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Author Topic: What do you think of pilot-wave view of quantum mechanics?  (Read 3936 times)

Offline McKay

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I found an article talking a bout a different view on quantum mechanics: http://www.wired.com/2014/06/the-new-quantum-reality
I was thinking about the universe as a kind of super-fluid for some time now, even posted some thoughts, questions in this forum. Too bad people dont really want to try a different view on quantum mechanics. Why is that? Aren't scientist supposed to be truth seekers and put aside any personal bias?

[MOD EDIT- please phrase subjects as questions in line with AUP]
« Last Edit: 10/07/2014 09:48:25 by Georgia »


 

Offline David Cooper

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #1 on: 04/07/2014 19:48:48 »
"Sheldon Goldstein, a professor of mathematics, physics and philosophy at Rutgers University and a supporter of pilot-wave theory, blames the ďpreposterousĒ neglect of the theory on ďdecades of indoctrination.Ē At this stage, Goldstein and several others noted, researchers risk their careers by questioning quantum orthodoxy."

This is how things work in every field. An army of trained enforcers dominate everywhere, pushing the orthodoxy as if it is fact and discouraging anyone from discussing alternative theories which are still compatible with the known facts. Fortunately, AGI systems will soon be able to analyse everything with complete impartiality and with perfect reasoning, at which point we will see some leading theories pushed down below their superior and much ridiculed rivals. Until then, it's just a matter of being patient.
 

Offline PmbPhy

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #2 on: 05/07/2014 12:38:30 »
Quote from: McKay
I found an article talking a bout a different view on quantum mechanics: http://www.wired.com/2014/06/the-new-quantum-reality
Did you read it and then search the web to find other sources of pilot waves and then pick up a book that discusses pilot waves? If so then your next task is to pick up a book on hidden variable theory and perhaps even a book or two by Bohm explaining his work in this area. Then you can say you have a good enough background knowledge to take an educated guess as to why people donít bother with it.

Quote from: McKay
I was thinking about the universe as a kind of super-fluid for some time now, even posted some thoughts, questions in this forum.
Why? What are the properties of such a fluid? Did you hypothesize this to account for a description of pilot waves?

Quote from: McKay
Too bad people dont really want to try a different view on quantum mechanics.
Hold on, please. Where did you get that idea from? In my experience itís certainly not true. The reason there are few (not absolutely zero) people who look into this is because experiments have shown that they donít exist.

In 1964 a physicist by the name of John Bell showed the physics community that it makes an observable difference whether a particle actually has a precise (although unknown) position prior to measurement or not. Bellís discovery made eliminated the view that a particle has a position prior to its position being measured. That effectively meant that there are no hidden variables. And the pilot wave theory is a hidden variable theory. Still there are those who keep trying and studying. So youíre quite mistaken when you assert/imply that nobody tries different views on quantum mechanics. However the reason few people do is because itís already been established that the orthodox view is the right one. This is only the written equivalent of ďa sound biteĒ on the topic. You canít expect a complete answer to such a question by reading such a ďsound biteĒ. Depending on your level of expertise you should pick up a book on the subject.

Quote from: McKay
Why is that?
Because you were mistaken in your assumption that we donít try different views on quantum mechanics. But after 30 to 40 years of thinking about the subject and the entire physics community gets nowhere and all observation is consistent with theory then thatís what we expect to happen when we have the right theory. So how would you expect to know when we have the physics right? When you believe that you have the physics right how would you approach looking for the errors in it when everything you could think of for the last several decades failed as it has for the rest of the physic community?

Aren't scientist supposed to be truth seekers and put aside any personal bias?
[/quote]
We sure are.
 

Offline JP

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #3 on: 08/07/2014 02:53:48 »
Though I disagree that pilot wave theory is revolutionary (most physicists know of it and believe that it is in agreement with the mathematics of quantum mechanics), it is not in violation of Bell's inequalities.  In fact, it appears to be in complete agreement with mathematics and experimental tests of quantum mechanics, but is also indistinguishible based on current experiment from the more standard Copenhagen interpretation.  Though these water drop experiments are cool, they're also really overhyped.  It's not some revolution in physics going on here--it's a neat classical analogy to a well known theory.  But there's nothing special about this--optical physicists have used ray models which are analogous to the pilot wave theory for decades.

In addition, it introduces the idea of a pilot wave in which particles interact non-locally with each other.  This is the inherent problem with interpretations of quantum mechanics: experimental results confirm that it is weird and counterintuitive, so no matter what interpretation you apply to explain those experiments, it will have counterintuitive features.  More here:

https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Bohm_interpretation.html
 

Offline PmbPhy

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #4 on: 08/07/2014 16:17:58 »
Thanks JP. Since that is contrary to what I know about pilot-waves I'd like to learn more about what you just said. Can you refer me to a text which will educate me on what you just elaborated? Thanks.
 

Offline jeffreyH

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #5 on: 08/07/2014 20:33:02 »
Though I disagree that pilot wave theory is revolutionary (most physicists know of it and believe that it is in agreement with the mathematics of quantum mechanics), it is not in violation of Bell's inequalities.  In fact, it appears to be in complete agreement with mathematics and experimental tests of quantum mechanics, but is also indistinguishible based on current experiment from the more standard Copenhagen interpretation.  Though these water drop experiments are cool, they're also really overhyped.  It's not some revolution in physics going on here--it's a neat classical analogy to a well known theory.  But there's nothing special about this--optical physicists have used ray models which are analogous to the pilot wave theory for decades.

In addition, it introduces the idea of a pilot wave in which particles interact non-locally with each other.  This is the inherent problem with interpretations of quantum mechanics: experimental results confirm that it is weird and counterintuitive, so no matter what interpretation you apply to explain those experiments, it will have counterintuitive features.  More here:

https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Bohm_interpretation.html

I thought the whole point about pilot wave theory was that it was deterministic. It takes out the uncertainty in interactions. Isn't that a big deal? Wasn't that deBroglie's point?
« Last Edit: 08/07/2014 20:35:28 by jeffreyH »
 

Offline jeffreyH

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #6 on: 08/07/2014 21:06:17 »
Interestingly, looking into hidden variable theory and Bell's Theorem led me to this.

http://en.wikipedia.org/wiki/No-go_theorem
"The WeinbergĖWitten theorem states that massless particles (either composite or elementary) with spin j > 1/2 cannot carry a Lorentz-covariant current, while massless particles with spin j > 1 cannot carry a Lorentz-covariant stress-energy. The theorem is usually interpreted to mean that the graviton (j = 2) cannot be a composite particle in a relativistic quantum field theory."

This is fascinating. I think exactly the opposite is true.
 

Offline jeffreyH

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #7 on: 08/07/2014 22:02:47 »
Quote from: McKay
I found an article talking a bout a different view on quantum mechanics: http://www.wired.com/2014/06/the-new-quantum-reality
Did you read it and then search the web to find other sources of pilot waves and then pick up a book that discusses pilot waves? If so then your next task is to pick up a book on hidden variable theory and perhaps even a book or two by Bohm explaining his work in this area. Then you can say you have a good enough background knowledge to take an educated guess as to why people donít bother with it.

Quote from: McKay
I was thinking about the universe as a kind of super-fluid for some time now, even posted some thoughts, questions in this forum.
Why? What are the properties of such a fluid? Did you hypothesize this to account for a description of pilot waves?

Quote from: McKay
Too bad people dont really want to try a different view on quantum mechanics.
Hold on, please. Where did you get that idea from? In my experience itís certainly not true. The reason there are few (not absolutely zero) people who look into this is because experiments have shown that they donít exist.

In 1964 a physicist by the name of John Bell showed the physics community that it makes an observable difference whether a particle actually has a precise (although unknown) position prior to measurement or not. Bellís discovery made eliminated the view that a particle has a position prior to its position being measured. That effectively meant that there are no hidden variables. And the pilot wave theory is a hidden variable theory. Still there are those who keep trying and studying. So youíre quite mistaken when you assert/imply that nobody tries different views on quantum mechanics. However the reason few people do is because itís already been established that the orthodox view is the right one. This is only the written equivalent of ďa sound biteĒ on the topic. You canít expect a complete answer to such a question by reading such a ďsound biteĒ. Depending on your level of expertise you should pick up a book on the subject.

Quote from: McKay
Why is that?
Because you were mistaken in your assumption that we donít try different views on quantum mechanics. But after 30 to 40 years of thinking about the subject and the entire physics community gets nowhere and all observation is consistent with theory then thatís what we expect to happen when we have the right theory. So how would you expect to know when we have the physics right? When you believe that you have the physics right how would you approach looking for the errors in it when everything you could think of for the last several decades failed as it has for the rest of the physic community?

Quote from: McKay
Aren't scientist supposed to be truth seekers and put aside any personal bias?
We sure are.

Actually Bell's Theorem states that there are no LOCAL hidden variables. While I really like the uncertainty in quantum mechanics and would like it to be true I think ultimately determinism will win in some shape or form.
« Last Edit: 08/07/2014 22:22:16 by jeffreyH »
 

Offline PmbPhy

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #8 on: 09/07/2014 13:48:56 »
Quote from: jeffreyH
Actually Bell's Theorem states that there are no LOCAL hidden variables.
Yeah. I know. I'm just tired of putting in the "Local" all the time.

You do understand what a local hidden variable is, don't you? A local hidden variable theory is a hidden variable theory in which distant events are assumed to have no instantaneous (or at least faster-than-light) effect on local events.

What do you think it means for a non-local hidden variable theory to be consistent with quantum mechanics?
 

Offline JP

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #9 on: 09/07/2014 15:23:58 »
Quote from: jeffreyH
Actually Bell's Theorem states that there are no LOCAL hidden variables.
Yeah. I know. I'm just tired of putting in the "Local" all the time.

You do understand what a local hidden variable is, don't you? A local hidden variable theory is a hidden variable theory in which distant events are assumed to have no instantaneous (or at least faster-than-light) effect on local events.

That's the key to why the pilot wave interpretation does work to describe quantum mechanics.  Particles have hidden variables, but there are non-local interactions.  This is the cost of the model.  In a hand-waving way, what Bell's theorem says is that all models will have to have built in weirdness--simplistic, local, hidden variables models don't match observation.

I'll try to find you a reference for Bohmian mechanics.  The ones I've used in the past when learning the subject are Bohm's original papers. 
http://adsabs.harvard.edu/abs/1952PhRv...85..166B
http://adsabs.harvard.edu/abs/1952PhRv...85..180B

This one seems to be a decent semi-layperson description: http://philsci-archive.pitt.edu/3026/1/bohm.pdf  I haven't read it in detail, but the mathematics is right.

You'll have to dig up the articles yourself as they're behind a paywall, but there's lots of places hosting them on the web.

A lot of what I've seen online is needlessly opaque in its notation.  One easy way of thinking about it is that Schrodinger's equation describes physics by assigning a complex-valued wavefunction to the particle.  Any complex valued function can be fully described by two real-valued numbers: amplitude and phase.  It turns out that you break Schrodinger's equation into two purely real-valued equations in terms of amplitude and phase.  These equations describe how particle trajectories evolve in time.  The cost is that these equations are nonlinear and the trajectories interact with each other in a non-local way. 
 

Offline jeffreyH

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #10 on: 09/07/2014 18:25:23 »
Quote from: jeffreyH
Actually Bell's Theorem states that there are no LOCAL hidden variables.
Yeah. I know. I'm just tired of putting in the "Local" all the time.

You do understand what a local hidden variable is, don't you? A local hidden variable theory is a hidden variable theory in which distant events are assumed to have no instantaneous (or at least faster-than-light) effect on local events.

What do you think it means for a non-local hidden variable theory to be consistent with quantum mechanics?

What it doesn't necessarily mean is superluminal communication. If that is the point you are driving at. It does have other very weird properties such as everything depends upon the state of everything else but that is just chaos theory writ large and we have no trouble accepting chaos theory.
 

Offline PmbPhy

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #11 on: 10/07/2014 05:05:06 »
Quote from: jeffreyH
What it doesn't necessarily mean is superluminal communication. If that is the point you are driving at. It does have other very weird properties such as everything depends upon the state of everything else but that is just chaos theory writ large and we have no trouble accepting chaos theory.
No. That's not my point. Local hidden variable theory is a hidden variable theory in which distant events are assumed to have no instantaneous (or at least faster-than-light) effect on local events. While a hidden variable theory can exist in which distant events have a delayed effect on local events the experiments of Aspect and others were set up precisely to exclude such cases.

Suppose there were such a thing as a pilot wave and pilot waves guided electrons around the nucleus of the atom. If that's true then electrons would have a classical trajectory and as such they'd radiate energy as they acccelerated. Since that's not observed then that cannot be the case.
 

Offline jeffreyH

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Re: Pilot-wave view of quantum mechanics - some research
« Reply #12 on: 10/07/2014 17:51:04 »
Quote from: jeffreyH
What it doesn't necessarily mean is superluminal communication. If that is the point you are driving at. It does have other very weird properties such as everything depends upon the state of everything else but that is just chaos theory writ large and we have no trouble accepting chaos theory.
No. That's not my point. Local hidden variable theory is a hidden variable theory in which distant events are assumed to have no instantaneous (or at least faster-than-light) effect on local events. While a hidden variable theory can exist in which distant events have a delayed effect on local events the experiments of Aspect and others were set up precisely to exclude such cases.

Suppose there were such a thing as a pilot wave and pilot waves guided electrons around the nucleus of the atom. If that's true then electrons would have a classical trajectory and as such they'd radiate energy as they acccelerated. Since that's not observed then that cannot be the case.

That's a valid point. I'll have to think about that.
 

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Re: Pilot-wave view of quantum mechanics - some research
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