The double slit experiment and Superposition

[Dalo]

Just now, Mordred said:

That's been done as empirically as possible. Your refusal to accept all the references provided isn't my problem.

You did not show at any time that

- a particle can go through both slits at the same time,

- that the interference pattern is destroyed by observation.

Your experiments, however impressive, are irrelevant to this thread.

[Mordred]

 Well thus far I have shown you don't understand the theories your supporting. I provided you what you need to learn to fix this lack. What you believe or don't believe isn't what I spend my time on forums dealing with. You keep thinking of particles as bullet like objects by that last descriptive. A wave can do precisely that Travel through two slits at one time.

 

[Dalo]

Just now, Mordred said:

 Well thus far I have shown you don't understand the theories your supporting. I provided you what you need to learn to fix this lack. What you believe or don't believe isn't what I spend my time on forums dealing with. You keep thinking of particles as bullet like objects by that last descriptive. A wave can do precisely that Travel through two slits at one time.

 

I know the theory, now show me the results in the particular case I have described.

[Mordred]

 Sure under QFT, when waves constructive interfere the amplitude of the wave increases. This is described by the creation and annihilation operators. In other words new photons get created by these increases. Old ones not in phase with each other via the sum over Histories under Bohm and QFT annihilate. That simple enough?

 Its all in the math above....

So far we have shot down your arguments due to lack of understanding them on your part. Care to go over the material I provided and make a more informed decision or argument ?

 

Edited December 14, 2017 by Mordred

[Dalo]

1 minute ago, Mordred said:

Sure under QFT, when waves constructive interfere the amplitude of the wave increases. This is described by the creation and annihilation operators. In other words new photons get created by these increases. Old ones not in phase with each other via the sum over Histories under Bohm and QFT annihilate. That simple enough?

So far we have shot down your arguments due to lack of understanding them on your part. Care to go over the material I provided and make an informed decision?

Nope, all you have done is explain or refer to theories I am not attacking. What I am looking for is much more modest:

show me an empirical proof of both points:

- that a particle can go through both slits; or at least,

- that observation destroys interference patterns in a double slit experiment.

As you see, nothing complicated, and you can use any theory you want as long as you do not stop at the theory, but show the empirical results.

[Mordred]

3 minutes ago, Dalo said:

tNope, all you have done is explain or refer to theories I am not attacking. What I am looking for is much more modest:

show me an empirical proof of both points:

- that a particle can go through both slits; or at least,

- that observation destroys interference patterns in a double slit experiment.

As you see, nothing complicated, and you can use any theory you want as long as you do not stop at the theory, but show the empirical result

What do you define as empirical. Hold your hand out so you can touch it? We have provided numerous experimental evidence for you to examine.

Secondly it is your obligation to provide the evidence to support your argument under the rules of the Speculation forum

[Dalo]

Just now, Mordred said:

What do you define as empirical. Hold your hand out so you can touch it? We have provided numerous experimental evidence for you to examine.

Secondly it is your obligation to provide the evidence to support your argument under the rules of the Speculation forum

Empirical by scientific criteria.

I have nothing to prove, since the facts are recognized by everybody, including you. What I am asking is that you prove what you claim, that the theory, any theory you may choose, leads to the practical results I have mentioned.

3 minutes ago, Mordred said:

We have provided numerous experimental evidence for you to examine.

This is the whole point, isn't it? You claim that you have provided empirical proofs, but I cannot see how what you have presented relates to the questions posed. Since you are the one claiming that you have proofs, the least you can do is show them unambiguously. Maybe I have not understood them, so why don't you tell me exactly what your empirical proofs consist of?

[Mordred]

Read the material my support is there as stated before I deal with physics and teaching it. Doesn't matter to me what you choose to believe in. I don't do useless metaphysics or disbelief arguments. ( a good metaphysics argument I have yet to see from this thread)

good visual aid

here the reference for how this works with constructive/destructive interference. You won't accept this either....

https://ocw.mit.edu/high-school/physics/exam-prep/physical-optics/interference-diffraction/8_02_spring_2007_ch14_inter_diffr.pdf

Edited December 14, 2017 by Mordred

[Dalo]

The idea that observation changes the object or phenomenon observed is a central tenet of the Copenhagen interpretation of quantum mechanics. I will not attempt to discuss the meaning of this principle for the whole domain of the theory, but will limit myself to the case I have presented in this thread.
Double slit experiments show interference patterns when one or two slits are open, but those same patterns seem to disappear when the experimenter tries to determine through which slit the particle has passed.
I have claimed that this disappearance is a mere theoretical phenomenon, based on the belief that it is the only sensible explanation when one takes into account the dual nature, or at least the wave, theory of light.
I would like to make it clear that my claim is not incompatible with this theory. The interference patterns may well be the result of constructive and destructive interference of particles moving together through the slits. They may even be the result of single particle interference.
What is essential is the reason why they seem to disappear when "observed".

I have found no indication, neither in the literature, nor in the reactions received in this forum, of an empirical proof that interference patterns effectively disappear when observation is involved. 
Rather, I am evermore convinced that the disappearance is a theoretical assumption, or conclusion if one prefers, rather than an observation.
No empirical proof of the disappearance of the interference patterns has ever been given, this, as far as I know.

If that is the case we are confronted with philosophical consequences that need to be explicitly stated. One of them is:
The idea that observation changes the result of an experiment, whatever the further merits of the idea, remains unproven in the case of double slit experiments.

Edited December 14, 2017 by Dalo

[DrP]

11 minutes ago, Dalo said:

Double slit experiments show interference patterns when one or two slits are open, but those same patterns seem to disappear when the experimenter tries to determine through which slit the particle has passed.

Hold on - when there is only one slit open surely you wont get an interference pattern? If you close a slit then you have just one slit and you get a normal beam out of it as you would for 1 slit, no?  -  am I wrong here? Have I missed or forgotten something from my uni days?  You still get the pattern if you fire off one photon at a time...  as if it 'knows' there are 2 slits..  I thought that it was this observation that proved it travelled as a wave not a particle.  If you cover a slit then you are left with 1 slit. Correct me if I am wrong.

The interference pattern as I see it is just the same as any wave interference pattern when 2 waves meet. There are 2 waves because that is how they emerge from the 2 slits. You can see it on water as a wave goes through 2 openings, you get the same interference pattern. Maybe my understanding of it is too basic.

 

 

[Dalo]

1 hour ago, DrP said:

when there is only one slit open surely you wont get an interference pattern?

I understand your confusion. maybe this will help

 

[swansont]

5 hours ago, Dalo said:

 I have nothing to prove, since the facts are recognized by everybody, including you. What I am asking is that you prove what you claim, that the theory, any theory you may choose, leads to the practical results I have mentioned.

You have dismissed evidence that has been presented based on criteria you have not discussed. Instead, you insist on a specific experiment without justification for the narrowing of what evidence you will accept.

It's not reasonable, and this schtick is getting old.

[Dalo]

1 minute ago, swansont said:

You have dismissed evidence that has been presented based on criteria you have not discussed. Instead, you insist on a specific experiment without justification for the narrowing of what evidence you will accept.

It's not reasonable, and this schtick is getting old.

Maybe if you could tell me what I need to prove, I would then try to do it. But it is not enough just to say it and expect an answer. I honestly have no idea what is expected of me.

[swansont]

1 hour ago, Dalo said:

 
Double slit experiments show interference patterns when one or two slits are open, but those same patterns seem to disappear when the experimenter tries to determine through which slit the particle has passed.
 

in single-slit interference, you know which slit it goes through, and the single-slit interference pattern does not disappear. It is not the same pattern as double-slit interference. Single-slit is a diffraction effect. Double-slit gives interference within the diffraction envelope of single slit. They are quite different patterns.

4 minutes ago, Dalo said:

Maybe if you could tell me what I need to prove, I would then try to do it. But it is not enough just to say it and expect an answer. I honestly have no idea what is expected of me.

Answer questions asked of you (you have ignored mine, though I have asked twice) and provide evidence for your assertions. It would also help if you stick to the main topic you bring up.

[Dalo]

1 minute ago, swansont said:

in single-slit interference, you know which slit it goes through, and the single-slit interference pattern does not disappear. It is not the same pattern as double-slit interference. Single-slit is a diffraction effect. Double-slit gives interference within the diffraction envelope of single slit. They are quite different patterns.

Yes, you are right on this point.

 

2 minutes ago, swansont said:

Answer questions asked of you (you have ignored mine, though I have asked twice) and provide evidence for your assertions. It would also help if you stick to the main topic you bring up

I am afraid that is not enough and you will have to be more specific. I do not know what you mean by proof or evidence because apparently what I have presented does not satisfy you.

[swansont]

1 minute ago, Dalo said:

 I am afraid that is not enough and you will have to be more specific. I do not know what you mean by proof or evidence because apparently what I have presented does not satisfy you.

The main problem is that you haven't presented anything. You claim that a Mach-Zehnder interferometer and two slit are different, but have not justified it. Which one of them is not showing interference?

I asked you a question about the resolution of a bubble chamber vs the size of a double slit for electron interference. Crickets.

 

[Dalo]

10 minutes ago, swansont said:

You claim that a Mach-Zehnder interferometer and two slit are different, but have not justified it.

In an interferometer a beam is split in two. Otherwise it would not work.

In a double slit, the question whether the particle splits in two is the central issue that needs to be resolved.

10 minutes ago, swansont said:

I asked you a question about the resolution of a bubble chamber vs the size of a double slit for electron interference.

The case of the vapor chamber, if that is what you mean, turned out to be a thought experiment. I had used it as if it were a real experiment. I  have never performed such an experiment and wouldn't know how to set it up. I am dependent on the information I get from the books and articles I read, or from video clips I watch on Youtube.

Edited December 14, 2017 by Dalo

[swansont]

11 minutes ago, Dalo said:

In an interferometer a beam is split in two. Otherwise it would not work.

Likewise in a double-slit experiment. The M-Z works with one photon at a time, too.

IOW, by clearly separating the path and seeing the same behavior, we have evidence that the double-slit must work the same way. Topologically they are the same.

Quote

The case of the vapor chamber, if that is what you mean, turned out to be a thought experiment. I had used it as if it were a real experiment. I  have never performed such an experiment and wouldn't know how to set it up. I am dependent on the information I get from the books and articles I read, or from video clips I watch on Youtube.

IOW, you are not interested in the actual physics involved and can't be bothered to learn the details. Here's the solution: don't make claims you are not willing to back up. The big problem here is that every time you get pressed on details, you fall back on "I'm not a scientist". But you also make assertions, and reject evidence, as if you have some expertise. You can't have it both ways.

Either ask questions and learn, or make assertions and back them up. You can't do both at the same time, on the same topic.

[studiot]

In your post#2 you describe Al Khalilli's lecture,

But you fail to observe what he hasn't told you about this presentation.

Can you see what is missing from this screenshot?

 

[Dalo]

45 minutes ago, swansont said:

IOW, you are not interested in the actual physics involved and can't be bothered to learn the details. Here's the solution: don't make claims you are not willing to back up. The big problem here is that every time you get pressed on details, you fall back on "I'm not a scientist". But you also make assertions, and reject evidence, as if you have some expertise. You can't have it both ways.

I am very much interested in details that I need to understand the principles involved. That does not mean that I need to know everything a physicist knows about the subject I am discussing. There is a difference between an expert who needs to know as much as possible to perform experiments or build "things", and the amount of information an outsider needs to be able to speak about a process. 

The same way, a good mechanic should be able to drive a car, but he does not need to become a race pilot. And vice versa.

Concerning the difference between interferometers and double slits, it is a complicated issue that certainly deserves more time than the few remarks I have allocated to it. What I did was in my opinion the only honest position I could take, and that is to propose to treat of this subject in its own thread.

Whatever the conclusion might be of this thread, I think it is my right to limit the range of my claim and to expect from others not to widen the subject unnecessarily. I have not in any way claimed that what I say of double slit experiments is applicable to interferometers, so why would you demand from me that I defend such a claim?

 

********************************************

37 minutes ago, studiot said:

In your post#2 you describe Al Khalilli's lecture,

But you fail to observe what he hasn't told you about this presentation.

Can you see what is missing from this screenshot?

 

No, and I am really not interested in diagrams or drawings that can be made to say or prove anything one wants. That is why I speak each time of empirical evidence and "real" or "live" experiments.

Edited December 14, 2017 by Dalo

[geordief]

 

19 minutes ago, studiot said:

In your post#2 you describe Al Khalilli's lecture,

But you fail to observe what he hasn't told you about this presentation.

Can you see what is missing from this screenshot?

 

Is that from AK's  programme?(no I don't know what is missing)

 

Btw I found Dalo's Single Slit Interface video ten or so posts back revelatory (and this thread comparatively easy to follow)

 

Is that video totally uncontraversial (insofar as anything can be)? 

Edited December 14, 2017 by geordief

[DrP]

2 minutes ago, geordief said:

Is that video totally uncontraversial (insofar as anything can be)? 

It seems like an attempt to explain diffraction by picturing a wave front as an infinite number of little waves fronts. I like the idea and follow it..  I do not know if it is accepted or not in mainstream science...  it certainly seems to be as an idea, but I am not sure there is any solid evidence or how you would test it. It is new to me anyway - when I was at college we learnt about DeBrogle and Bragg although I remember little about them as I have used nothing about what I learnt from them in my professional life. .

[geordief]

3 minutes ago, DrP said:

It seems like an attempt to explain diffraction by picturing a wave front as an infinite number of little waves fronts. I like the idea and follow it..  I do not know if it is accepted or not in mainstream science...  it certainly seems to be as an idea, but I am not sure there is any solid evidence or how you would test it. It is new to me anyway - when I was at college we learnt about DeBrogle and Bragg although I remember little about them as I have used nothing about what I learnt from them in my professional life. .

I also like it . It seems to help me with my self questioning  "when is a slit a slit?" "(I am starting from scratch ,just trying to keep up with the posse at the closest distance possible  )

Edited December 14, 2017 by geordief

[DrP]

I looked up Huygens Principle....  which it seems to be about  -  it seems believable, but as I said - I do not know if it is accepted or testable..  it seems like calculus for waves.  

 

[geordief]

3 minutes ago, DrP said:

I looked up Huygens Principle....  which it seems to be about  -  it seems believable, but as I said - I do not know if it is accepted or testable..  it seems like calculus for waves.  

 

Bigger fleas have little fleas 
Upon their backs to bite 'em 
And little fleas have lesser fleas 
And so on, ad infinitum

 

Spike Milligan