Understanding Single Particle Interference in Quantum Physics

[marlon]

Sure, and if we would look at crimes through the glasses of a criminal, we might not need justice at all.

LOL

Nope that is NOT what i said. You should have written that we would not see "a crime", allthough we are looking at the same action that we, in our world, would call a crime. Crime is defined in our world...

Do you see what i mean ?

Particles and waves are classical properties. The duality between the two is a QM property.

marlon

 

[Careful]

LOL

Nope that is NOT what i said. You should have written that we would not see "a crime", allthough we are looking at the same action that we, in our world, would call a crime. Crime is defined in our world...

Do you see what i mean ?

Particles and waves are classical properties. The duality between the two is a QM property.

marlon

Nope, you confirm again what I said. You watch trough the world in QM glasses, in either you accepted all the possible discomforts and assume QM to be the holy mother. The fact that you constantly say ``you should say like that'' given your bias which is exactly the thing the other party is questioning is irrational.

You said ``Again, if we would look at QM through QM glasses, we would not be spending so much time discussing about the strangeness of this socalled "duality between particles and waves"´´ which is correct. In the same way, if we would look at a crime in the way a criminal thinks about it, we cannot condemn him. This does not imply in any way that we would not see a crime, just that we would *treat* the criminal according to his own judgements (but possibly interpret it from a very different perspective). Perhaps I should have clarified this ``subtlety'' but I thought it was clear.

 

[Anonym]

Marlon:” what i mean with "looking at QM through classical eyes" is just the same as Reilly saying "it is in the eyes of the beholder".

That what I meant. I did not mention two contradictions, just one. I took Railly words also literally:” That means, of course, that there is no theory of certain events.” Correct, I do not know what you say about that.” All i wanted to say is that we, as human beings are more familiar with the concepts of classical physics.” No information added. To be concrete, please, go to Google, type a key words: Hilbert space, dispersion free, classical mechanics. You will find my recent paper together with other relevant contributions. I will appreciate obtaining your opinion on it.

 

[eep]

The only language we have to express ourselves comes from the "classical" eye. Human language wasn't developed to talk about strange quantum particles, and the reason why we call it "wave-particle" duality is because yes, quantum particles have both properties of classical particles and waves. The idea of something being a wave is complementary to something being a particle, so it seems obvious to me that the language we use to talk about quantum particles only hints at what is really going on, but there is no way around it. When one person talks to another, we always have to use "classical" language because that's the realm with language deals with.

 

[Careful]

The only language we have to express ourselves comes from the "classical" eye. Human language wasn't developed to talk about strange quantum particles, and the reason why we call it "wave-particle" duality is because yes, quantum particles have both properties of classical particles and waves.

No, that is not the reason why we call it wave particle duality.
Wave-particle duality means that those entities which manifest themselves as particles to us, also undergo wavelike phenomena. That is not the same as saying that quantum particles have properties of classical waves, a potentially important distinction it seems to me. This is all we can deduce from observations.

The idea of something being a wave is complementary to something being a particle, so it seems obvious to me that the language we use to talk about quantum particles only hints at what is really going on, but there is no way around it.

Sure, there is a way around it : we ``simply'' have to come up with something better.

When one person talks to another, we always have to use "classical" language because that's the realm with language deals with.

Correct, but the reason why we use classical language is because the latter is suggested by the world we live in. There is *in principle* no reason why we could not speak in quantum language by using quantum logic.

 

[eep]

No, that is not the reason why we call it wave particle duality.
Wave-particle duality means that those entities which manifest themselves as particles to us, also undergo wavelike phenomena. That is not the same as saying that quantum particles have properties of classical waves, a potentially important distinction it seems to me. This is all we can deduce from observations.

How is "undergo wavelike phenomena" any different than saying they have properties of classical waves??

Correct, but the reason why we use classical language is because the latter is suggested by the world we live in. There is *in principle* no reason why we could not speak in quantum language by using quantum logic.

The reason why we can't speak in quantum language using quantum logic is because our language has evolved in the macroscopic realm.

 

[Careful]

How is "undergo wavelike phenomena" any different than saying they have properties of classical waves??

Well, by saying that a wavicle has properties of a classical wave, you indicate that it is the wavicle itself which behaves as a classical wave under some circumstances; a conclusion which is by no means necessary.

The reason why we can't speak in quantum language using quantum logic is because our language has evolved in the macroscopic realm.

Sure, and in what does this differ from what I said before : I never said I met somebody who spoke it fluently.

 

[marlon]

Nope, you confirm again what I said.

How is that ? Besides, when did i confirm what you said the first time ? I am not following here, sorry.

You watch trough the world in QM glasses, in either you accepted all the possible discomforts and assume QM to be the holy mother.

Possible discomforts ? You mean all the "strangeness" of QM right ? If so, then what you say is NOT what i mean because through QM glasses, there would be no such strangeness.

The fact that you constantly say ``you should say like that'' given your bias which is exactly the thing the other party is questioning is irrational.

I don't get this. What do you mean here ?

You said ``Again, if we would look at QM through QM glasses, we would not be spending so much time discussing about the strangeness of this socalled "duality between particles and waves"´´ which is correct. In the same way, if we would look at a crime in the way a criminal thinks about it, we cannot condemn him. This does not imply in any way that we would not see a crime, just that we would *treat* the criminal according to his own judgements (but possibly interpret it from a very different perspective).

Not at all. If we are looking through the criminal's glasses we would not know what a crime is because a crime is something that has been defined using our "classical" (non criminal glasses) principles.

Again, i don't think you are getting the point or perhaps i am not making myself clear enough. What i mean is this : when looking through QM glasses you do not know what classical physics is. Looking through " the criminal's glasses" means that you do not know what "non criminal behaviour is" so judging is not even relevant here. In our "non criminal world" we don't put an innocent guy to trial right (or we would recognize there is something seriously wrong here).

But, coming back to the particle wave duality. The duality exists because we are familiar with waves and particles from classical physics. When we first found out about the strangeness of QM via the doubble slit experiment, we tried (succesfully) to explain what is going on using our classical concepts. This does NOT mean that QM behaves classically ofcourse. We said, hey we have got particles like electrons that exhibit interference, which we are used to be a wave like behaviour. So, particles and waves have a dual nature on the atomic scale. That is what happened and that is what i wanted to say. Even, concepts like superposition are explained using quantum interference, which has it's same basis in the doubble slit exp.

I hope you understand what I am saying here.

greets
marlon

 

[marlon]

Well, by saying that a wavicle has properties of a classical wave, you indicate that it is the wavicle itself which behaves as a classical wave under some circumstances; a conclusion which is by no means necessary.

No, there is a direct reference to classical wave behaviour in the double slit exp since that is the only wavelike behaviour that we know (at that stage in the development of the QM formalism).

But that is not the point, the point is that the concepts (eg interference, diffraction) of wavelike behaviour apply also to particles. That is all.

marlon

 

[marlon]

No, that is not the reason why we call it wave particle duality.
Wave-particle duality means that those entities which manifest themselves as particles to us, also undergo wavelike phenomena.

Look, what you write above is EXACTLY what i am talking about. You are using two concepts that you know from classical physics (that is what i mean by looking at QM through classical glasses) and you acknowledge that "particles" exhibit wavelike behaviour. You knew what a particle was and you excpected it to behave like one, but in QM it does NOT. That is why the duality is there and that is what i wanted to say.

That is not the same as saying that quantum particles have properties of classical waves, a potentially important distinction it seems to me.

I don't get the distinction here. Care to elaborate.

This is all we can deduce from observations.

So you can deduce that particles "also undergo wavelike phenomena" but they do not "have properties of classical waves" ? Again, i don't get what is so fundamentally different about the two expressions here.

I think this is a semantics thing we've got goin' on here...

greets
marlon

 

[eep]

Yeah, I think it is just semantics. This is what I mean when I say there's a problem expressing quantum ideas using our language, because our language doesn't have a good way to explain wave-particle duality, for example. saying a particle has properties of a wave makes no sense. waves and particles are complimentary ideas (classically), but we have to use both in order to try and express what's going on in the quantum mechanics. There's a good discussion about this throughout Heisenberg's "Physics and Beyond"

 

[Careful]

Possible discomforts ? You mean all the "strangeness" of QM right ? If so, then what you say is NOT what i mean because through QM glasses, there would be no such strangeness.

Even as someone who accepts QM, it is quite something to state that you are at least not slightly bothered by it . It means that you are in a complete denial of realism (or locality if you prefer copenhagen), probably you are willing to sacrify general relativity (without too much motivation) - although Rovelli wants to ``unify'' GR with MWI - too. I have never met someone who did not feel at least slightly uncomforatble with either the collaps postulate, or the consciousness crap.

Not at all. If we are looking through the criminal's glasses we would not know what a crime is because a crime is something that has been defined using our "classical" (non criminal glasses) principles.

I said to you that if a judge were to punish the criminal according to the latter's standards; the bandit would walk out free and hence, we would not need justice at all. Now, you interpret my first sentence ``if we would look through the glasses of a criminal, then we would not need justice at all'' as literally meaning that ``you think all the time like the criminal''. Then, I tried to explain you that ``to look through ones glasses'' had to be interpreted as ``to imagine her/his point of view'' and that does not imply at all that I have to share this person's opinions, neither that I am incapacitated to declare his act a crime even though he is not punished for it. The reason for not punishing the criminal, even though we know he/she commited a crime according to the letter of the law, is that it might make no sense to punish someone for something he/she considered to be morally acceptable given his/her circumstances. Similarly, the fact that by accepting the QM laws as the holy mother you are released of the wave/particle duality problem, does not mean at all this is the right way to proceed given the fact that QM has the dual nature embraced in it's axioms (wavefunction and reduction).

Even, concepts like superposition are explained using quantum interference, which has it's same basis in the doubble slit exp.

Superposition is not a logical consequence of (quantum) interference.

I hope you understand what I am saying here.

I got what you said the first time, but I doubt whether the reverse is also true.

 

[Careful]

Look, what you write above is EXACTLY what i am talking about. You are using two concepts that you know from classical physics (that is what i mean by looking at QM through classical glasses) and you acknowledge that "particles" exhibit wavelike behaviour. You knew what a particle was and you excpected it to behave like one, but in QM it does NOT.

The double slit experiment with electrons says that the entity which we observe to be the electron does not behave like a free particle, neither as a particle in a classical random noise field, but instead undergoes wavelike phenomena. QM says more than that, it says that those entities are represented by probability waves individually and that observation consists of applying a projector (or corresponding acts in other interpretations). Moreover, it also declares that the reality content behind the observed effects is entirely revealed through observation (even BM takes the schizoid attitude that the wave isn't real).

So, if you agree with what I say about wave particle duality, then you also acknowledge that QM draws possibly wrong conclusions, otherwise we disagree about it. QM is simply agnostic about wave particle duality, the latter merely serving as a guideline for its axiomatic system.

 

[Careful]

Yeah, I think it is just semantics.

To get the semantics right is usually the first step to progress.

This is what I mean when I say there's a problem expressing quantum ideas using our language, because our language doesn't have a good way to explain wave-particle duality, for example. saying a particle has properties of a wave makes no sense.

Right, therefore my protest. I believe my formulation is much better (since it does not suffer from any such problems) and if you think about it, you might see some other possibilities.

waves and particles are complimentary ideas (classically),

Yes, and that is why I said a week ago that it might be desirable to develop a particle theory of waves (albeit it is difficult) and as far as I am concerned, this does not need to have anything to do with the distinction quantum/classical (in either $$\hbar$$).

but we have to use both in order to try and express what's going on in the quantum mechanics. There's a good discussion about this throughout Heisenberg's "Physics and Beyond"

For quantum mechanics as it stands now yes, to describe what might be going on in the double slit experiment and other phenomena, no.

 

[marlon]

Even as someone who accepts QM, it is quite something to state that you are at least not slightly bothered by it .

Ofcourse you would not be bothered by it because it is "the only reality" you would know (if you look through the QM glasses). The reason we are bothered by QM (if we look at it through classical glasses) is because it is contra intuitive. Why is that so ? Well, because the contra intuitivity comes from the fact that our classical way of thinking does not apply to phenomena at the atomic scale. But if we were all born in a "QM world" the situation is a 180° different from the situation we are really in. In other words, we are used to look through classical glasses and that is why particles and waves do NOT seem strange to us.

It means that you are in a complete denial of realism (or locality if you prefer copenhagen),

Why ? I never spoke about the validity of QM what so ever and i never talked about the possible interpretations of it's formalism.

probably you are willing to sacrify general relativity (without too much motivation)

Why ? Care to motivate ?

Besides, i asked you another question in my previous post to you. Why did you not answer that ?

I have never met someone who did not feel at least slightly uncomforatble with either the collaps postulate, or the consciousness crap.

Ofcourse, that is perfectly normal because these concepts are contra intuitive to our classical world. This is excatly what i am saying. I still think you are not getting my point.

I said to you that if a judge were to punish the criminal according to the latter's standards; the bandit would walk out free and hence, we would not need justice at all.

But that is wrong because there would be no trial in the first place because no crime has been committed. Looking through the criminal's glasses implies that criminal behaviour is "normal". Just the same as normal behaviour is normal when we look through "normal" glasses. There would be a crime if one committed an act that is defined as normal behaviour, when looking through normal glasses.

Then, I tried to explain you that ``to look through ones glasses'' had to be interpreted as ``to imagine her/his point of view'' and that does not imply at all that I have to share this person's opinions, neither that I am incapacitated to declare his act a crime even though he is not punished for it.

BINGO : this is exactly why you are missing my point. You cannot judge his acts because they would seem normal to you. Again, you do not know the "abnormal criminal behaviour" (read : normal behaviour) or at least it would seem contra intuitive to you. This is, going back to QM <--> classical physics, is what i mean by : we only knew about particles and waves as they were defined in classical physics. Then, QM comes in, and we observe there is strangeness going on. We call that strange because we are NOT familiar with "objects" that exhibit borth particle and wavelike behaviour. Solution : duality. Looking through QM glasses means that we found out about QM first and this behaviour would seem normal to us. The duality is NOT a problem in that case.

Why is it so difficult to see that analogy ?

The reason for not punishing the criminal, even though we know he/she commited a crime according to the letter of the law, is that it might make no sense to punish someone for something he/she considered to be morally acceptable given his/her circumstances.

Wrong again, you are mixing the two perspectives here. Note that i never did that. I always start from one perspective and then we come to some strange behaviour that seems contra intuitive.

Also, you are talking about the perspective of different individuals. that is NOT something i have been doing. We all look at physics in the same way, the duality is the same for all of us. When i say "look through classical glasses", i mean we all have to do that.

Similarly, the fact that by accepting the QM laws as the holy mother you are released of the wave/particle duality problem, does not mean at all this is the right way to proceed given the fact that QM has the dual nature embraced in it's axioms (wavefunction and reduction).

Again you are mixing perspectives.
Ofcourse QM has a dual nature because it's very fundaments are defined by looking at them through classical glasses. Why ? Because there is no other way. Just look at how the concept of wavefunction is born. The introduction of probabilities (Born etc etc) was necessary because our classical principles didn't work anymore for certain phenomena. This is just the very same story.

Superposition is not a logical consequence of (quantum) interference.

?

I SAID : "Even, concepts like superposition are explained using quantum interference, which has it's same basis in the doubble slit exp."

Are you saying this is NOT correct ? Are you saying there are not related ?Because that is all they need to be to prove my original point.

http://www.cs.caltech.edu/~westside/quantum-intro.html


Really, you cannot just regurgitate these cheap "dogma's" because i cannot do anything with that. What is your point ? What do you want to say ?

I got what you said the first time.

I seriously doubt that. Actually, if you reread our lasts posts, you will notice that i am always saying the same stuff over and over again. Especially on the criminal glasses stuff you do not seem to be able to get my point. It is quite easy though because the analogy is the same as the stuff about the duality.

marlon

 

[marlon]

QM says more than that, it says that those entities are represented by probability waves individually and that observation consists of applying a projector (or corresponding acts in other interpretations). Moreover, it also declares that the reality content behind the observed effects is entirely revealed through observation (even BM takes the schizoid attitude that the wave isn't real).

This is completely irrelevant. Clearly, you are jumping from one topic to another. If you reread my post to which you replied the above :

[QUOTE = marlon]
You are using two concepts that you know from classical physics (that is what i mean by looking at QM through classical glasses) and you acknowledge that "particles" exhibit wavelike behaviour. You knew what a particle was and you excpected it to behave like one, but in QM it does NOT.
[/QUOTE]

i ask you what your answer has to do with what i wanted to say to you (in the "marlon again" quotation) ? We were talking about duality and it's connection to classical physics. Suddenly, you bring in stuff on "what QM tells us more then the doubble slit exp". We were only talking about the latter experiment, so no need to bring in things like "the wave isn't real"...That is another discussion. We know there is wavelike behaviour, like you said yourself several times. PERIOD.

So, if you agree with what I say about wave particle duality,

I agreed about your formulation in the quotation above. My response as to why i agreed is in my own quotation below. Again, py point was that you needed them classical basis concepts to explain what is going on with this strange behaviour of the doubble slit exp.

then you also acknowledge that QM draws possibly wrong conclusions, otherwise we disagree about it.

?

What does this have to do with anything ? Again, let's stick to our ORIGINAL point of discussion which did NOT involve discussiong the "possibly wrong conclusions of QM". Yousee, you are already using the QM formalism now because you are talking about it's "conclusions", while originally we were talking about the doubble slit exp (beginning of the QM formalism).

marlon

 

[Careful]

Ofcourse you would not be bothered by it because it is "the only reality" you would know (if you look through the QM glasses). The reason we are bothered by QM (if we look at it through classical glasses) is because it is contra intuitive. Why is that so ? Well, because the contra intuitivity comes from the fact that our classical way of thinking does not apply to phenomena at the atomic scale. But if we were all born in a "QM world" the situation is a 180° different from the situation we are really in. In other words, we are used to look through classical glasses and that is why particles and waves do NOT seem strange to us.

Like I said in the beginning, it is pointless to argue against someone who has a bias concerning the very point of discussion.

Why ? I never spoke about the validity of QM what so ever and i never talked about the possible interpretations of it's formalism.

I don't need to know your interpretation in order to be sure that my sentence was correct.

Why ? Care to motivate ?

No, perhaps you could tell us why you would see no conflict with GR. I admit (as I have done previously) that there might be *formally* no problems in say Rovelli's program (although I haven't seen any proper implementation of the constraints so far), however it seems to me there are much better alternatives for the same price.

Besides, i asked you another question in my previous post to you. Why did you not answer that ?

Because I answered it to eep.

Ofcourse, that is perfectly normal because these concepts are contra intuitive to our classical world. This is excatly what i am saying. I still think you are not getting my point.

You simply have no point regarding my analogy : I explained you what it means and you keep on saying nonsense (like your comment below).

But that is wrong because there would be no trial in the first place because no crime has been committed. Looking through the criminal's glasses implies that criminal behaviour is "normal".

No, it does not imply it is considered normal, it is just so that it might make no sense to condemn someone who does not realize he did something wrong. On the other hand, if he knows he is guilty, he might punish himself. So in both cases, no intervention from justice is required.

BINGO : this is exactly why you are missing my point. You cannot judge his acts because they would seem normal to you. Again, you do not know the "abnormal criminal behaviour" (read : normal behaviour) or at least it would seem contra intuitive to you. This is, going back to QM <--> classical physics, is what i mean by : we only knew about particles and waves as they were defined in classical physics.

Of course not, psyschologists and phychiatrists are exactly trying to understand the ``logic'' of the criminal in order to be able to make effective interventions where necessary so that the patient can abandon his reasoning. Now, you are telling us that since they are temporarily looking ``through the glasses of the patient'', that they lose their ability to recognize the desease. Really, this is to crazy for words ...

Why is it so difficult to see that analogy ?

I am sorry, but you are simply not listening to what I said.

Ofcourse QM has a dual nature because it's very fundaments are defined by looking at them through classical glasses. Why ? Because there is no other way. Just look at how the concept of wavefunction is born. The introduction of probabilities (Born etc etc) was necessary because our classical principles didn't work anymore for certain phenomena. This is just the very same story.

Again nonsense, you are just not aware of any different ways. Perhaps you should take a look at the board games I was referring you once to.

?

I SAID : "Even, concepts like superposition are explained using quantum interference, which has it's same basis in the doubble slit exp."

Are you saying this is NOT correct ? Are you saying there are not related ?

I simply said that superposition is not a logical consequence of quantum interference. Does that imply that they are not related ? Of course not, since superpostion implies interference. (again, perhaps you should once care to read posts of others)

I seriously doubt that. Actually, if you reread our lasts posts, you will notice that i am always saying the same stuff over and over again. Especially on the criminal glasses stuff you do not seem to be able to get my point. It is quite easy though because the analogy is the same as the stuff about the duality.

marlon

You simply had no point to start with (and you think you do, while I ignore it, so I am not surprised you keep on doing that).

Careful

 

[Careful]

This is completely irrelevant. Clearly, you are jumping from one topic to another. If you reread my post to which you replied the above :

Perhaps Marlon, you should have also copied the FIRST line of that post. Then it would be clear to the reader that I was not arguing against or for your post, but that I was merely adding some thoughts about how QM deals with wave particle duality; a topic which is entirely legitimate in this context since you are constantly arguing from the QM point of view, you are not even willing to drop it even for the sake of discovering where it might lead you.

You are using two concepts that you know from classical physics (that is what i mean by looking at QM through classical glasses) and you acknowledge that "particles" exhibit wavelike behaviour. You knew what a particle was and you excpected it to behave like one, but in QM it does NOT.

Yes in QM it does not, but the whole point under discussion is whether there is no different way to interpret these experiments in which particles are still classical (self-interacting) particles without being in conflict with wave particle duality (and, yes it seems very possible to me).

i ask you what your answer has to do with what i wanted to say to you (in the "marlon again" quotation) ? We were talking about duality and it's connection to classical physics.

No, marlon you were dictating the ``quantum truth'' with no room for any discussion whatsoever, so it is entirely appropriate to see what QM has to say about it. Your are constantly attempting to reverse the discussion : QM in your eyes is the only true view on the microworld so the rest must be an illusion, you even go that far as to suggest that the problem does not even exist (and thereby discrediting many brilliant scientists who have spend lot's of time on it). So, for a change I will ask you a few questions (to start with) :
(a) to what extend are the laws of QM applicable to our world ?
(b) How do you percieve it in relation to GR ?

Again, py point was that you needed them classical basis concepts to explain what is going on with this strange behaviour of the doubble slit exp.

And that is rubbish, see the complex random walks I have referred you to at least two times before : Richard Feynman, Ted Jacobson, Tomasso Toffoli and others have worked on that for some time.

?

What does this have to do with anything ?

Are you too limited to simply admit that QM does give a very specific and peculiar answer to wave particle duality which is possibly wrong ?

 

[marlon]

Like I said in the beginning, it is pointless to argue against someone who has a bias concerning the very point of discussion.

Why do i have a bias and on what ?

I don't need to know your interpretation in order to be sure that my sentence was correct.

But i was not talking about my interpretation. YOU were the one that started bringing in interpretations and I was the one saying not to do that. My entire point was to avoid using such concepts because they are irrelevant to tis discussion. Why ? because we are talking about the very axioms of the QM formalism, not about it's possible interpretations.

Seems to me you are just fillibustering...

No, perhaps you could tell us why you would see no conflict with GR. I admit (as I have done previously) that there might be *formally* no problems in say Rovelli's program (although I haven't seen any proper implementation of the constraints so far), however it seems to me there are much better alternatives for the same price.

Ofcourse QM and GR have very different "natures" but that is NOT what ae are talking about. Really, i don't get why you start talking about GR while we were discussiong the doubble slit experiment ?

Seems to me you are just fillibustering...

Because I answered it to eep.

Still no anser

No, because you avoided answering that question. Why would anyone do that ? Huh ?

No, it does not imply it is considered normal, it is just so that it might make no sense to condemn someone who does not realize he did something wrong. On the other hand, if he knows he is guilty, he might punish himself. So in both cases, no intervention from justice is required.

Ok, clearly you are joking. Besides, again you make the same mistake. You talk about condemming someone who does not realize he did something wrong. You use TWO perspectives here : the correct glasses and the criminla's glasses. Several times i told you that this was NOT what i wanted to say and i clearly explained to you why.

Seems to me you are just fillibustering...

Of course not, psyschologists and phychiatrists are exactly trying to understand the ``logic'' of the criminal in order to be able to make effective interventions where necessary so that the patient can abandon his reasoning.

Seems to me you are just fillibustering...

Now, you are telling us that since they are temporarily looking ``through the glasses of the patient'', that they lose their ability to recognize the desease. Really, this is to crazy for words ...

AGAIN WRONG. In this analogy i used to compare with the doubble slit exp, you cannot just look through the other glasses temporarily. Your error is that you asume the doctors know both worlds but they just look at one of them temporarily and use the correct world's principles to judge. THAT IS INCORRECT if you look at what happens with the duality in QM. If you look through the QM glasses, the laws of QM are the only ones you know. Just think of it like we discovered QM first without knowing anything of classical physics. THAT IS WHAT I MEAN BY "LOOKING TROUGH THE QM GLASSES". In that case, the duality would not strike us as something strange.


You DON'T know what a classical world would look like, just like initially we did not know how the QM world would behave. In your analogy above you are implying that the doctors know the "correct world".

Why don't you (or dont' want to) get that analogy.

I am sorry, but you are simply not listening to what I said.

But then why do i always have to clarify my point to you ?

Again nonsense, you are just not aware of any different ways. Perhaps you should take a look at the board games I was referring you once to.

So you say the following in my quote is nonsense :

Ofcourse QM has a dual nature because it's very fundaments are defined by looking at them through classical glasses. Why ? Because there is no other way. Just look at how the concept of wavefunction is born. The introduction of probabilities (Born etc etc) was necessary because our classical principles didn't work anymore for certain phenomena. This is just the very same story.

You say "you are not aware of any different ways". HOW DO YOU KNOW THAT ?

If you look at the formalism (THE FORUMULA'S) how can you say that ? Even better, how can you prove what you say ?

You are not saying anything here, sorry, but this is just meaningless. Look at the formalism man, look at how the theory was actually constructed and tell me again, how do you prove what you say ?

I simply said that superposition is not a logical consequence of quantum interference. Does that imply that they are not related ? Of course not, since superpostion implies interference. (again, perhaps you should once care to read posts of others)

Pff, again, WHAT HAS THIS TO DO WITH THE PARTICLE WAVE DUALITY ?

You simply had no point to start with (and you think you do, while I ignore it, so I am not surprised you keep on doing that).

That i noticed too. You just keep saying general remarks without any proof nor respect for the actual QM formalism. I am seriously doubting to continue this discussion with somebody who just keeps saying NO with any good counter arguments.

Really, you are not saying anything...
Seems to me you are just fillibustering...

marlon

 

[marlon]

Perhaps Marlon, you should have also copied the FIRST line of that post. Then it would be clear to the reader that I was not arguing against or for your post, but that I was merely adding some thoughts about how QM deals with wave particle duality; a topic which is entirely legitimate in this context since you are constantly arguing from the QM point of view, you are not even willing to drop it even for the sake of discovering where it might lead you.

I know you won't like it but let's reread your comment then : you said (i leave out the first sentence because it does not contribute to the actual content but, ok, we are clear on the intention why you wrote this quote)

YOU SAID THIS :

QM says more than that, it says that those entities are represented by probability waves individually and that observation consists of applying a projector (or corresponding acts in other interpretations). Moreover, it also declares that the reality content behind the observed effects is entirely revealed through observation (even BM takes the schizoid attitude that the wave isn't real).

First of all, when i said this has nothing to do with the particle wave duality i mean this : the particle wave duality and how we described it is something that is an inherent property to the very fundament of QM. What interpretation you assign to the measurement results of the formalism is irelevant because the duality is defines the actual formalism. Now, unless you claim the we have different formalism for QM you are horribly wrong in what you say for that specific reason. The different interpretations are in the RESULTS, NOT THE ACTUAL FORMALISM.

Yes in QM it does not,

Actually, what you do here is just saying that i am right in all i have said.

but the whole point under discussion is whether there is no different way to interpret these experiments in which particles are still classical (self-interacting) particles without being in conflict with wave particle duality (and, yes it seems very possible to me).

In all honesty, i could never deduce from your words we are talking about that. Besides, it's rubbish (or at least how you formulate it) for these reasons :

1) a classical self interacting particle does NOT exist because self interaction is a QM thing

2) how can a classical particle NOT be in conflict with the duality ?

3) this "seems" possible to you ? Well, i am glad for you but how about some proof's ? I don't know ?

Finally, what would be the use ?

No, marlon you were dictating the ``quantum truth'' with no room for any discussion whatsoever, so it is entirely appropriate to see what QM has to say about it.

What you call the "quantum truth" is just the actual formalism. There is only one way to look at that, just like there is only one way for looking classical physis, or GR. The formalism is NOT the same as the measurement interpretations. Now, if you deny this, the please, SHOW ME A DIFFERENT FORMALISM THAT HAS BEEN ACCEPTED IN PEER REVIEWED JOURNALS...

Your are constantly attempting to reverse the discussion : QM in your eyes is the only true view on the microworld so the rest must be an illusion,

There is only one QM formalism, YES. But, since you seem to be suggesting that i am missing one, please fill me in on that ...

you even go that far as to suggest that the problem does not even exist (and thereby discrediting many brilliant scientists who have spend lot's of time on it).

What problem ? That there is more then the "quantum truth" ? Well, show me some references then. Besides, again this has actually NOTHING to do with what we ORIGINALLY were talking about : particle wave duality in the QM FORMALISM.

So, for a change I will ask you a few questions (to start with) :
(a) to what extend are the laws of QM applicable to our world ?

atomic scaled phenomena

(b) How do you percieve it in relation to GR ?

the QM formalism has no relation to GR because they are applicable in different physical regimes.

And that is rubbish, see the complex random walks I have referred you to at least two times before : Richard Feynman, Ted Jacobson, Tomasso Toffoli and others have worked on that for some time.

Give me references to prove that i am wrong. A name is not good enough...Show me papers where those people actually stated that what i have said is "rubbish".

Are you too limited to simply admit that QM does give a very specific and peculiar answer to wave particle duality which is possibly wrong ?

But the QM's formalism does NOT give an anser to the duality, the duality is one of the fundametal observations making up this formalism.

Are you too limited to NOT have noticed that ?

marlon

 

[Anonym]

Marlon:” Again, what contradiction ? Do you think i mean that QM is also "a dispersion free theory" (whatever that may be ?). NOT AT ALL.
There is no contradiction because i am not talking about QM nor its formalism.”

Let me try to clarify my point farther. And let me start from the beginning:

Smiley10:” Believe it or not I'm having trouble understanding quantum physics.”

My interpretation is that Smiley10 quote R. Feynman joke from the Lectures. Obviously that implies that he/she read the lectures. In addition, my interpretation is that Smiley10 is not an engineer, he/she is a physicist and a very good physicist. R.Feynman was famous also with his sense of humour. R.Feynman was also outstanding teacher. Here the example of his pedagogical joke:"nobody understands quantum mechanics" (after that he start to explain).I received several interpretations of my interpretation. Only Smiley10 was adequate.

I am not interesting at all to search for contradictions or inconsistency in your point of view or anybody else. To be consistent is not important for me. I will try to explain that later. During wave packet description session I try to focus on W. Heisenberg UR: (delta x)*(delta p) > 0. In classical physics (delta x)*(delta p) = 0 . My question was: what is the connection between delta x in QM, delta x in Newtonian mechanics (Newtonian “ball”) and delta x in E. Schrödinger/ R.J. Glauber? Now I think I am very close to answer (mathematically).

Look now on the following interpretation of R. Feynman simple statement :"nobody understands quantum mechanics":

Vanesch:” The situation is the following: in "ordinary" QM, the formalism is entirely understood ; in quantum field theories (such as QED), even the formalism is not entirely understood, but well enough to do some calculations. In other words, we know that the calculations that are done, are mathematically somehow unsound, but this can be explained away by saying that it must be an approximation to something else (effective field theories).

But Feynman wasn't talking about the formalism, he was talking about the "physical meaning". This is what is not understood, although several attempts with varying degrees of success have been invented. Nobody really knows what the mathematical objects in a quantum theory actually represent.

Some claim that it is just a mathematical tool which gives you statistical outcomes of experiments (in other words, that one shouldn't look for any physical meaning) - fine, but they can't come up with an explicit underlying physical mechanism ! Some (Bohr, with Copenhagen) claim that there IS no explicit physical mechanism, that all there is, is "statistics". This is essentially the "standard" Copenhagen interpretation: the quantum-mechanical formalism links statistically setups and outcomes of a "classical" macroscopic world, and there is no underlying explanation for this link. The formalism of quantum mechanics simply allows you to calculate the probabilities, but doesn't represent anything physical, because there IS nothing physical at that scale.

Others (such as me) claim that the formalism of quantum theory is to be taken seriously, and that it represents genuine physical quantities. These views are "many worlds" views, because you cannot avoid that way, to make a distinction between "the physical state" and "observed reality by an observer", which is so terribly weird.

Others think that the quantum formalism has something real to it, but that there is also an explicit "projection" mechanism. However, this usually introduces some clashes with relativity.

Still others think that there's something fundamentally wrong with the quantum formalism, although it makes correct predictions in many cases, for an ununderstood reason.

This is a discussion that goes on now for almost 80 years, and is usually referred to as the "measurement problem" of quantum theory. However, and that is the nice part: you don't need to think about all this to get the formalism working in practical cases, and in any case, it is a good idea to learn very well the formalism before delving into these issues.

So, the practical attitude to adopt when learning the formalism of quantum theory, is simply this: "quantum theory is a mathematical model which allows you to generate statistical predictions for outcomes of experiment, but for which no evident physical interpretation is known." From the moment that you try to do so, you delve into the problems of the measurement problem, which haven't really been resolved since about 80 years. This is what Feynman meant.”

Marlon:” There is no contradiction because i am not talking about QM nor its formalism.”

And I did not find where you was talking about CM or its formalism either.

” All i wanted to say is that we, as human beings are more familiar with the concepts of classical physics.”

Here I think you are wrong.
Now we arrived to the interconnection between physics, mathematics and biology. It is clear that they are different aspects of the integrated human activity called development of human culture. But you need also to differentiate them. It seems to me that the proper distinction will be achieved if you will define the physics as an empirical science (axiomatically considered as an auxiliary definition). Thus no room for the solipsism will be left.
I guess that human brain is natural realization of quantum computer. It will be properly investigated in future using standard physical tools (Careful restaurant). I guess that You, Vanesch, Smiley10, Careful, Eep, Zbyszek, Ueit, Reilly and me more familiar with the concepts of quantum physics (Linear Hilbert space,linear superpositions are it inherent feature). Only when you or me express yourself verbally or by writings the collapse of wave packet take place. Feed-back loop force you and me try to be consistent.

 

[masudr]

My question was: what is the connection between delta x in QM, delta x in Newtonian mechanics (Newtonian “ball”) and delta x in E. Schrödinger/ R.J. Glauber? Now I think I am very close to answer (mathematically).

The connection is:

$$[\hat{A},\hat{B}] \equiv i\hbar \{ A, B \} \equiv i \hbar \left( \frac{\partial A}{\partial x}\frac{\partial B}{\partial p} - \frac{\partial A}{\partial p}\frac{\partial B}{\partial x} \right),$$

where it is understood that x, p are canonical co-ordinates.

From the above definition, it is straightforward that $\{ x, p \} = 1$, and so $[x, p] = i \hbar$. The differences truly arise since in QM we have associated observables with spectra of operators, and (if you follow through on the mathematics) the relation between the root of the variances arise.

 

[Anonym]

Masudr:” The differences truly arise since in QM we have associated observables with spectra of operators, and (if you follow through on the mathematics) the relation between the root of the variances arise.”

So, why you do not follow through on the mathematics?
You can’t put “=” in your expression. It is not a mathematics (see P.Ehrenfest).Notice, that you must use the mathematical languages which are matched. Otherwise, it is like you talk clever things using Chinese with equally clever guy who know only English. You reformulated my question. But I already look for answer.

 

[masudr]

So, why you do not follow through on the mathematics?

The derivation of uncertainty relations given the non-commutativity of the corresponding operators is fairly standard in most advanced QM texts and I'd assumed you'd seen it. See for example Shankar, 2nd ed., pps. 237-239 (you can preview it for free on Google Books, search for "shankar ramamurti derivation of the uncertainty relations" and it's the first hit).

You can’t put “=” in your expression. It is not a mathematics (see P.Ehrenfest).

Yes sorry, it should be an identity sign. I have corrected it now (I had to clear my browser cache to see the effects though).

 

[Anonym]

Masudr:” Yes sorry, it should be an identity sign”

Masudr, come on! It must be expectation value.

 

[Dense]

Originally Posted by Dense
I find it helps to think of it this way:

Imagine lightning. You know how, before the visible lighting bolt strikes, the phenomenon first finds the path of least resistance; and once that path has been carved out in the atmosphere between the two charges, the bolt slams down that path.

So now imagine that a photon has been created, and before it starts to travel you stop time. With time stopped, all of the photon's possible paths are carved out in front of it. Imagine each of these paths as if they were independent photons. Now some of these paths are going to interfere with each other.

Now start up time again. The photon is going to travel down one of these paths. If it's one of the paths that interfered with another potential path, it's going to look as if the photon interfered with itself. Not because it actually did, but because the potential path it followed had already interfered with another potential path.

I'm not saying this is really what happens, I'm just saying it's an analogy that helps me understand the outcome.

This is pretty close to Bohmian Mechanics (maybe you didn't realize this...)

Sorta-kinda. Similar to Bohm's "pilot wave," with all possible "pilot waves" in the photon's phase space going out, outside of time, and interfering with each other.

The analogy only needs one more dimension on top of time for it to make sense.

 

[Dense]

I have read a seminar of Anthony zee once where he uses almost the very same formulation.

Wow! Do you know where I might find the text of that seminar?

 

[masudr]

Masudr, come on! It must be expectation value.

Aren't you getting confused with the time derivative of the expectation of an observable:

$$\frac{d}{dt}\langle A\rangle = \frac{i}{\hbar}\langle [H,A] \rangle + \frac{\partial A}{\partial t}$$​

This is explained for time-independent observables in Wikipedia's Ehrenfest thm. article.

What I'm talking about is something different (but still related, as with most things in physics). This is to do with pairs of observables; Paul Dirac saw the link between the commutation relations and the Poisson bracket and it's the same as I gave above. See Wikipedia's article on the can. comm. relation, for example.

Ehrenfest's theorem follows from the fact that the Hamiltonian generates time translations of canonical co-ordinates. e.g. in classical mechanics we have

$$\frac{\mathrm{d}}{\mathrm{d}t} f=\frac{\partial }{\partial t} f + \{\,f,H\,\}.$$​

So no, it shouldn't be an expectation value. The commutator between two operators are proportional to the Poisson bracket, no expectation needed.

 

[Careful]

Give me references to prove that i am wrong. A name is not good enough...Show me papers where those people actually stated that what i have said is "rubbish".

No problem, here you have some:

* Simulating physics with computers, international journal of theoretical physics Vol 21, nos 6/7 1982 R.P. Feynman
* Feynmans Relativistic Chessboard model as an Ising model
H.A. Gersch, International Journal of theoretical physics Vol 20, No, 7,1981
* The Schrodinger equation and Dirac Free particle equations without Quantum mechanics, G.N. Ord, Annals of physics 250, 51-62
* Random walks, continuum limits and Schrodingers equation, Phys Rev A, Vol 54, number 5, 1996

These are all about quantal random walks, a specific road towards the wave particle duality problem has been taken by Toffoli (by considering interfering ensembles of ket and bra's).

I am not even going to dignify the rest with a response except for :

In all honesty, i could never deduce from your words we are talking about that. Besides, it's rubbish (or at least how you formulate it) for these reasons :

1) a classical self interacting particle does NOT exist because self interaction is a QM thing

2) how can a classical particle NOT be in conflict with the duality ?

3) this "seems" possible to you ? Well, i am glad for you but how about some proof's ? I don't know ?

Finally, what would be the use ?

(1) What the hell forbids me to consider classical self interacting particles ? Never heard of classical electromagnetic selfinteraction of the electron ?
(2) Easy, it can undergo wave motion under influence of its own wave field.
(3) I gave a clear argument that it is not impossible, for example Hestenes thought zitterbewegung of spinorial particles to be responsible for the apparent duality.


The use, ohw you would get rid of wave particle duality, you would not need any collaps/consciousness, the theory could be determinstic ... minor things which I am sure are not of your concern.

First of all, when i said this has nothing to do with the particle wave duality i mean this : the particle wave duality and how we described it is something that is an inherent property to the very fundament of QM. What interpretation you assign to the measurement results of the formalism is irelevant because the duality is defines the actual formalism. Now, unless you claim the we have different formalism for QM you are horribly wrong in what you say for that specific reason. The different interpretations are in the RESULTS, NOT THE ACTUAL FORMALISM.

If you believe I was speaking about different interpretations, then yes ... sigh. Anyway, it is clear to any idiot that the way one thinks about wave particle duality is intimately connected to the measurement problem. This Toffoli bra and ket model actually treats particles differently, as well as the waves, and the measurement is entirely local and realist. In the QM model on the other hand, you either need a nonlocal collapse, a nonlocal equation of motion for particles (BM) or you have to give up reality and incoorporate something which measures the particle without actually collapsing the wave (MWI). But a local realist measurement postulate is alas not possible in the light of **QM** wave particle duality.

Careful

 

[reilly]

marlon has been doing the heavy lifting, and doing it well.

I have a question for the contrarians -- how many of you have made a living doing QM? That is, how many contrarians know QM's practical aspects in addition to the millions of words about the abstract theory? I know there are some, but I do wonder how many have been in the trenches.

Again; QM is fundamentally empirical, designed to deal withy phenomena that simply defy the logic of classical physics. Small wonder that the theory, as it is now, has the problems associated with language and logic(L&L) in either one of two camps -- ordinary L&L, which does not cut it, or some QM L&L, all of which have many problems, discussed all through the physics community.

The simple point is: for all practical purposes, we are classical folks, stuck in the very strange quantum world, so far without the L&L tools to feel comfortable with observed reality at the atomic or smaller level. Seems to me, the issue should not be one of competeing ideologies, but rather one of trying to understand better the fundamental issue: why does QM work so well? (That's where the physics is.)

Regards,
Reilly Atkinson

 

[Careful]

marlon has been doing the heavy lifting, and doing it well.

The heavy ranting you mean.

Again; QM is fundamentally empirical, designed to deal withy phenomena that simply defy the logic of classical physics. Small wonder that the theory, as it is now, has the problems associated with language and logic(L&L) in either one of two camps -- ordinary L&L, which does not cut it, or some QM L&L, all of which have many problems, discussed all through the physics community.

Right, that is exactly how I take QM and this gives me plenty of liberties.

The simple point is: for all practical purposes, we are classical folks, stuck
in the very strange quantum world, so far without the L&L tools to feel comfortable with observed reality at the atomic or smaller level. Seems to me, the issue should not be one of competeing ideologies, but rather one of trying to understand better the fundamental issue: why does QM work so well? (That's where the physics is.)

Exactly, but then you have to be prepared to see things differently and show in what sense QM is an approximation (for example S. Adler is doing this). Actually, many of my views towards QM and entanglement in particular were held by J. Bell (as I learned yesterday while reading his nouvelle cuisine) so I can hardly understand the protest.

 

[Anonym]

Masudr, come on. This is explained for time-independent observables in Wikipedia's Ehrenfest thm. article. See Wikipedia's article on the can. comm. relation, for example. For more detailed discussion see P.A.M. Dirac The Principles.
Look at this point alternatively: why not? Take brackets from both sides. Left is well defined. Right is not defined. This is break-through penetration point.Here somehow fails J. von Neumann, E.P.Wigner, G. Birkhoff, P. Jordan, E.C.G. Stueckelberg and S.L. Adler

 

[masudr]

Masudr, come on. This is explained for time-independent observables in Wikipedia's Ehrenfest thm. article. See Wikipedia's article on the can. comm. relation, for example. For more detailed discussion see P.A.M. Dirac The Principles.

That's not helpful at all. Tell me if you have a problem with the following:

$$[\hat{A},\hat{B}] \equiv i\hbar \{ A, B \} \equiv i \hbar \left( \frac{\partial A}{\partial x}\frac{\partial B}{\partial p} - \frac{\partial A}{\partial p}\frac{\partial B}{\partial x} \right).$$

And if so, a reference to where it is wrong.

 

[marlon]

No problem, here you have some:

* Random walks, continuum limits and Schrodingers equation, Phys Rev A, Vol 54, number 5, 1996

I took the effort of reading this publication and i did not find any clue to denies what i have said. Please, show me, in this paper, the part where you think what i have said (which is just mainstraim physics) is incorrect. Let's work with this one.

I am not even going to dignify the rest with a response except for :

That's a bit easy no ?

Besides, i am still waiting for the answers to MY questions...

(1) What the hell forbids me to consider classical self interacting particles ? Never heard of classical electromagnetic selfinteraction of the electron ?

Err, the fact that it does NOT exist, maybe ?

Show me some self interacting particles in classical physics please. Again, if you make a hollow claim, please take the effort of using mainstream physical examples. Otherwise, what you say is just ...empty stuff...

(2) Easy, it can undergo wave motion under influence of its own wave field.

Huh ? Mainstream physics examples please ?

(3) I gave a clear argument that it is not impossible,

No you did not, but i am giving you the chance to do that again.

for example Hestenes thought zitterbewegung of spinorial particles to be responsible for the apparent duality.

That's the first time you talk about that to me. Also, regurgitating some terms is useless. What do you mean by "spinorial particles responsible for apparent duality" ? Mainstream physics only please...

But again, what does this have to do with our original discussion which is limited to the original QM formalism. We were only look at the "standard view" and certainly NOT about measurement problems.

The use, ohw you would get rid of wave particle duality, you would not need any collaps/consciousness, the theory could be determinstic ...

HUH ? What the hell are you talking about ? Are you laughing with me ?

I cannot take this seriously anymore.

minor things which I am sure are not of your concern.

Yeah, very clear. I am sure that if people read what you say here, your point will be sooooooo convincing.

Clearly, my dear friend, you are not used to real scientific discussions. You seem to be of one of them pop science guys.

If you believe I was speaking about different interpretations, then yes ... sigh.

That's something, you see it is not so hard to swallow your proud and follow mainstream physics.

And YES, you are always talking about different interpretations while i was ONLY talking about the standard QM formalism. NO measurement problems...

Anyway, it is clear to any idiot that the way one thinks about wave particle duality is intimately connected to the measurement problem.

MEASUREMENT PROBLEM ?

Why ? Guess i must be anidiot then, so, please enlighten me.

This Toffoli bra and ket model actually treats particles differently, as well as the waves, and the measurement is entirely local and realist. In the QM model on the other hand, you either need a nonlocal collapse, a nonlocal equation of motion for particles (BM) or you have to give up reality and incoorporate something which measures the particle without actually collapsing the wave (MWI). But a local realist measurement postulate is alas not possible in the light of **QM** wave particle duality.

Careful

WRONG. You are again mixing measurement problems with the formalism. I am not going into that again since i have been doing that ad nauseum".

marlon

 

[marlon]

Right, that is exactly how I take QM and this gives me plenty of liberties.

That is NOT what you have been saying to me. reilly, i leave the honour to you

Exactly, but then you have to be prepared to see things differently and show in what sense QM is an approximation (for example S. Adler is doing this).

C'mon man, you are being so weak here. you have been ranting to me about how i am wrong in saying what i have been saying to you many times. Now, Reilly said basically the same (ESPECIALLY HIS FIRST SENTENCE HERE) and you agree ?

Actually, many of my views towards QM and entanglement in particular were held by J. Bell (as I learned yesterday while reading his nouvelle cuisine) so I can hardly understand the protest.

BUT I WAS NOT TALKING ABOUT THAT ! How many times do i need to repeat the fact that i was NOT referring to measurement interpretations. I was ONLY talking about the standard QM formalism and i never denied there are "different views", NOTHING MORE !


marlon