Single-Particle Interference for BIG objects-what does it mean for a lay person?

[OOO]

Certainly we can draw pictures, create machines (which is what this experiment is--a machine), and write computer simulations that mimic somebody's idea of what QM behavior is, whether right or wrong. However, we need to remember that such machines are contrived. By that, I mean we intentionally designed the machine to partly mimic some conception we have about QM, whether it is right or wrong. I believe these experimenters realized this, as we see in their disclaimer near the end of the paper. Once the machine is built and works, we should be careful not to presume it can teach us something. The same could be said for a computer program. If I write a program (create an experiment, design a machine) that demonstrate my interpretation of QM, then I can't point to the program and say, "See, I was right! --and look what else it reveals!". I'm not saying it never will--I'm just saying we have to remember it was contrived to accomplish some purpose.

This is a very good point. The experiment can certainly not teach us new physics. The interesting thing about it is, that it is at all possible to contrive such a relatively complicated and nonlinear system to behave in some respect like a quantum system. This leads one to think that there probably could be some hidden (and presumably rather simple) math behind it, that shows us how quantum field theory could be reformulated (regardless whether it has something to do with Bohm or not) to make way for new physics without sacrificing QFT's tremendously accurate predictions. That's the reason why I was asking primarily for the math.

 

[OOO]

However, the paper explains the model rather clearly, but without the equations.
The main point is the transfer of momentum from the wave to the particle that is linked to the slope of the surface where the particle hits it.
What is missing is an explanation of the the wave generated at that moment.

Another point which is not clear for me is how the damping is compensated by the excitation.

Did you understand what role the "Faraday instability" plays in the experiment ? Does it help only in enabling the droplet to jump up and down indefinitely or does it also take part in the generation of the waves or the so-called "walkers" ?

As to the "main point": I think one of the main points is that the waves emitted from the droplet interact with it at some later time. I don't understand how this should work (apart from reflection at the boundaries, which is trivial). Is the droplet faster, is the wave faster ?

 

[mn4j]

I believe you. Only I'm not willing to read something from someone who writes loads of BS, even if he were right in this special case. Apart from the mathematical details I think you could also dream "explanations" for it by looking up into the clouds. I'd consider this accidental knowledge.

Any open minded physicist will take Mills more seriously, when an experiment appears to validate his theory, even if he were a liar and a fraud, which is hardly the case with Mills. Mills explanation of electron diffraction predates this experiment.

I Chapter 8 of his book (Page 341), Mills says the following:

In the case of photon diffraction, the far field interference pattern given by Eqs. (8.22-
8.23) is due to conservation of angular momentum of the photon interaction with the slits. The
pattern is not due to constructive and destructive inference of photon electric fields. Photons can
not be created or destroyed by superimposing. If this were true, it would be possible to cool a
room or to cloak an object by illumination. Constructive and destructive interference violates the
first and second laws of thermodynamics1. The correct physics is based on conservation of the photon angular momentum and photon energy.
The incident photons have a size compare to their wavelength as given in the Equation of
the Photon section. A diffraction pattern is observed when the slit dimensions are comparable to
the photon wavelength. The physical basis of the mechanism is that each photon interacts with
the slit apparatus to give rise to an electron or polarization current. Each photon is reemitted,
and the regions of high and low intensity due to more or less photons impinging at locations of
the detector are generated as the number of photons diffracted become large. The pattern is based
on conservation of the momentum of the slit-source currents and re-emitted photon distribution.
Here, in the case of each incident and diffracted photon, the transverse displacement is related to
the change in the transverse component of the angular momentum of the photon. The
corresponding pattern is representative of the aggregate momentum distribution of slit-apparatus
current induced by many photon interactions. The same physics of momentum conservation in
the electric and magnetic radiation fields determines the radiation pattern of a multipole source as
given in the Excited States of the One-Electron Atom (Quantization) section.

You can not simply write it off as BS. This experiment directly illustrates something very similar to what Mills is talking about. In the article the authors suggest that to their knowledge no known theory exists to explain what they observed. Mills theory appears to explain just that, but they were not aware of it. Methinks you should take Mills more seriously than you do. The guy is not stupid.

 

[OOO]

Any open minded physicist will take Mills more seriously, when an experiment appears to validate his theory, even if he were a liar and a fraud, which is hardly the case with Mills. Mills explanation of electron diffraction predates this experiment.

I Chapter 8 of his book (Page 341), Mills says the following:


You can not simply write it off as BS. This experiment directly illustrates something very similar to what Mills is talking about. In the article the authors suggest that to their knowledge no known theory exists to explain what they observed. Mills theory appears to explain just that, but they were not aware of it. Methinks you should take Mills more seriously than you do. The guy is not stupid.

You're citing this as if it was the Holy Bible. I've had the questionable chance to take a look at his book as well and to be honest, I haven't read more than about 5 pages in it when it became clear to me that something's not quite right with this guy. Then I skimmed through the rest of this book and this further confirmed my suspicion. I admit that this kind of judgement is superficial but I'm doing my own probabilistic inference on this.

Someone who likes to write out every formula in ugly detail, especially the trivial undergraduate type stuff, is suspicious. Likewise I don't fall for someone who seems to pretend that he has remedied all of the world's problems at once. Not to mention all those people around him that mutually cite one another. And we don't have to mention his money-making here, I'm not jealous of someone who makes money from dirt, but his self-confidence is in glaring disproportion with his scientific successes.

We always have to be aware of the fact that all of this world's most intractable misbeliefs are put forward by people who have invested too much of their lives into questionable concepts and when they notice, it's too late. It's easier to keep believing than to acknowledge one's own ignorance. If you wish you may apply this to all of us, it's a psychological invariant.

 

[lalbatros]

Did you understand what role the "Faraday instability" plays in the experiment ? Does it help only in enabling the droplet to jump up and down indefinitely or does it also take part in the generation of the waves or the so-called "walkers" ?

I did not understand it in the detail.
I just understood that the "Faraday instability" occurs when there is a tendency to grow droplets spontaneously when the excitation is high enough.
We can guess that below the instability but close enough a single droplet will have a long lifetime,
and conversly far below the instability (like without excitation) any droplet with have a very short lifetime.
The role of the instability is related to the level of the excitation that ensure the necessary condition for the experiment.

As to the "main point": I think one of the main points is that the waves emitted from the droplet interact with it at some later time. I don't understand how this should work (apart from reflection at the boundaries, which is trivial). Is the droplet faster, is the wave faster ?

This is indeed the most interresting aspect that we should investiggate in detail.
You remark about which is faster is excellent.
Clearly the wave can go faster than the droplet: like when the droplet stays in place.
Could the droplet sometime go faster than the wave: it is not clear for me, it depend on how the droplet bounces on the wave.

 

[rewebster]

I wonder if they tested for 'charge' on the oil drops?

http://en.wikipedia.org/wiki/Oil-drop_experiment

 

[lalbatros]

Just to say that the model equation shown under reference 10 of the paper explains rather completely what happens.

 

[OOO]

Just to say that the model equation shown under reference 10 of the paper explains rather completely what happens.

Hmm, there seems to be a typo in this equation. They speak of two terms on the RHS whereas there is a second 'equals'. So I guess the second '=' should be a '-' because the second term is described as viscous damping.

 

[lalbatros]

Hmm, there seems to be a typo in this equation. They speak of two terms on the RHS whereas there is a second 'equals'. So I guess the second '=' should be a '-' because the second term is described as viscous damping.

yes ;)

 

[Anonym]

This is a beautiful experiment. Probably the most beautiful I've seen on the subject of interference patterns. I'm still reading it and it very well may be key to understanding what REALLY happens when photons, electrons, etc pass through slits, as opposed to "wavefunction collapse" hoopla. One thing to note as you read is the difference between the waves being discussed. Particularly:
- The droplet is always a particle
- It interacts with it's environment through the wave-like disturbance
- It's interaction with it's environment determines it's trajectory
- It's path through the slit determines where it ends up on the detector
- Not all paths have the same probability, with the probabilities matching the classical single slit diffraction pattern.
- knowing the path of the particle does not in any way affect the result!
- The particles are localized throughout the experiment

The results of this paper are frightfully close to Randell Mills' explanation of the double slit experiment in his CQM theory.

I think you are going too far. Probably, it is the consequence that you are allergic to the cats. Another thing to note as you read is the difference between the waves being discussed: it is the classical physics (see post #20). Therefore, it has nothing to do with photons and may provide the complementary understanding of the situation, but not “what REALLY happens when photons, electrons, etc pass through slits, as opposed to "wavefunction collapse" hoopla”.

I would be happy listen to the confirmation and the additional information from the alternative lab.

Regards, Dany.

P.S. I am not familiar with Randell Mills' writings but, again, the quoted page use notion of the photon. I guess the writer is not familiar with A.Einstein analysis Phys.Zeit. 10, 185, (1909).

 

[lalbatros]

The "wavefunction collapse hoopla” is just an easy axiomatic shortcut.
It is actually an interaction process.
But the detailled analysis of this process is not necessarily useful for the overall understanding and it is certainly very complicated.
Just as it is meaningless to explain the human behaviour from atomic physics, it is also meaningless to explain the "hoopla" from detailled interactions. (but it has a meaning for the scientific principles and should studied and understood for itself)

 

[Anonym]

The "wavefunction collapse hoopla” is just an easy axiomatic shortcut.
It is actually an interaction process.
But the detailled analysis of this process is not necessarily useful for the overall understanding and it is certainly very complicated.
Just as it is meaningless to explain the human behaviour from atomic physics, it is also meaningless to explain the "hoopla" from detailled interactions. (but it has a meaning for the scientific principles and should studied and understood for itself)

Do you understand what you wrote? I am certainly not. And we certainly understand the spontaneous phase transitions. In addition, my dictionary says hoop-la: noise (e), balagan (h), tararam (r).

Regards, Dany.

 

[rewebster]

Do you understand what you wrote? I am certainly not. And we certainly understand the spontaneous phase transitions. In addition, my dictionary says hoop-la: noise (e), balagan (h), tararam (r).

Regards, Dany.

(those two words don't come up in a physics conversation very often--hmmm)

 

[lalbatros]

Do you understand what you wrote? I am certainly not. And we certainly understand the spontaneous phase transitions. In addition, my dictionary says hoop-la: noise (e), balagan (h), tararam (r).

Regards, Dany.

I was just quoting you.
Here is the original sentense:

Therefore, it has nothing to do with photons and may provide the complementary understanding of the situation, but not “what REALLY happens when photons, electrons, etc pass through slits, as opposed to "wavefunction collapse" hoopla”.

What did you mean?

I understood the "hoopla" as a synonym for "magic trick".
In french, this word could be used by a magician.
In physics I think indeed that the wf collapse is a shortcut to avoid useless complications, therefore it is -for me- similar to a trick.
But a useful trick.
The rest of my prose was a digression about reductionism in science.

Btw, I don't see the link with phase transitions ...

 

[Anonym]

I was just quoting you.
Here is the original sentense:

You are not quoting me. You are quoting my quotation of mn4j. Read his post #23, I consider he express himself clearly and that consistent with my dictionary translations to English/Hebrew/Russian.

In physics I think indeed that the wf collapse is a shortcut to avoid useless complications, therefore it is -for me- similar to a trick.
But a useful trick.

The wave packet collapse is not a trick; it is universally valid experimental fact that must be explained by the physical theory. Again I prefer to quote mn4j:” There exists a physical reality which underlies all scientific inquiry, without which science is meaningless.”

The rest of my prose was a digression about reductionism in science.

I don’t agree with you. I consider that we are pretty close to start investigation of the human brain using understanding of the quantum physics.

I don't see the link with phase transitions

We know the collapse is instant and discontinuous, so what else it may be?

Regards, Dany.

 

[lalbatros]

You are not quoting me. You are quoting my quotation of mn4j. Read his post #23, I consider he express himself clearly and that consistent with my dictionary translations to English/Hebrew/Russian.

Sorry, I focused on a thread within the thread!

The wave packet collapse is not a trick; it is universally valid experimental fact that must be explained by the physical theory. Again I prefer to quote mn4j:” There exists a physical reality which underlies all scientific inquiry, without which science is meaningless.”

This is of course subject to discussion.
I also agree that it is experimentally validated.
But experience does not contradict the hypothesis that the collapse is the result of an interaction with the usual laws of physics. This is actually the point of view developped by Landau & Lifchitz in the introductory chapter 7 of "Quantum mechanics".
I really do think that the "measurement postulate" is a useful intellectual shortcut that avoid long and useless development. By useless I mean that they are generally useless, but of course they are not useless if the fundamentals of QM are under study.
A physician does not need genetics to treat a flu and similarly there is -usually- no need to go further than the "measurement postulate" for example when interpreting lab mesurements.

I don’t agree with you. I consider that we are pretty close to start investigation of the human brain using understanding of the quantum physics.

Here we really disagree.
Quantum physics will never be of any utility to understand the human brain.
Of course, QP explains chemistry -in principle-, and in this sense QM is needed just as it is needed for any physics as soon as the quantum level is involved.
I don't know exactly what you meant by "using QP to understand the brain".
If you were thinking to the measurement postulate, then you are back on old-fashion misconception, that can be traced back to the hippie movement.
If you are thinking to a reductionist approach to the understanding of the brain, then I think it is a loss of time. But science is a risky activity ...

We know the collapse is instant and discontinuous, so what else it may be?

Here there must be a misunderstanding with vocabulary.
"Phase transition" refers to a precise concept in thermodynamics and statistical physics.
But "phase transition" doesn't specifically mean something in QP.

I hope this sets us back on track,

L

 

[fleem]

"Describing" a certain behavior of the universe involves citing the tools needed to be able to predict the directly measurable parameters of the outcome of experiments involving that behavior.

"Explaining" a behavior of the universe involves showing how that behavior is a result of certain simpler behavior(s) of the universe. It is reductionism.

"Understanding" a behavior of the universe is an ambiguous term that can sometimes mean "knowing the description" and other times mean "knowing the explanation".

QM explains classical mechanics. It also happens to reveal that classical mechanics is not correct--QM is more precise, and profoundly so in experiments involving very low energy levels. It is highly doubtful we will find that classical mechanics can explain QM!

When a person truly understands the description of, for example, the double slit experiment, then that person will see that QM is simply not compatible with classical mechanics. This is because QM is not compatible with certain axioms of Newtonian mechanics, like those having to do with conservation of energy (one way to look at QM is that it allows violations of conservation of energy while the experiment has not yet been observed) and/or those axioms having to do with causality working only in absolute and continuous time and space. It is unfortunate that popularized "descriptions" of the double-slit experiment, and others, as well as popularized "descriptions" of special relativity experiments like the twin paradox, are actually mere Newtonian shadows of the experiments that clearly show that incompatibility. It is no wonder there are so many people that do not realize that QM and SR are simply incompatible with Newtonian mechanics. It leads to many people trying to explain QM (and SR) with Newtonian terms. That's like trying to explain the workings of the human spleen in terms of sociology--one is more fundamental than the other (society is based upon people, which are each based upon their organs), and you can't use the other to explain the one.

We have the description of QM but not the explanation. Terms like superposition, wavefunction collapse, multiple universes, Copenhagen interpretation, hidden variables are most certainly not explanations. Each is either just a word without meaning, a word that means "don't try to explain", or an explanation of only a small part of QM.

Now I'd like to introduce you all to what I believe may be the beginnings of an explanation of superposition and non-locality. I do ask that the reader hesitate to criticize until he is familiar with why superposition and non-locality are totally incompatible with classical mechanics. Here is the explanation:

The laws of physics must be obeyed in all inertial reference frames. In fact, the laws of physics must be obeyed in an inertial reference frame whether there happens to be an observer in a reference frame, or not. Therefore the laws of physics are always obeyed in all inertial reference frames all the time.

This includes reference frames traveling at c. In an inertial reference frame traveling at c, the entire universe is flattened perpendicular to the direction of travel, and an observer in that frame measures zero time to travel from the point of departure to the point of arrival--because the distance between those points is zero.

Now imagine a reference frame traveling at c from one atom to another atom. In that reference frame, the two atoms occupy the same point in space. Note that the two atoms also are superimposed in a reference frame traveling at c from the destination to the source.

Now imagine that an electron orbital on one of those atoms is excited, and thus there is an opportunity for energy to be transferred to an orbital in the other atom. Since there is no distance between the two atoms in these various reference frames traveling at c, this transfer of energy takes zero time, and therefore is not subject to causality.

There are, however, restrictions on how the energy can be transferred. For one thing, the exclusion principle applies. For another, the phase of the orbitals must be right to allow the energy to transfer (just as the phase in a radio transmitting antenna and a radio receiving antenna must be right to allow a radio photon to be transferred).

Now remember that the laws of physics must be obeyed in all reference frames that we can find that travel from the source to the destination as well as those reference frames that travel from the destination back to the source. So energy will travel only when the phase of the two orbitals is correct in all of those reference frames. An analysis reveals that the energy will transfer according to basic wave mechanics, but without causality (because there is no time in these reference frames traveling at c).

 

[Anonym]

Dear people...thanks for all your replies..but did you forget that I am a layperson.

You forget that you ask to explain the content of the paper published in PRL, October 2006. It is the frontier of the modern physics.

Sorry, I focused on a thread within the thread!

The OP asks about http://www.physorg.com/news78650511.html. The paper has nothing to do with QM, collapse, theory of measurements, human brain, etc.

The paper claim the experimental demonstration the wave mechanical behavior of the physical system described by the Newtonian mechanics only, no fields relevant (EM and/or gravitation). Apparently, it is outstanding achievement; therefore, first of all, it should be verified and confirmed.

Regards, Dany.

 

[lalbatros]

Anonym,

I don't see why you mention the brain in this context.
I used the brain myself just to illustrate that reductionism can be useless, a fact that is generally accepted, specially by engineers (I am one).
The comparison with the quantum measurement postulate is obvious: it is in principle possible to reduce the QM measurement postulate to the solution of the evolution equation including the interaction with the measurement device. But this would not provide any insight in the interpretation of anything practical except the foundations of QM.

For the rest, I do think this paper is somewhat related to the theory of measurement.
In this model system, particles are droplets and wave functions are capillary waves, and measuring particles can reveal statistically an interference pattern of the waves. The correspondence between QM and this model is clear ... and it is interresting to see what the limits of this correspondence are. That's why I pushed the question about entanglement.

I also think the experimental verification is useless.
Firstly because it makes little doubt it will be verified without much problems.
Secondly because what happens is pretty much easy to understand and even to modelize.
And third because the particular realisation in of little importance.
What really matters is that a set of deterministic equations (droplet+waves motion and interaction) can lead to a behaviour more or less similar to the observations in QM.
Therefore, it is more important to understand this system and other similar systems theoretically and to identifiy clearly the eventual limitations of the comparison with QM.

 

[Anonym]

Anonym,I don't see why you mention the brain in this context.
I used the brain myself just to illustrate that reductionism can be useless, a fact that is generally accepted, specially by engineers (I am one).

That means that there is no way I can communicate with you. See my post #157 in “cat in a box paradox” session. Even worse, for me using Zz metaphor you are sitting on a cow on Alpha Centauri.

I don’t understand you. Imagine outsider that volunteer to perform your everyday professional work and think how he looks in your eyes. In addition, the foundations of physics are generally considered the most difficult area of the scientific research. If you are an engineer, be practical. Sell your absurd ideas to Hollywood.

Regards, Dany.

 

[lalbatros]

Ok Anonym, as I can see you are more interrested in sociology than in physics.

 

[Viva-Diva]

You forget that you ask to explain the content of the paper published in PRL, October 2006. It is the frontier of the modern physics.
.

Wow that makes me happy as I fished out that paper even though I am not a science person. Did you know about this paper already before?

 

[OOO]

Ok Anonym, as I can see you are more interrested in sociology than in physics.

Don't worry, our beloved friend likes to pretend that he's some sort of bhuddistic monk or something. But mumbling incoherently is not the same as knowing.

 

[Anonym]

Wow that makes me happy as I fished out that paper even though I am not a science person. Did you know about this paper already before?

No. Thank you. I consider the paper masterpiece. If it is correct, it is Nobel Prize level.

Regards, Dany.

 

[Viva-Diva]

Wow! I feel so happy!

(But then if it is on Nobel Prize value...why weren't you aware of it? Being a scientist, don't you keep track of latest litrature? )

 

[Anonym]

why weren't you aware of it? Being a scientist, don't you keep track of latest litrature?

I try. My research interests now in the relativistic QM and the measurement theory (information). I missed it. A posteriori it is obvious that we should look on fluids first of all. They describe also something totally unexpected and I should return to study hydrodynamics. However, it is better late than never.

Regards, Dany.

 

[lalbatros]

I try. My research interests now in the relativistic QM and the measurement theory (information). I missed it. A posteriori it is obvious that we should look on fluids first of all. They describe also something totally unexpected and I should return to study hydrodynamics. However, it is better late than never.

I generally advise people to go back to the basics, and I apply that to myself too.
Practically this means for me a collection of reference books.
I specially like the Landau & Lifchitz series that I read several time in detail during my engineering hobby time.
Other books are Jackson, gravitation by MTW, Weinberg, ...

Twenty years ago I read the collection of papers in "Quantum theory and Measurement" edited by Wheeler.
I wonder how much this subject has evolved since then on the theoretical side.
The experimental side has confirmed QM in more and more details.

Great problems need great people or time ... unless one just understand there is no problem at all.
(Landau QM chap 7)

 

[Anonym]

I specially like the Landau & Lifchitz series that I read several time in detail during my engineering hobby time.Other books are Jackson, gravitation by MTW, Weinberg, ...
Twenty years ago I read the collection of papers in "Quantum theory and Measurement" edited by Wheeler.

I remember, you already told me that few months ago.

This is actually the point of view developped by Landau & Lifchitz in the introductory chapter 7 of "Quantum mechanics".

Par.7. L.D. presented John von Neumann theory of measurements (on fingers as he usually liked to do). Eq. (7.1) is the original J. v. Neumann assumption and it is wrong. L.D. ignored that J. v. Neumann used the standard math method Reductio ad absurdum. It was further discussed in details by F.London and E.Bauer, W&Z, p.217.

By the way, L.D. didn’t write hydrodynamics. His student V.G. Levich wrote it. That book I should read again.

Regards, Dany.

 

[LinJieFu]

Can anyone help me with this? If so, please do. If you have a paper or text to point me to, that would be great. Here goes: When a double slit experiment with respect to single particle interference is conducted, and only one particle is emitted for the entire event, what is the observed result that suggests that a single particle has interfered with itself?

 

[DrChinese]

Can anyone help me with this? If so, please do. If you have a paper or text to point me to, that would be great. Here goes: When a double slit experiment with respect to single particle interference is conducted, and only one particle is emitted for the entire event, what is the observed result that suggests that a single particle has interfered with itself?

Welcome to PhysicsForums, LinJieFu!

Generally, you cannot conclude there is self-interference from a single observation. There will be a dispersion pattern over a sufficiently large number of events which indicates this result.