A Implications of quantum foundations on interpretations of relativity

[AnssiH]

(Note: You do give a reference to a Cramer paper a little further in your post. I'll take a look at it, but I'm already familiar with the basics of the TI from reading other things Cramer has written, so I doubt that paper will tell me anything I don't already know.)

Excellent! I was about to give you that reference for the third time, which would have started to seem a bit odd

By "follow my references" I simply meant that I had already given you exactly that same Cramer's paper as a reference by saying "there's a whole list of references in this Wikipedia page" - first of which was exactly that paper. Sorry if that was unclear (I appreciate you may have better things to do with your time than try to follow references through 2 links :) )

Anyhoo now that that's cleared out, the one particular point you wanted clarification on was whether or not "superposition" is a feature of quantum mechanics, or a feature of particular interpretations of QM - you seem to believe it is the former, and I made the claim it's the latter.

This thread is about the connection between SR and QM interpretations, and transactional interpretation operates in the static Minkowski spacetime via positing temporally two directional transactions, to produce Bell experiment correlations in that static spacetime structure. In other words, that acts as an explanation to those observables that are in Copenhagen viewed as "superposition" and "entanglement". Meaning, the concept of superposition doesn't appear in TI. Meaning, superposition is a feature of some interpretations. I'm surprised that you are familiar with TI but not familiar with its transaction mechanism. I realize there may not be exactly these same words used in his paper about this - which is why I said it requires some amount of understanding / thinking this thing through, to realize what I'm saying is true (possible distorted semantics aside). It is not an attack on you or anyone as a person - just a general statement of the circumstance (everyone need to think about these things in order to understand them - to believe something without understanding it is the exact anti-thesis of scientific philosophy )

ps, I noticed few people expressed doubt emoticons to my post. Would love to know what parts about it - and it would be interesting to discuss those parts, whatever they might be. Yes, I can dig up published references to whatever it is you guys have doubts about! We are here to increase each other's understanding.

Best regards!
-Anssi

 

[PeterDonis]

the concept of superposition doesn't appear in TI

Yes, it does. The superposition is in the multiple "offer waves" that get sent out, and the multiple "response waves" that get sent back. One of those offer-response pairs is randomly selected to become the actual result; that corresponds to collapse.

Also, in my post #65, which was where I brought up superposition in the context of this thread, I did not refer to superposition in general, but to superposition of different spacetime geometries. No interpretation of QM has a way to deal with that, including the TI. TI says that offer and response waves travel along light cones; but if we have a superposition of different spacetime geometries, we have a superposition of different light cone structures, and TI cannot handle that.

 

[RUTA]

Summary:: If the Bell theorem is interpreted as nonlocality of nature, then what does it tell us about the meaning of Einstein theory of relativity?

Physicists often discuss interpretations of quantum mechanics (QM), but they rarely discuss interpretations of relativity. Which is strange, because the interpretations of quantum non-locality are closely related to interpretations of relativity.

What different interpretations of QM can tell us about those interpretations of relativity? Which interpretations of relativity seem natural from the perspective of which interpretations of QM?

Wow, how did I miss this thread? All of my recent publications deal directly with this topic!

SR, GR, QM, and QFT can all be understood as providing adynamical constraints in the block universe, see our book, "Beyond the Dynamical Universe" (Oxford UP, 2018). But, I much prefer our recent results based more precisely on principle explanation, since that does not depend on the block universe view or any other ontological claims.

This paper was the 15th most downloaded physics paper in Scientific Reports for 2020: Answering Mermin's Challenge (https://www.nature.com/articles/s41598-020-72817-7). See Top 100 in Physics (https://www.nature.com/collections/ihggebhehd). Here is a shorter layperson's version in ScienceX: Einstein's missed opportunity to rid us of 'spooky actions at a distance' (https://sciencex.com/news/2020-10-einstein-opportunity-spooky-actions-distance.html). Here is a 3-min video linking to our 2021 paper in Entropy: Beyond Causal Explanation (https://encyclopedia.pub/10904). I have attached a pedagogical version under review at AJP. I have also attached our essay that just won Honorable Mention in the Gravity Research Foundation 2021 Essay Contest where we extend the idea to GR; this paper is under review at IJMPD with other winning essays in the GRF essay contest.

Of course, Demystifier is aware of all this work, I'm just posting for any newbies drawn to his thread :-)

The bottom line is that the so-called "nonlocality" evidenced by quantum entanglement does not render QM "incomplete" or "wrong" as some claim. In fact, QM is as complete as possible given that everyone must measure the same value for Planck's constant h. Indeed, the mystery of quantum entanglement and the ineluctably probabilistic nature of QM are necessary consequences of that fact, i.e., the relativity principle applied to the measurement of h. This is in complete analogy to SR where the mysteries of time dilation and length contraction are necessary consequences of the relativity principle applied to the measurement of c. We're hoping this principle account of quantum entanglement will catch on, since it's already widely adopted for SR in the introductory physics textbooks.

People are still free to consider constructive counterparts (causal mechanisms) such as the luminiferous aether or pilot waves. But, theories of the aether were abandoned long ago, so I don't hold out much hope for causal accounts of quantum entanglement.

 

[zonde]

Yes, it does. The superposition is in the multiple "offer waves" that get sent out, and the multiple "response waves" that get sent back. One of those offer-response pairs is randomly selected to become the actual result; that corresponds to collapse.

Now you are arguing against Cramer not AnssiH.
From https://www.researchgate.net/publication/226312851_Transactional_Interpretation_of_Quantum_Mechanics:
We note here that the sequence of stages in the emitter-absorber transaction presented here employs the semantic device of pseudo-time”, describing a process between emitter and absorber extending across lightlike or timelike intervals of spacetime as if it occurred in a time sequence external to the process. This is only a pedagogical convention for the purposes of description. The process itself is atemporal, and the only observables come from the superposition of all of the steps that form the final transaction.

and

The “standard” Transactional Interpretation, with its insights into the mechanism behind wave function collapse through transaction formation, provides a new view of the situation that make the retreat to Hilbert space unnecessary. The offer wave for each particle can be considered as the wave function of a free particle and can be viewed as existing in normal three dimensional space. The application of conservation laws and the influence of the variables of the other particles of the system comes not in the offer wave stage of the process but in the formation of the transactions. The transactions “knit together” the various otherwise independent particle wave functions that span a wide range of possible parameter values into an interaction, and only those wave function sub-components that are correlated to satisfy the conservation law boundary conditions are permitted to participate in transaction formation. The “allowed zones” of Hilbert space arise from the action of transaction formation, not from constraints on the initial offer waves, i.e., particle wave functions.

Also, in my post #65, which was where I brought up superposition in the context of this thread, I did not refer to superposition in general, but to superposition of different spacetime geometries. No interpretation of QM has a way to deal with that, including the TI. TI says that offer and response waves travel along light cones; but if we have a superposition of different spacetime geometries, we have a superposition of different light cone structures, and TI cannot handle that.

Isn't that your personal research? Or you have reference? I why do you make such arguments in interpretations subforum anyways?

 

[zonde]

So how about instead of throwing away realism or locality, we throw away the idea of particles? In that case, actually a local realist explanation of Bell experiment becomes quite trivial. Place an observational limit (instead of "existence limit") to quantized EM detection events (you can't observe it unless it manifests an interaction event), and what you get is fully wave-like propagation of EM energy from emission to the two detection sites. Modification of the wave-like energy through polarization filters (or any mechanism that do not cause a "collapse" - i.e. yield an actual detection event) would yield a cosine correlation to the "probabilities of quantized detection interactions to occur". Not a great surprised - the wave propagation is best described by Schrödinger's Equation - so if we manage to keep the propagation as waves, from emission to detection, we expect to always get a result that is fully aligned with QM expectations, while maintaining fully ordinary local realist mechanisms.

It just does not work. Detection events are paired up like particles. You can't throw away that because it's just experimental fact (I believe experimental limit for efficiency of pairing up downconverted photons is around 99%).

 

[PeterDonis]

Now you are arguing against Cramer

I don't see where you're getting that from, since nothing in what you quoted from Cramer's paper contradicts what I said.

Isn't that your personal research?

No, it's a well known fact that is one of the key motivations for searching for a theory of quantum gravity, which anyone with the background knowledge to post in an "A" level thread on this topic should already be aware of.

 

[zonde]

I don't see where you're getting that from, since nothing in what you quoted from Cramer's paper contradicts what I said.

Sure, I can explain where I see contradiction. In standard QM the process of getting a measurement is rather sequence of events. There is a time when there is wavefunction (which can be represented as superposition dependent on the choice of basis) and later there is collapse and result of measurement. Cramer on the other hand says it is "atemporal process" (actually seems like an oxymoron), so it should mean that "offer waves" actually do not exist at any moment in time. So there is no temporal process of wavefuntion collapse.
And in standard QM there is superposition of states of entangled systems that leads to specific measurements observed in Bell inequality tests. And here Cramer says : "The application of conservation laws and the influence of the variables of the other particles of the system comes not in the offer wave stage of the process but in the formation of the transactions." So there is no superposition of entangled pair states. "offer waves" for each particle are independent. They determine outcome of measurement of particular particle and only at outcome level they become interdependent. Clearly he proposes to discard many particle superpositions.

 

[PeterDonis]

In standard QM the process of getting a measurement is rather sequence of events.

No, it isn't. The basic math of QM is "atemporal", just like Cramer describes the TI; it is a mathematical process for making predictions. There is no claim made that that mathematical process corresponds to an actual physical process that takes place in time. Some interpretations of QM make such a claim (obviously the TI is not one of them), but not the basic math of QM.

Similar remarks apply to what you say about "superpositions" later in your post.

 

[zonde]

No, it isn't. The basic math of QM is "atemporal", just like Cramer describes the TI; it is a mathematical process for making predictions. There is no claim made that that mathematical process corresponds to an actual physical process that takes place in time. Some interpretations of QM make such a claim (obviously the TI is not one of them), but not the basic math of QM.

Before measurement entangled state of pair of particles is described as
$|\psi \rangle=|H_A H_B\rangle+|V_A V_B\rangle$ (1)
After measurement it is say
$|\psi \rangle=|V_A V_B\rangle$ (2)
If you say that there is no time when (1) is true, and (2) is true at all times for particular pair of particles, then there is no superposition.
If you say that (1) is true at all times then you are using no collapse interpretation.

 

[PeterDonis]

Before measurement entangled state of pair of particles is described as
$|\psi \rangle=|H_A H_B\rangle+|V_A V_B\rangle$ (1)
After measurement it is say
$|\psi \rangle=|V_A V_B\rangle$ (2)

No, that's not what the basic math of QM says. The basic math of QM only says that your state (1) is the one you use to predict the probabilities for various results of the measurement, and state (2) is the one you use to predict the probabilities for future measurements once you know the result of this one.

Any other claim is interpretation dependent.

 

[zonde]

No, that's not what the basic math of QM says. The basic math of QM only says that your state (1) is the one you use to predict the probabilities for various results of the measurement, and state (2) is the one you use to predict the probabilities for future measurements once you know the result of this one.

Any other claim is interpretation dependent.

It does not matter. From the text I quoted I read Cramer as saying that (1) never represents physical reality i.e. there is no superposition of entangled particle states.

 

[PeterDonis]

It does not matter.

Yes, it does. Saying that a particular aspect of the math, in this case superposition, is not "in reality" is one thing. Saying that it is simply not there at all is another. The latter claim is the one I was arguing against (not against you, but against the poster who originally made the claim in this thread). If all you are asserting is the former claim, we are in agreement.

I quoted I read Cramer as saying that (1) never represents physical reality

Yes, that's what the TI says.

i.e. there is no superposition of entangled particle states.

"In reality", yes. But the superposition is still there in the math, because the math is the same as the standard math of QM. As I have already said, to what extent the things that happen in the math also happen "in reality" is interpretation-dependent; the TI is one interpretation. But the math is still the same for all interpretations.

 

[PeterDonis]

It does not matter.

I would argue that what does not matter is the differing claims that different interpretations make about "reality". None of those claims are experimentally testable, since all interpretations of QM make the same predictions for actual experimental results. They just tell different stories about why the results are what they are. To me, such differences do not matter. The TI tells one story; other interpretations tell other story. In the TI story, "superpositions" never exist "in reality"--but the TI still says there is a random, unpredictable choice among different alternatives, just as the math of standard QM does. It gives us no help at all in explaining why one particular result happens instead of another.

What does matter is when such differences are used to construct different theories, that make different predictions about actual experimental results. For example, the GRW stochastic collapse model is a different theory; it makes different predictions from standard QM about the results of certain (very hard to do) experiments. So far, as I understand it, what experiments we can do along these lines make the model seem unlikely; but at least it's testable vs. standard QM. TI, in its current form, is not. Perhaps a different theory drawing inspiration from TI will come along one day, and then we can test it.

 

[zonde]

I would argue that what does not matter is the differing claims that different interpretations make about "reality". None of those claims are experimentally testable, since all interpretations of QM make the same predictions for actual experimental results. They just tell different stories about why the results are what they are. To me, such differences do not matter.

Yes, good point. I recognize your position as quite rational.
However I have different take on interpretations. As I see it is possible to find flaws in interpretations even if they declare that they agree with all the predictions of QM.
It is possible that they can't predict outcomes of some experiments even if they have the same math for some other experiments.
And they can be inconsistent and they can be unscientific. Say if interpretation is inconsistent it can't make unequivocal predictions - it's a fail. And if it is unscientific it will never ever give us any knowledge (say I tend to consider TI as unscientific because it seems as equivalent to superdeterminism - eternally-global consistency rule that determines what combinations of outcomes are valid).

But if we would get rid of all the trash it might just happen that it would be clearer where to look for a new theory not just interpretation.

 

[PeterDonis]

It is possible that they can't predict outcomes of some experiments even if they have the same math for some other experiments.

This doesn't make sense. All interpretations use the same math. If something only uses the same math for some experiments, but different math (or no math at all, so it can't even make a prediction) for others, it isn't an interpretation of QM; it's a different theory.

they can be inconsistent

This doesn't make sense either. The math of QM is consistent, so any interpretation based on it should also be consistent.

and they can be unscientific

This is a purely subjective criterion which comes down to personal opinion.

f we would get rid of all the trash it might just happen that it would be clearer where to look for a new theory not just interpretation.

If you really believe this you should not be posting about it here. You should be publishing a new paper that "gets rid of all the trash" and shows how that points the way to a new theory.

 

[zonde]

This doesn't make sense. All interpretations use the same math. If something only uses the same math for some experiments, but different math (or no math at all, so it can't even make a prediction) for others, it isn't an interpretation of QM; it's a different theory.

This doesn't make sense either. The math of QM is consistent, so any interpretation based on it should also be consistent.

Interpretations can use quite different math. They just have to demonstrate that it can be reduced to standard QM math. But it is conceivable that it reduces nicely to QM math in some cases, but in other cases it doesn't.
For example Bohmian Interpretation is claimed to be no collapse interpretation, but I can't wrap my head around how it then predicts BI violations. As I remember in one thread Demystifier tried to explain that but was not very successful at that. But of course it might be that he have found a way, however I will remain rather skeptical until I see such explanation.

This is a purely subjective criterion which comes down to personal opinion.

Well, would you call Poppers falsifiability subjective too?

If you really believe this you should not be posting about it here. You should be publishing a new paper that "gets rid of all the trash" and shows how that points the way to a new theory.

Sorry but why? You shared your opinion, I shared mine. How did you arrived at such farfetched suggestion?

 

[PeterDonis]

Interpretations can use quite different math. They just have to demonstrate that it can be reduced to standard QM math. But it is conceivable that it reduces nicely to QM math in some cases, but in other cases it doesn't.

In the latter case, again, it's not an interpretation; it's a different theory, which just happens to have standard QM as one approximation under certain conditions.

You might not want to use "interpretation" that way, but in this forum, that is how that term is used.

Bohmian Interpretation is claimed to be no collapse interpretation, but I can't wrap my head around how it then predicts BI violations.

It's a no collapse interpretation because the actual, physical state of the system includes the unobservable particle positions, so the results of actual, physical measurements are not due to any random choice among alternatives, they are due to whichever branch of the wave function happens to contain the unobservable particle positions.

It predicts BI violations because it is explicitly nonlocal: the equation of motion for the unobservable particle positions includes the quantum potential, which allows an interaction anywhere in the universe to instantaneously affect the motion of the unobservable particles anywhere else in the universe. (Yes, "instantaneously" means we are violating relativity; AFAIK there is no generally accepted relativistic version of the Bohmian interpretation.)

 

[zonde]

It's a no collapse interpretation because the actual, physical state of the system includes the unobservable particle positions, so the results of actual, physical measurements are not due to any random choice among alternatives, they are due to whichever branch of the wave function happens to contain the unobservable particle positions.

You describe the situation after beamsplitter, where there are two separate branches. But even at beamsplitter particle is not behaving randomly. In which branch particle will end up is determined by pilotwave and initial position of particle.
But too much determinism will make it contradict Kochen-Specker Theorem.

It predicts BI violations because it is explicitly nonlocal: the equation of motion for the unobservable particle positions includes the quantum potential, which allows an interaction anywhere in the universe to instantaneously affect the motion of the unobservable particles anywhere else in the universe. (Yes, "instantaneously" means we are violating relativity; AFAIK there is no generally accepted relativistic version of the Bohmian interpretation.)

Yes quantum potential is nonlocal and it allows an interaction anywhere in the universe to instantaneously affect the motion of the particles anywhere else in the universe. But will it affect the right particle at the right time in the right way? That's the question that requires the answer. Otherwise it's just handwaving.

 

[PeterDonis]

You describe the situation after beamsplitter

No, I describe the situation at all times according to the Bohmian interpretation. You even agree with me:

In which branch particle will end up is determined by pilotwave and initial position of particle.

Exactly; that's what I'm saying. Which means there is no collapse in this interpretation because, given the initial position of the particle, one single measurement result is determined to occur. There is no random choice between alternatives; the "alternatives" in the wave function (pilot wave) are there in the math but not in reality according to this interpretation.

too much determinism will make it contradict Kochen-Specker Theorem.

I don't know what you mean here. The Bohmian interpretation's predictions are exactly the same as standard QM, so it doesn't contradict the theorem.

will it affect the right particle at the right time in the right way?

Of course. Why wouldn't it?

That's the question that requires the answer.

It already has an answer. See above.

 

[Fra]

This is a purely subjective criterion which comes down to personal opinion.

Well, would you call Poppers falsifiability subjective too?

I think the distinction is between hypothesis/conjecture generation and falsification of candidates.

The hypothesis generation may well be subjective, but the falsification is not. Popper tried to deny the fuzzy inductive part of science, by sweeping the process of conjecture generation under the rug, and instead focus on falsification to make science seems like a clean deductive reasoning (which it clearly isn't).

For a theorist, the hypothesis-building part seems to be the big and important part, but unfortunately the problem of PREMATURELY judging a hypothesis (without actually making falsifiable predictions), is not falsifable, because while while a theory can be "wrong", a hypothesis generator can not be "wrong" as it can learn and correct! It can perhaps be more or less efficient in learning. So one must judge a theory for optimal hypothesis generation, in a different way - which way? but this is way beyond Poppers description which i find simplistic. I read his book long time ago and it left me unsatisfied and frustrated.

/Fredrik

 

[PeterDonis]

would you call Poppers falsifiability subjective too?

To the extent that it is equivalent to "experimentally testable", no. But the term "unscientific" is not the same as "not falsifiable". If you meant the latter, that's what you should have said.

 

[PeterDonis]

I think the distinction is between hypothesis/conjecture generation and falsification of candidates.

As far as Popper's criterion goes, yes, I think this distinction is key. Popper's criterion can usually be applied reasonably if you already have a hypothesis in hand. But it offers no help at all in finding a hypothesis.

However, the term "unscientific", as I just remarked to @zonde in my previous post, is not the same as "not falsifiable". The latter is a reasonably precise term that can be referenced to something specific (Popper's criterion). The former is not.

 

[AnssiH]

Yes, it does. The superposition is in the multiple "offer waves" that get sent out, and the multiple "response waves" that get sent back. One of those offer-response pairs is randomly selected to become the actual result; that corresponds to collapse.

Also, in my post #65, which was where I brought up superposition in the context of this thread, I did not refer to superposition in general, but to superposition of different spacetime geometries. No interpretation of QM has a way to deal with that, including the TI. TI says that offer and response waves travel along light cones; but if we have a superposition of different spacetime geometries, we have a superposition of different light cone structures, and TI cannot handle that.

Hey Peter :)

I'm afraid that is your personal interpretation of TI, not in any way required or useful in the actual framework of TI. The idea of retarded and advanced waves operate exclusively in a static spacetime structure, which means you can think of them as static shapes where correlations merely appear to exist between space-like separated events. The whole idea hinges on Minkowski's notion of time being an illusion to conscious observers (which is why I don't really think of it as realistic... But that of course is an opinion only)

You seem to possibly interpret that mechanism as if "spacetime itself evolves over time" - that would just mean you add a redundant time evolution to time evolution - which cannot be observed. So why include it into an interpretation? There is no need since you already can posit any possible correlation as occurring due to the emission event already having feedback "from the static future". It's pretty simple idea really.

The idea that there would be multiple spacetimes (multiple universes) in superposition is completely redundant component in this interpretation - it yields no effect to the outcome.

I can only repeat - you seem to have little bit confused view of what superposition is. It's an explanation to Bell experiment correlations. An explanation. Others exist. We've seen at least three concepts already that don't contain superposition, since Ruta brought up the concept of relativistic measurement of Planck constant:

Here is a shorter layperson's version in ScienceX: Einstein's missed opportunity to rid us of 'spooky actions at a distance' (https://sciencex.com/news/2020-10-einstein-opportunity-spooky-actions-distance.html).

Pretty interesting idea Ruta! There's actually more interesting facets to Planck constant when applied to relativity (such as the idea of "relativistic black holes" via extreme doppler shifts), those would be interesting to discuss in some other thread perhaps I'm afraid I don't know any publications that would have brought that up though, so maybe not on this forum.

Cheers everyone!
-Anssi

 

[PeterDonis]

I'm afraid that is your personal interpretation of TI

The first part, about superposition in general, is a simple statement of how TI works mathematically. It's taken straight from the Cramer paper you yourself linked to.

For the second part, about curved spacetime, see below.

The idea of retarded and advanced waves operate exclusively in a static spacetime structure

Sure, and that's fine as long as we are assuming spacetime is classical, so there is only one spacetime structure.

But the whole premise of the search for a theory of quantum gravity is that spacetime structure should not be classical--that it should work like everything else does, where you have amplitudes for different spacetime structures, and where the spacetime structure can get entangled with other quantum degrees of freedom via interactions. Any such entangled state will not have well-defined light cones and so the TI would not work, at least not in its current form. I have not seen Cramer or anyone else advocating TI propose a way for the TI to work in such a case.

If your position is that spacetime structure should not be quantum, that it should remain as a classical entity even though everything else is quantum, then you would not be alone; I believe Freeman Dyson, among others, proposed a similar viewpoint. But I have not seen Cramer or anyone else advocating TI propose such a viewpoint.

You seem to possibly interpret that mechanism as if "spacetime itself evolves over time"

No, that is not at all what I'm saying. See above.

 

[AnssiH]

It just does not work. Detection events are paired up like particles. You can't throw away that because it's just experimental fact (I believe experimental limit for efficiency of pairing up downconverted photons is around 99%).

Yeah indeed, but here's the interesting thing - what is the criteria that makes us say "that's a particle"?

It's a discrete reaction on a detection plane - a piece of matter - made of discrete collection of atoms, right?

How do those atoms react to energy, according to our theory of atoms? They react by stepping up a quantized energy level (often explained as an electron reaching the next harmonic wave mode - exactly the hypothesis behind Planck's Law).

Before someone asks for a reference to this claim:
https://en.wikipedia.org/wiki/Planck's_law
Yes I know Wikipedia is not considered a valid reference but come on boys, if you really doubt the validity of Planck's Law, there's hundreds of references right at the bottom of that page for you to investigate.

So if atoms already are rigged to be only capable of storing quantized energy steps, how exactly do we purport to differentiate between "a particle causing that quantized reaction", vs "a wave causing that quantized reaction"? Either way, what we see is an atom stepping up one energy level.

(And how exactly do you reconcile for the fact that particle may have more energy content than the next wave mode of an electron can absorb? But that's a bonus question)

Put this together with the fact that the system acts as a wave until that quantized interaction occurs (that's the moment when we say "we saw a particle"), and put it together with the fact that plain wave mechanics predict a simple cosine correlation for a Bell experiment (because you are simply filtering a direction component out from a vector when you offset a filter from the actual wave polarization - this is part of basic wave mechanics)

It's pretty silly to claim that classical mechanics predict a linear correlation in Bell experiment - they only do so if we assume there really are particles, or that energy absorption mechanisms are continuous, neither of which is really supported by evidence.

Have fun,
-Anssi

 

[PeterDonis]

Before someone asks for a reference to this claim

We don't need a reference for Planck's Law itself in an "A" level thread on QM. Anyone with the requisite background knowledge for an "A" level thread on QM should already be familiar with Planck's Law.

The same does not apply to other claims you have been making in this thread, which is why you got asked for references for those other claims.

how exactly do we purport to differentiate between "a particle causing that quantized reaction", vs "a wave causing that quantized reaction"?

By constructing models for each alternative, looking for experimental scenarios where the models make different predictions, and running the experiments to see which way nature votes. If the predictions of both models are the same, then we have no way of distinguishing between them by experiment, at least not that particular experiment.

So what models are you using for "particle causing that quantized reaction" and "wave causing that quantized reaction" that lead you to claim that they make the same predictions for an "atom absorbing energy" experiment? And will that also be true for any experiment whatever? Or are there other experiments we could use to distinguish between these two models (because they make different predictions for those other experiments)?

It's pretty silly to claim that classical mechanics predict a linear correlation in Bell experiment

What classical mechanics model makes this prediction? The class of models Bell considered didn't make such a prediction; the only common feature that class of models has is that it can't produce correlations that violate the Bell inequalities.

 

[AnssiH]

There is a time when there is wavefunction (which can be represented as superposition dependent on the choice of basis) and later there is collapse and result of measurement. Cramer on the other hand says it is "atemporal process" (actually seems like an oxymoron), so it should mean that "offer waves" actually do not exist at any moment in time. So there is no temporal process of wavefuntion collapse.

Yeah, it seems like an oxymoron because TI only works if you literally assume the existence of static Minkowski spacetime

So "there is no dynamic time" in it.

One way to look at it is to realize that the problem with Bell experiment correlations - if we view them as coming out from measuring a property of particles that literally flew from emitter to detector - is that once we have measured the outcomes, we can no longer go back to influence the emission because it has already happened.

So that's where the idea of superposition comes to play - as one explanation to those correlations (and it can in itself be interpreted in multitude of ways of course).

But just think about a static spacetime - of course it could have correlations going which ever way - if someone wants to posit that as an interpretation, it can always be done. And that is TI. To think about TI in terms of time evolution and superposition that dynamically evolves and at some point collapses, is to think in oxymoronic / redundant terms.

The fact that a static spacetime interpretation can always be done seems so trivially obvious to me that I can't believe Einstein would have missed that opportunity - I suspect he did not. He probably just didn't care much about it. (Much like we don't care to seriously posit the possibility of solipsism, just as an example)

-Anssi

 

[AnssiH]

We don't need a reference for Planck's Law itself in an "A" level thread on QM. Anyone with the requisite background knowledge for an "A" level thread on QM should already be familiar with Planck's Law.

Thanks, that's a relief

By constructing models for each alternative, looking for experimental scenarios where the models make different predictions, and running the experiments to see which way nature votes. If the predictions of both models are the same, then we have no way of distinguishing between them by experiment, at least not that particular experiment.

Yuup, and that's where we enter the wonderful world of interpretations and philosophy.

So what models are you using for "particle causing that quantized reaction" and "wave causing that quantized reaction" that lead you to claim that they make the same predictions for an "atom absorbing energy" experiment? And will that also be true for any experiment whatever? Or are there other experiments we could use to distinguish between these two models (because they make different predictions for those other experiments)?

Good question. At least I struggle to think of experiments to differentiate between these possibilities, because they appear similar in such a fundamental level of our observational limits (because we just can't directly "just see energies" without using a piece of matter that reacts to it). That's why the difference is fundamentally a matter of interpretation.

Basically if you view any type of "orientation wave filter" classically, the expected "energy dampening" is of course just basic trigonometry since you are removing a direction component from a wave, so it's cos^2(angle). In terms of QM, that exact idea (and math) represents the dampening of the probability of detecting a particle after the filter. Basically exactly this:


(Not intended as a reference, just an example of the mathematical concept)

In terms of an "atom absorbing quantized energy" idea, by dampening wave energy with a filter you would still be literally making it less probable for any atom to be able to react to that energy (as you are approaching the lowest possible energy limits, you would start seeing sparse reactions). The only difference is that in the latter case you "interpret" the situation as if there is low energy wave energy present - which you cannot detect with matter unless certain energy threshold is reached. And in the former case you "interpret" the situation as if there's a superposition (of your flavor) present in the system for the particles that are "making a journey" (as per your assumption that they indeed exist)

So, while I don't know about a published paper that would discuss this sort of treatment (I'd imagine some might exist, I just don't know about them), but on the other hand I'm really talking about trigonometry and very basic wave mechanics. And I do struggle to find a case where an actual observational difference could be found - looks like an interpretation to me.

What classical mechanics model makes this prediction? The class of models Bell considered didn't make such a prediction; the only common feature that class of models has is that it can't produce correlations that violate the Bell inequalities.

That I don't know - I was merely referring to the comment made with the correlation picture at the end of the Overview section here:
https://en.wikipedia.org/wiki/Bell's_theorem#Overview

The more accurate full comment of course is this;
Many other possibilities exist for the classical correlation subject to these side conditions, but all are characterized by sharp peaks (and valleys) at 0°, 180°, and 360°, and none has more extreme values (±0.5) at 45°, 135°, 225°, and 315°

In order to have sharp peaks and valleys, you must be assuming the possibility of detecting arbitrarily small energies after the filters - but that is already excluded by our model of an atom.

Where-as the QM correlation as pictured is - as I'm sure you know - exactly cosine correlation. The important part of course being that the QM correlation does not represent an actual detection, but the probability of a detection. So another way to put it is to simply say - in the classical views (as purported by that Wikipedia article) everyone assumes any and every energy level can detected - even though we are using atoms to do so

-Anssi

 

[PeterDonis]

in the classical views (as purported by that Wikipedia article)

I don't see how what you quoted from the Wikipedia article appears anywhere in the actual literature I've read about Bell's Theorem and related theorems.

More generally, I don't think that Wikipedia article is a good reference for a discussion of Bell's Theorem. The very first sentence in the "Overview" is false:

"The theorem is usually proved by consideration of a quantum system of two entangled qubits with the original tests as stated above done on photons."

No, the theorem is proved using math that has nothing whatsoever to do with quantum mechanics. Once the theorem is proved, then the obvious fact that the predictions of QM violate the Bell inequalities means that QM must violate at least one of the premises of the theorem. But the actual proof of the theorem has nothing to do with QM. It's just a proof that any theory satisfying the premises must make predictions that satisfy the Bell inequalities.

The important part of course being that the QM correlation does not represent an actual detection, but the probability of a detection.

No, the "QM correlation" is a prediction of what the correlation will be after the measurements are made and the results are known. It is not a prediction of a probability of anything.

It is true that QM cannot predict what the individual measurement results will be, it can only predict probabilities. But that does not mean its prediction of the correlation between results is probabilistic. It isn't. QM predicts that the correlation will be exactly $\cos \theta$. It does not predict that the correlation has probability $p$ of being one value and probability $q$ of being another value.

 

[PeterDonis]

I struggle to think of experiments to differentiate between these possibilities

I wasn't just asking for experiments, I was asking for models. Before you can even think about doing an experiment to compare the predictions of models, you have to have models to compare.

if you view any type of "orientation wave filter" classically

Why would absorption of light by an atom have anything to do with an "orientation wave filter"? What model of light leads you to this?

Basically, it looks to me like you don't have a well-defined model in mind at all; you're just waving your hands. Without a well-defined model of "light as a wave" and "light as a particle", you have no basis for making any claims at all about what we should see in experiments and whether it should be different depending on whether light is a wave or a particle.

(Note, btw, that in our current best theory of light, quantum electrodynamics, light is neither a wave nor a particle, it is a quantum field.)