Against "interpretation" - Comments

[Orodruin]

It is the interpretation that makes a theory useful.

No, it is the operative definitions of how to relate mathematical concepts of the theory to measurable quantities that make a theory useful. This is not interpretation in the common nomenclature typically used here, regardless of what Born and Schrödinger thought about the issue.

 

[Dale]

But to give precise references - if you still want them - I need to do some research.

So I found a few references that clearly disagree with your definition of "theory" at least.

Wikipedia says "A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method" https://en.wikipedia.org/wiki/Scientific_theory where clearly a theory must be testable. The purely mathematical concept of theory that you propose is not testable, so it does not fit the Wikipedia definition.

I also found a paper entitled "What is a scientific theory?" by Patrick Suppes from 1967 (Philosophy of Science Today) who says "The standard sketch of scientific theories-and I emphasize the word 'sketch'-runs something like the following. A scientific theory consists of two parts. One part is an abstract logical calculus ... The second part of the theory is a set of rules that assign an empirical content to the logical calculus. It is always emphasized that the first part alone is not sufficient to define a scientific theory".

As he describes this as the "standard sketch" and as this also agrees with the Wikipedia reference and my previous understanding, then I take it that your definition of theory is not that which is commonly used. I have not found a similar clear definition of "interpretation", but clearly the term theory includes the mapping to experimental outcome that is necessary to make it useful on its own for designing and analyzing experiments. Thus, by the standard usage it is also not the interpretation which makes a theory useful, the theory is already useful without an interpretation.

 

[A. Neumaier]

Wikipedia says "A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method" https://en.wikipedia.org/wiki/Scientific_theory where clearly a theory must be testable. The purely mathematical concept of theory that you propose is not testable, so it does not fit the Wikipedia definition.

Since you quote wikipedia, let me also quote it:

An interpretation of quantum mechanics is an attempt to explain how the mathematical theory of quantum mechanics "corresponds" to reality. [...] An interpretation (i.e. a semantic explanation of the formal mathematics of quantum mechanics) [...]

This says exactly what I claimed. The same meaning is also echoed in another wikipedia page not related to quantum mechanics:

The mathematics of probability can be developed on an entirely axiomatic basis that is independent of any interpretation: see the articles on probability theory and probability axioms for a detailed treatment.

From another well-known common source on quantum mechanics:

Mathematically, the theory is well understood [...] The problems with giving an interpretation [...] are dealt with in other sections of this encyclopedia. Here, we are concerned only with the mathematical heart of the theory, the theory in its capacity as a mathematical machine, and — whatever is true of the rest of it — this part of the theory makes exquisitely good sense.

... and by implication, everything else is interpretation, about which ''there is very little agreement''. Very little is said in the cited article about how an observable or a state is related to reality, no operational definition is given how to measure a state or an observable. Loose connections are given in Section 3.4 (Born's rule) and statement (4.2) (special case of eigenstates). The second connection is too special to be representative of the meaning of QM; the first connection is already interpretation dependent (the formulation assumes collapse, a controversial feature) and nevertheless fraught with problems, as is said explicitly on the same page:

• The distinction between contexts of type 1 and 2 remains to be made out in quantum mechanical terms; nobody has managed to say in a completely satisfactory way, in the terms provided by the theory, which contexts are measurement contexts, and
• Even if the distinction is made out, it is an open interpretive question whether there are contexts of type 2; i.e., it is an open interpretive question whether there are any contexts in which systems are governed by a dynamical rule other than Schrödinger's equation.

But without contexts of type 2, nothing at all follows about the relation between the formalism and measurable cross sections or detection events. Thus the uninterpreted theory must be silent about the latter.

No, it is the operative definitions of how to relate mathematical concepts of the theory to measurable quantities that make a theory useful. This is not interpretation in the common nomenclature typically used here, regardless of what Born and Schrödinger thought about the issue.

So please spell out the operative definitions that relate the mathematical concepts of quantum theory to measurable quantities. You'll find that this is impossible to do independent of any of the interpretations of quantum mechanics that can be found in the literature. (Shut-up-and-calculate works only because it leaves the interpretation to the community without spelling out precisely what it consists of.)

Thus interpretation is a prerequisite for making quantum theory useful.

 

[Ian J Miller]

In my opinion, there is a problem with interpretations in that when you have a different one, you cannot know in advance that there are no circumstances where you will not get to either different outputs, or easier ways of going about something. I know here you are not supposed to mention your own work, but with QM there is a small group of interpretations where it is assumed there is a physical wave (De Broglie, Bohm). Now, if you assume the wave is the cause of diffraction in the two slit experiment, then you might consider the wave has to travel with the particle. This gives a physical relationship not present in standard QM, and when coupled with Euler's complex number theory (from which the antinode is not complex) you get a much simpler means of calculating properties of the chemical bond. (You also get a relationship that has not been noted in standard theory.) Now, whether simplified means of calculating is worth bothering about is a matter of opinion, but for me it is.

 

[A. Neumaier]

Theory is the formal, purely mathematical part, and interpretation tells how this formal part relates to reality / observation. In simple cases, the interpretation is simply done by choosing the right words for the formal concepts, but in relativity, more is needed since it is no longer intuitive, and in quantum mechanics, much more is needed since the meaning is - a mess.

Another independent wikipedia source also follows my notion of interpretation:

Attempts to formalize the principles of the empirical sciences use an interpretation to model reality, in the same way logicians axiomatize the principles of logic. The aim of these attempts is to construct a formal system that will not produce theoretical consequences that are contrary to what is found in reality. Predictions or other statements drawn from such a formal system mirror or map the real world only insofar as these scientific models are true.

 

[akvadrako]

This is just arguing over definitions, right? Maybe the only thing that can be said is there is enough disagreement that when these words are important, they should be defined in each discussion. Even if one definition is 90% popular, that's still pretty ambiguous. If PF had a mentor-editable glossary that might cut down on the convergence times.

 

[A. Neumaier]

This is just arguing over definitions, right?

Yes, because the Insight article defining this thread tries to change definitions:

It doesn’t make sense to distinguish an interpretation from a theory. There are no interpretations of QM, there are only theories.

Without good reasons, I think; see my post #4.

 

[Dale]

This says exactly what I claimed.

I am not convinced that this is exactly the same as what you were claiming. First, this is the definition of interpretation, not the definition of theory. The definition of theory is not consistent with your definition of theory. The theory itself includes the mathematical framework as well as the mapping to experiment. It specifically rejects your definition of theory as being only the math.

Now, as to whether this section on interpretation is consistent with your view of interpretation depends a little on what is meant by “corresponds with reality”.

I believe you intend to include both the mapping to experiment and also metaphysical claims about reality. In that case there is some overlap between the definition of theory and interpretation since they both include the mapping to experiment. This usage would be consistent with the term “minimal interpretation” to describe that mapping.

However, the phrase “corresponds to reality” could be taken to refer exclusively to the metaphysical statements only. After all, it is possible to assert a relation to measurement while not asserting whether or not the results of measurements are “real”.

I don’t think that definition is as strong a support for your position as you think. At best it gives a kind of messy overlap between theory and interpretation where the useful part (link to measurement) is part of both.

In either case, the theory consists of the portion that is experimentally testable, the mathematical framework and the mapping to experiment. If you like the overlapping concept then you could talk about the objective interpretation and the subjective interpretation to distinguish between the scientific and philosophical portions of the interpretation.

I would only agree that the objective interpretation is what makes a theory useful, and that is already part of the theory itself.

Edit: I just noticed this discrepancy

Theory is the formal, purely mathematical part, and interpretation tells how this formal part relates to reality / observation.

You say that the interpretation provides the relationship to “reality/observation”. The standard definitions of theory include the relationship to observation and your quoted Wikipedia definition of interpretation includes only the relationship to “reality”.

So I think your mistake is including the link to observation in the interpretation whereas both the definitions of theory and interpretation disagree and place the link to observation in theory and not interpretation.

 

[bhobba]

I believe you intend to include both the mapping to experiment and also metaphysical claims about reality.

Good point I hadn't thought of before.

John Baez's writings has often influenced me in my views on interpretations:
http://math.ucr.edu/home/baez/bayes.html

In particular:
'It turns out that a lot of arguments about the interpretation of quantum theory are at least partially arguments about the meaning of the probability!'

You have to have an interpretation of probability to do the mapping. Interpretations like the ensemble do only that. I would call them minimal.

An interesting observation is that in math we generally do not worry about interpretations of probability - we either apply it as most books like Feller's classic do or we simply look at the consequences of the Kolmogorov axioms as books on rigorous probability theory do. People generally do not get caught up much in the interpretation issue - but in Quantum Theory we have all sorts of, how to put it, 'vigorous' discussions about it. That always has struck me as, well interesting.

But others go further - even Copenhagen goes further (at least in some versions - there seems no standard version). But it generally seems to be something like (from a blog discussion on it):
1. A system is completely described by a wave function ψ, representing an observer's subjective knowledge of the system. (Heisenberg)
2. The description of nature is essentially probabilistic, with the probability of an event related to the square of the amplitude of the wave function related to it. (The Born rule, after Max Born)
3. It is not possible to know the value of all the properties of the system at the same time; those properties that are not known with precision must be described by probabilities. (Heisenberg's uncertainty principle)
4. Matter exhibits a wave–particle duality. An experiment can show the particle-like properties of matter, or the wave-like properties; in some experiments both of these complementary viewpoints must be invoked to explain the results, according to the complementarity principle of Niels Bohr.
5. Measuring devices are essentially classical devices, and measure only classical properties such as position and momentum.
6. The quantum mechanical description of large systems will closely approximate the classical description. (The correspondence principle of Bohr and Heisenberg)

The above contains quite few debatable points:

1. Is a quantum system completely described by the wave function?
2. Wave particle duality - its really neither wave or particle - it's quantum stuff.
3. There are in a sense no classical systems - its all really quantum stuff. If you do not view it as all quantum stuff you face a problem - exactly where is the dividing line?

Every one of those really requires a thread of their own, so I will not discuss them here except to say modern interpretations like decoherent histories realize they are issues and try to correct them - which was the view of the blog I got it from. But we should not be too harsh, Copenhagen was formulated in the early days of QM - things have moved on a lot since then.

On thing that always brings a bit of a smile to my face is Einstein was the original champion of the Ensemble interpretation. It seems to have come through mostly unchanged to modern times. But Copenhagen, championed by his old sparring partner, and good friend, Bohr, didn't. Could it be Einstein, after his debates with Bohr saw to the heart of it better? Einstein was wrong to object to QM so strongly at it's birth, but eventually he came to accept it as correct. To be fair though his objections did strengthen the theory. But to his dying day thought it incomplete - which due to various unresolved issues like quantum gravity is of course true - but may change in the future - or actually be shown as incomplete.

Thanks
Bill

 

[Lord Jestocost]

Maybe, the following quotes might help to clarify some issues (from “The Philosophy of Quantum Physics” by Cord Friebe, Meinard Kuhlmann, Holger Lyre, Paul M. Näger, Oliver Passon and Manfred Stöckler, 2018):

“Not only in philosophy, but even in physics itself, one depends on interpretations. Mathematical formalisms such as the one presented in basic form in the previous chapter are in themselves rather abstract; they say nothing about concrete reality. They require an interpretation, initially in the sense that the mathematical symbols and operations must be associated with elements of physical reality……

If one tries to proceed systematically, then it is expedient to begin with an interpretation upon which everyone can agree, that is with an instrumentalist minimal interpretation. In such an interpretation, Hermitian operators represent macroscopic measurement apparatus, and their eigenvalues indicate the measurement outcomes (pointer positions) which can be observed, while inner products give the probabilities of obtaining particular measured values. With such a formulation, quantum mechanics remains stuck in the macroscopic world and avoids any sort of ontological statement about the (microscopic) quantum-physical system itself….

The first stage of interpretation of the mathematical formalism establishes the connection to the empirical world as far as needed for everyday physics in the laboratory or at the particle collider. Born’s rule allows a precise prediction of the probabilities of observing particular outcomes in real, macroscopic measurements. The fact that this minimal interpretation makes statements only about macroscopic, empirically directly accessible entities such as measurement setups, particle tracks in detectors or pulses from a microchannel plate may be quite adequate for those who see the goal of the theory within an experimental science such as physics as being simply the ability to provide empirically testable predictions. For the metaphysics of science, this is not sufficient, and most physicists would also prefer to have some idea of what is behind those measurements and observational data, i.e. just how the microscopic world which produces such effects is really structured. In contrast to the instrumentalist minimal interpretation, however, every additional assumption which might lead to a further-reaching interpretation remains controversial……”

 

[A. Neumaier]

an instrumentalist minimal interpretation. In such an interpretation, Hermitian operators represent macroscopic measurement apparatus, and their eigenvalues indicate the measurement outcomes (pointer positions) which can be observed, while inner products give the probabilities of obtaining particular measured values. With such a formulation, quantum mechanics remains stuck in the macroscopic world

... but still has the problem to say what probabilities mean. Observed are only frequencies, not probabilities.

The first stage of interpretation of the mathematical formalism establishes the connection to the empirical world as far as needed for everyday physics in the laboratory or at the particle collider.

This is presumably what @Dale calls objective interpretation.

ost physicists would also prefer to have some idea of what is behind those measurements and observational data, i.e. just how the microscopic world which produces such effects is really structured.

and this would be what he calls subjective interpretation.

 

[A. Neumaier]

Now, as to whether this section on interpretation is consistent with your view of interpretation depends a little on what is meant by “corresponds with reality”.

Yes. For me, experiment is an obvious part of everyday reality. If we deny it this status, nothing objective is left. Fo you, reality seems to be something metaphysical, unrelated to experience (of which experimental evidence is a part).

I would only agree that the objective interpretation is what makes a theory useful, and that is already part of the theory itself.

OK, so let me try to make your terminology precise, as I understand you.

1. A mathematical framework defines the concepts of a theory and develops their logical implications.
2. An objective interpretation relates the concepts of the theory unambiguously to experiment.
3. A subjective interpretation gives a metaphysical description underlying the objective interpretation.
4. A theory consists of its mathematical framework and its objective interpretation.
5. An interpretation consists of the objective interpretation of the theory and its subjective interpretation.
6. Thus the objective interpretation is the intersection of interpretation and theory.

Can we agree on that? Then I'll accept this terminology for the sake of our discussion.

 

[ftr]

But to his dying day thought it incomplete

It is incomplete in the sense that all couplings and mass are put in by hand and are not emergent from the theory

Mathematical formalisms such as the one presented in basic form in the previous chapter are in themselves rather abstract; they say nothing about concrete reality.

Although mass and couplings are part of concrete reality but see above.

 

[bhobba]

It is incomplete in the sense that all couplings and mass are put in by hand and are not emergent from the theory.

There are many reasons it's incomplete. Only time will tell us if they are resolvable or not.

Thanks
Bill

 

[Dale]

Fo you, reality seems to be something metaphysical

Yes, by definition “reality” is a concept which is defined by and studied in the philosophical discipline of ontology which is one of the major branches of metaphysics. It is not that I doubt that experiments are real, it is just that the whole concept of reality is a philosophical one that cannot be addressed by the scientific method.

OK, so let me try to make your terminology precise, as I understand you.

This is not my terminology. This is an effort to construct a compromise terminology for clarity here.

My terminology would not make use of subjective and objective. All of the objective parts would be theory and all of the subjective parts would be interpretation in my terminology with no overlap between theory and interpretation. I believe that is the standard usage of the word “theory” and although it less clear I also believe that is the standard usage of the word “interpretation”.

However, I think your previous post is good compromise terminology for the purposes of this discussion. It clarifies the concepts and allows the discussion to proceed. Let’s use it for now.

 

[Lord Jestocost]

There are many reasons it's incomplete.

Quantum mechanics might seem to be incomplete if one prefers to come back to the idea of an objective real world, i.e. the reality concept of classical physics.

 

[A. Neumaier]

It is not that I doubt that experiments are real, it is just that the whole concept of reality is a philosophical one that cannot be addressed by the scientific method.

I had always meant reality in the common sense, not in the philosophical sense; and I think wikipedia als has this usage - it makes sense to me that way. So please reread my previous posts, substituting everywhere experiment for reality, and measured for real.

However, I think your previous post is good compromise terminology for the purposes of this discussion. It clarifies the concepts and allows the discussion to proceed. Let’s use it for now.

Ok. So we agree that objective interpretation is a prerequisite for making quantum theory useful, since it is part of the scientific theory called quantum theory.

Then I think all relevant dispute in the quantum foundations is in the unsolved problem of giving a precise meaning to the objective interpretation of quantum mechanics in a way consistent with the mathematical framework (about which there is almost general agreement). It is here where the different interpretations differ. To check this, let me repeat my request from post #93; it was addressing precisely the objective interpretation part of quantum theory:

No, it is the operative definitions of how to relate mathematical concepts of the theory to measurable quantities that make a theory useful. This is not interpretation in the common nomenclature typically used here, regardless of what Born and Schrödinger thought about the issue.

So please spell out the operative definitions that relate the mathematical concepts of quantum theory to measurable quantities. You'll find that this is impossible to do independent of any of the interpretations of quantum mechanics that can be found in the literature. (Shut-up-and-calculate works only because it leaves the interpretation to the community without spelling out precisely what it consists of.)

(So according to our compromise terminology, and in agreement with the claim by @Demystifier in the insight article under discussion, we would have as many different quantum theories as there are interpretations of quantum mechanics. Because this is not the way spoken about quantum physics in practice - there is only one quantum theory - the shut-up-and-calculate part - and there are many interpretations, I believe that the compromise terminology is not reflecting actual practice, but for the moment we may ignore this to be able to proceed.)

 

[Dale]

So please spell out the operative definitions that relate the mathematical concepts of quantum theory to measurable quantities.

I don't know enough about quantum mechanics to do that. QM is not the only scientific theory and not the only place where interpretations arise.

However, even if I did know enough QM to do that I would not. Frankly, the obsession with interpretations is the reason why I stay out of the QM forum. I would like to know more about QM, but I have no interest whatsoever in becoming embroiled in the 10000 th pointless argument on the topic here. The constant deluge of such threads is a real turn-off for me, which is a pity because in my case it has diluted the educational mission of PF as a whole.

This insights article is not specifically about QM and frankly, I think that the current discussion about specific interpretations of QM in this thread is off-topic and I have suggested its removal. The QM forum's obsession with interpretations is not something that I want spreading to other parts of the forum.

I refuse to pick up any QM-related gauntlet. Let's keep the discussion general, about theories, interpretations, and the scientific method.

So according to our compromise terminology, and in agreement with the claim by @Demystifier in the insight article under discussion, we would have as many different quantum theories as there are interpretations of quantum mechanics

I think you are misusing the compromise terminology. The various interpretations of any given theory, when presented with a given experimental setup, would all predict the same quantitatively measurable outcomes, no?

 

[DarMM]

An interesting observation is that in math we generally do not worry about interpretations of probability - we either apply it as most books like Feller's classic do or we simply look at the consequences of the Kolmogorov axioms as books on rigorous probability theory do. People generally do not get caught up much in the interpretation issue - but in Quantum Theory we have all sorts of, how to put it, 'vigorous' discussions about it. That always has struck me as, well interesting.

Funnily enough I always thought QM was very similar to probability theory in this regard. Although most people just apply it, there is a pretty active community of debate on Foundations, e.g. Frequentist vs Kolmogorov vs De Finetti vs Jaynes. Famously summed up in I.J. Good's title "46656 Varieties of Bayesians" for the Third Chapter of his 1983 book "Good Thinking: The Foundations of Probability and Its Applications".

 

[A. Neumaier]

This insights article is not specifically about QM and frankly, I think that the current discussion about specific interpretations of QM in this thread is off-topic and I have suggested its removal.

Isn't this very strange? In view of the fact that the article begins with the very first sentence

I am against “interpretations” of Quantum Mechanics (QM)

and ends with the very last sentence

There are no interpretations of QM, there are only theories

the topic is clearly the non-interpretation of quantum mechanics, though the title is different, and the argument is made more abstractly.

The various interpretations of any given theory, when presented with a given experimental setup, would all predict the same quantitatively measurable outcomes, no?

For the case of quantum mechanics, that's the real question. I believe not, if taken literally. This is why even Nobel prize winners such as Weinberg and t'Hooft spend significant effort on the interpretation issue. Though they did it only after their retirement: While paid they researched more important issues and kept the issues on the back burner.

The various interpretations of quantum mechanics would predict it only by being quite liberal with the interpretation details, and assuming a lot about the culture of doing physical experiment (which is far more complex than what interpretations usually consider).

I answered the above though you want to keep the discussion off quantum mechanics. But then it becomes nearly empty. In most fields of science there is agreement on the interpretation, hence no way to discuss your question meaningfully. The only exceptions are quantum mechanics, statistical mechanics, and applied probability theory, which share some of the foundational problems.

But historically, the question whether light was wave or matter was another such topic, and the interpretations ultimately gave different predictions. These were checkable, which decided in favor of the wave nature, long before it was known what waved...

 

[A. Neumaier]

Funnily enough I always thought QM was very similar to probability theory in this regard. Although most people just apply it, there is a pretty active community of debate on Foundations, e.g. Frequentist vs Kolmogorov vs Di Finetti vs Jaynes. Famously summed up in I.J. Good's title "46656 Varieties of Bayesians" for the Third Chapter of his 1983 book "Good Thinking: The Foundations of Probability and Its Applications".

J. von Plato, Creating modern probability, Cambridge Univ. Press, Cambridge 1994.

discusses the history of the concept and interpretation of probability.L. Krüger, G. Gigerenzer and M.S. Morgan (eds.), The Probabilistic Revolution: Ideas in the Sciences, Vol. 2, MIT Press, Cambridge, MA, 1987.

discuss the history of probability in the various fields of application. L. Sklar, Physics and Chance, Cambridge Univ. Press, Cambridge 1993.

discusses the philosophical problems of the probability concept, with an emphasis on statistical mechanics.

 

[Dale]

the topic is clearly the non-interpretation of quantum mechanics,

Good point, but I personally will not participate in your QM interpretation fights. Those discussions have already completely deterred me from learning QM here.

For the case of quantum mechanics, that's the real question. I believe not, if taken literally.

the interpretations ultimately gave different predictions.

Then they are different theories, per the standard definition, and calling them merely different interpretations is somewhat of a misnomer.

In most fields of science there is agreement on the interpretation, hence no way to discuss your question meaningfully.

Whether there is agreement on the interpretation or not is irrelevant. The question is a question about science and the scientific method generally. QM doesn’t own a monopoly on these topics simply because the community argues more.

To do meaningful science you need a theory. The theory must include the objective interpretation. The subjective interpretation is scientifically unnecessary, and depending on the theory it may be controversial or non-controversial.

 

[bhobba]

Although most people just apply it, there is a pretty active community of debate on Foundations, e.g. Frequentist vs Kolmogorov vs Di Finetti vs Jaynes. Famously summed up in I.J. Good's title "46656 Varieties of Bayesians" for the Third Chapter of his 1983 book "Good Thinking: The Foundations of Probability and Its Applications".

You are probably correct (drats I used that word - probably). It's likely we get a rather different sample on this forum to what people using QM generally do. Certainly when I did my studies in probability and stats nobody worried about it, although as you advance you pick up that there is a debate about its foundations, just like there is debate about the foundations of math itself. I wasn't that attracted personally to the area, liking analysis better, but always enjoyed the lectures of the professor taking it - he was a funny guy so took more subjects in it than I had to. My view on foundations would likely be described as rigorously Kolmogorovian but intuitively frequentest.

Thanks
Bill

 

[DarMM]

My view on foundations would likely be described as rigorously Kolmogorovian but intuitively frequentest.

What! You degenerate!

Seriously though, yes I think the interpretation debate is much louder here (and on the net in general) than it is in day to day practice in physics. Now I think two things about this.

On the one hand I think that is because many in the interpretation "wars" don't realize that beyond a certain point there are currently no more no-go theorems and even though interpretation X might make more personal sense to you, that's as far as it goes. At a certain point you just have people saying position X is "obviously daft" not recognizing that every interpretation by necessity has something that classically is "obviously daft". Also often advocates of interpretations don't know the fully modern version of their interpretation and what they should be accepting with it. Just compare "Beginner's MWI" with it's basic idea of splitting universes, with the modern version that comes out from Wallace et al's work of uncountably infinite worlds, approximate splittings, human perspective being what possibly defines worlds, etc. People don't realize that a properly worked out version of their favorite interpretation has more "obviously daft" features than they think.

On the other hand I think people who don't engage with the interpretations aren't "pragmatists unconcerned with philosophical mumbo jumbo", there is something deeply strange about entanglement and measurement in quantum theory and when I've spoken to these people and shown them things like the Kochen-Specker theorem, Bell's theorem, PBR theorem, they then do become interested in interpretations, i.e. most physicists think there is nothing to this because they carry around a vague interpretation¹ that they don't think about much and really doesn't make much sense when analysed. Not because there isn't a problem and only a pedantic philosopher would think so.

¹The general impression I get is that they think the wave function is a real thing that undergoes collapse upon measurement, without really thinking how odd measurement as a fundamental is or what even is collapse. The almost pop science "It's in two places at once until observed"

 

[bhobba]

What! You degenerate!

You bet your sweet Bippy. I only study it to become an actuary so I can get the big bucks

On the other hand I think people who don't engage with the interpretations aren't "pragmatists unconcerned with philosophical mumbo jumbo", there is something deeply strange about entanglement and measurement in quantum theory and when I've spoken to these people and shown them things like the Kochen-Specker theorem, Bell's theorem, PBR theorem, they then do become interested in interpretations, i.e. most physicists think there is nothing to this because they carry around a vague interpretation that they don't think about much and really doesn't make much sense when analysed. Not because there isn't a problem and only a pedantic philosopher would think so.

Regardless of ones attitude to interpretation there is something quite deep going on with entanglement:
https://arxiv.org/abs/0911.0695

And indeed the program of describing a classical world purely with QM has made great strides but is still not quite there yet - maybe it never will be in which case Einstein may have the last laugh over his good friend Bohr. Interestingly, even though they were good friends, and admired each other greatly, as reported by Ohanian - 'When Bohr visited the institute in 1948, Einstein refused to meet with him. In a comical incident during this visit, Einstein sneaked into an office in which Bohr was having a discussion with Pais, and found himself suddenly face to face with Bohr – but he merely wanted to borrow some tobacco for his pipe from a tin sitting on a shelf.'. Maybe Einstein, who evidently was only a shadow of his former self in his later years, became sick and tired of debating with Bohr.

Thanks
Bill

 

[bhobba]

The general impression I get is that they think the wave function is a real thing that undergoes collapse upon measurement, without really thinking how odd measurement as a fundamental is or what even is collapse. The almost pop science "It's in two places at once until observed"

OMG - that's pretty close to my view when I started posting here about 10 years ago now. My views have changed a LOT, and even now are changing as I learn more - but not at the rate they did during my first few years of posting - I wince thinking about some of my early posts.

Thanks
Bill

 

[atyy]

People don't realize that a properly worked out version of their favorite interpretation has more "obviously daft" features than they think.

Copenhagen is agreed by many proponents to be obviously daft. Have you read Landau and Lifshitz's QM textbook? They say this in a polite way, perhaps too polite as not everyone gets their message.

 

[StoneTemplePython]

Funnily enough I always thought QM was very similar to probability theory in this regard. Although most people just apply it, there is a pretty active community of debate on Foundations, e.g. Frequentist vs Kolmogorov vs Di Finetti vs Jaynes. Famously summed up in I.J. Good's title "46656 Varieties of Bayesians" for the Third Chapter of his 1983 book "Good Thinking: The Foundations of Probability and Its Applications".

My view on foundations would likely be described as rigorously Kolmogorovian but intuitively frequentest.

I hope this doesn't need to be forked into another thread. I found the above to be alarming.

Kolmogorov was sympathetic to the frequentist interpretation advocated by Richard von Mises and in fact believed his axioms were Taylor Kolmogorov made for a frequentist concept of probability. Reference: pages 43-45 of Probability and Finance by Shafer and Vovk, which includes a translated letter from Kolmogorov regarding exactly this point. Also of interest, page x of the book's Preface

Vovk's work on the topics of the book evolved out of his work, first as an undergraduate and then as a doctoral student, with Andrei Kolmogorov, on Kolmogorov's finitary version of von Mises's approach to probability.

- - - - -
From what I can tell, the books referenced in the quote and in post 112 are about philosophy and general audience books/ writeups. They aren't math books. (I do happen to like Gigerenzer though.) People complain about general public books on QM all the time. I don't see why we shouldn't have similar sentiment here.

 

[DarMM]

I hope this doesn't need to be forked into another thread. I found the above to be alarming.

As did I, bhobba is one of those dangerous frequentists who use Kolmogorov's axioms for their own nefarious ends.

Kolmogorov was sympathetic to the frequentist interpretation advocated by Richard von Mises and in fact believed his axioms were Taylor Kolmogorov made for a frequentist concept of probability.

Kolmogorov did have a different view to von Mises though, the whole "propensities" view and is often listed separately to frequentism in books on interpretations of probability theory. Later in life he had the complexity interpretation, again different from von Mises's view. It's these views I listed above informally as "Kolmogorov". Some still argue¹ that the complexity view is a form of Frequentism, if you take that view replace "Frequentist vs Kolmogorov" with "von Mises vs Kolmogorov".

From what I can tell, the books referenced in the quote and in post 112 are about philosophy and general audience books/ writeups. They aren't math books. (I do happen to like Gigerenzer though.) People complain about general public books on QM all the time. I don't see why we shouldn't have similar sentiment here.

A similar sentiment regarding what though? There is a debate about foundations and interpretation in probability with various schools that disagree with each other. Jaynes for example is fairly scathing of Frequentism in his book "Probability Theory: The logic of Science". @A. Neumaier 's references simply discuss this issue. The complaints about general books on QM is more related to their sensationalist content, inaccuracies or often taking a specific view on things and providing that view as the explanation. @A. Neumaier 's books don't seem to be doing that. In fact I don't understand the connection at all. What sentiment should we have, ignore books discussing interpretational issues?

¹ Just like in QM there are debates about how to classify interpretations!

 

[Demystifier]

Then they are different theories, per the standard definition, and calling them merely different interpretations is somewhat of a misnomer.

My insight is precisely to point out that such standard definition is inadequate. It can be applied to other sciences too, but since this standard definition is rarely used in other sciences, this insight is in fact most relevant to QM.