The double slit experiment

Foundations of physics and/or philosophy of physics, and in particular, posts on unresolved or controversial issues

Re: The double slit experiment

Postby minkwe » Sun May 04, 2014 8:04 pm

Well since you are impatient to know the answer, let me give you the brief version. You will have to ask specific questions to get detailed explanations.

1) quanta/particles can transfer momentum to the walls if the slits.
2) The amount of momentum transferred, determines the angle of deflection of the particle.
3) Transfered momentum is quantized. Therefore the particles are deflected into discrete directions.
4) The allowed directions are determined by the relationship between the normal modes if the slit system and the frequency of the quanta/particle.
5) Since different slit systems have different normal modes, the diffraction patterns are different.
6) The pattern produced, and the slit system producing it have a dual relationship. They can be expressed as Fourier transforms of each other.
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Re: The double slit experiment

Postby gill1109 » Mon May 05, 2014 3:22 am

minkwe wrote:Then you may ask, why do particles prefer to go into the maxima rather than the minima, and that is what my explanation will answer (in fact it is not my explanation, it has been known but ignored since the beginning of quantum theory. I guess it was not mysterious enough for the copenhageners).

Could you give a reference or name to the explanation which was known but ignored since the beginning of quantum theory? I am not intending to weigh into the discussion; I would just like to know whose approach you are following. I know of quite a few nice explanations and am just wondering which is your favourite. I agree, the two slit experiment is not really so mysterious at all ...
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Re: The double slit experiment

Postby jreed » Mon May 05, 2014 6:12 am

Although you don't realize it, this is Lande's theory. Look him up on the web. If you do some research on this, you will find it has already been researched and investigated. He wrote many books on it but it never became a popular interpretation of quantum mechanical effects. You don't have to answer any questions for me. I have several of his books where these questions are explained with his theory. I read these books, but the same problems of understanding quantum mechanical effects occur in his theory, except in a different form. As someone told me once, that's conservation of trouble: You can move trouble around, but never get rid of it.
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Re: The double slit experiment

Postby minkwe » Mon May 05, 2014 7:02 am

jreed wrote:Although you don't realize it, this is Lande's theory. Look him up on the web. If you do some research on this, you will find it has already been researched and investigated. He wrote many books on it but it never became a popular interpretation of quantum mechanical effects. You don't have to answer any questions for me. I have several of his books where these questions are explained with his theory. I read these books, but the same problems of understanding quantum mechanical effects occur in his theory, except in a different form. As someone told me once, that's conservation of trouble: You can move trouble around, but never get rid of it.

Rather than lump it up as Lande's why don't you ask specific questions that you have issues with the explanation so far. Or do you think you know exactly what I'm going to say? What is the trouble that you say is being moved around? I'm not familiar with Lande's theory but you appear to be so why don't you state what the problem is with Lande's theory.

I assumed you were genuinely interested in the explanation. Are you?
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Re: The double slit experiment

Postby minkwe » Mon May 05, 2014 7:19 am

gill1109 wrote:
minkwe wrote:Then you may ask, why do particles prefer to go into the maxima rather than the minima, and that is what my explanation will answer (in fact it is not my explanation, it has been known but ignored since the beginning of quantum theory. I guess it was not mysterious enough for the copenhageners).

Could you give a reference or name to the explanation which was known but ignored since the beginning of quantum theory? I am not intending to weigh into the discussion; I would just like to know whose approach you are following. I know of quite a few nice explanations and am just wondering which is your favourite. I agree, the two slit experiment is not really so mysterious at all ...


My explanation is inspired by early work by William Duane Epstein, Ehrenfest and Compton which you can find in:

http://www.pnas.org/content/9/5/158.full.pdf
Duane, W. "The transfer in quanta of radiation momentum to matter." Proceedings of the National Academy of Sciences of the United States of America 9.5 (1923): 158.

Epstein & Ehrenfest:
http://www.ncbi.nlm.nih.gov/pmc/article ... 5-0015.pdf
Epstein PS, Ehrenfest P. The Quantum Theory of the Fraunhofer Diffraction. Proc Natl Acad Sci U S A. 1924 Apr;10(4):133–139.
In an important paper published on the pages of these PROCUIEDINGS, W. Duane' makes a successful "attempt to formulate a theory of the reflection
of X-rays by crystals, based on quantum ideas without reference to interference laws." A. H. Compton, enlarging upon a hint contained in Duane's paper, has recently pointed out that the latter's hypothesis can be justified by the application of the general rules of the theory of quanta to the translatory motions of a crystal lattice. ...


and by Arthur Compton:
http://www.ncbi.nlm.nih.gov/pmc/article ... 4-0003.pdf
Compton AH. The Quantum Integral and Diffraction by a Crystal. Proc Natl Acad Sci U S A. 1923 Nov;9(11):359–362.
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Re: The double slit experiment

Postby Ben6993 » Mon May 05, 2014 7:26 am

This is not a Bell simulation thread, but does a diffraction effect as above have any relevance to the Bell's simulations? The Bell's simulations use uniform randomness of an angle, or on a sphere, but not all the random data points become particle pairs. That seems like a diffractionless scenario. It will also be possible to generate non-uniform random data on a sphere. Ie a sort of diffraction pattern sampling. For example trying to simulate random points on a dimpled golf ball, where the points in the hollows are sampled less often than points on the raised parts. Maybe such a sampling would lead to fewer wasted data points. Or maybe not.
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Re: The double slit experiment

Postby gill1109 » Mon May 05, 2014 9:09 am

Ben6993 wrote:This is not a Bell simulation thread, but does a diffraction effect as above have any relevance to the Bell's simulations? The Bell's simulations use uniform randomness of an angle, or on a sphere, but not all the random data points become particle pairs. That seems like a diffractionless scenario. It will also be possible to generate non-uniform random data on a sphere. Ie a sort of diffraction pattern sampling. For example trying to simulate random points on a dimpled golf ball, where the points in the hollows are sampled less often than points on the raised parts. Maybe such a sampling would lead to fewer wasted data points. Or maybe not.

I explained some way above here in this topic that there is a connection to Bell and even to CHSH type experiments. Unfortunately the time and spatial layout of source, setting randomizers, and measurement devices does not exclude many of the loopholes ... which is exactly why the ideal Bell-CHSH experiment has the spatial layout which it does ...

Image

The "reduced" two slit experiment (reduced to two parties, two settings, one combined outcome with three values) can't be put into this form because the step of combining two measurement outcomes into 1 (are the two outcomes equal or different?) has kind of been done for us on the screen (does the particle arrive in a positive or negative interference zone or not at all)?

So Bell-CHSH experiment is a kind of pulled apart two slit experiment with two spatial separated measurement devices, not just one. But the Bell-type math would be just the same.

PS to Michel - thanks for the references, this is fascinating!
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Re: The double slit experiment

Postby minkwe » Mon May 05, 2014 10:31 am

Ben6993 wrote:This is not a Bell simulation thread, but does a diffraction effect as above have any relevance to the Bell's simulations? The Bell's simulations use uniform randomness of an angle, or on a sphere, but not all the random data points become particle pairs. That seems like a diffractionless scenario. It will also be possible to generate non-uniform random data on a sphere. Ie a sort of diffraction pattern sampling. For example trying to simulate random points on a dimpled golf ball, where the points in the hollows are sampled less often than points on the raised parts. Maybe such a sampling would lead to fewer wasted data points. Or maybe not.

Hi Ben,
This experiment has very little if anything to do with Bell. I think it is a stretch to link the two and a recipe for endless confusions, not to talk of "loopholes". There is no "entanglement" here, and no spin involved.
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Re: The double slit experiment

Postby gill1109 » Mon May 05, 2014 5:32 pm

minkwe wrote:1) quanta/particles can transfer momentum to the walls if the slits.
2) The amount of momentum transferred, determines the angle of deflection of the particle.
3) Transfered momentum is quantized. Therefore the particles are deflected into discrete directions.
4) The allowed directions are determined by the relationship between the normal modes if the slit system and the frequency of the quanta/particle.
5) Since different slit systems have different normal modes, the diffraction patterns are different.
6) The pattern produced, and the slit system producing it have a dual relationship. They can be expressed as Fourier transforms of each other.

(5) says that a particle at the slit on the right feels if the slit on the left is open or closed. Reminds me of Bell-CHSH experiment loopholes.
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Re: The double slit experiment

Postby minkwe » Mon May 05, 2014 9:54 pm

gill1109 wrote:
minkwe wrote:5) Since different slit systems have different normal modes, the diffraction patterns are different.

(5) says that a particle at the slit on the right feels if the slit on the left is open or closed. Reminds me of Bell-CHSH experiment loopholes.

It is puzzling how anyone who understands English could reasonably infer such a thing from the statement given. Astounding indeed!
Last edited by minkwe on Mon May 05, 2014 11:02 pm, edited 1 time in total.
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Re: The double slit experiment

Postby gill1109 » Mon May 05, 2014 10:40 pm

minkwe wrote:
gill1109 wrote:
minkwe wrote:1) quanta/particles can transfer momentum to the walls if the slits.
2) The amount of momentum transferred, determines the angle of deflection of the particle.
3) Transfered momentum is quantized. Therefore the particles are deflected into discrete directions.
4) The allowed directions are determined by the relationship between the normal modes if the slit system and the frequency of the quanta/particle.
5) Since different slit systems have different normal modes, the diffraction patterns are different.
6) The pattern produced, and the slit system producing it have a dual relationship. They can be expressed as Fourier transforms of each other.

(5) says that a particle at the slit on the right feels if the slit on the left is open or closed. Reminds me of Bell-CHSH experiment loopholes.

Can you read?

http://www.sciphysicsforums.com/spfbb1/viewtopic.php?f=18&t=5
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Re: The double slit experiment

Postby FrediFizzx » Mon May 05, 2014 11:24 pm

minkwe wrote:
gill1109 wrote:
minkwe wrote:5) Since different slit systems have different normal modes, the diffraction patterns are different.

(5) says that a particle at the slit on the right feels if the slit on the left is open or closed. Reminds me of Bell-CHSH experiment loopholes.

It is puzzling how anyone who understands English could reasonably infer such a thing from the statement given. Astounding indeed!

Yes it is quite astounding but then Richard is not a physicist so I would think he is just making up stuff here.
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Re: The double slit experiment

Postby gill1109 » Tue May 06, 2014 5:42 am

FrediFizzx wrote:
minkwe wrote:
gill1109 wrote:Michel's (5): "Since different slit systems have different normal modes, the diffraction patterns are differen"
says that a particle at the slit on the right feels if the slit on the left is open or closed. Reminds me of Bell-CHSH experiment loopholes.

It is puzzling how anyone who understands English could reasonably infer such a thing from the statement given. Astounding indeed!

Yes it is quite astounding but then Richard is not a physicist so I would think he is just making up stuff here.

You could think that if you want to. The forum rules say:

Disclaimer: Some of what you read on this forum may not be the truth so use your own judgement.

This holds for all of us, and all of what we read on this forum. Use your own judgement. BTW I studied mathematics and physics at Cambridge University, UK. One of my teachers was Stephen Hawking. I'm an elected fellow of the IOP ... but no, I do not call myself a physicist.
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Re: The double slit experiment

Postby jreed » Tue May 06, 2014 6:26 am

minkwe wrote:
jreed wrote:Although you don't realize it, this is Lande's theory. Look him up on the web. If you do some research on this, you will find it has already been researched and investigated. He wrote many books on it but it never became a popular interpretation of quantum mechanical effects. You don't have to answer any questions for me. I have several of his books where these questions are explained with his theory. I read these books, but the same problems of understanding quantum mechanical effects occur in his theory, except in a different form. As someone told me once, that's conservation of trouble: You can move trouble around, but never get rid of it.

Rather than lump it up as Lande's why don't you ask specific questions that you have issues with the explanation so far. Or do you think you know exactly what I'm going to say? What is the trouble that you say is being moved around? I'm not familiar with Lande's theory but you appear to be so why don't you state what the problem is with Lande's theory.

I assumed you were genuinely interested in the explanation. Are you?


Back where we were a few days ago...
Thanks for those references. I'm familiar with Duane's theory as it's a cornerstone in Lande's theory, and all this is familiar from Lande's theory. I'm in agreement with your explanation of the diffraction of electrons. This is all part of Lande's theory. I've always thought his theory was interesting and needs to be more thoroughly investigated.

What I was referring to as "trouble" was moving the quantum weirdness from the electron to the slits. Previously the probability amplitude of the electron was spread out, based on its wave function, and the probability of arrival at the screen is computed by squaring the absolute value of this function. Now, the point electron is somehow interacting with the whole slit assembly. This requires a non-local interaction which goes against the realist assumptions. This was one of the complaints against Lande's explanation.
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Re: The double slit experiment

Postby gill1109 » Tue May 06, 2014 6:31 am

jreed wrote:What I was referring to as "trouble" was moving the quantum weirdness from the electron to the slits. Previously the probability amplitude of the electron was spread out, based on its wave function, and the probability of arrival at the screen is computed by squaring the absolute value of this function. Now, the point electron is somehow interacting with the whole slit assembly. This requires a non-local interaction which goes against the realist assumptions. This was one of the complaints against Lande's explanation.

Thank you Jim, that is exactly what I was pointing out. And then various "gentlemen" here started making snide remarks about non-physicists not being able to read, or something.

Michel's (5) was "Since different slit systems have different normal modes, the diffraction patterns are different". Which effectively says that a particle at the slit on the right can feel if the slit on the left is open or closed.

This reminded me of Bell-CHSH experiment loopholes. But then I am just a mathematician, or worse: merely a statistician. Never picked up a thing in my years studying physics at Cambridge (being taught by Stephen Hawking, among others).
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Re: The double slit experiment

Postby minkwe » Tue May 06, 2014 11:33 am

jreed wrote:Back where we were a few days ago...
Thanks for those references. I'm familiar with Duane's theory as it's a cornerstone in Lande's theory, and all this is familiar from Lande's theory. I'm in agreement with your explanation of the diffraction of electrons. This is all part of Lande's theory. I've always thought his theory was interesting and needs to be more thoroughly investigated.

What I was referring to as "trouble" was moving the quantum weirdness from the electron to the slits. Previously the probability amplitude of the electron was spread out, based on its wave function, and the probability of arrival at the screen is computed by squaring the absolute value of this function. Now, the point electron is somehow interacting with the whole slit assembly. This requires a non-local interaction which goes against the realist assumptions. This was one of the complaints against Lande's explanation.

Hi jreed,
This is why I wanted to start by dispelling the misconceptions. Very often, people confuse mathematical calculations with physics, a phenomenon which is very popular but actually garbage. Most of the "trouble" you are referring to has to do with misinterpretation of the mathematics. Just because you compute something one way doesn't mean your calculation is actually what is happening physically. For example, the idea that a "probability amplitude is spread out", does not mean an electron is spread out. It is this disconnect that is leading to "mysticism". Another example, is when people interpret the path-integral formalism as actually suggesting that particles take all possible paths, instead of simply looking at it as a method of calculation which gives us the correct end-result (same thing with constructive/destructive interference of wave theory).

Now you say the "trouble" in my explanation is that an electron, is somehow interacting with a whole slit assembly. Do you know what normal modes are (http://en.wikipedia.org/wiki/Normal_modes)? Have you ever heard or seen Newton's cradle (http://en.wikipedia.org/wiki/Newton's_cradle)? Look at the animation and tell me if the left most pendulum is interacting with the whole device or just the ball next to it. Is Newton's cradle mysterious to you? In fact, you don't even have to look far. When you press down a key on your keyboard, what is interacting? Is your whole finger interacting with the whole key, or are only the molecules which come into contact interacting with each other? Is your finger non-local/non-realist? Is Newton's cradle non-local/non-realist?

I don't see the "trouble" you are talking about.
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Re: The double slit experiment

Postby minkwe » Tue May 06, 2014 11:41 am

gill1109 wrote:Michel's (5) was "Since different slit systems have different normal modes, the diffraction patterns are different". Which effectively says that a particle at the slit on the right can feel if the slit on the left is open or closed.

Wrong. It does not "effectively" say anything close to what you say at all. Point (5) says absolutely nothing about particles. Let alone, particles having feelings. It says simply a well known and uncontroversial fact that double slits have different normal modes than single slits. But based on your penchant for mysticism, I'm not surprised you would interpret it that way, it reflects more your imagination than what was actually written. You could have asked for clarification if it wasn't clear to you. But no, you just had to introduce loopholes into something which has absolutely nothing to do with it.
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Re: The double slit experiment

Postby jreed » Tue May 06, 2014 4:24 pm

minkwe wrote:Now you say the "trouble" in my explanation is that an electron, is somehow interacting with a whole slit assembly. Do you know what normal modes are (http://en.wikipedia.org/wiki/Normal_modes)? Have you ever heard or seen Newton's cradle (http://en.wikipedia.org/wiki/Newton's_cradle)? Look at the animation and tell me if the left most pendulum is interacting with the whole device or just the ball next to it. Is Newton's cradle mysterious to you? In fact, you don't even have to look far. When you press down a key on your keyboard, what is interacting? Is your whole finger interacting with the whole key, or are only the molecules which come into contact interacting with each other? Is your finger non-local/non-realist? Is Newton's cradle non-local/non-realist?

I don't see the "trouble" you are talking about.


Here's the trouble. When you say normal modes are excited in the slit assembly, normal modes of what? Are you saying that a single electron can excite normal modes in a macroscopic object? Some possibilities are: Normal modes of motion, normal modes of the electromagnetic field (but we also see neutron diffraction), maybe normal modes of the aether, if you're still a non-believer in relativity. There aren't many other things to excite.
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Re: The double slit experiment

Postby minkwe » Tue May 06, 2014 5:04 pm

jreed wrote:Here's the trouble. When you say normal modes are excited in the slit assembly, normal modes of what? Are you saying that a single electron can excite normal modes in a macroscopic object?

Surely you can go back and read what I wrote and notice that I have not once suggested that "normal modes are excited by electrons". Please confirm that you misunderstood this, because I never said that.

Some possibilities are: Normal modes of motion, normal modes of the electromagnetic field (but we also see neutron diffraction), maybe normal modes of the aether, if you're still a non-believer in relativity. There aren't many other things to excite.

Again, I don't know were you got the idea of "excitation" in anything I said. Please read the link I gave about normal modes. Every physical object has normal modes and pay attention to what I'm actually saying as opposed to what you imagine I might be saying. You still haven't pointed to any "trouble" in my explanation. I genuinely want to explain the details and answer all your questions but you will have to read what I actually write.
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Re: The double slit experiment

Postby gill1109 » Tue May 06, 2014 10:37 pm

minkwe wrote:
gill1109 wrote:Michel's (5) was "Since different slit systems have different normal modes, the diffraction patterns are different". Which effectively says that a particle at the slit on the right can feel if the slit on the left is open or closed.

Wrong. It does not "effectively" say anything close to what you say at all. Point (5) says absolutely nothing about particles. Let alone, particles having feelings. It says simply a well known and uncontroversial fact that double slits have different normal modes than single slits. But based on your penchant for mysticism, I'm not surprised you would interpret it that way, it reflects more your imagination than what was actually written. You could have asked for clarification if it wasn't clear to you. But no, you just had to introduce loopholes into something which has absolutely nothing to do with it.

Maybe the problem is you have less imagination than me?
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