The thermal interpretation of quantum physics

[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.

 

[ftr]

So does TI says anything about which slit or slits. Or silent on the issue.

 

[A. Neumaier]

So does TI says anything about which slit or slits. Or silent on the issue.

The C60 field goes through both slits, analogous to a classical electromagnetic field, and materializes at the screen in the form of individual C60 molecules.

 

[vanhees71]

So it says the same as the (minimal) standard interpretation...

 

[Demystifier]

The C60 field goes through both slits, analogous to a classical electromagnetic field, and materializes at the screen in the form of individual C60 molecules.

So it says the same as the (minimal) standard interpretation...

For the sake of comparison, let me tell what what standard Bohmian mechanics (BM) and instrumental Bohmian mechanics (IBM) say.
In BM, C60 goes through one slit only. In IBM, C60 goes through both slits, but the macroscopic pointer on the screen moves to one position only.

 

[EPR]

If the wavefunction goes through both slits what happens to the unactualized possibilities in the TI?

 

[A. Neumaier]

If the wavefunction goes through both slits

The field goes through both slits. This has nothing to do with wave functions (in general there is no wave function but only a density operator).

what happens to the unactualized possibilities in the TI?

They are not actualized, that's all.

 

[EPR]

So it's another description - nice to have but not an interpretation per se. Maybe one day we'll have a complete interpretation. We don't have one. There isn't an interpretation of quantum mechanics

 

[A. Neumaier]

So it's another description - nice to have but not an interpretation per se.

It was always enough to consider what is the case rather than what is just a possibility but then does not happen.

 

[timmdeeg]

I might have misconceptions with the following, so please clarify.

The C60 field goes through both slits, analogous to a classical electromagnetic field, and materializes at the screen in the form of individual C60 molecules.

If the C60 field can be thought as being spread out over a larger area (how large?) and during measurement contracts instantaneously to form a C60 molecule then this notion seems to replace the collapse of the wave function by the collapse of a field. Thereby this field is presumably a real thing, not just a mathematical construct. But if correct so far isn't this an unphysical notion?

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.

Has the TI two views, one where a complex molecule is a field and another one where a complex molecule is rigid?

 

[A. Neumaier]

If the C60 field can be thought as being spread out over a larger area (how large?) and during measurement contracts instantaneously to form a C60 molecule then this notion seems to replace the collapse of the wave function by the collapse of a field. Thereby this field is presumably a real thing, not just a mathematical construct. But if correct so far isn't this an unphysical notion?

In the TI, both fields and collapse are physical. But in general, collapse is described not by jumping into an eigenstate but by the output of an appropriate quantum instrument.

Has the TI two views, one where a complex molecule is a field and another one where a complex molecule is rigid?

No. the TI is a single interpretation. But C60 can be modeled by standard quantum mechanics in different details and in different situations, leading to different descriptions.

The description of C60 as a field is appropriate for C60 beams (as prepared in double slit experiments); these are described by a current (constructible for arbitrary bound states according to a method due to Sandhas). The description of C60 as a reasonable rigid molecule is appropriate for a C60 molecule at the surface of a screen (as measured in double slit experiments). Both descriptions are therefore needed to analyze double slit experiments.

 

[timmdeeg]

In the TI, both fields and collapse are physical. But in general, collapse is described not by jumping into an eigenstate but by the output of an appropriate quantum instrument.

But doesn't the instantaneous collapse of a physical field (to form a molecule on the screen) violate Special Relativity?

The description of C60 as a reasonable rigid molecule is appropriate for a C60 molecule at the surface of a screen (as measured in double slit experiments). Both descriptions are therefore needed to analyze double slit experiments.

My question in #734 was related to your statement "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." Which I understood such that the rigid C60 "moves along a fuzzy world tube ..." before it is materialized at the screen. Thanks for clarifying that now.

 

[A. Neumaier]

My question in #734 was related to your statement "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." Which I understood such that the rigid C60 "moves along a fuzzy world tube ..." before it is materialized at the screen. Thanks for clarifying that now.

Well, behind a double slit, it changes its shape due to diffraction to a union of two fuzzy spheres centered on the two slits. Moreover this affects only the wholesale shape, not the internal shape. Local and nonlocal qualities coexist.

I have never seen a relativistic discussion of the double slit experiment, so cannot answer your other question.

 

[EPR]

There is no coherent explanation of the double slit experiment. If assumptions of how the world is and how it works is true, the double slit shouldn't produce the patterns it does. This is the weakest point in quantum physics and the topic of many many thousands of unresolved debates. It is where literally all interpretations fail and possibly the biggest mistery of nature at this time.

 

[Mentz114]

There is no coherent explanation of the double slit experiment. If assumptions of how the world is and how it works is true, the double slit shouldn't produce the patterns it does. This is the weakest point in quantum physics and the topic of many many thousands of unresolved debates. It is where literally all interpretations fail and possibly the biggest mistery of nature at this time.

I must say I do not agree. If QFT predicts that a 'collision' between succesive molecules and the slits produces an interference pattern - what is incoherent about that ?

 

[EPR]

I must say I do not agree. If QFT predicts that a 'collision' between succesive molecules and the slits produces an interference pattern - what is incoherent about that ?

QFT is the best and the only coherent 'interpretation' of reality to date. By FAR. No question about it. Though it contains in itself the only mistery - the measurement problem.

The so called world is a collection of fields that produce, 'create'(okay i will back off slightly here) and substitute that term with the more acceptable term - 'emerge' a classical world at the classical limit.

QFT was the best and most coherent description of the world when i started researching this topic 15 years ago. It is still by far the best scientific attempt to explain the world without noise and nonsense. Backed up by thousands successful experiments and established facts. Hardcore science at its best. Can't ask for more.

 

[PeterDonis]

There is no coherent explanation of the double slit experiment. If assumptions of how the world is and how it works is true, the double slit shouldn't produce the patterns it does. This is the weakest point in quantum physics and the topic of many many thousands of unresolved debates.

QFT was the best and most coherent description of the world when i started researching this topic 15 years ago. It is still by far the best scientific attempt to explain the world without noise and nonsense. Backed up by thousands successful experiments and established facts. Hardcore science at its best. Can't ask for more.

These two statements of yours appear inconsistent. Which of them do you really mean to say?

 

[EPR]

These two statements of yours appear inconsistent. Which of them do you really mean to say?

One of them says 'the most coherent description of reality', while the other says 'there is no coherent explanation of the double slit experiment'.

Though obviously related, one of them is an almost complete worldview(sans GR and gravity), the other is the final(though still far away) obstacle to understanding the relationship between the classical and quantum world(the MP). Exemplified in my quote "Though it(QFT) still contains in itself the only mistery - the measurement problem. "

 

[PeterDonis]

One of them says 'the most coherent description of reality', while the other says 'there is no coherent explanation of the double slit experiment'.

Unless you are claiming that double slit experiments are not real, having a coherent explanation of reality should include having a coherent explanation of the double slit experiment.

one of them is an almost complete worldview(sans GR and gravity), the other is the final(though still far away) obstacle to understanding the relationship between the classical and quantum world

Either QFT solves this problem or it doesn't. If it does, then the obstacle you describe has been overcome. If it doesn't, then you don't have a coherent description of reality, since gravity is part of reality.

So, again, which is it?

 

[EPR]

Unless you are claiming that double slit experiments are not real, having a coherent explanation of reality should include having a coherent explanation of the double slit experiment.

You misquote me
I said "QFT is the best and the only coherent 'interpretation' of reality to date. "

When the MP is solved(if it's ever solved), i would remove the inverted commas. The most precisely tested theory in history, agreeing with observations at the level of one part 10 to the power of 9, already provides a vision of what the world is like. The united world of quantum and classical scale. A world of fields.

Either QFT solves this problem or it doesn't. If it does, then the obstacle you describe has been overcome. If it doesn't, then you don't have a coherent description of reality, since gravity is part of reality.

So, again, which is it?

No, QFT does not solve the MP. However it already provides a picture of reality.

 

[PeterDonis]

No, QFT does not solve the MP.

Ok.

However it already provides a picture of reality.

But not of all of reality, since that would require solving the MP.