Ontology is to quantum theory what hardware is to computation theory

[martinbn]

Yes, but the question is how to represent the real stuff (such as electron) with a mathematical object. If you represent it by a wave function, then you must have collapse (unless you accept many worlds), which leads to non-locality and Lorentz violation. If you say that it is not represented by a wave function, then you should say something about representing real stuff with another mathematical object. And yet people like @martinbn refuse to say anything concrete of this sort. For me they are non-realists at least in some weak sense, not by claiming that reality doesn't exist (which would be a strong non-realism), but by refusing to say something about the mathematical object that represents this real stuff.

You dont need to represt the object (say the electron) itself. And the wave function doesn't do that. The wave function represents the state of the object.

I don't see how you can claim that any of this implies Lorentz violation!

 

[Demystifier]

You dont need to represt the object (say the electron) itself.

Why not?

And the wave function doesn't do that. The wave function represents the state of the object.

Would you say that state of the object is quantitative, but the object itself is qualitative? Is it why you think that object itself doesn't need to be represented with math?

I don't see how you can claim that any of this implies Lorentz violation!

As soon as you try to represent object with math, you get nonlocality in the Bell sense. Most explicit attempts to write down a mathematical model of this nonlocality violate Lorentz invariance. The best known examples are explicit collapse and Bohmian mechanics. If you have a counterexample in mind, namely a nonlocal Lorentz invariant mathematical representation of the object, I would like to see it.

 

[martinbn]

Why not?Would you say that state of the object is quantitative, but the object itself is qualitative? Is it why you think that object itself doesn't need to be represented with math?As soon as you try to represent object with math, you get nonlocality in the Bell sense. Most explicit attempts to write down a mathematical model of this nonlocality violate Lorentz invariance. The best known examples are explicit collapse and Bohmian mechanics. If you have a counterexample in mind, namely a nonlocal Lorentz invariant mathematical representation of the object, I would like to see it.

I think I probably didn't understand you. What do you mean by represent the object mathematically? What is an example (doesn't have to be quantum)?

 

[Demystifier]

I think I probably didn't understand you. What do you mean by represent the object mathematically? What is an example (doesn't have to be quantum)?

- Classical particle can be represented by the position in space, i.e. by the coordinates ##(x,y,z)##. This perhaps does not say everything about the particle (e.g. its mass and charge), but at least says something.

- A classical wave can be represented by a function of the form ##f(x,y,z,t)##, or by its Fourier transform ##F(k_x,k_y,k_z,\omega)##, which also may not say everything about the wave, but at least says something.

- If one does not know the position of the classical particle, then one can associate a probability distribution ##p(x,y,z)##. However, this does not represent the classical particle. Instead, in the Bayesian interpretation of probability, it represents our incomplete knowledge about the particle, because it is assumed that the particle has position even when we don't know it. Alternatively, in the frequentist interpretation of probability, it represents an ensemble of particles, not one particle.

- In quantum physics one may want something similar, some mathematical object that represents some objective property (of the single particle) which exists even when we don't know it. In standard textbook quantum physics, the only mathematical quantity at our disposal is the wave function ##\psi(x,y,z)## (or something closely related to it), but, depending on interpretation, ##\psi## represents an ensemble of particles, or our incomplete knowledge about the particle. Hence the analogy with classical physics suggests that we need another mathematical object that says something about the single particle itself, irrespective of our knowledge. Bohmian mechanics is an example of an attempt to introduce such another mathematical object.

- Or, if the analogy with classical physics is misleading, then the wave function itself should be interpreted as something that represents the particle itself, which leads to ##\psi##-realist interpretations such as many worlds or objective collapse on one side, or ##\psi##-information interpretations such as QBism and relationalism on the other side. The ##\psi##-information interpretations seem to be saying that a mathematical representation of a single particle itself independent of our knowledge - does not exist. They do not say that the particle itself does not exist, but they say that the mathematical representation of the particle itself does not exist. If this is more or less how you (@martinbn) think of it, then would you say that the particle itself is something that only has a quality, not a quantity?

Does it help?

 

[Fra]

I think I roughly understand what Demystifiers seeks, and I also think that this question in principle, does not necessarily restrict itself to only Bohmian meachanics, because I can related to this, even from the "agent/qbism" view in the following way:

We often hear from realist side rethorical questions such as "is the moon there when noone is looking". Note that this question is quite similar to also asking
"does the truth exists even before we learn about it"
"does the laws of physics exist before we learned about them"
"does a piece of information, exist before it's communicated/inferred"
...
ie. there is an idea that there is a "native or local" truth of actual matter, but that that always has to be communicated/inferred to/by an external/remote observer. These "layers" of inference or interactions obviousl screens the "real" from the observer, so the "observable" can never bee anything by the apparent/renormalized information.

The "naked" truth, can in this view never be seen directly, as any inferences must pass through all the layers of interaction/communication.(ie without making a "measurement") For example, there is no way to probe inside a cell, without somehow passing (mechanicall or via electromagnetic radiation) the cell wall, so in principle these layes always "distorts" the image related to the real thing.

I think Demysitifier seeks at least a principal picture of the "naked structure", ie what is an "electron" if we could "peak inside" without goign through all the layers of interactions, out the the pointers in the classical lab?

In QM/QFT this naked structure is not observable, they are finetuned to match the effective structure, as measured essentially at the macroscopic boundary/environment of the system. This structure also takes on the nature of an abstract parameter space, that is defined only statistical in terms of "classical" things and data collected at the far boundary.

This is first of all unsatisfactory, but it also is a problem because it similarly means that the hamiltonian is also fitted exeperimentally, and the worst part is that at leasdt in principle, this has to be done for each observational scale, so we have a set of effective theories only, which is even more unsatisfactory. And the more unified theory we try to find, in order to have ONE theory where we via renormalizations can change the scale, the more fine tuning do we seen to required. And at some point this breaks down, because the complexity of the data likely exceeds our "observational platform".

So what I wanted to say is that, no matter how differently we think about this, Demystifiers quest for ontology here, is actuall quite analogous to what I call the "intrinsic view". This intrinsic view, is exactly (I think) the "ontology" that we talk about here. And as I see it, this does not stay philosophy because if we can find this, we should be able to make som serious progress in unification work (even though the connecttion may be far fetched for some, it is what drives me)

/Fredrik

 

[Fra]

As soon as you try to represent object with math, you get nonlocality in the Bell sense. Most explicit attempts to write down a mathematical model of this nonlocality violate Lorentz invariance. The best known examples are explicit collapse and Bohmian mechanics. If you have a counterexample in mind, namely a nonlocal Lorentz invariant mathematical representation of the object, I would like to see it.

If I am trying to rephrase this in my preferred terms, then it seems the represnetation of all ontologies you ask for, would be like considering the set of all "intrinsic observer views". Ie. it is a generalization of the notion of "observable". I think the solipsist HV are also of this type.

The normal notion of observer, IMO, forbids most observers, and keeps only those that asymptotically form some agreement. While this is not a strange requirement from the perspective of "objevtive science" I think it really misses some deep workings. (Specifically the mechanism by which the objectivity is chosen; ie. it solves the finetuning probelm)

Anyway, if we toy with the idea that we have this set of all ontolgies. Ie. the set of all hidden variables, or the set of all agents "microstates" (that are screened from other agents), then I agree that the "apparent causal rules/correlations" viewed from this set would be completely nuts and violate common sense! In the agent view this has a perfectly natural explanation: two agents does not causally act upon each other based on their hidden states, because that would be completely unlogical and irrational.(And Bells theorem assumes this, which is why it does not apply) They respond only to the "effective view" of the other agent. ie. the view that you get from the screened "naked state". This is why locality (in the einsteinian sense is guaranteeed) because an agent can not respond to anything unless it's first communicated.

The problem is when you try to describe this process in the netwonian paradigm, with state space what is fixed and timeless laws and an initial condition. It forces you to increase the complexity and do alto of fine tuning - to the point where it's not possibe - and and at that point we are also lost in chaos.

/Fredrik

 

[vanhees71]

Good. But in your view, what kind of theories are ruled out by the violation of Bell inequalities; all realistic theories, or just the local realistic ones? And am I right that Bohmian mechanics is non-realistic in your view?

Only local realistic ones. Since Bohmian mechanics is only a reinterpretation of (non-relativistic) QT without any predictions that violates the standard laws of QT, it's also non-realistic.

 

[vanhees71]

You dont need to represt the object (say the electron) itself. And the wave function doesn't do that. The wave function represents the state of the object.

I don't see how you can claim that any of this implies Lorentz violation!

Somehow in the debate with philosophers you have the problem that they don't understand that non-relativistic QM of course violates Lorentz invariance, simply because it's a non-relativistic theory. The only consistent relativistic QT is local relativistic quantum field theory, and there of course nothing violates Lorentz invariance for observables (like transition probabilities or cross sections calculated from Poincare-covariant S-matrix elements).

 

[Morbert]

Somehow in the debate with philosophers you have the problem that they don't understand that non-relativistic QM of course violates Lorentz invariance, simply because it's a non-relativistic theory. The only consistent relativistic QT is local relativistic quantum field theory, and there of course nothing violates Lorentz invariance for observables (like transition probabilities or cross sections calculated from Poincare-covariant S-matrix elements).

You can have a theory that is not Lorentz invariant but still local right? E.g. A lagrangian that is not a scalar or scalar density (therefore not Lorentz invariant) but still depends only on coordinates and time derivatives (therefore local)

 

[vanhees71]

No, locality means that there are no faster-than-light signals. The nonrelativistic interactions are described by instantaneous (potential) forces and thus violate locality by assumption.

The locality is implemented by construction in relativistic QFTs by having Lorentz-invariant-equivalent local Lagrangians and quantization conditions ensuring the microcausality condition for local observables.

 

[Morbert]

No, locality means that there are no faster-than-light signals. The nonrelativistic interactions are described by instantaneous (potential) forces and thus violate locality by assumption.

But what if your Hamiltonian has no such terms? E.g. In a standard EPR thought experiment, the dynamics are such that no action Bob performs on his particle can instantaneously affect any expectation values or response rates re/ Alice's particle. This state of affairs can be obtained even without Lorentz invariance.

 

[Fra]

I would say the issue is that lorentz invariance or any other observer equivalence) is not defined for the "set of all possible bare/naked/intrinsics views" (which represents the ontologies) but for the views where these are inferred. This ia how lack of the "observed symmetries" isnt a problem per see.

Before their inference rules and relations are defined, the set of all views is i think no metric space. Ie. The notion of neighbourhood around an agent is not defined.

i would expect it to be the task of any such theory/paradigm to explain how a lorentz invariant "layers" is defined or emergent from the underlying set. [i expect all this to start happen at some extreme temperature however where spacetime may not be defined aa 4d yet. ]

/Fredrik

 

[physika]

Yes, but the question is how to represent the real stuff (such as electron) with a mathematical object. If you represent it by a wave function, then you must have collapse (unless you accept many worlds), which leads to non-locality and Lorentz violation. If you say that it is not represented by a wave function, then you should say something about representing real stuff with another mathematical object. And yet people like @martinbn refuse to say anything concrete of this sort. For me they are non-realists at least in some weak sense, not by claiming that reality doesn't exist (which would be a strong non-realism), but by refusing to say something about the mathematical object that represents this real stuff.

.
how could it be described (or represented) if it is not even defined (not the value) i.e. "what is" the thing/object/entity, we do not know if it is a particle or a wave or an excitation of the field.
and by the way the representation by a mathematical object would be something else, not an ontological problem per se.
what mathematical object it will be, will be seen later.I will return later with the Lorentz Invariance.

.

 

[Demystifier]

how could it be described (or represented) if it is not even defined (not the value) i.e. "what is" the thing/object/entity, we do not know if it is a particle or a wave or an excitation of the field.

We don't know what it is, but we have some ideas what it might be. We can represent our ideas.

 

[gentzen]

Somehow in the debate with philosophers you have the problem that they don't understand that non-relativistic QM of course violates Lorentz invariance, simply because it's a non-relativistic theory.

Somehow "philosophers" seems to be used here as a "stand-in" for people eager to discuss QM without proper understanding of the underlying physics. In an actual discussion between some real philosopher and some real physicist, it is much harder to decide who is responsible for the debate going nowhere. See for example this discussion between Tim Maudlin (a philosopher) and Lev Vaidman (a physicist):

The debate starts at 36:20 and gets stopped at 44:33 (by a moderator). My link above starts at 39:00, where the debate gets hot. In this debate, Tim Maudlin defends more or less Demystifier's position, while Lev Vaidman defends an idea that I personally first learned about from A. Neumaier's book.

(*) Or maybe I do. The thermal interpretation by @A. Neumaier might be the only realistic interpretation in this sense, but AFAIK this interpretation is not published in any peer reviewed journal.

What exactly would be different, if he would publish it in a peer reviewed journal? It is an interpretation (mostly in the orthodox/Copenhagen spirit), so the reviewers certainly won't reject it for having its own set of issues. If he would try to publish it in a physics journal, then he would probably be forced to use less words, and focus more on what is different to other interpretations. Is it this what you are hoping for? If he would try to publish it in a philosophy journal, then his many words would probably be no problem at all. The only difference to the current state would then be that he could not continue to revise and enlarge his paper again and again (like he did with his latest paper). In this respect, I admit that his book was indeed very helpful for me, because it was a stable target that I could read from start to finish, and then be done with it. (In fact, I still hope that he will publish his second planned book at some point, so that I can read and enjoy it just like his first book, as a stable whole.)

Or is it more that as long as it is not published in a peer reviewed journal, it is not a stable target for reference or attack in peer reviewed papers?

 

[Fra]

"what is" the thing/object/entity, we do not know if it is a particle or a wave or an excitation of the field.

Or maybe neither of those?

Those terms all come with a classical tang.

It is tempting wheen seeking abstractions is to restrict oneself to the common "classical ontologies". You might as well ask, what "is" a field or particle anyway? We only think we know because of classical ideas where one implicitly adds the newtonian behaviour to the ontologies.

If you ask from the stance of inference, what is a "field", its not as clear anymore. Instead from that stance other things are more clear, that are simultaneously not clear in classical ontology.

I think each ontology comes with implicit assumptions on behaviour. Same goes for geometrical ontologies. Gaming ontologies. We can call it a "dice" or a "random walker".. the evolution of rhe dice or evolution of the geometry... different abstractions or ontologies but serving compatible purposes and thinking tools (a term demystifiers uses alot). I am not a fan of geometrical ontologies, i prefer those or gaming.

/Fredrik

 

[martinbn]

...
See for example this discussion between Tim Maudlin (a philosopher) and Lev Vaidman (a physicist):

The debate starts at 36:20 and gets stopped at 44:33 (by a moderator). My link above starts at 39:00, where the debate gets hot. In this debate, Tim Maudlin defends more or less Demystifier's position, while Lev Vaidman defends an idea that I personally first learned about from A. Neumaier's book.
...

I watched the ten mins you suggested and my impression is different. I agree it seems that Tim Maudlin defends the usual Bohm-Bell possition. Lev defends more or less standard QM possition. But the whole collapse of the debate seem to me to come from the fact that "be-able" is not precisely defined.

 

[WernerQH]

Or maybe neither of those?

Those terms all come with a classical tang.

It is tempting wheen seeking abstractions is to restrict oneself to the common "classical ontologies". You might as well ask, what "is" a field or particle anyway? We only think we know because of classical ideas where one implicitly adds the newtonian behaviour to the ontologies.

Exactly. Quite a few here on PF insist that the idea of wave-particle duality is outdated, and everything is fine when you talk about quantum objects and field excitations instead. But the duality is still there. When you want to emphasize continuity, you turn to "fields", when discreteness is essential, you say "excitations". Is the emission of radiation a continuous or a discontinuous process? The experimental evidence seems to be overwhelmingly clear, but some theorists (perhaps because of their love for differential equations) still insist on it being continuous because of Schrödinger's equation.

I am not a fan of geometrical ontologies, i prefer those or gaming.

My preferences are the exact opposite. But this should not distract from an interesting discussion.

 

[vanhees71]

Indeed, there's no duality but one consistent picture called quantum field theory. Of course, radiative processes are continuous. There are no "quantum jumps" in Q(F)T!

 

[WernerQH]

Indeed, there's no duality but one consistent picture called quantum field theory. Of course, radiative processes are continuous. There are no "quantum jumps" in Q(F)T!

I also detest quantum jumps, when they refer to e.g. collapsing wave functions. But how can you insist on talking about a series of detector clicks as something continuous?

 

[vanhees71]

It depends of course on the time resolution. If you resolve the "click" of, e.g., a Geiger counter with an oscilloscope you'll see that it's a continuous signal:

https://lcamtuf.coredump.cx/geiger/old/old/

 

[Morbert]

In an actual discussion between some real philosopher and some real physicist, it is much harder to decide who is responsible for the debate going nowhere. See for example this discussion between Tim Maudlin (a philosopher) and Lev Vaidman (a physicist):

It's Tim's fault. Always. His writings are frustrating to read. E.g. here he makes a comment about labels falling off boxes that shows he simply hasn't developed the intuition for these kinds of discussions at the level of public outreach he engages in.

 

[WernerQH]

It depends of course on the time resolution. If you resolve the "click" of, e.g., a Geiger counter with an oscilloscope you'll see that it's a continuous signal:

https://lcamtuf.coredump.cx/geiger/old/old/

So you dismiss the essential microscopic event causing the click of the Geiger counter?

Perhaps the rivers of ink which have been expended discussing the nature of the 'continuous' over the centuries, from Aristotle to Heidegger, have been wasted. Continuity is only a mathematical technique for approximating very finely grained things. The world is subtly discrete, not continuous. The good Lord has not drawn the world with continuous lines: with a light hand, he has sketched it in dots, like Seurat.

(Carlo Rovelli, emphasis added)

 

[physika]

Or maybe neither of those?

Those terms all come with a classical tang.

It is tempting wheen seeking abstractions is to restrict oneself to the common "classical ontologies". You might as well ask, what "is" a field or particle anyway? We only think we know because of classical ideas where one implicitly adds the newtonian behaviour to the ontologies.

If you ask from the stance of inference, what is a "field", its not as clear anymore. Instead from that stance other things are more clear, that are simultaneously not clear in classical ontology.

I think each ontology comes with implicit assumptions on behaviour. Same goes for geometrical ontologies. Gaming ontologies. We can call it a "dice" or a "random walker".. the evolution of rhe dice or evolution of the geometry... different abstractions or ontologies but serving compatible purposes and thinking tools (a term demystifiers uses alot). I am not a fan of geometrical ontologies, i prefer those or gaming.

/Fredrik

Obvious.

Yesterday I was going to edit, but it is something implicit, nobody wants to restrict themselves conceptually, I was going to put "X" or "Y" as the other option, because the "classical analogies" thing is already so hackneyed, nobody wants to waste time, endlessly on it (useless talk), excuses for others to write more.

 

[Demystifier]

What exactly would be different, if he would publish it in a peer reviewed journal?

If it was published, I would not have doubts whether I should include it on the list of "official" interpretations.

 

[Demystifier]

Of course, radiative processes are continuous.

Continuous but random. Is there an explicit equation in standard quantum theory which describes a continuous random process? (I saw such equations in stochastic theories, but they are not a part of standard quantum theory.)

 

[Fra]

My preferences are the exact opposite. But this should not distract from an interesting discussion.

The two stances can interestingly charactereized liek this...

in the geometrical/manifold ontology, the "information" guiding the random walker is I think naturally thought of as existing somehow objectively, independently of the random walker (delocalized over the whole manifold). (Unless there is a feedback, like in General relativity, but we can't handle that in QFT - which I think is a hint)

=> Here all random walkers, can be thought of as "walking" the same "objective" manifold module observer symmetry transformations. But we have trouble to understand, how a single random walker can LEARN about the whole manifold, just by walking without distoring the very same during the inference process? The idea is that the do NOT infer anything, they just exist and the manifold parameters and all information is fine tuned, without explanation. We can imagine a sort of closed explanation, which makes it in a certain sense "simple", but requires fine tuning. But this is why i do not like it, it has low explanatory value, it's more a "description".

in the dice/gaming ontology, the "information" guiding the player, is encoded in the dice, which is naturally thought of as beeing encoded and controlled locally along with the player itself. Ie. the dice is encoded locally, and presumably the result of an inference on it's own history of interactions. So the dice is ideally always "explained" in terms of inference. And the idea is naturally also in gaming that players are evolutionary selected, so only those with good dices survive. Those that doesn't are not banned, but not abundant.

=>The problem is to understand how the dices of a multiplayer game evolve, and does there spontanesouly appear nash type equilbirums? Can we make more progress here, without the same fine tuning? And does these have any physical significance? Theser are open questions (just like finding a fine tuning answer of previous type).

/Fredrik

 

[jbergman]

In interpretations of quantum mechanics there are two types of physicists: those who care about ontology and those who don't. The ontologists, or realists, want to know what is the world made of. The non-realists, on the other hand, think that this question is not relevant to physics.

Usually the two types of physicists don't understand each other. A realist can't understand how a physicist may not care about what is the physical world made of. A non-realist, on the other hand, can't understand how a serious scientist may care about the metaphysical notion of "reality" that does not have any practical consequences.

To help mutual understanding between the two types of physicists, I would like to propose an analogy, or at least a good metaphor. The two types of physicists are somewhat like the two types of computer scientists; those who care about hardware and those who don't.

Suppose that you ask how a computer program works. There are two kinds of explanation one can give to you. One explanation is something like - there is an electric current flowing through the microchip, which consists of many transistors, where each transistor is made of silicon in a pnp configuration, ... This explains how the computer works at the hardware level. The other explanation, on the other hand, will completely ignore the hardware and explain you the algorithm of the specific computer app; it explains how the computer program works at the software level.

The software guy will tell you that it is the computation algorithm that really explains how the program works, while the hardware implementation is not really important for understanding from the point of view of computation theory. The hardware guy will tell you that only understanding the hardware gives you the true understanding how the computer really works. The hardware guy gives you an ontological explanation, while the ontology is irrelevant to the software guy.

Of course, both the hardware guy and the software guy are right in some sense. And more importantly, there is no really any controversy about that, it's not that hardware guys and software guys don't understand each other. They only put more emphasis on different aspects of computation theory, which are complementary to each other.

Likewise, I believe, that two ways of thinking in quantum foundations are also complementary to each other. Realists and non-realists in quantum theory are analogous to hardware guys and software guys in computation theory. I believe that this way of thinking about realists and non-realists can help in better mutual understanding between them.

The problem with this analogy is there is always another layer. For instance, the hardware guy might not know the physics behind the components he uses.

Like Sean Carroll often says, at some point there are probably just brute facts that we have to accept as true until we have reason to believe there is something deeper.

 

[WernerQH]

guiding the random walker

You presuppose the (continuous!) existence of a "random walker" or "player". @vanhees71 assumes the continuous existence of electrons and photons ("field excitations") at least for some interval of time. But I consider only the creation and destruction events as real. The QFT formalism just describes the statistical correlations between these events.

 

[Fra]

You presuppose the (continuous!) existence of a "random walker" or "player". @vanhees71

Actually I do not.

But those discussions doesn't belong here I think. The above was a simplified view with those good points left out.

(In my own view, the continuum is an "approximatation", not the other way around, for this reason I even think standard probability theory is problematic, because the real number isn't justified, it is a valid embedding however. But I confusing the physical and mathemtatical complextions, is probably why we sit here today with so much divergences in our theories. The alternative to continum probability, would be combinatorics and permutations etc, but for complex systems that just gets unmanagable. Like Boltzmanns entropy, counting complexions)

/Fredrik

 

[Fra]

You presuppose the (continuous!) existence of a "random walker" or "player". @vanhees71 assumes the continuous existence of electrons and photons ("field excitations") at least for some interval of time. But I consider only the creation and destruction events as real. The QFT formalism just describes the statistical correlations between these events.

What is continous to one observer, may be discontinous to another one, and I see no problem with that. The wave collapse refers to the original observer, the decoherence does not. These two views does not have to match.

/Fredrik

 

[Fra]

The problem with this analogy is there is always another layer. For instance, the hardware guy might not know the physics behind the components he uses.

Like Sean Carroll often says, at some point there are probably just brute facts that we have to accept as true until we have reason to believe there is something deeper.

The version of this I subscribe to is that at some point, I (or genereally, the agent) are simply unable to formulate further questions, this is the layer where the turtles stop, which one can consider as an axiomatic status. The problem is thta this layer, will probably depend on the observer. Which is my each observer stops seeing turtles at different levels, which also seems to be the trouble when trying to form observer equivalence.

/Fredrik

 

[Structure seeker]

I'd like to come back to this point:

Wave functions are not observables. Their only meaning is to provide the probabilities (probability distributions) for the outcome of measurements via Born's rule.

I do not think you are in the position to determine what is and is not the meaning of the wave function. If it turns out from experiments that it also has another meaning, you'd have to accept it I suppose. And interference is due to the wavefunction, doesn't it have a meaning there as well?

I follow the consistent history interpretation, that wavefunction collapse is just entanglement with the macroscopic measurement device. That means your measurements of observables are merely wavefunctions entangled with a macroscopic object. Due to that entanglement, as far as I understand the interpretation, the Schrodinger equation squashes the wavefunction to a small point-like classical value of the quantum property. But the essence of what it is is still a wavefunction. In my definition of what is real, the entanglement in fact means that "the value of the measured observable" is not independent of the state of the measuring device so it is only real if you word it as "the value of the observable as measured by the measuring device" which then should be interpreted as "the wavefunction is [some formula] in the device and [the value] of the measured object" but then described as density matrix.

I thought that's also what quantum physics tells, that classical reality is dependent on the measurement setting, isn't that right?

But as I see it: quantum reality, the wavefunction, is not measurable without affecting it but all the more real.

 

[Simple question]

The debate starts at 36:20 and gets stopped at 44:33

Fantastic example of a debate between a hardware guy (Tim) and a software guy (Lev) !

The thing is even when beable are precisely defined, as computer-circuit and computer-users are, some software guy cannot care less. It would not be an issue if the software guy did not made grand (hand-wavy) claims about the result they claim which are factually incorrect.

But I think this thread is more about elucidating the importance of ontologies.
The software guy also has an ontology, and his own high-level beable (like quine) could even be fun as hell. So this is a result of some sort. But that ontology is not the claimed one anymore. It is computing "science", not computer science.

Again, when taken to task, by pinpointing that the result is not great or even blatantly false, then the software guy will say that it can also represent "hardware stuff", even "user stuff". And this is mostly true. But then when the hardware guy explain that this does not need a explaining, because it exists first, and actually retrofitting the hardware schematics into the software space just change the ontological level (37:40)

The problem with this analogy is there is always another layer. For instance, the hardware guy might not know the physics behind the components he uses.

Actually I think the analogy precisely address that issue.
Claims about ontologies, are not about "being first" (instead of derivative/emergent), or being "more grounded" (instead of philosophical). Those claims are precisely there to stop the infinite regress at a level where "reality" gets asserted.

Tim Maudling retry explaining it at 43:48, and the response is literally "you construct..."

No, you don't "construct". Nor does the hardware guy need to know about quantum fields. His hardware-ontology precisely define that its domain stop at some timing / frequency response/etc, even hardware-bugs!!! Gravity is useless to him, as well as QM. A bit a electronics and biology will do.

As usual, despite the facts observed in laboratory, that show that nature (yes that menial level of ontology) deal in non-local correlation, and probability conservation... this thread will inevitably turn into philosophical rambling about "fundamental randomness", and micro-causality.

Any discipline must be rooted in something, and science without some ontology is a chicken without head.

 

[A. Neumaier]

The thermal interpretation by @A. Neumaier might be the only realistic interpretation in this sense, but AFAIK this interpretation is not published in any peer reviewed journal.

Its published in a peer reviewed book!