Copenhagen & Many Worlds Falsified?

[SimonA]

"confirm by his earlier results<sp>"?

You're forgetting that OTHER people will confirm his results, not him!

Secondly, at the bottom of that article, the manuscript was only recently submitted to PRL (July 2004). It is anything but a done deal, and anyone who has tried to publish anything in PRL would know this (you can get up to FOUR referees reviewing your paper).

Thirdly, as mentioned above, even if it appears in a peer-reviewed journal, it will then finally be presented to the physics community and be tested, questioned, and prodded. The road to being an accepted observation, ideas, etc. in physics can be a very long, arduous, and tedious process.

I wouldn't put a bet on the apparent "death" of CI if I were you.

Okay provisionally confirmed the results of his previous study all pending peer review - if you'd prefer :-)

Someone will surely find plasters for CI but but it does seem to be limping quite badly...

Simon

 

[Ontoplankton]

And here's an article by Cramer which may be of interest ---> http://www.analogsf.com/0409/altview2.shtml

Here he goes again:

I predict that a new generation of "Quantum Lawyers" will begin to populate the physics literature with arguments challenging what "is" is and claming that the wounded interpretations never said that interference should be completely absent in a quantum which-way measurement.

That's because, as far as I can tell, MWI never did say that, at least not in its more recent versions (see here, here, ...). I'm sure something similar is true for Copenhagen.

Unless there's something I've missed, Cramer is attacking strawmen to sell his transactional interpretation. That's a nasty thing to do, IMHO.

 

[ZapperZ]

Okay provisionally confirmed the results of his previous study all pending peer review - if you'd prefer :-)

Er.. what previous study?

As far as I know, this IS the only study. The brouhaha so far has been on this one, which from what I understand, was put on ArXiv, and then retracted. So now it has officially been submitted for peer-review publication. He hasn't verified anything previously in print.

Zz.

 

[SimonA]

Er.. what previous study?

As far as I know, this IS the only study. The brouhaha so far has been on this one, which from what I understand, was put on ArXiv, and then retracted. So now it has officially been submitted for peer-review publication. He hasn't verified anything previously in print.

As far as I know nothing has been published (and been peer reviewed) by Afshar on this yet. Obviously science requires that for good reason but at the end of the day all of us interested in science should be interested in anything which potentially advances our understanding surely ?

The study mentioned in the article I linked and the one being discussed here was first done by Afshar last year and then repeated by him at Harvard. His team have just done a new experiment at very low light intensity using a detector that can detect the arrival of a single quantum of light. I'm no quantum physicist but Afshar seems convinced this has proven that the CI is inconsistent with the quantum formalism.

I doubt it will include anything from this latest experiement but for those in the US Afshar will be on NPR's Science Friday program tonight.

For those of us elsewhere there will be a live broadcast of the program here;

http://sciencefriday.com/streaming.html

More details here ---> http://www.sciencefriday.com/pages/2004/Jul/hour2_073004.html

Simon

 

[Garth]

Is not the essential feature of this result that, although the Copenhagen Interpretation says a photon and a particle can be observed either as a wave or a particle, depending on the experiment, but NOT at the same time, the Ashfar experiment seems to show that they are both simultaneously?

 

[SimonA]

Yes Garth - although Afshar is going even further and suggesting that the only quantisation that's occurring is in the particles of the emmiter (and detector). Cramer went with this when he used the Hanbury-Brown-Twiss effect in his 1986 paper.

To me (and I'm just talking crazy ideas here..) this suggests that's because the particles that make the emmiter require a certain level of energy spread across them before their orbital shells are full and they release it as a quanta of energy. So this is in some ways a packet because of how its released but its nature is very much wave like and passes through both slits. The only way I could think of explaining the wave nature is if there were waves on the surface of the ZPF. Another possibility is that it is an actual particle (i.e. there is something in light that is by nature unit like) but its infinitisimally lower in 'density' (wrong word but can't think of another more appropriate) than the ZPF and so just hovers at the surface (this would apply to all "massless" 'particles' such as EM). Thus the wave is like its wake in the ZPF but it doesn't actually rise out of it and so doesn't hit the walls between the slits. But that's another discussion :-)

If anyone missed the Afshar interview its available here ---> http://www.npr.org/features/feature.php?wfId=3804795

(You may have to be on Media Player 9 ---> http://www.microsoft.com/windows/windowsmedia/9series/player.aspx for it to work...

Simon

 

[SimonA]

Many of you people have basically got your knickers twisted because you've believed the false interpretation that water is bucket like

 

[ZapperZ]

Many of you people have basically got your knickers twisted because you've believed the false interpretation that water is bucket like

Or maybe we're not as guillable as you are. For example:

The study mentioned in the article I linked and the one being discussed here was first done by Afshar last year and then repeated by him at Harvard. His team have just done a new experiment at very low light intensity using a detector that can detect the arrival of a single quantum of light. I'm no quantum physicist but Afshar seems convinced this has proven that the CI is inconsistent with the quantum formalism.

If there is such a thing as a photon detector that has 100% quantum efficiency, we would NEVER have a detection loophole in an EPR-type experiment. The fact is that we DON'T (and there is still the possibility of a detection loophole in EPR-type experiments).

I find that this discussion is rather moot, and premature, considering that the ACTUAL publication isn't out yet. I thought we have already learned the lessons from all the brouhaha surrounding Pon and Fleishmann's "cold fusion" paper.

Zz.

 

[SimonA]

Or maybe we're not as guillable as you are.

I'm not the one hanging on an interpretation that nature is only determined when I decide how I want to set my experiment up. You call me gullible because new evidence has been suggested that supports my view that CI was for gullible people. I don't have a problem with the formalism, I have a problem with this observer dependent interpretation that has led to wacky new age theories. But then again I have some time for some of Bohm's ideas and they have resulted in the same kind of thing :-)

For example:

If there is such a thing as a photon detector that has 100% quantum efficiency, we would NEVER have a detection loophole in an EPR-type experiment. The fact is that we DON'T (and there is still the possibility of a detection loophole in EPR-type experiments).

So we have to admit we're just scratching the surface at present ? If so I agree...

I find that this discussion is rather moot, and premature, considering that the ACTUAL publication isn't out yet. I thought we have already learned the lessons from all the brouhaha surrounding Pon and Fleishmann's "cold fusion" paper.

Well I think Afshars results are significant enough (unless he's blatantly lying or the "experimenter effect" is of massive significance), to consider CI does not agree with the formalism. And I'm prepared to speculate on that just as the peer reviewers will be when they read his paper.

Simon

 

[Garth]

To me this suggests that's because the particles that make the emmiter require a certain level of energy spread across them before their orbital shells are full and they release it as a quanta of energy. So this is in some ways a packet because of how its released but its nature is very much wave like and passes through both slits.
Simon

Does this result therefore simply endorse the Schrödinger coordinate representation in which particles/photons are wave packets of energy? Particles have also inertial mass whereas photons do not.

 

[SimonA]

Does this result therefore simply endorse the Schrödinger coordinate representation in which particles/photons are wave packets of energy? Particles have also inertial mass whereas photons do not.

I took the liberty of editing my post there slightly (was late at night!) but I would be more interested in thinking about "what is mass ?". Standard theory would say its to do with how much the quarks 'jitter about'. Relativity says its the amount the particle stretches space-time. And you could even speculate about inertia being the result of all particles retaining a kind of remnant of entanglement from the big bang.

But I find some of the ideas of people like Bernhard Haisch to be very interesting in making progress towards some kind of explanation with a more sound epistemology. This article gets to some of these issues on the second page ---> http://www.science-spirit.org/articles/Articledetail.cfm?article_ID=126

Simon

 

[selfAdjoint]

Well there's another "matter is illusion" idea from the more professionally connected physicsts, that mass is just an interaction with a Higgs field. The standard model says that three particles, the weak force bosons, get mass that way, and the speculation is that when all the chips are down, all particle mass will come that way.

But it has been pointed out that most of the mass in our world comes from protons and neutrons, and most of their mass comes, not from the quarks that are their "matter particles" but from the binding energy of the massless gluons that hold them together.

 

[ZapperZ]

I'm not the one hanging on an interpretation that nature is only determined when I decide how I want to set my experiment up. You call me gullible because new evidence has been suggested that supports my view that CI was for gullible people. I don't have a problem with the formalism, I have a problem with this observer dependent interpretation that has led to wacky new age theories. But then again I have some time for some of Bohm's ideas and they have resulted in the same kind of thing :-)

I'm sorry, but where exactly did I say that I'm for one interpretation over another? Just because I question the validity (and interpretation) of this experiement somehow automatically, by default, made me someone who is in favor of CI?

As an experimentalist, I have no patience for such dogma, nor would I ever want to dictate what Nature wants to do. I've encountered way too many instances where such insistance (mainly by theorists) crumble spectacularly. If Nature does end up with an "observer dependent interpretation", so be it. It appears that you have already dictated what Nature should and should not be, simply based on a matter of taste.

Well I think Afshars results are significant enough (unless he's blatantly lying or the "experimenter effect" is of massive significance), to consider CI does not agree with the formalism. And I'm prepared to speculate on that just as the peer reviewers will be when they read his paper.

Call me silly, but I'd rather hold judgement until I actually see the full paper. Obviously, this criteria appears rather trivial on here.

Zz.

 

[Eye_in_the_Sky]

I'm not the one hanging on an interpretation ...

... where exactly did I say that I'm for one interpretation over another? Just because I question the validity ... [of the claim that "CI is not a tenable interpretation of QM"] ... somehow automatically, by default, [that] made me someone who is in favor of CI?

Hey ... ditto for me! ... I'm with ZapperZ on this one.

With all due respect, SimonA, do not presume that one's defense of CI on this matter is on account of a belief that "CI is the correct explanation of the underlying reality behind QM". One's defending of CI may only be on account of one's belief that "CI is not in conflict with the Afshar results".

By the "Afshar results" I mean:

Summary of reported results:

a) No WG + both slits open --> no loss;

b) WG + only one slit open --> 6% loss;

c) WG + both slits open --> < 0.1% loss.

(Note: Anyone wishing to see a summary of the Afshar experiment, see post #11 (click here) of this thread.)

--------------------------------------

One More Important Point

One more important point needs to be made. The "tenability of CI" is quite independent of the "experimental validity the Afshar results", for those very results (even if there turns out to be some factor which invalidates the experiment) are precisely what CI predicts!

--------------------------------------

 

[SimonA]

Okay I appreciate your impartiality Eye_in_the_Sky and ZapperZ. I'm interesting in trying to understand what's actually going on and so I find the epistemological side interesting.

But with Eye_in_the_Sky I do believe you are confusing the quantum formalism with the Copenhagan Interpretation. All the quantum interpretations agree with the formalism. What the Copenhagen Interpretation suggests is the the outcome of the experiment is dependent on how you set the experiment up, on the detection itself. The formalism predicts Afshars results as expected, but Afshsar is measuring the 'particle' going through the slit and the interference patterns and this is why the interpretation itself is challenged - not the formalism which is common to all the interpretations.

 

[Eye_in_the_Sky]

Rebuttal to SimonA

... But with Eye_in_the_Sky I do believe you are confusing the quantum formalism with the Copenhagan Interpretation.

In an earlier post, I responded to the following question:

Do you have any idea how Afshar concludes this separates one QM interpretation from another?

The essential content of my response was (from post #13 of this thread):

I think it's fair to say that, in the literal sense, by definition, an "interpretation of a formalism" is something necessarily consistent with that formalism. Of course, in the process of formulating such an interpretation, one could err in some way, and consequently, end up with something which does, in fact, contradict the formalism.

... what Afshar and Cramer have claimed[*] regarding "Copenhagen" and "Many Worlds" amounts to the following:

These interpretations fail on account of certain unwitting implications which contradict the quantum formalism.

That is to say, Afshar and Cramer claim that the authors of these interpretations have unintentionally "stepped out of line" with the quantum formalism, making assertions which, when given the proper consideration, turn out to have implications which contradict the formalism itself.[**]
_____________________


[*] This is only one of two parts of their claim. The other part is that these interpretations fail in relation to what the experimental facts happen to be (whence the significance of the Afshar results).

[**] Does the content of this post serve to dispel the strangeness about which ZapperZ wrote (in the second post of this thread)?

... SimonA, does this information cause you to change your belief concerning the above cited potential point of confusion on my part?

--------------------------
--------------------------

... Afshsar is measuring the 'particle' going through the slit ...

No, Afshar is not measuring the 'particle' going through one (or the other) of the slits. Afshar is measuring the 'particle' position at the screen σ₂ (see diagram).

An "inference" is then made by which the "σ₂-measurement" is deemed to be physically equivalent to the "slit-measurement".

I could now go on and cite for you various principles of CI and how they "forbid" such an "inference". But that may well do nothing to change your opinion, because in your view CI - as a "formal body of principles" - is inconsistent. That means: if your position is true, then one can use CI to prove anything(!). Therefore, in order to satisfy you, I must "step out" of CI and produce a generalized-consistency-proof for CI (... which, if not impossible, is probably next to impossible).

So, then, what we really need in order to settle this matter (once and for all) is a clear argument - which you yourself (or by an authority you trust) find to be acceptable - by which CI (allegedly) implies that the "σ₂-measurement" and the "slit-measurement" are physically equivalent ... and I will then plainly demonstrate how that argument involves the erroneous application of some principle.

[... Perhaps, you can quote a source, or provide a link. In the absence of that, perhaps you would accept the manner in which I am able to "fill in the gaps" in Cramer's PowerPoint Presentation. In fact, I have already attempted to do just that in post #15 of this thread, entitled Cramer, in the name of "Copenhagen".

Moreover, in post #19 of this thread, in the second half of that post, I have provided two distinct points of view from CI which (with the appropriate consideration) may (... although, I doubt it) convince you of the invalidity of Cramer's claim.]

---------------------

 

[ZapperZ]

I offer my criticism to this Afshar/Cramer's point not based on an inherent philosophy, but rather on the experiment itself. That is why I want to reserve my comments till I see the DETAILS of the measurement - usually it is in the details where it can make or break an experiment.

From what I have read so far, there is one major problem that I have detected <no pun intended> - the detection mechanism itself. I have pointed out already one problem with assuming a 100% efficiency of a photo detector. The 2nd problem is that in a photon detector, when you try to detect it, you DESTROY it. ALL photon detectors that I know of require that the photon be absorbed, and either current or photoelectrons are then emitted. This current/photoelectrons are the tell-tale signs that a photon was there.

Therefore, I am VERY suspicious of a claim that (i) a photon passed through a particular slit and THEN (ii) that photon is later on detected at a screen/detector. You can only make claim (i) only if you have a 2-slit setup for example, and you BLOCK the other slit, or put a photodiode at the other slit (and thus destroying the photons that hit that slit). This isn't what was done in this experiment from what I have understood.

This is why I want to wait till the damn thing comes out, examine the details, and THEN figure out how valid the experimental results are. ONLY after that can we address if the results mean one thing or another, which isn't necessarily as clear as one thinks. It isn't unusual that a set of results can be interpreted in widely different ways (the magnon and phonon coupling scenario for the "kink" in ARPES spectra for the cuprate superconductors is a prime example), especially when it is still an active, research front field.

Zz.

 

[Eye_in_the_Sky]

I offer my criticism to this Afshar/Cramer's point not based on an inherent philosophy, but rather on the experiment itself.

I have two questions:

(i) Are you speaking of the same Afshar experiment alluded to in Cramer's PowerPoint Presentation (i.e. the one in post #1 of this thread)?

(ii) Are you the same ZapperZ who wrote (in post #2 of this thread):

... So how he [Cramer] came up with the conclusion that they [CI and MW] offer a result that differ from the QM formalism itself is puzzling. This is because if that is true, then one can LOGICALLY falsify both interpretations without having to do any experiment.

Please answer: "yes, yes" / "yes, no" / "no, yes" / or "no, no".

 

[ZapperZ]

I have two questions:

(i) Are you speaking of the same Afshar experiment alluded to in Cramer's PowerPoint Presentation (i.e. the one in post #1 of this thread)?

(ii) Are you the same ZapperZ who wrote (in post #2 of this thread):

Please answer: "yes, yes" / "yes, no" / "no, yes" / or "no, no".

(i) yes + the Cramer's Analog comments + http://users.rowan.edu/~afshar/ + conversation with someone who has actually seen the first version of the preprint that was retracted from arXiv.

(ii) yes (unless my evil twin Skippy has been up to no good again).

Zz.

 

[Eye_in_the_Sky]

(i) Are you speaking of the same Afshar experiment alluded to in Cramer's PowerPoint Presentation (i.e. the one in post #1 of this thread)?

(i) yes + the Cramer's Analog comments + http://users.rowan.edu/~afshar/ + conversation with someone who has actually seen the first version of the preprint that was retracted from arXiv.

Then, hold it one itty-bitty second! Where in the galaxy! did you get the impression that in the Afshar experiment a measurement of any kind is performed at the site of the slits?

(... or was it Skippy who answered question (i)?)

 

[ZapperZ]

Then, hold it one itty-bitty second! Where in the galaxy! did you get the impression that in the Afshar experiment a measurement of any kind is performed at the site of the slits?

(... or was it Skippy who answered question (i)?)

He somehow knew which pinhole the photon passed though. [I used the double slit as a generic example]

This is why I emphasized that I need to actually read the paper since by making such a statement, I immediately assume that there was some kind of measurement, rather than an inference. If it is the latter, than there's more than enough ammo to go around at arguing against the results and conclusion. So I automatically guessed the former since it has to be on a stronger ground.

So, did I interpret the experiment incorrectly?

Zz.

 

[Eye_in_the_Sky]

I immediately assume that there was some kind of measurement, rather than an inference.

I have a little picture for (!)you(!) (... Skippy already knows about it.).

... If it is the latter, than there's more than enough ammo to go around at arguing against the results and conclusion.

... "results"? ... "conclusion"?

If by "results" you mean (note: WG = wire grid):

(from post #11 of this thread, "Afshar Setup")

Summary of reported results:

a) No WG + both slits open --> no loss;

b) WG + only one slit open --> 6% loss;

c) WG + both slits open --> < 0.1% loss.

... and if by "conclusion" you mean:

(from post #11 of this thread, "Afshar Setup")

Conclusion:

Since the results of c) are very nearly the same as those of a) and, on the other hand, appreciably different from those of b), the situation in c) must be that of "wave-like" behavior (i.e. the quantum system interacts with both slits, and not just one slit). That is to say, two waves are propagating, one from each slit, and in the vicinity of WG these waves overlap and interfere to produce minima at the locations of the wires in WG. For this reason, WG is essentially transparent to the incident beam.

... then there is zero "ammo". These are merely confirmations of what QM predicts.

--------------------

(ii) Are you the same ZapperZ who wrote (in post #2 of this thread):

"... So how he [Cramer] came up with the conclusion that they [CI and MW] offer a result that differ from the QM formalism itself is puzzling. This is because if that is true, then one can LOGICALLY falsify both interpretations without having to do any experiment."

(ii) yes (unless my evil twin Skippy has been up to no good again).

... so ... it was Skippy.

--------------------

So, did I interpret the experiment incorrectly?

You gave Afshar and Cramer the benefit of the doubt - that was quite noble of you ... yet, quite incorrect.

--------------------

I offer my criticism to this Afshar/Cramer's point not based on an inherent philosophy, but rather on the experiment itself.

If Afshar's results are experimentally valid, then we obtain a confirmation of a QM prediction; if Afshar's results are not valid, then we obtain no new information.

... The only real "debate" is one over the question of whether or not CI (MWI, or whatever else) "permits" or "forbids" the inference.

 

[SimonA]

Well I do appreciate what you're both saying and I've never (nor have Afshar or Cramer to my knowledge) said that this experiment contradicts "QM". The issue is with Bohrs interpretation.

Bohr writes (1939):

...the very fact that in quantum phenomena no sharp separation can be made between an independent behavior of the objects and their interaction with the measurement instruments, lends indeed to any such phenomena a novel feature of individuality which evades all attempts at analysis on classical lines, because every imaginable experimental arrangement aiming at a subdivision of the phenomena will be incompatible with its appearance and give rise, within the latitude indicated by the uncertainty relations, to other phenomena of similar individual character.

I got that quote from this page --> this page which summarises the hub of why Afshar is saying "Einstein was right" (but not why he says "for the wrong reason" which is due to the claim that quantisation is a property of the emmiter and the detector along the lines quoted by Cramer in his 1986 paper on the Hanbury-Brown-Twiss effect)

From Einstein's point of view, it seemed the "free choice" we have of which of the two possible measurements to make involves one and the same system. But from Bohr's point of view, in order to give terms like "position" and "momentum" empirical significance, "system" must be interpreted in the sense of that which is observed. And since the experimental arrangement necessary for alternative observations of position and momentum are mutually exclusive, he concluded that the two observations refer to the properties of two distinct phenomenal objects. There was simply no "same system" in a sense that both position and momentum could be observed.

Simon

 

[Eye_in_the_Sky]

I feel compelled to qualify a statement I made in post #52 of this thread. That statement appears to suggest a point of view which I neither intended to convey nor accept as valid. The statement was:

... The only real "debate" is one over the question of whether or not CI (MWI, or whatever else) "permits" or "forbids" the inference.

These words appear to suggest that there can be no "real" debate over the experimental validity of the Afshar results. This is something which I did not wish to convey. On the contrary, issues of this kind (i.e. questions concerning the validity of experimental results) are at the very heart of what makes physics what it is really about - namely, about what happens in the "world". Moreover, not only are such issues essential, but they can also involve highly nontrivial, subtle, complex, and intricate matters.

Therefore, to qualify what I meant in making the above quoted statement, my intention was to say no more than:

With regard to the question of the validity of CI (MWI, or whatever else) as an interpretation of QM, the only real "debate" is over whether or not it "permits" or "forbids" the inference.

 

[slyboy]

There was an article on the Ashfar experiment in the New Scientist a couple of weeks ago. This made what was going on in it much clearer to me than it was from Cramer's powerpoint presentation. I think that the experiment only violates Copenhagen if you take a VERY VERY VERY (+ many more VERY's) naive version of Copenhagen. The experiment does no more than show that it is possible to measure much more sophisticated things than straightforward observables in QM. This is already well-known, and you might as well say that any measurement of a POVM that has ever been made violates Copenhagen, which is clearly ridiculous.

These people clearly do not understand quantum measurement theory, which is inexcusable for anyone making such claims about the foundations of quantum mechanics. They also do not understand what complementarity is, which is much more excusable because it is a very vague and imprecise notion. However, it is clear from Bohr's writings that he meant something more sophisticated than wave-particle duality.