Undergrad The thermal interpretation of quantum physics

[A. Neumaier]

Are you saying that TI is just plain old interpretation and has no significant practical value of any sort other than "explaining".

No. It is a new interpretation that explains the measurement problem. But (like any other interpretation of quantum mechanics) it does not change any of the predictions that could be relevant for quantum computers.

 

[ftr]

No. It is a new interpretation that explains the measurement problem. But (like any other interpretation of quantum mechanics) it does not change any of the predictions that could be relevant for quantum computers.

So do you think all other interpretations also only try to explain the measurement problem but not "ontology" to any level.

 

[A. Neumaier]

So do you think all other interpretations also only try to explain the measurement problem but not "ontology" to any level.

Well, some interpretations, including the thermal interpretation, also specify an ontology. But ontology is also explanation only, not prediction.

Some interpretations (Bohm, Ghirardi-Rimini-Weber) make in principle different predictions but below current limits of observability. But the thermal interpretation does not change anything in the quantum formalism hence does not change a single prediction.

 

[ftr]

In what sense it specifies an ontology. My guess is that you say there are fields(numbers representing whatever) and the expectation value is the characterestic and that is that. Is that correct.

 

[A. Neumaier]

In what sense it specifies an ontology. My guess is that you say there are fields(numbers representing whatever) and the expectation value is the characterestic and that is that. Is that correct.

The ontology of the thermal interpretation is defined by stating that everything computable from the collection of all q-expectations of a quantum system is an objective property of the system. Thus in quantum field theory, field expectations define local properties and $n$-point functions define for $n>1$ nonlocal properties. Intuitively, field expectations specify properties like densities and currents in small open regions.

 

[ftr]

@A. Neumaier, does TI imply that all other interpretations are highly misguided (not to use a stronger language) since all of them try to explain the probability point of view which they take as the correct starting point.

 

[A. Neumaier]

@A. Neumaier, does TI imply that all other interpretations are highly misguided (not to use a stronger language) since all of them try to explain the probability point of view which they take as the correct starting point.

The thermal interpretation explains probability in a different way than the other interpretations. Therefore there are no direct implications for interpretations with a different starting point.

 

[ftr]

The thermal interpretation explains probability in a different way than the other interpretations. Therefore there are no direct implications for interpretations with a different starting point.

Thanks, although I am not convinced, but I may try to elaborate and clarify my question later.

The book

• A. Neumaier, Coherent Quantum Physics: A Reinterpretation of the Tradition, de Gruyter, Berlin 2019.

just appeared and gives a polished, now authoritative exposition of the thermal interpretation.

Do you think that your book might be considered as peer reviewed since the editorial board consists of heavy duty people.
Is the e-book printable or not?

 

[A. Neumaier]

Do you think that your book might be considered as peer reviewed

Yes.

Is the e-book printable or not?

I don't know. It is probably like any other e-book?

 

[ftr]

@A. Neumaier, thanks. One more question if you don't mind. Early on I read as you were writing about TI, I remember that you said that the photon responsible for the electrostatic force is real photon, does that stand now or is it that my memory is not so good.

 

[A. Neumaier]

you said that the photon responsible for the electrostatic force is a real photon.

No. The Coulomb force is mediated by virtual photos, real photons necessarily oscillate, hence cannot be static. But this has nothing to do with the TI.

 

[ftr]

@A. Neumaier, I hope you don't get sick of my questions.

1. What does TI imply about the value of a property of a particle before measurement is it still undefined?
2. what does TI imply anything about the path of a particle. I mean is it possible to compute it?
Thanks.

 

[A. Neumaier]

@A. Neumaier, I hope you don't get sick of my questions.

1. What does TI imply about the value of a property of a particle before measurement is it still undefined?
2. what does TI imply anything about the path of a particle. I mean is it possible to compute it?

Independent of any measurement, a particle has at all times lots of objectve but numerically uncertain properties. It moves along a fuzzy world tube centered around the path given by the q-expectations of the position, with a width given approximately by the square root of the sum of the q-variances. All properties including their uncertainties are in principle computable. Measuments reveal approximatioms of the theoretical values.

 

[timmdeeg]

It moves along a fuzzy world tube centered around the path given by the q-expectations of the position, with a width given approximately by the square root of the sum of the q-variances.

Is in the case of say a C60 molecule its geometrical structure maintained or fuzzy too?

 

[A. Neumaier]

Is in the case of say a C60 molecule its geometrical structure maintained or fuzzy too?

In a frame where 4 nuclei have positions with fixed q-expectations, the nuclei have quite definite locations (uncertainty tiny). But the electrons are delocalized over the whole molecule, and have the shape of the whole geometry.

 

[EPR]

In a frame where 4 nuclei have positions with fixed q-expectations, the nuclei have quite definite locations (uncertainty tiny). But the electrons are delocalized over the whole molecule, and have the shape of the whole geometry.

Nuclei goes through 1 slit, the electrons through 2?

 

[timmdeeg]

In a frame where 4 nuclei have positions with fixed q-expectations, the nuclei have quite definite locations (uncertainty tiny). But the electrons are delocalized over the whole molecule, and have the shape of the whole geometry.

Why 4 nuclei? Electron delocalisation requires pi bonds like e.g. in benzene. In C60 fullerenes we have covalent bonds. But apart from that and if I understand you correctly the path of a molecule is fuzzy before measurement but the position of the nuclei to each other obey the laws of chemical bonding, correct?

 

[timmdeeg]

Nuclei goes through 1 slit, the electrons through 2?

No, nuclei plus electrons are a unit. The molecule passes the two slits.

 

[EPR]

No, nuclei plus electrons are a unit. The molecule passes the two slits.

Not if nuclei have definite locations. In general, these macro quantum superpositions observed in the last years are far less clear as they seem semi classical and 'semi' quantum. Or better - they are both(you start with a big, heavy molecule which is almost classical in size and still get wave bahaviour as if size and mass were not of great concern).

 

[DrClaude]

Electron delocalisation requires pi bonds like e.g. in benzene. In C60 fullerenes we have covalent bonds.

That's a non-sequitur. Pi bonds are covalent bonds. And there are plenty of pi bonds in C₆₀.

 

[A. Neumaier]

Why 4 nuclei?

Because 4 points are needed to fix a definite frame in space. Thus fixing the mean positions of 4 nuclei produces an approximate rest frame of the C60 molecule. Because such a molecule is quite rigid, it determines the position of all nuclei up to a tiny uncertainty.

Nuclei goes through 1 slit, the electrons through 2?

In a moving frame (relevant when one wants to do diffraction experiments with C60) , there is additional uncertainty. In a double slit experiment, the whole molecule is delocalized over the region of the slit and later over the region of the diffraction pattern, and localizes only when hitting the detection screen.

In C60 fullerenes we have covalent bonds.

Yes, but the electrons are nevertheless delocalized, because of their indistinguishability. In the Hartree-Fock approximation usually employed by chemists when discussing the nature of bonds, one considers approximate effective electrons confined to an atomic orbital. Then one has a notion of delocalization for these effective electrons, leading to a different concept of delocalization.

 

[timmdeeg]

Thanks for your explanations.

Yes, but the electrons are nevertheless delocalized, because of their indistinguishability.

Ah I see, this makes the difference in how Chemists understand delocalized electrons.

 

[timmdeeg]

That's a non-sequitur. Pi bonds are covalent bonds. And there are plenty of pi bonds in C₆₀.

Yes indeed, I've been mistaken here.

 

[timmdeeg]

In a frame where 4 nuclei have positions with fixed q-expectations, the nuclei have quite definite locations (uncertainty tiny).

If I understand it correctly q-expectations play a decisive role in your TI. Searching the web this seems to mean a specific kind of average. My guess is the "average" of all possible outcomes. Could you please explain the meaning of q-expectations in the case of the double-slit experiment where the outcomes have unequal weights?

 

[A. Neumaier]

If I understand it correctly q-expectations play a decisive role in your TI. Searching the web this seems to mean a specific kind of average. My guess is the "average" of all possible outcomes. Could you please explain the meaning of q-expectations in the case of the double-slit experiment where the outcomes have unequal weights?

In the TI, the q-expectation of A is not an average but just the trace of the product of density operator times A. Please first read Part II to understand the basics.

 

[timmdeeg]

In the TI, the q-expectation of A is not an average but just the trace of the product of density operator times A. Please first read Part II to understand the basics.

Thanks.

 

[ftr]

In a moving frame (relevant when one wants to do diffraction experiments with C60) , there is additional uncertainty. In a double slit experiment, the whole molecule is delocalized over the region of the slit and later over the region of the diffraction pattern, and localizes only when hitting the detection screen.

I think in your FAQ and TI writing the double slit experiment is not well illuminated. IS it possible for you to specifically address the double slit for TI and how the q-expectation give rise to the interference pattern.

 

[A. Neumaier]

I think in your FAQ and TI writing the double slit experiment is not well illuminated. IS it possible for you to specifically address the double slit for TI and how the q-expectation give rise to the interference pattern.

My FAQ hasn't been much updated the last few years, hence is nearly silent about the thermal interpretation. The web page for the latter is here. For the double slit experiment see Section 4.3 of Part IV of my preprint series,

• Foundations of quantum physics IV. More on the thermal interpretation.

 

[ftr]

My FAQ hasn't been much updated the last few years, hence is nearly silent about the thermal interpretation. The web page for the latter is here. For the double slit experiment see Section 4.3 of Part IV of my preprint series,

• Foundations of quantum physics IV. More on the thermal interpretation.

Thanks. Of course I have read that and followed some of the discussions on it. It makes sense to me as far as the bucket analogy for the single point detection, however, I am still not clear about the interference pattern and the part you mentioned about the delocalization of the Molecule.

 

[A. Neumaier]

Thanks. Of course I have read that and followed some of the discussions on it. It makes sense to me as far as the bucket analogy for the single point detection, however, I am still not clear about the interference pattern and the part you mentioned about the delocalization of the Molecule.

Whole molecules with their delocalized electrons (in a moving coordinate system whose origin and orientation is itself uncertain) are bucketwise detected. The double slit dynamics is essentially that of the center of mass, which has a density field to which the buckets respond. The inner structure of the molecule does not matter in the setting, only the total mass; the inverse of the latter defines the scale of the concrete diffraction pattern.