider purely phenomenological ("praxic interpretation" as you call it).

That is not quite what I am saying. What we feel or want is irrelevant. Nature is as nature is. And the nature of our questing toward understanding things is that we observe things happen and construct mental models to "explain them". As we push deeper and deeper there must always be a level of praxic interpretation below the level of ontic interpretation to give it meaning in any scientific sense. Either it is perpetual chicken and egg and we never stop delving deeper or there is some level past which we cannot resolve. Maybe our current phenomonlogical wall can be pushed deeper but for now we cannot resolve any observables below the level of those in QM. (There are no probes that get us past Heisenberg's uncertainty principle).

Just as with the literal chicken and egg question there's a natural starting point (an egg is an egg whether it's a chicken egg or not...) there is a natural starting point in Science based on the scientific method. An act of observation is an act of observation whether it is consistent with one or many ontological interpretations or not. You can say EMW or BPW models "explain" quantum phenomena but they are of the "Gods and Demons" variety of explanation in that they are not testable. It is thus scientifically meaningless to say one or the other is true. If in future they become testable then they will be testable with a new set of operations in the lab/observatory. These new operations will be there first before the tests can be performed and you can again argue over the "interpretations" beyond their pragmatic meaning...

I disagree that "correspondence rules" (praxic interpretation) is deeper than ontic models. "Correspondence rules" is a bridge that connects ontic model with reality.
But I agree that current explanations that do not make any testable predictions beyond some common set of already known experimental facts does not lead to any new scientific knowledge. At best these models can be viewed as "working hypotheses" with the hope that in the future they will be modified so that they give novel testable predictions.

 

[jambaugh]

Your answer is inconsistent with your earlier answer

Because you're excerpt was my description of *mathematics* given for comparison to science...

I disagree. "if you do this then that will always occur" is a prediction and in science we don't start with predictions.

no that is our end, but to give meaning to those predictions we must define "doing this" vs "doing that", the words used to make those predictions are the primatives and their meaning is based on their use to make those predictions... and thus terms that have no empirical connection to predictions which can fail are without meaning.

Do you say that predictions using Lorentz relativity where made and published before SR? I might have hole in my knowledge about historical situation at the time when SR came up, but I won't believe you without proper reference.

Why do you think they're called Lorentz transformations and not Einstein transformations... (digging up reference here...)
Lorentz, Hendrik Antoon (1904), "[URL='https://en.wikisource.org/wiki/Electromagnetic_phenomena']Electromagnetic phenomena in a system moving with any velocity smaller than that of light", Proceedings of the Royal Netherlands Academy of Arts and Sciences, 6: 809–831[/URL]

Lorentz's famous transformations were developed to explain the MM experiment and that explanation utilized the concept of an aether which acting upon measuring rods caused them to shorten, and acting upon clocks caused them to slow according to the Lorentz's transformations in such a way as to make determination of ones motion through the aether unobservable. Einstein's contribution (in SR) was to take the unobservability of the aether as reason to excise it and take seriously the actual relativity of time. But the mathematics is identical to the Lorentz et al's aether version and the likewise the subsequent predictions had Einstein simply stuck with the Aether Model but continued with the E=mc^2 (in the rest frame) awkward as it may have been. This is why you keep seeing "Einstein was wrong" posts in the usenet forums every month or so with their rediscovery of aether models of relativity.

Now you are silly. Since when explanations based on conspiring demons and deities can make equally good predictions about reality as scientific theories?

They can if I ascribe to their personalities the desire and to their abilities the power to make systems obey e.g. Schrodinger's equation. Yes it is silly, but so to is the notion of infinite worlds being created every instant as quantum systems evolve. It is an example of hyperbole.

"Correspondence rules" is common term in philosophy of science:
https://plato.stanford.edu/entries/structure-scientific-theories/#IntTheStrPerSynVie

CI says that there is no deeper reality of individual members of quantum system ensembles than that given by wave function i.e. there are no hidden variables. I see this claim ontic enough to disagree with you. In contrast minimal statistical (ensemble) interpretation remains agnostic about existence of hidden variables so this is the one I would consider purely phenomenological ("praxic interpretation" as you call it).

Yes you are correct there. CI has an additional positivists caveat. It is by analogy the difference in saying the aether in relativity is not observable and asserting there is no aether. It is the difference in theology between being a pure agnostic or an agnostic atheist (believing there is no God but there is no means to prove or give evidence of that belief). You are welcome to reject CI in favor of Von Neuman's ensemble interpretation. I don't see a real difference. I reject the aether as a meaningful concept (in SR). I reject reality between measurements as a meaningful concept.

I disagree that "correspondence rules" (praxic interpretation) is deeper than ontic models. "Correspondence rules" is a bridge that connects ontic model with reality. But I agree that current explanations that do not make any testable predictions beyond some common set of already known experimental facts does not lead to any new scientific knowledge. At best these models can be viewed as "working hypotheses" with the hope that in the future they will be modified so that they give novel testable predictions.

Which is why I distinguish models from theories. As I've been using the terms for the past decades, Scientific Theories are systems of empirical prediction. Models are scaffolding for theories which include ontological hypotheses but as I qualify it should be taken as models and their ontology not necessarily be taken seriously. I may be deviating from some common usage of the terms but it is to my mind a natural divide. My essential point is that theories don't necessarily need models and QM is a theory for which CI chooses to actively reject the use of models.

I am find with agreeing to disagree w.r.t. one's personal beliefs. My ire is raised with CI is misrepresented and inanely "proven to be scientifically untenable" by means of its misrepresentation. (You = anybody reading this for...) If you choose to accept Jesus Christ as your Lord and Savior, then fine. If you choose to have faith in pilot waves guiding the very atoms, then fine! If you choose to believe in infinite worlds, in one of which you won the lottery, then fine. But it is an act of faith not science.

 

[jambaugh]

Thanks. Yes. But I see it misses one difference, namely that in dBB the wave function is ontological, in CI not. But to reinterpret some really existing object as describing only knowledge about some object is also some sort of getting rid of what we cannot see.No, given that an interpretation which "reifies" the wave function - dBB - has no problem with Bell's theorem.

Careful with the logic there. "Only exists if..." as in is a necessary condition for there being a problem. You're asserting it is not a sufficient condition which it is not and which was not my claim. My criticism of dBB is not that it runs afoul of Bell, it can't as it agrees with QM.

My problem with dBB is twofold. The aforementioned unobservability and also the point of its formulation is to provide a consistent reality but (as I understand dBB which may be quite wrong!) the necessity of causal propagation of pilot waves FTL and back in time undermine the very objectivity of the reality one is trying to assert. If the future may update the present then the present state of reality is contingent and hypothetical.

 

[zonde]

Which is why I distinguish models from theories. As I've been using the terms for the past decades, Scientific Theories are systems of empirical prediction. Models are scaffolding for theories which include ontological hypotheses but as I qualify it should be taken as models and their ontology not necessarily be taken seriously. I may be deviating from some common usage of the terms but it is to my mind a natural divide. My essential point is that theories don't necessarily need models and QM is a theory for which CI chooses to actively reject the use of models.

Say, do you take "atoms" seriously?

 

[jambaugh]

Say, do you take "atoms" seriously?

As phenomena? yes. As objects with objective state? Yes when I'm working at the classical level (gross position and momentum and low enough energies). But then as a contingent model for the underlying quantum phenomenology.

Note by the way, I can be perfectly serious about the meaning of "solid" vs "liquid" vs "gas" and at the same time point out that these lose meaning when talking about individual atoms. To my mind, "objective reality" is a similar emergent property which is perfectly useful in context but becomes meaningless when we resolve things beyond a certain point.

 

[Boing3000]

That is an interesting discussion (at least from my layman's perspective)

I reject the aether as a meaningful concept (in SR). I reject reality between measurements as a meaningful concept.

But yet, even if you take the minimal ensemble interpretation, because after all QM only describe probabilities on ensemble of events, you won't go so far as to say that elements composing those ensemble do not exist ?

(as I understand dBB which may be quite wrong!) the necessity of causal propagation of pilot waves FTL

My understanding is that the pilot wave only evolve in time and not in space. So I don't think it "propagate" in any classical(SR) sense. It seem to be very well in tune with what Bell's inequality allow us to guess about the underlying process/model.
I also am under the impression that some form of determinism is reintroduced by the pilot wave. Wouldn't that open the door for true new behavior/falsifiability ?

 

[zonde]

As phenomena? yes. As objects with objective state? Yes when I'm working at the classical level (gross position and momentum and low enough energies). But then as a contingent model for the underlying quantum phenomenology.

"Atom" is not a phenomena. It is unobservable ontic entity in many models. But without this unobservable ontic entity and models that are built on it many scientific theories would become unimaginably contrived.
What value your position then has?

Note by the way, I can be perfectly serious about the meaning of "solid" vs "liquid" vs "gas" and at the same time point out that these lose meaning when talking about individual atoms. To my mind, "objective reality" is a similar emergent property which is perfectly useful in context but becomes meaningless when we resolve things beyond a certain point.

Scientific approach assumes "objective reality" as given (experimental facts, their records, shared information etc. are objective). If you want to investigate possibility that it is not as objective as it is assumed you would have to develop different philosophical framework for that. So it's not science anyways.

 

[AlexCaledin]

This is probably the best philosophical framework!

"Suppose that physics, or rather nature, is considered analogous to a great chess game with millions of pieces in it, and we are trying to discover the laws by which the pieces move. The great gods who play this chess play it very rapidly, and it is hard to watch and difficult to see."

Richard P. Feynman, https://www.amazon.com/dp/0679601279/?tag=pfamazon01-20, page 53

 

[jambaugh]

That is an interesting discussion (at least from my layman's perspective)

But yet, even if you take the minimal ensemble interpretation, because after all QM only describe probabilities on ensemble of events, you won't go so far as to say that elements composing those ensemble do not exist ?

Nope, because while the probabilities describe ensemble events (and thus too the wave functions as they are utilized) the measurements are singular events (hence the need to collapse our descriptions.) An electron detector goes 'click' and each time I identify that as the detection of a singular electron, that is what an electron is as a phenomenon and I believe that phenomenon exists. I must in order to believe in the resulting sample proportions. I then looking at many such clicks over many detectors can derive proportions and compare to calculated probabilities and confirm or falsify QM predictions.

My understanding is that the pilot wave only evolve in time and not in space. So I don't think it "propagate" in any classical(SR) sense. It seem to be very well in tune with what Bell's inequality allow us to guess about the underlying process/model.
I also am under the impression that some form of determinism is reintroduced by the pilot wave. Wouldn't that open the door for true new behavior/falsifiability ?

As for propagation (and again I'm inexpert here) I assumed it obeyed the same superposition principle as e.g. classical EM waves. Thus although you can speak of the totality of the EM field over space only propagating in time, one can also speak of components causally propagating at the speed of light thus through space and time as with e.g. the light on my car's blinker signaling my turn.

With respect to falsifiability, not when the non-time-forward causality is fundamentally unobservable... (like the unobservable but asserted instantaneous communication between EPR pairs when you assert reality of the wave function.) I am not fully up to speed with dBB interpretation though so I would refer you to someone who has studied it in more depth.

 

[jambaugh]

"Atom" is not a phenomena. It is unobservable ontic entity in many models. But without this unobservable ontic entity and models that are built on it many scientific theories would become unimaginably contrived.
What value your position then has?

Yes the atom is an unobservable ontic entity in many models. It is also an observable quantum phenomenon in various repeatable laboratory experiments ... see for example atom traps and atomic emission and absorption experiments. We can "see" atoms as well as we can "see" distant galaxies or cars in our rear view mirror. The scanning tunneling electron micoscope can resolve individual atoms on a crystaline surface. Seeing those via the physical experiment is the pheonomenological event that affirms our ontological treatment in said model.

Scientific approach assumes "objective reality" as given (experimental facts, their records, shared information etc. are objective). If you want to investigate possibility that it is not as objective as it is assumed you would have to develop different philosophical framework for that. So it's not science anyways.

Yes you are quite right but the objective reality of our records of measurement is not fundamental. It is a contingent, tentative objectivity we can assert at the large scale and which is assured by the Correspondence Principle in QM. As my thesis advisor was want to say "all is quantum", but we treat most of it classically because we can and we found that gets bacon on the table as we evolved. And this in turn is how we "bootstrap" the study of nature plus it is why we are forced to "collapse" our quantum descriptions. We don't have the means to manipulate truly quantum symbols... i.e. use actual representative quantum systems to communicate. We instead use classically recorded letters and words and symbols. Perhaps poetry could get you further if you could at the same time impose scientific rigor? Who knows? Maybe one day we can use quantum computers as brain implants to conceptualize quantum systems directly... or maybe some smart fellow will simply reformulate QM in a way that makes it all perfectly natural to dispense with the classical records... I don't know how you can publish a paper though using quantum paper and quantum ink nor how the peer reviewers can be sure they are reading what you wrote.

 

[jambaugh]

Let me add one other bit of sophomore level philosophical pondering.

The phenomenologist's dilemma begins when he despairs of knowing anything but the sensations he experiences since all (empirical) knowledge must pass through this barrier of phenomena.

But the dilemma is only at knowing "a reality". If you don't take it too seriously you can happily construct whatever realities fit your sensations. We build up object models of our environment and through these ... and always tentatively... we extend ourselves to the "objects" we use to further probe our environment. We even extend our singular selves to the community of others we perceive to communicate with us.

You take this "reality" around you only as seriously as it deserves given its ability to describe the extensive accumulation of experiences. You thereby push back this phenomenological wall. But it can't be removed.

Once you become an experimental physicist exploring quantum phenomena you have pushed this phenomenological wall to the Observer/System divide. You treat the measuring devices and recording devices and intermediate dynamical filtering devices as classical objects which you use to probe the wall further.

 

[Boing3000]

Nope, because while the probabilities describe ensemble events (and thus too the wave functions as they are utilized) the measurements are singular events (hence the need to collapse our descriptions.)

That is also my understanding. Hence the collapse is not part of any phenomenon/model/reality. It belongs to the interpretation domain/framework which deal in probability complex waves and "information".
Thus I still don't understand why somebody keen on falsifiability would use a "interpretation" where one of its tenet is some unorbservable phenomenon like "collapse"

An electron detector goes 'click' and each time I identify that as the detection of a singular electron, that is what an electron is as a phenomenon and I believe that phenomenon exists. I must in order to believe in the resulting sample proportions. I then looking at many such clicks over many detectors can derive proportions and compare to calculated probabilities and confirm or falsify QM predictions.

This is also my understanding, but I cannot reconcile it with one of your previous statement

CI says that there is no deeper reality of individual members of quantum system ensembles than that given by wave function i.e. there are no hidden variables.

You may not want to call them "hidden variables", but right now, they are actually the only "real" thing: quantized value that "tick". Whatever "deeper" reality there may (or not) be, it seems to me that taking the stance that only the aggregate behavior are "real" is pretty illogical.

With respect to falsifiability, not when the non-time-forward causality is fundamentally unobservable... (like the unobservable but asserted instantaneous communication between EPR pairs when you assert reality of the wave function.)

Why would "instantaneous" correlation be unorbservable ? Is this a scam ? Also did not Bell's theorem actually kind of explain it ?
What would forbid us to augment the precision of photon arrival time as precisely as we want to ?

 

[Denis]

My problem with dBB is twofold. The aforementioned unobservability and also the point of its formulation is to provide a consistent reality but (as I understand dBB which may be quite wrong!) the necessity of causal propagation of pilot waves FTL and back in time undermine the very objectivity of the reality one is trying to assert. If the future may update the present then the present state of reality is contingent and hypothetical.

Unobservability is not an issue for me. Reality is not obliged to be completely observable, in all details.
FTL is necessary in every realistic or causal interpretation. Which is the point of Bell's theorem, who was aware of dBB theory, and that it requires FTL, and he wanted to show that this is not an argument against dBB, because it is necessary in any realistic causal interpretation.
But there is nothing backward in time in dBB theory. It simply does not have any fundamental Lorentz symmetry. Effective Lorentz symmetry, which gives no FTL signalling, is unproblematic. But the ontological description requires a hidden preferred frame. What is the problem? Yet another hidden variable in a hidden variable interpretation.

 

[PeterDonis]

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