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Offline mpc755

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Experimental evidence of pilot-wave theory
« on: 03/06/2011 12:02:46 »
"New 'Double Slit' Experiment Skirts Uncertainty Principle"
http://www.scientificamerican.com/article.cfm?id=new-double-slit-experiment-skirts-uncertainty-principle [nofollow]

"Intriguingly, the trajectories closely match those predicted by an unconventional interpretation of quantum mechanics known as pilot-wave theory, in which each particle has a well-defined trajectory that takes it through one slit while the associated wave passes through both slits. The traditional interpretation of quantum mechanics, known as the Copenhagen interpretation, dismisses the notion of trajectories, and maintains that it is meaningless to ask what value a variable, such as momentum, has if that's not what is being measured."

A moving particle has an associated wave. In a double slit experiment the particle travels a single path and enters and exits a single slit. It is the associated wave which enters and exits both slits. The associated wave creates wave interference upon exiting the slits. As the particle exits a single slit, the direction it travels is altered by the interference it encounters. Detecting the particle causes there to be a loss of coherence of the associated wave, in the above experiment the loss of coherence is not great enough for there not to be an interference pattern.
« Last Edit: 03/06/2011 12:22:19 by mpc755 »


 

Offline imatfaal

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Experimental evidence of pilot-wave theory
« Reply #1 on: 03/06/2011 12:26:46 »
Interesting - I cannot read the actual article as no subscription to Science (after posting will see is arxiv has preprint).  If it measures position to arbitrary high precision and can still measure momentum it seems to blow HUP principle apart - so I guess that part is typical hype in the editorial section that isn't repeated in the actual article.  HUP doesn't stop us measuring or calculating both position and velocity at the same time, it imposes a maximum level of certainty (σxσp≥h/4π) ie if the standard dev of the position is very tight then the standard dev of the momentum must be large. 

David Deutch (who does have a fairly large vested interest in present explanation) claims that the experiment shows nothing new and the results are in line with current mainstream understanding. 
 

Offline mpc755

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Experimental evidence of pilot-wave theory
« Reply #2 on: 03/06/2011 12:31:39 »
I am able to read the article without a subscription.

This does not blow up HUP. What it means is the particle travels a well defined path and constantly occupies a particular point in three dimensional space. In de Broglie wave mechanics the particle occupies a very small region of the wave. However, you can't know exactly where the particle is in the wave without detection, so HUP still stands.

'Steinberg stresses that his group's work does not challenge the uncertainty principle, pointing out that the results could, in principle, be predicted with standard quantum mechanics. But, he says, "it is not necessary to interpret the uncertainty principle as rigidly as we are often taught to do", arguing that other interpretations of quantum mechanics, such as the pilot-wave theory, might "help us to think in new ways".'
« Last Edit: 03/06/2011 12:41:20 by mpc755 »
 

Offline imatfaal

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Experimental evidence of pilot-wave theory
« Reply #3 on: 03/06/2011 12:54:55 »
MPC - I mean the Science article upon which the SciAm/Nature editorial (you have linked to) is based upon. Have you actually read the peer-reviewed article or is this based on the editorial?

I stand to be corrected (JP/BC etc are you there?) but I believe that the HUP does not allow for non-rigid interpretations - if the inequality I put in the above post is compromised then a lot of physics needs to be re-thought. 
 

Offline mpc755

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Experimental evidence of pilot-wave theory
« Reply #4 on: 03/06/2011 12:58:10 »
Based on the editorial.

Does a relaxed interpretation of HUP void the inequality? The 'weak measurement' in the article seems to be in line with your statement, "if the standard dev of the position is very tight then the standard dev of the momentum must be large." The standard dev of the measurement is not very tight.
« Last Edit: 03/06/2011 13:05:04 by mpc755 »
 

Offline imatfaal

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Experimental evidence of pilot-wave theory
« Reply #5 on: 03/06/2011 13:10:04 »
Thanks. 

Exactly - either the product of the two measurements' uncertainty together is greater that hbar/2, in which case the HUP holds or it is less in which case it is in trouble.  It's an either/or - I don't think there is a third "relaxed" way (although that's the bit I would need confirmed).
 

Offline yor_on

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Experimental evidence of pilot-wave theory
« Reply #6 on: 04/06/2011 22:00:50 »
It's a statistical approach. They do it over a amount of particles and from there define it/them. It has nothing to do with HUP. To put it simple. Assume you have a infinite amount of detectors situated in the 'path' of your photon(s) then remove them one after one. Now you will have a statistical path.
« Last Edit: 04/06/2011 22:21:57 by yor_on »
 

Offline imatfaal

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Experimental evidence of pilot-wave theory
« Reply #7 on: 04/06/2011 22:34:16 »
Yoron - if you are measuring (any way) position and momentum at the same time then HUP is there as a limit of certainty. 

I dunno if you can get the full article in Science cos I would like a read :-) I think the headline and editorials are probably just very misleading.

My point is that either (per the editorials) HUP is challenged -or it is not; there is no halfway house. 

To say that because it is statistical then HUP does not apply is not I believe correct - look at the particular formulation I provided above, those sigmas are standard deviation signs.  If you can tell any tiny thing from a third/fourth/fifth particle about your test particle (even using statistical devices) then HUP applies.  I had been taught that you couldn't build up info and find a way around HUP; there is no way around it.

As soon as you know enough to determine which slot the particle passed through then the interference disappears (or it should).   You can even put your detector such that it only knows which path the particle took AFTER it has collided with the detector - that observation will destroy the interference pattern, although causality seems to forbid it (this is forerunner of the delayed choice quantum eraser experiment that MPC and I have been banging head about across the forums). 

« Last Edit: 04/06/2011 22:42:29 by imatfaal »
 

Offline yor_on

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Experimental evidence of pilot-wave theory
« Reply #8 on: 04/06/2011 22:54:32 »
I said it was a statistical approach, didn't I?

Most of those weak measurements, that I know of at least, build on manipulating statistics. And as statistics never will be the measurement you refer to, writing "if you are measuring (any way) position and momentum at the same time then HUP is there as a limit of certainty." then it has nothing to do with HUP as I see it.

What it has to do with is limiting the 'uncertainty' and looked at that way it's interesting.
Here is his (free) publications, so far. Aephraim M. Steinberg.
 

Offline imatfaal

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Experimental evidence of pilot-wave theory
« Reply #9 on: 04/06/2011 23:14:46 »
I said it was a statistical approach, didn't I?
Yep - and I said I don't think that matters.
Quote
Most of those weak measurements, that I know of at least, build on manipulating statistics.
And as statistics never will be the measurement you refer to, writing "if you are measuring (any way) position and momentum at the same time then HUP is there as a limit of certainty." then it has nothing to do with HUP as I see it.
  but where are the statistics coming from - they must be the results of measurements.
Quote
What it has to do with is limiting the 'uncertainty' and looked at that way it's interesting.
Here is his (free) publications, so far. Aephraim M. Steinberg.
I think you are right here - and the headlines are just plain wrong.  Will check the papers out - I note the important one is not linkable yet
 

Offline yor_on

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Experimental evidence of pilot-wave theory
« Reply #10 on: 04/06/2011 23:39:07 »
Well Imatfaal, there is a version of HUP that is the modern in where 'time' suddenly becomes 'fuzzy' for the measurements, and then there are the definition you made, which to me is the correct one. For stating that you can manipulate HUP statistically and so 'remove it' you will need to go with the 'fuzzy time' version.

HUP states that "certain physical quantities, like the position and momentum, cannot both have precise values - at the same time -. The narrower the probability distribution for one, the wider it is for the other."

To measure at -one time- on -one particle- is HUP.

To me :)
« Last Edit: 04/06/2011 23:41:53 by yor_on »
 

Offline yor_on

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Experimental evidence of pilot-wave theory
« Reply #11 on: 04/06/2011 23:56:09 »
Those who taught you that you couldn't get around it are both right and wrong. You can't get around it, if you by that mean that you will know that single particle without measuring it, but you can get around it statistically. Look at it as a matter of 'size', the chair you sit on is all built up from uncertain relations :) by particles obeying HUP. In the same way you can associate a 'certainty' to your chair you can by building up statistical evidence assume that what you now describe has a greater probability than what it would have if described before your collection of 'circumstantial proofs'

That's what 'weak measurements' is all about to me. It's the 'truth' of probability used to prove what we otherwise can't know, as proved if we would measure on -one particle-.

So HUP is not violated in itself, but 'circumstanced' maybe, by clever inducing.

Then again, I think that although this may work (?) I would not trust my life on a device built to this standard.
« Last Edit: 04/06/2011 23:58:47 by yor_on »
 

Offline mpc755

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Experimental evidence of pilot-wave theory
« Reply #12 on: 05/06/2011 13:40:47 »
Isn't this focus on HUP missing the point? Pilot-wave theory explains what occurs physically in nature in a double slit experiment better than the Copenhagen interpretation of QM.

"New 'Double Slit' Experiment Skirts Uncertainty Principle"
http://www.scientificamerican.com/article.cfm?id=new-double-slit-experiment-skirts-uncertainty-principle [nofollow]

'"Experiments are only relevant in science when they are crucial tests between at least two good explanatory theories," Deutsch says. "Here, there was only one, namely that the equations of quantum mechanics really do describe reality." David Deutsch of the University of Oxford, UK, is not convinced that the experiment has told us anything new about how the universe works. He says that although "it's quite cool to see strange predictions verified", the results could have been obtained simply by "calculating them using a computer and the equations of quantum mechanics".'

Yes, exactly. You can crunch some numbers and figure out the correct probability of the results. What does that have to do with understanding what occurs physically in nature in a double slit experiment? Nothing.

'Interpretation of quantum mechanics by the double solution theory - Louis de BROGLIE'
http://aflb.ensmp.fr/AFLB-classiques/aflb124p001.pdf [nofollow]

"I think that when this interpretation is further elaborated, extended, and eventually modified in some of its aspects, it will lead to a better understanding of the true coexistence of waves and particles about which actual Quantum mechanics only gives statistical information, often correct, but in my opinion incomplete."

A moving particle has an associated wave. In a double slit experiment the particle travels a single path and enters and exits a single slit. It is the associated wave which enters and exits both slits. The associated wave creates wave interference upon exiting the slits. As the particle exits a single slit, the direction it travels is altered by the interference it encounters. Detecting the particle strongly causes there to be a loss of coherence of the associated wave, there is no wave interference, and the direction the particle travels is not altered.

The analogy is a boat double slit experiment. The boat enters and exits a single slit. The bow wave enters and exits both slits. As the boat exits a single slit the direction it travels is altered by the bow wave exiting both slits. If you place buoys at the exits of the slits in order to detect the boat the bow wave is turned into chop and the direction the boat travels is not altered.

In any double slit experiment ever performed, if detectors are placed at the exits to the slits why is the particle always detected exiting a single slit? Because it always enters a single slit. It is the associated wave which enters and exits multiple slits.
« Last Edit: 05/06/2011 13:53:53 by mpc755 »
 

Offline imatfaal

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Experimental evidence of pilot-wave theory
« Reply #13 on: 06/06/2011 12:31:03 »
Chad Orzel has done a great blog on this paper  here

 

Offline yor_on

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Experimental evidence of pilot-wave theory
« Reply #14 on: 06/06/2011 13:20:31 »
It depends on how you define reality.

Do it from probability and it will 'work'. But let's assume you're in a fight and decide to strike back. You do and the other guy falls. So now you done 'something', although you can count on it as probabilities you also have had a localized direct interaction as defined in the 'arrow of time' and after the interaction there can be no doubt that this was the only outcome that you ever have observed.

It's a very philosophical question, ignoring all math possible here :)
Math is a tool, without you understanding what you want to define it becomes only a logical definition of symmetries. You use your imagination and then test your logic.
==

There is a way of trying the definitions we have mathematically too, but that is more of a game as you won't have an idea, possibly you could arrange all theorems after some definition of 'weighting' them as more or less 'proved' and then run them for 'bending' their symmetry, changing them according to the mathematical rules we know, possibly? That could be rather interesting if someone wrote such a program. But you would have to be a really knowledgeable mathematician to do it, and programmer too.
==

Simply put. If mathematics is a 'universal truth' then no theorems can be excluded for describing reality, including those that do not fit 'reality' at all. That's the quagmire to me.
==

And 'logic' can take you to a place where 'logic' ends. As in Chaos theory and non linearity. What you have left then is symmetries, and those other ideas that describes 'patterns', and that will depend on your definitions. You cannot assume that because you are following some linear logic to its end, then that must be a description of 'reality'. Nature doesn't work that way.
« Last Edit: 06/06/2011 13:44:28 by yor_on »
 

Offline mpc755

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Experimental evidence of pilot-wave theory
« Reply #15 on: 06/06/2011 13:28:49 »
If we are discussing logic then it is only logical to understand the particle always being detected exiting a single slit is evidence the particle always enters a single slit and it is the associated wave which enters and exits both slits in a double slit experiment.

In every double slit experiment ever performed, placing detectors at the entrances of the slits detects the particle entering a single slit. In every double slit experiment ever performed, placing detectors at the exits to the slits detects the particle exiting a single slit. This is evidence the particle always enters and exits a single slit and it is the associated wave which enters and exits both.
« Last Edit: 06/06/2011 13:43:25 by mpc755 »
 

Offline yor_on

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Experimental evidence of pilot-wave theory
« Reply #16 on: 06/06/2011 13:46:45 »
Sorry, was filling in my answer there.
Missed your response.

As I said, your definitions of reality will define your logic. And here you define reality in one way, using logic to prove your point :) Reality is a very weird idea.
 

Offline mpc755

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Experimental evidence of pilot-wave theory
« Reply #17 on: 06/06/2011 15:15:59 »
Reality is not a weird idea. Not understanding what occurs physically in nature and instead of saying, "I don't know", deciding to make stuff up like the Copenhagen interpretation of QM causes absurd ideas.

All you have to understand in order to remove the weirdness is a moving physical particle has an associated physical wave.
 

Offline yor_on

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Experimental evidence of pilot-wave theory
« Reply #18 on: 06/06/2011 15:32:02 »
Well, You make a definition and from there you create your proofs. If you can succeed in showing us other that your proofs create a more understandable reality, and that they hold to our evaluation, you're on your way :)

As for defining a particle, and a wave.
Sure, try it on, but you can't use this experiment as a proof. You will need to find some other experiment for proving that point. Doesn't mean you need to be wrong, or the theory.
 

Offline mpc755

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Experimental evidence of pilot-wave theory
« Reply #19 on: 06/06/2011 16:34:02 »
The following is a modified 'Delayed Choice Quantum Eraser' experiment which is explained by pilot-wave theory, and as far as I know, can not be explained by the Copenhagen interpretation of QM.

In the image here: http://en.wikipedia.org/wiki/File:Kim_EtAl_Quantum_Eraser.svg [nofollow], instead of having a single beam splitter BSc have two beam splitters BSca and BScb. Have the photons reflected by mirror Ma interact with BSca and have the photons reflected by mirror Mb interact with BScb. Do not combine the red and blue paths. Have additional detectors D1a, D2a, D1b, and D2b. Have the photons reflected by and propagate through BSca be detected at D1a and D2a. Have the photons reflected by and propagate through BScb be detected at D1b and D2b. If you compare the photons detected at D1a and (D1b or D2b) with the photons detected at D0, the corresponding photons detected at D0 will form an interference pattern. If you compare the photons detected at D2a and (D1b or D2b) with the photons detected at D0, the corresponding photons detected at D0 will form an interference pattern. What is occurring is all photons of a certain polarization are being detected at one pair of detectors, for example D1a and D1b, and all photons of the opposite polarization are being detected at the other pair of detectors, for example D2a and D2b. Interference patterns do not even need to be created in order to determine the interference patterns created at D0. The interference patterns at D0 are being created regardless of what else occurs in the experiment. What the detection at the other detectors allows for is discerning one interference pattern at D0 from the other.
« Last Edit: 06/06/2011 16:49:41 by mpc755 »
 

Offline imatfaal

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Experimental evidence of pilot-wave theory
« Reply #20 on: 06/06/2011 17:02:16 »
MPC - as I have said before, your modified dcqe experiment needs to be carried out to have any validity.  I am pretty damn certain it won't work - as would be many others; you cannot offer it as proof of any theory. 
 

Offline mpc755

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Experimental evidence of pilot-wave theory
« Reply #21 on: 06/06/2011 17:03:51 »
I realize the experiment needs to be performed.
 

Offline mpc755

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Experimental evidence of pilot-wave theory
« Reply #22 on: 15/06/2011 08:27:04 »
The following is a modified 'Delayed Choice Quantum Eraser' experiment which is explained by pilot-wave theory, and as far as I know, can not be explained by the Copenhagen interpretation of QM.

In the image here: http://en.wikipedia.org/wiki/File:Kim_EtAl_Quantum_Eraser.svg [nofollow], instead of having a single beam splitter BSc have two beam splitters BSca and BScb. Have the photons reflected by mirror Ma interact with BSca and have the photons reflected by mirror Mb interact with BScb. Do not combine the red and blue paths. Have additional detectors D1a, D2a, D1b, and D2b. Have the photons reflected by and propagate through BSca be detected at D1a and D2a. Have the photons reflected by and propagate through BScb be detected at D1b and D2b. If you compare the photons detected at D1a and (D1b or D2b) with the photons detected at D0, the corresponding photons detected at D0 will form an interference pattern. If you compare the photons detected at D2a and (D1b or D2b) with the photons detected at D0, the corresponding photons detected at D0 will form an interference pattern. What is occurring is all photons of a certain polarization are being detected at one pair of detectors, for example D1a and D1b, and all photons of the opposite polarization are being detected at the other pair of detectors, for example D2a and D2b. Interference patterns do not even need to be created in order to determine the interference patterns created at D0. The interference patterns at D0 are being created regardless of what else occurs in the experiment. What the detection at the other detectors allows for is discerning one interference pattern at D0 from the other.

No need for mirrors Ma or Mb. Replace Ma with BSca and Mb with BScb.
 

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Experimental evidence of pilot-wave theory
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