There is no Copenhagen interpretation of QM

[Demystifier]

Many physicists say that they prefer the "Copenhagen" interpretation of QM, but it does not mean that all these physicists prefer the same (or even a very similar) interpretation. There are at least 4 very different interpretations that are sometimes referred to as "Copenhagen":

1. Shut up and calculate - this is actually the interpretation that most practical physicists adopt.

2. Positivism - QM is only about the results of measurements, not about reality existing without measurements. (This is essentially the philosophy of Bohr.)

3. Collapse interpretation - when the measurement is performed, then the wave function collapses. (von Neumann)

4. Information interpretation - the wave function does not represent reality, but only the information about reality. (It is somewhat similar to 2., but still significantly different from it.)

What do you think?
I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

 

[xepma]

How is "shut up and calculate" an interpretation? What's the interpretation of the wavefunction in the case of #3, and how is it different from #4? If, according to #2, everything is about the measurements, then in what way is such a measurement process different from #3?

No, I don't agree with you - all of the four points you mention are features of the same interpretation (which is a little outdated anyway). They do not exclude each other at all.

 

[Demystifier]

How is "shut up and calculate" an interpretation?

Well, perhaps it should not be called an interpretation, but it certainly is one view of QM.

What's the interpretation of the wavefunction in the case of #3, and how is it different from #4?

In 3. one assumes that the wave function is real, i.e., that it exists even without measurements. Many physicists think that way.

If, according to #2, everything is about the measurements, then in what way is such a measurement process different from #3?

See my answer above.

No, I don't agree with you - all of the four points you mention are features of the same interpretation (which is a little outdated anyway). They do not exclude each other at all.

I agree that they do not exclude each other, still I don't agree that they are the same. Many physicists think of 1-4 as DIFFERENT, so in this sense they ARE different (for those physicists).

 

[Fra]

I think I partly agree with Demystifier that there are versions of Copenhagenish type interpretations.

I often consider myself to be close to this interpretation at least relative to some others, like bohm etc, but I am still more radical than many others so I count myself as different than the most common version.

The shut up & calculate interpretation is more like no interpretation to me. It's what you use when you use QM to solve actual problems in calculations. That is not the place to question the theory.

This is to me mainly the difference between the engineering perspective of a theory as a tool, and the fundamental scientific perspective that ponders how to make the tools better.

From then engineering view, you don't need to understand why it works.

But for the tool maker, understanding why it works, and ponder how it can be even better is the whole point.

In 3. one assumes that the wave function is real, i.e., that it exists even without measurements. Many physicists think that way.

I'm probably 4, and in that view the collapse is simlpy an information update. Not really a mystery. By nature the collapses are thus also subjective (if that makes it unreal or real depends if you talk about objective or subjective reality - IMO there is only subjective reality), which leaves it as no contradiction if one observer sees a collapse and one sees a gradual transition. It's just different views.

Wether the wavefunction exists without measurement, I think it kind of does, but it doesn't exist without a measurement-history, since I think of the wavefunction as a steady state structure. Which is why it's constantly evolving. Without measurement, there is the self-evolution (schrödinger), but this self-evolution is perturbed upon measurement.

Except for radical views such as evolving law, copenhagen is IMO the "least speculative" and most in line with the scientific method of the more commona interpretations. That's not to say I don't see problems, but that is IMO problems with quantum mechanics structure, not problem of "interpretations".

/Fredrik

 

[ThomasT]

Many physicists say that they prefer the "Copenhagen" interpretation of QM, but it does not mean that all these physicists prefer the same (or even a very similar) interpretation. There are at least 4 very different interpretations that are sometimes referred to as "Copenhagen":

1. Shut up and calculate - this is actually the interpretation that most practical physicists adopt.

2. Positivism - QM is only about the results of measurements, not about reality existing without measurements. (This is essentially the philosophy of Bohr.)

3. Collapse interpretation - when the measurement is performed, then the wave function collapses. (von Neumann)

4. Information interpretation - the wave function does not represent reality, but only the information about reality. (It is somewhat similar to 2., but still significantly different from it.)

What do you think?
I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

Any interpretation of qm would eventually involve 1., wouldn't it? 2. and 4. are definitely part of the CI. But not 3. -- at least not literally.

The way I look at it, there's an approach to understanding what qm means and what can be said about Nature that might be called 'Copenhagenish' and included in a collection of statements called the CI.

So, I suppose I disagree with you. 2. and 4. are part of an approach that seeks to define what qm does (objectively) mean (not what it might mean if we take certain constructions literally), and what sorts of limitations on what can be objectively demonstrated and communicated about Nature given the quantum of action and the requirements for objective communication.

 

[DrChinese]

Many physicists say that they prefer the "Copenhagen" interpretation of QM, but it does not mean that all these physicists prefer the same (or even a very similar) interpretation. There are at least 4 very different interpretations that are sometimes referred to as "Copenhagen":

1. Shut up and calculate - this is actually the interpretation that most practical physicists adopt.

2. Positivism - QM is only about the results of measurements, not about reality existing without measurements. (This is essentially the philosophy of Bohr.)

3. Collapse interpretation - when the measurement is performed, then the wave function collapses. (von Neumann)

4. Information interpretation - the wave function does not represent reality, but only the information about reality. (It is somewhat similar to 2., but still significantly different from it.)

What do you think?
I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

I personally see all of the above as Copenhagen, especially the first 2. The third starts getting into the interpretation side of things a little, although I think the fuzziness of the collapse concept (when does it occur? is it physical?) is attached to Copenhagen.

 

[Dmitry67]

The problem with these versions of CI is that CI proponents switch from one to another (even unconsciously) making them very difficult to "catch"

They can discuss, for example, subject "are virtual particles real?" claiming that contrary to the virtual ones the real particles DO exist. And at the same time, when asked about the mysterious collapse they can hide behind "wavefunction is just an information, just an knowledge, it is not real"

 

[ueit]

Many physicists say that they prefer the "Copenhagen" interpretation of QM, but it does not mean that all these physicists prefer the same (or even a very similar) interpretation. There are at least 4 very different interpretations that are sometimes referred to as "Copenhagen":

1. Shut up and calculate - this is actually the interpretation that most practical physicists adopt.

2. Positivism - QM is only about the results of measurements, not about reality existing without measurements. (This is essentially the philosophy of Bohr.)

3. Collapse interpretation - when the measurement is performed, then the wave function collapses. (von Neumann)

4. Information interpretation - the wave function does not represent reality, but only the information about reality. (It is somewhat similar to 2., but still significantly different from it.)

What do you think?
I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

Every theory that pretends to be about physics must have an ontology and an interpretation that connects the math with the assumed ontology. Different QM interpretations have different choices about ontology. Having said that these are my comments to your 1-4 choices:

1 equals 2. At a minimum, the instrument readings must be a part of the ontology. Without them there is nothing to calculate. The difference between 1 and 2 is only one of the form, 1 being less explicit.

3 must be a constituent of 1 and 2 because the collapse changes the way the calculations are performed. If the wave-function is interpreted as a calculation tool to relate experimental preparations and instrument readings, 3 does not qualify as a distinct interpretation.

About 4, I cannot quite understand what new ontology the word "information" brings.

I think that characteristic of CI is that it only accepts macroscopic objects as a part of its ontology. Various flavors differ in what the fundamental properties of these objects are (instrument readings, brain-information, or knowledge, etc).

 

[Fredrik]

About 4, I cannot quite understand what new ontology the word "information" brings.

If I understand 4 correctly, it's the "interpretation" I've been supporting in a large number of posts here. There are many different ways to say the same thing, for example:

4'. The wavefunction doesn't represent the properties of the physical system. It represents the properties of an ensemble of systems that have been identically prepared.

4''. QM is a set of rules that tell us how to compute the probabilities of possible results of experiments. Nothing more, nothing less. It doesn't include, and doesn't need, an ontological interpretation.

The first is the way Einstein said it. The books by Ballentine and Isham use similar language. (Note that the ensemble in question consists of the systems that are being measured in all the similar experiments that we can perform, and that we don't have to perform all of them. We just need a large enough number to get good statistics).

The second is the way I've been saying it. I don't consider the "ontology" in 4' an ontological interpretation of the wavefunction, since it doesn't describe what the system "is" on its own.

Edit: I'm too lazy to rewrite the above, so I'll just add this comment. What Demystifier actually had in mind is probably the view that the wavefunction represents our knowledge of the system. I just find that one weird and kind of dumb. At the very least, it would require some technical definition of "knowledge" to make sense.

 

[Fredrik]

Many physicists say that they prefer the "Copenhagen" interpretation of QM, but it does not mean that all these physicists prefer the same (or even a very similar) interpretation.
...
I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

I agree that people don't seem to mean the same thing. Most seem to mean an extreme version of 3, in which it is postulated that measurement devices are exactly classical, and the "collapse" is a physical process that changes the superposition exactly into an eigenstate. Niels Bohr is probably spinning in his grave.

2. Positivism - QM is only about the results of measurements, not about reality existing without measurements. (This is essentially the philosophy of Bohr.)

As I said in the other recent thread...

You too associate the CI with positivism? I really don't see how the CI can be thought of as an example of positivism. As far as I can tell, positivism, or at least logical positivism (I'm not sure if there's a significant difference), requires theories to be verifiable, but the CI is a fantastic example of a theory that's falsifiable but not verifiable.

I realize that the CI may in part have been inspired by positivistic thinking, since it doesn't include an ontological intepretation, but I see no reason to say that it is positivism.

What about the intepretation proffered by Ballentine (described in my previous post)? Should that be another item on your list, or do you think it's covered by 2 or 4, or "isn't Copenhagen at all"?

 

[lightarrow]

4. Information interpretation - the wave function does not represent reality, but only the information about reality. (It is somewhat similar to 2., but still significantly different from it.)

Are you referring to Zeilinger's interpretation? :
http://homepage.univie.ac.at/johannes.kofler/Files/Publications/Kofler,%20Zeilinger%20(2006)%20-%20Information%20and%20the%20Schroedinger%20cat%20paradox.pdf

 

[WaveJumper]

Are you referring to Zeilinger's interpretation? :
http://homepage.univie.ac.at/johannes.kofler/Files/Publications/Kofler,%20Zeilinger%20(2006)%20-%20Information%20and%20the%20Schroedinger%20cat%20paradox.pdf

I think this is the only interpretation that attempts at making some sense. Though, every one of all the propositions(interpretations) of how the world might be outside of our perception, makes me want to throw up.

 

[kote]

In fact Bohr and Heisenberg never totally agreed on how to understand the mathematical formalism of quantum mechanics, and none of them ever used the term “the Copenhagen interpretation” as a joint name for their ideas. In fact, Bohr once distanced himself from what he considered to be Heisenberg's more subjective interpretation (APHK, p.51). The term is rather a label introduced by people opposing Bohr's idea of complementarity, to identify what they saw as the common features behind the Bohr-Heisenberg interpretation as it emerged in the late 1920s.

http://plato.stanford.edu/entries/qm-copenhagen/​

It's easy for a view to sound confused and inconsistent when it's presented by its opponents and never its supposed founders.

 

[zenith8]

1. Shut up and calculate - this is actually the interpretation that most practical physicists adopt.

An interpretation of quantum mechanics is 'a statement which attempts to explain how quantum mechanics informs our understanding of nature'. The above formulation attempts to do no such thing, so it's not an interpretation. To state otherwise simply means you're not interested in interpretations and you don't understand them, because you're an engineer.

2. Positivism - QM is only about the results of measurements, not about reality existing without measurements. (This is essentially the philosophy of Bohr.)

Positivism as a concept was effectively 'disproved' (if one can do such a thing in philosophy) by the late 1960s.

Truth begins in sense experience, but does not end there. Positivism fails to prove that there are not abstract ideas, laws, and principles, beyond particular observable facts and relationships and necessary principles, or that we cannot know them. Nor does it prove that material and corporeal things constitute the whole order of existing beings, and that our knowledge is limited to them.

Positivism ignores all humanly significant and interesting problems, citing its refusal to engage in reflection; it gives to a particular methodology an absolutist status and can do this only because it has partly forgotten, partly repressed its knowledge of the roots of this methodology in human concerns.

As we all know (not!), one can conceive of QM describing objectively existing real waves and particles (Bohm interpretation) in a perfectly straightforward way, so the Bohrian positivistic rhetoric of finality and inevitability of CI ('We see that it cannot be otherwise', 'This is something there is no way round', 'The situation is an unavoidable one', the 'most direct expression of a fact..as the only rational interpretation of quantum mechanics' etc.) is simply incorrect. He uses circular demonstrations of consistency disguised as compelling arguments of inevitability.

3. Collapse interpretation - when the measurement is performed, then the wave function collapses. (von Neumann)

This is usually taken to require that the wave function represents an objectively-existing physically real wave field which collapses (instantaneously, at infinite speed across the whole universe, if you make your experiment big enough). Which kind of implies something like the GRW viewpoint (with all of its well-known problems, including the Schroedinger equation not being correct).

Recall that in the Bohm view, things are made of particles guided by the wave so even though the objectively-existing real field (represented mathematically by the wave function) never actually collapses (the Schroedinger equation is correct) particular branches are picked out by whichever one the particles deterministically end up in, so it effectively collapses. To me this is the obvious way around all the usual weirdness measurement bollocks.

Or some people mean that 'knowledge' or 'information' instantaneously collapses, in which case you mean option (4):

4. Information interpretation - the wave function does not represent reality, but only the information about reality. (It is somewhat similar to 2., but still significantly different from it.)

Quite simply cannot be correct: as I have argued in this forum before, for anyone who keeps up with modern developments in experimental physics, the evidence for the fact that 'the wave field exists' is unequivocal:

In matter-wave optics experiments for example - we find that it is possible to diffract, reflect, focus, interfere, do stimulated emission with the wave field (the thing that is mathematically represented by the wave function). This is clear experimental evidence for the objective existence of the wave. If the wave can be subject to and utilized in such a process, it logically follows that the wave field must exist in order to act and be acted upon.

Just thinking about the two-slit experiment, it is not possible for a field representing 'information' or 'knowledge' to interfere with itself, and to behave like it satisfies a wave equation, if it does not in fact represent a real wave. It just isn't. I'm sorry, but it's true.


So, personally I think the above considerations show that any claims that the Copenhagen Interpretation must be the logically preferred interpretation of right-thinking physicists (which one still hears quite often) cannot be correct. Such claims often have their basis in a misunderstanding of what Copenhagen means (as Demystifier points out), but also from 'not thinking very hard about the alternatives', or from uncritical hero-worship of [insert name of favourite 1920s scientists here]. Today it is simply untenable to regard the views of Bohr and Heisenberg as in any sense standard or canonical. They are more 'smoke and mirrors' than a unique compelling world view forced on us by experiment. The meaning of quantum theory is today an open question.

Today it is also clear (to bang on about my favourite topic) that the rejection of Bohmian hidden variables theories by Bohr, Heisenberg, Pauli et al. - not merely as hopeless but as downright meaningless - was ultimately irrational (particularly if we use their reasoning).

 

[zenith8]

Though, every one of all the propositions(interpretations) of how the world might be outside of our perception, makes me want to throw up.

You must never become a police detective. When trying to solve a case, vomiting on anyone who attempts to present you with reasoned arguments based on suggestive evidence is not usually helpful.

 

[WaveJumper]

Just thinking about the two-slit experiment, it is not possible for a field representing 'information' or 'knowledge' to interfere with itself, and to behave like it satisfies a wave equation, if it does not in fact represent a real wave. It just isn't. I'm sorry, but it's true.

This view is close to imposing our classical view of reality(the human baggage) on the quantum realm.
I think the whole point in not being able to deduce a meaningful description of reality from quantum theory is because qunatum theory demands that the Universe be an ON-OFF phenomenon. The continuity and solidity of the world exists only in the imagination(whatever that really is), fed by senses that cannot discern the waves of energy and information that make up the quantum level of existence.
If QM is right, we are all flickering in and out of existence all the time at 10^-43sec. intervals. If we could fine-tune our senses, we could actually see the gaps in our existence. We are here, and then not here, and then here again. The sense of continuity(and continuous motion) is an illusion and is held only by our memories in the elusive concept of Time(this isn't too different from how we are fooled to believe in continuous motion by looking at 50Hz or 100Hz tv screens).
This poses serious challenges to the notion that space, matter and time are fundamental concepts. If these are to go, there is only information left as a fundamental concept(0's and 1's) but we are still far from reaching a convincing information interpretation of qm, IMO.

 

[yossell]

I agree with original poster that different people have different things in mind by 'copenhagen' interpretation. But I'm not sure Bohr held the kind of extreme positivism you ascribe to him. It's also noteworthy that complementarity, which played a big role in writings and thought, doesn't appear at all in your list. However, I find him an interesting and difficult writer and I don't really understand his thought.

yossell

 

[zenith8]

This view is close to imposing our classical view of reality(the human baggage) on the quantum realm.

A realm which these days we can photograph, video, and manipulate at the atomic level with repeatable results. Remember 'the quantum realm' just means 'quite small things'.

I think the whole point in not being able to deduce a meaningful description of reality from quantum theory is because qunatum theory demands that the Universe be an ON-OFF phenomenon.

Look, we're just trying to understand the Schroedinger equation here..

The continuity and solidity of the world exists only in the imagination(whatever that really is), fed by senses that cannot discern the waves of energy and information that make up the quantum level of existence.
If QM is right, we are all flickering in and out of existence all the time at 10^-43sec. intervals. If we could fine-tune our senses, we could actually see the gaps in our existence. We are here, and then not here, and then here again.

Oh God.

The sense of continuity(and continuous motion) is held only by our memories in the elusive concept of Time.
This poses serious challenges to the notion that space, matter and time are fundamental concepts. If these are to go, there is only information left as a fundamental concept(0's and 1's).

And your reason for not taking the obvious answer (as is done in every other theory of physics, and indeed science) is what.. I mean, are you trying to impress some woman, or something? Sometimes being mysterious can be cool, right!

Pressure is due to atoms repeatedly banging on the sides of a container, no? Not in The Mysterious World of Wavejumper, because reality winks out of existence every 10^-43 seconds. Hmmm..

OK - why don't we say nature 'acts as if' atoms bang on the side of the container. Then if we teach it that way, people will understand it, even though it's just umm.. a metaphor, or whatever.

 

[WaveJumper]

A realm which these days we can photograph, video, and manipulate at the atomic level with repeatable results.

Yet, after 80 years of study its ontology is even more mysterious(which happens to be what this thread is about).

And your reason for not taking the obvious answer (as is done in every other theory of physics, and indeed science) is what..

Obvious answer to what?

Pressure is due to atoms repeatedly banging on the sides of a container, no? Not in The Mysterious World of Wavejumper, because reality winks out of existence every 10^-43 seconds. Hmmm..

That's how it looks from the classical perspective(and it oddly obeys the Schroedinger's equation). The "mysterious world of WaveJumper" is the same as saying "the mysterious ontology of the quantum world of WaveJumper".

OK - why don't we say is because nature 'acts as if' atoms bang on the side of the container. Then if we teach it that way, people will understand it, even though it's just umm.. a metaphor, or whatever.

That's how it is. And the quantum realm cannot be locally deterministic. Yet our 'classical' logic happens to be just that - local deterministic.

 

[zenith8]

Yet, after 80 years of study its ontology is even more mysterious(which happens to be what this thread is about).

It's only mysterious because you choose to make it so. As has been known for more than half a century, one can interpret quantum mechanics very simply in terms of motions of particles obeying a non-classical dynamics (because they are pushed around by the wave field). [see de Broglie-Bohm hidden variables theories]. This is just like how you can explain classical statistical mechanics in terms of the classical dynamics of particles, and it is in agreement with modern experimental evidence for the existence of both particles and waves. And yet you insist in trotting out all this out-there new-age babble in preference? Well, I don't understand it.

That's how it looks from the classical perspective(and it oddly obeys the Schroedinger's equation).

Oddly, he says.

That's how it is. And the quantum realm cannot be locally deterministic. Yet our 'classical' logic happens to be just that - local deterministic.

You're just willfully misunderstanding the whole thing - as you were last time we argued. Just because non-local connections between particles (mediated by the wave field) are possible does not mean that local interactions do not occur (i.e. that particles do not exert a force on things they bump into). I mean, what?

 

[WaveJumper]

It's only mysterious because you choose to make it so. As has been known for more than half a century, one can interpret quantum mechanics very simply in terms of motions of particles obeying a non-classical dynamics (because they are pushed around by the wave field). [see de Broglie-Bohm hidden variables theories]. This is just like how you can explain classical statistical mechanics in terms of the classical dynamics of particles, and it is in agreement with modern experimental evidence for the existence of both particles and waves. And yet you insist in trotting out all this out-there new-age babble in preference? Well, I don't understand it.

How does the existence of particles and waves point to continuous movement of the electrons, say in the Hydrogen atom(without radiating energy)? Is the de Broglie-Bohm view of the atom different from Bohr's?

You're just willfully misunderstanding the whole thing - as you were last time we argued. Just because non-local connections between particles (mediated by the wave field) are possible does not mean that local interactions do not occur (i.e. that particles do not exert a force on things they bump into).

How? David Bohm's notion was that the universe was an unbroken wholeness, right? The CI does not need an explanation for local effects in a non-local universe, because these local effects don't exist prior to measurement.

Just because non-local connections between particles (mediated by the wave field) are possible does not mean that local interactions do not occur (i.e. that particles do not exert a force on things they bump into.

Can you give me a link that says that there is continuous movement of particles in the context of De Broglie-Bohm's or any other interpretation?

Oddly, he says.

How is it not odd that an interpretation would assert that a quantum system does not have any properties before measurement, yet the Schroedinger equation gives us the exact probability of where an electron might land on the screen of the double slit experiment?

 

[ytuab]

How does the existence of particles and waves point to continuous movement of the electrons, say in the Hydrogen atom(without radiating energy)? Is the de Broglie-Bohm view of the atom different from Bohr's?

In standard quantum mechanics, can you explain why the electron doesn't radiate energy?

For example, in Helium atom, in the parts nearer to the spin-up electron or the spin-down electron, the magnetic fields are theoretically produced even in the standard QM.
(Because the two electrons are apart.)

While the two electrons are moving, the magnetic fields are changing, and the electromagnetic waves are emitted?

 

[ueit]

If I understand 4 correctly, it's the "interpretation" I've been supporting in a large number of posts here. There are many different ways to say the same thing, for example:

4'. The wavefunction doesn't represent the properties of the physical system. It represents the properties of an ensemble of systems that have been identically prepared.

What do you mean by "system"?

4''. QM is a set of rules that tell us how to compute the probabilities of possible results of experiments. Nothing more, nothing less. It doesn't include, and doesn't need, an ontological interpretation.

As I pointed out before there can be no physical theory that does not have some kind of ontology. What you probably have in mind is that CI does not ascribe beable status to the wavefunction. But the theory need to have some beables, the "system" you are referring to, the instrument readings, etc.?

 

[WaveJumper]

In standard quantum mechanics, can you explain why the electron doesn't radiate energy?

It doesn't continuously radiate energy because it does not circle the nucleus in orbits. The HUP prohibits it from having definite position and momentum at the same time.

For example, in Helium atom, in the parts nearer to the spin-up electron or the spin-down electron, the magnetic fields are theoretically produced even in the standard QM.
(Because the two electrons are apart.)

While the two electrons are moving, the magnetic fields are changing, and the electromagnetic waves are emitted?

I'd tentatively say that from our derived logical point of view(not according to the mathematical formalism), 'particles' appear to move continuously and in trajectories(there would not have been a classical world had it not been so).
On a more formalised mathematical level however, the whole notion of classical continuous movement is an illusion. A bound electron should be understood as a standing wave spread over an area of space according to probability distributions. If we are to assign a classical trajectory for the electron, the closest i can think of is Feynman's path integral but it is a sum of an infinity of possible trajectories.

In the words of Oppenheimer:

"If we ask, for instance, whether the position of the electron remains the same, we must say ‘no’; if we ask whether the electron’s position changes with time, we must say ‘no’; if we ask whether the electron is at rest, we must say ‘no’; if we ask whether it is in motion, we must say ‘no’."

 

[ytuab]

It doesn't continuously radiate energy because it does not circle the nucleus in orbits. The HUP prohibits it from having definite position and momentum at the same time.

I'd tentatively say that from our derived logical point of view(not according to the mathematical formalism), 'particles' appear to move continuously and in trajectories.
On a more formalised mathematical level, the whole notion of classical continuous movement is an illusion. A bound electron should be understood as a standing wave spread over an area of space according to probability distributions. If we are to assign a classical trajectory for the electron, the closest i can think of is Feynman's path integral but it is a sum of an infinity of possible trajectories.

In the words of Oppenheimer:

"If we ask, for instance, whether the position of the electron remains the same, we must say ‘no’; if we ask whether the electron’s position changes with time, we must say ‘no’; if we ask whether the electron is at rest, we must say ‘no’; if we ask whether it is in motion, we must say ‘no’."

the whole notion of classical continuous movement is an illusion. OK.
So you say that the electron's motions are an illusion, they don't radiate energy in standard QM?

But How do you explain about the relativistic mass change of the electron?

Please see the link http://en.wikipedia.org/wiki/Relativistic_quantum_chemistry
...........
It is written as follows,
A nucleus with a large charge will cause an electron to have a high velocity. A higher electron velocity means an increased electron relativistic mass, as a result the electrons will be near the nucleus more of the time and thereby contract the radius for small principal quantum numbers.
..........

The relativistic mass change are bigger in Li++ He+ than hydrogen atom.
If you say the electrons are not actually moving, what cause the relativic mass change?
Or you are saying that even if the electrons are not actually moving, the relativistic mass change will occur?

I think your idea is contrary to the standard relativistic theory.
How do you think about it?

 

[WaveJumper]

the whole notion of classical continuous movement is an illusion. OK.
So you say that the electron's motions are an illusion, they don't radiate energy in standard QM?

But How do you explain about the relativistic mass change of the electron?

Please see the link http://en.wikipedia.org/wiki/Relativistic_quantum_chemistry
...........
It is written as follows,
A nucleus with a large charge will cause an electron to have a high velocity. A higher electron velocity means an increased electron relativistic mass, as a result the electrons will be near the nucleus more of the time and thereby contract the radius for small principal quantum numbers.
..........

The relativistic mass change are bigger in Li++ He+ than hydrogen atom.
If you say the electrons are not actually moving, what cause the relativic mass change?
Or you are saying that even if the electrons are not actually moving, the relativistic mass change will occur?

I think your idea is contrary to the standard relativistic theory.
How do you think about it?

I am sure you are aware that your questions are touching foundational questions that are not resolved, namely - the problem of outcomes. Pure quantum states already represent a complete description of of the (physical) state of the system, and their evolution is given by the deterministic Scroedinger equation. Yet, there exists NO fundamental mechanism that would determine which particular outcome is realized in each measurement so that a 'realist' picture of the world we perceive and measure would appear. What matters to most physicists, i would say, is that, whenever there is a measurement there is a particle and observables can be derived and the value of that particluar observale is inline with the predictions of the theory.

 

[Demystifier]

How does the existence of particles and waves point to continuous movement of the electrons, say in the Hydrogen atom(without radiating energy)?

The wave determines the quantum potential. The quantum potential determines the quantum force, due to which the electron and its electromagnetic field do not move classically. Radiation would occur if the motion was classical, but it is not classical and there is no radiation.

Is the de Broglie-Bohm view of the atom different from Bohr's?

Yes it is.

How is it not odd that an interpretation would assert that a quantum system does not have any properties before measurement, yet the Schroedinger equation gives us the exact probability of where an electron might land on the screen of the double slit experiment?

Well, it depends on what do you mean by a "property". If probability is a property, then yes, a system has a property before a measurement even in the Bohr's interpretation. But THAT property cannot be revealed by a SINGLE measurement on the system. So either that property is not a property of a single system, or that property is a hidden property (hidden variable) of a single system.

 

[Fredrik]

What do you mean by "system"?

I mean the object on which we do a measurement. I don't think we need an operational or a mathematical definition here, but if you want to read about such things, see e.g. p. 75-76 in this book. I tried to link directly to page 75, but it didn't work. You'll have to search for the word "uneasiness", which only appears on page 75.

A comment about his notation: Every state vector $|\omega\rangle$ corresponds to a positive linear functional $A\mapsto\omega(A)\equiv\langle\omega|A|\omega\rangle$ on the set of observables. Note that two different normalized states that belong to the same ray (only differ by a phase factor) correspond to the same functional. When he talks about "the state" $\omega$, what he has in mind is this functional (or the corresponding equivalence class of state preparation procedures), not a state vector.

As I pointed out before there can be no physical theory that does not have some kind of ontology. What you probably have in mind is that CI does not ascribe beable status to the wavefunction. But the theory need to have some beables, the "system" you are referring to, the instrument readings, etc.?

A theory is defined by a mathematical model and a set of axioms that tells us how to interpret the mathematics as predictions about results of experiments. What I meant is that there's no need to interpret anything in the model ontologically. See also #135 in the other thread.

 

[Varon]

Many physicists say that they prefer the "Copenhagen" interpretation of QM, but it does not mean that all these physicists prefer the same (or even a very similar) interpretation. There are at least 4 very different interpretations that are sometimes referred to as "Copenhagen":

1. Shut up and calculate - this is actually the interpretation that most practical physicists adopt.

2. Positivism - QM is only about the results of measurements, not about reality existing without measurements. (This is essentially the philosophy of Bohr.)

3. Collapse interpretation - when the measurement is performed, then the wave function collapses. (von Neumann)

4. Information interpretation - the wave function does not represent reality, but only the information about reality. (It is somewhat similar to 2., but still significantly different from it.)

What do you think?
I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

This thread gives such a spectrum of insights and summarize each proponent (Fredrik, Dr. Chinese, Fra, etc.) position. After 2 years of analyzing it. Have you got additional to add or to alter the above 4 interpretations of Copenhagen? Pls. modify it based on your 2 years findings. Thanks.

 

[A. Neumaier]

whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

This is no different than with other interpretations.

There is no SINGLE interpretation that may be called "the statistical interpretation".
There is no SINGLE interpretation that may be called "Bohmian mechanics".

What is meant is in each case in the eye of the beholder - with smaller subcommunities agreeing on a particular formulation, usually fixed by a particular reference.

 

[Varon]

This is no different than with other interpretations.

There is no SINGLE interpretation that may be called "the statistical interpretation".
There is no SINGLE interpretation that may be called "Bohmian mechanics".

What is meant is in each case in the eye of the beholder - with smaller subcommunities agreeing on a particular formulation, usually fixed by a particular reference.

In your formulation. I know you believe particles don't exist but they are just momentum of the field as told by Quantum field theory. Now I want to know is. Is there 100% proof and evidence that particles are really just momentum of the quantum field? Or is just a conjecture? This is supposed to be just a model for QFT. But is there solid proof that in a 430-atom buckyball when you send this off in a double slit, the buckyball quantum wave splits in the slits and splattered all over the detector. Meaning the 430-atom buckyball shatterred into many fragments in the detector as you believe. But rather than proving this. Just prove the general QFT idea that particles are just momentum of the field. Is there experiment that can distinguish this? If this can't be proven. Maybe this particular QFT model is just a temporary belief system to aid in the calculations. Someday. QFT may give rise to or superceded by a return to particles being primary and field just their emanations. Is this impossible? Why?

 

[A. Neumaier]

In your formulation. I know you believe particles don't exist but they are just momentum of the field as told by Quantum field theory.

Not momentum of the field (which is not even a well-defined notion), but localized concentrations of the field.

Now I want to know is. Is there 100% proof and evidence that particles are really just momentum of the quantum field? Or is just a conjecture?/QUOTE]
It is part of the traditional preparation procedure of particles, which may serve as their definition. One prepares them in a very localized source and let's them move in a very focussed direction. In a field theoric interpretation, it is these properties that give them the particle character.

But this is off-topic here; if you want to discuss it further, do it in the IR thread
https://www.physicsforums.com/showthread.php?t=490492

 

[yoda jedi]

What do you think?

I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

I Agree.