Copenhagen interpretation of Quantum Theory

[quddusaliquddus]

I found a website that says:

"The still-dominant "Copenhagen interpretation" of Quantum Theory developed by Niels Bohr, Werner Heisenberg, Wolfgang Pauli, and others says two basic things:

1. Reality is identical with the totality of observed phenomena (which means reality does not exist in the absence of observation), and
2. Quantum mechanics is a complete description of reality; no deeper understanding is possible."

Is it true that the "Copenhagen interpretation" of Quantum Theory is the dominant theory?

And is number 1 and 2 true?

Is it also true that the 'rules' of the Universe seem to change reflect the 'maths'.

Is it also true that Non-Locality (defined as phenomenon that occurrences on one side of the Universe can instantly effect 'matter' on the other side of the Universe) happens? (Im not sure if 'happens' is the correct word to use here.

 

[setAI]

the Copenhagen Interpretation hasn't been 'dominant' for many years -

“Political scientist" L David Raub reports a poll of 72 of the "leading
cosmologists and other quantum field theorists" about the "Many-Worlds
Interpretation" and gives the following response breakdown [T].

1) "Yes, I think MWI is true" 58%
2) "No, I don't accept MWI" 18%
3) "Maybe it's true but I'm not yet convinced" 13%
4) "I have no opinion one way or the other" 11%

Amongst the "Yes, I think MWI is true" crowd listed are Stephen Hawking
and Nobel Laureates Murray Gell-Mann and Richard Feynman. Gell-Mann and
Hawking recorded reservations with the name "many-worlds", but not with
the theory's content. Nobel Laureate Steven Weinberg is also mentioned
as a many-worlder, although the suggestion is not when the poll was
conducted, presumably before 1988 (when Feynman died). The only "No,
I don't accept MWI" named is Penrose.

The findings of this poll are in accord with other polls, that many-
worlds is most popular amongst scientists who may rather loosely be
described as string theorists or quantum gravitists/cosmologists. It
is less popular amongst the wider scientific community who mostly remain
in ignorance of it.” http://www.anthropic-principle.com/preprints/manyworlds.html


non-local interpretations of QM have been shown to be unphysical: http://arxiv.org/abs/quant-ph/9906007

 

[quddusaliquddus]

So what is the dominant quantum theory among the physicists? Can someone sum up the major conclusions of the dominant theory about quantum physics please?

 

[setAI]

as the reference to the poll indicates- it is MWI- since this poll the MWI has been experimentally verified http://www.quiprocone.org/Protected/Lecture_2.htm - since around the year 2000 the Everett interpretation has been confirmed as the only EXPERIMENTALLY VALID interpretation of QM- all other [non multiverse[ interpretations no longer fit with observations- as a result we now have the field of quantum computers- which are only predicted and described by the Everettian MWI-

 

[DaveC426913]

Does MWI invalidate the outcome of Schrodinger's thought experiment - that the cat is both alive and dead until observed?

Seems to me MWI says that we find ourselves in one of the two possible worlds (oversimplifying), either the 'alive cat' one or the 'dead cat' one.

 

[Son Goku]

as the reference to the poll indicates- it is MWI- since this poll the MWI has been experimentally verified http://www.quiprocone.org/Protected/Lecture_2.htm - since around the year 2000 the Everett interpretation has been confirmed as the only EXPERIMENTALLY VALID interpretation of QM- all other [non multiverse[ interpretations no longer fit with observations- as a result we now have the field of quantum computers- which are only predicted and described by the Everettian MWI-

That makes no sense to me. Isn't it Quantum Mechanics itself which is verified, not any given interpretation. The interpretations are different ways of viewing and ranking the importance and reality of mathematical entities in Quantum Mechanics and this can't be tested in experiment.

I also think, though I'm not sure, that Hawking believes that there is probably other universes, in the form of disconnected spacetimes, rather than in the sense of QM's many worlds view.

 

[ZapperZ]

the Copenhagen Interpretation hasn't been 'dominant' for many years -

“Political scientist" L David Raub reports a poll of 72 of the "leading
cosmologists and other quantum field theorists" about the "Many-Worlds
Interpretation" and gives the following response breakdown [T].

1) "Yes, I think MWI is true" 58%
2) "No, I don't accept MWI" 18%
3) "Maybe it's true but I'm not yet convinced" 13%
4) "I have no opinion one way or the other" 11%

Amongst the "Yes, I think MWI is true" crowd listed are Stephen Hawking
and Nobel Laureates Murray Gell-Mann and Richard Feynman. Gell-Mann and
Hawking recorded reservations with the name "many-worlds", but not with
the theory's content. Nobel Laureate Steven Weinberg is also mentioned
as a many-worlder, although the suggestion is not when the poll was
conducted, presumably before 1988 (when Feynman died). The only "No,
I don't accept MWI" named is Penrose.

The findings of this poll are in accord with other polls, that many-
worlds is most popular amongst scientists who may rather loosely be
described as string theorists or quantum gravitists/cosmologists. It
is less popular amongst the wider scientific community who mostly remain
in ignorance of it.” http://www.anthropic-principle.com/preprints/manyworlds.html


non-local interpretations of QM have been shown to be unphysical: http://arxiv.org/abs/quant-ph/9906007

You have made this assertion many times on here, and I think it is about time you are challenged for it.

1. The VERY FACT that one can conduct A POLL on this means that the acceptance of some form of interpretation of QM means it is still A MATTER OF TASTE! Real physics isn't done this way. You cannot simply adopt something and call it physics when all you can base it on is PREFERENCE! So by the very act that you are citing A POLL of OPINIONS shows CONCLUSIVELY that this is NOT a done deal! Don't you see this?

If you don't believe me, show me any other part of accepted physics that is done via such a popularity contest. Did the acceptance of BCS Theory of Superconductivity done via such a similar poll? Or was it simply based on an astounding body of evidence?

2. If you think MWI has already a slam-dunk case and is widely accepted, please open a QM text that is being taught to undergraduate physics students all over the world and show me where such a scenario is being used.

3. If you think MWI is generally accepted to be the ONLY interpretation of QM, please look at, for example, Tony Leggett's paper[1] on the Schrodinger Cat-type states and point out to me where he has used such interpretation to derive the coherence energy gap in those SQUID experiments from Delft/Stony Brook.

Zz.

[1] A.J. Leggett, J. Phys.: Cond. Matt v.14, p.415 (2002).

 

[vanesch]

The only "No,
I don't accept MWI" named is Penrose.

This has even an interesting note (which I have from Penrose's book "The road to reality"). In fact, Penrose argues that a MODIFICATION of quantum theory is in order, for he doesn't see how ONE CAN ESCAPE the MWI picture if the current quantum formalism is to hold universally (including Penrose's last refuge, which is gravity).

So Penrose's reasoning is rather: current quantum formalism LEADS automatically to MWI, and because that's a view I cannot accept, a *modification* of the formalism is probably due.

 

[vanesch]

2. If you think MWI has already a slam-dunk case and is widely accepted, please open a QM text that is being taught to undergraduate physics students all over the world and show me where such a scenario is being used.

3. If you think MWI is generally accepted to be the ONLY interpretation of QM, please look at, for example, Tony Leggett's paper[1] on the Schrodinger Cat-type states and point out to me where he has used such interpretation to derive the coherence energy gap in those SQUID experiments from Delft/Stony Brook.

Zz.

[1] A.J. Leggett, J. Phys.: Cond. Matt v.14, p.415 (2002).

I don't think the point was that MWI is *the* accepted view on quantum theory. But whenever it is mentioned (I can testify about that), it provokes vivid reactions by some, as if it were some totally crazy fringe view one shouldn't really consider. And this, it isn't either.

As you point out, the interpretation doesn't really matter it you really want to do physics: one should pick one's interpretation with which one can devellop ones intuition best. As you know, I prefer MWI for that - for me, it eliminates a lot of "bogus" questions IMO. You have your own view, which probably satisfies you also most.

 

[ZapperZ]

I don't think the point was that MWI is *the* accepted view on quantum theory.

But vanesch, I'm rebutting the claim that "... as the reference to the poll indicates- it is MWI- since this poll the MWI has been experimentally verified..."!

This is bogus, and I'm surprised you didn't address this. I have seen no experimental evidence that validates MWI and invalidates others. Have you?

But whenever it is mentioned (I can testify about that), it provokes vivid reactions by some, as if it were some totally crazy fringe view one shouldn't really consider. And this, it isn't either.

Note that nowhere in my criticism was there any denegration of MWI.

As you point out, the interpretation doesn't really matter it you really want to do physics: one should pick one's interpretation with which one can devellop ones intuition best. As you know, I prefer MWI for that - for me, it eliminates a lot of "bogus" questions IMO. You have your own view, which probably satisfies you also most.

It is, however, ethically dubious that, while in support of MWI, one also turns a blind eye when there are outrageous claims being made such as what setAI was doing. I would like to see this "experimental" evidence that singly verified MWI and nothing else.

Zz.

 

[vanesch]

But vanesch, I'm rebutting the claim that "... as the reference to the poll indicates- it is MWI- since this poll the MWI has been experimentally verified..."!

This is bogus, and I'm surprised you didn't address this. I have seen no experimental evidence that validates MWI and invalidates others. Have you?

I started a post on it, and then I killed it because I didn't like the way I wrote it :-)

Of course, at the point we are now, all interpretations being empirically equivalent, there' s no way to prove one over another.

However, there's - at least in principle - a way to distinguish views where there is a genuine, irreversible collapse and views - such as MWI, but also such as Bohmian mechanics for instance - where the superposition remains forever, by trying to observe quantum interference phenomena at "macroscopic" scales.
In this sense, the "superposition for ever" views are in fact more falsifiable than the "I put my Heisenberg cut somewhere, but I can pick were I want" views, because if the quantum interference is not observed, then the first class of views is ruled out, while the second class has always enough wiggle room to wiggle out.

 

[setAI]

the only interpretation of QM that succesfully predicts quantum computing is the MWI- Deutsch has DEFINED quantum computation as computation across parallel universes-

the experimental evidence of quantum computation- specifically independant CNOT operations carried out in parallel on single photons- physically demonstrates the MWI- and demonstrates that non-multiverse interpretations are unphysical- according to the leaders of the field-

as I have said before- this is all rather recent- but I guarantee you within 5-10 years the physical verification of the MWI will be in all the texbooks- from that point Copenhagen and Hidden Variable interpretations will only be historical footnotes-

Qunatum Mechanics IS the physics of parallel universes

 

[ZapperZ]

the only interpretation of QM that succesfully predicts quantum computing is the MWI- Deutsch has DEFINED quantum computation as computation across parallel universes-

the experimental evidence of quantum computation- specifically independant CNOT operations carried out in parallel on single photons- physically demonstrates the MWI- and demonstrates that non-multiverse interpretations are unphysical- according to the leaders of the field-

Sorry, but you should know by now that on here, such statements are empty. Please provide me the exact citation of this experiment.

Zz.

 

[ZapperZ]

I started a post on it, and then I killed it because I didn't like the way I wrote it :-)

Of course, at the point we are now, all interpretations being empirically equivalent, there' s no way to prove one over another.

However, there's - at least in principle - a way to distinguish views where there is a genuine, irreversible collapse and views - such as MWI, but also such as Bohmian mechanics for instance - where the superposition remains forever, by trying to observe quantum interference phenomena at "macroscopic" scales.
In this sense, the "superposition for ever" views are in fact more falsifiable than the "I put my Heisenberg cut somewhere, but I can pick were I want" views, because if the quantum interference is not observed, then the first class of views is ruled out, while the second class has always enough wiggle room to wiggle out.

But really, this is irrelevant to MY point. I'm not debating the validity of ANY of the interpretations of QM. I'm debating the erroneous conclusion here that MWI has hit a home run with some "experimental" observation. I'm just disappointed that you didn't come in any sooner than you did and corrected such dubious statements, and you had to wait till *I* come in. Even then, you simply restated why you "prefer" MWI and not to debunk what setAI has said.

One could adopt the Winnie the Pooh interpretation of QM, for all I care. Until there are experimental evidence to distinguish all of them, such a discussion is strictly philosophical and a matter of TASTES, not physics.

Zz.

 

[quddusaliquddus]

I'm sorry guys. You lost me ages ago. Are there major conclusions about QM that all the interpretations agree on?

 

[setAI]

Sorry, but you should know by now that on here, such statements are empty. Please provide me the exact citation of this experiment.

Zz.

you are obviously skimming the thread and not actually looking at the evidence already presented- but here it is again- a video demonstration and detailed lecture of the soon-to-be-famous experiment where a single photon is split and CNOT computations are performed in parallel universes then rejoined- http://www.quiprocone.org/Protected/Lecture_2.htm

 

[ZapperZ]

you are obviously skimming the thread and not actually looking at the evidence already presented- but here it is again- a video demonstration and detailed lecture of the soon-to-be-famous experiment where a single photon is split and CNOT computations are performed in parallel universes then rejoined- http://www.quiprocone.org/Protected/Lecture_2.htm

Sorry, but you obviously haven't been following any of my postings, because if you have, you would have realized that such things are not considered to be 'evidence', at least not a valid citation.

I will ask this for the very last time. Please give me the citation for the evidence that you have so claimed.

Failure to do so will imply that you are basing your argument on speculative, non-peer reviewed sources which are not acceptable per our Guidelines. I will have no choice but to have remove your posts and have you submit your arguments to the IR forum for evaluation.

Zz.

 

[setAI]

Sorry, but you obviously haven't been following any of my postings, because if you have, you would have realized that such things are not considered to be 'evidence', at least not a valid citation.

I will ask this for the very last time. Please give me the citation for the evidence that you have so claimed.

Failure to do so will imply that you are basing your argument on speculative, non-peer reviewed sources which are not acceptable per our Guidelines. I will have no choice but to have remove your posts and have you submit your arguments to the IR forum for evaluation.

Zz.

PEER REVIEWED documentation has already been provided!

here are some of the main papers and their citebase stats-

http://xxx.lanl.gov/abs/quant-ph/9906007
http://www.citebase.org/cgi-bin/citations?id=oai:arXiv.org:quant-ph/9906007

http://xxx.lanl.gov/abs/quant-ph/0104033
http://www.citebase.org/cgi-bin/citations?id=oai:arXiv.org:quant-ph/0104033


http://www.arxiv.org/abs/quant-ph/0210204
http://www.citebase.org/cgi-bin/citations?id=oai:arXiv.org:quant-ph/0210204


here are some of the research programs that are using the observed behavior of this experiment for quantum computation research:
http://www.vcpc.univie.ac.at/~ian/hotlist/qc/research.shtml

this is quite unbelievable and you are abusing this forum with your empty claims that this is not rigorously peer reviewed science- this research has been at the forefront of mainstream quantum mechanics for nearly a decade now- any user of physicsforums claiming to be a mentor should know all of this already- it says in your profile that you are physicist zapper- I guess I am dissapointed that you are not giving us more information about this news and are instead actually arguing against it?!?

I will report any abuses against this peer-reviewed research to Warren-

 

[vanesch]

I'm just disappointed that you didn't come in any sooner than you did and corrected such dubious statements, and you had to wait till *I* come in.

Uh oh :grumpy:

I made my first post (my time) in this thread when I first saw it at 5:25 PM concerning Penrose, my second at 5:29 PM replying to you, then I typed a long post which I finally didn't submit exactly addressing the issue you mentioned and you came in at the issue at 5:48 PM, when I was finding out whether I'd put myself in the traffic jam or whether I'd stay a bit longer in my office

 

[vanesch]

the only interpretation of QM that succesfully predicts quantum computing is the MWI- Deutsch has DEFINED quantum computation as computation across parallel universes-

Well, I hate to disturbe a fellow MWI-er, but I fail to see how one can say that quantum computation proves MWI. Honestly, quantum computation is nothing else but the unitary evolution of states of a system, and it is sufficient to put the Heisenberg cut AFTER obtaining the final result to be in agreement with Copenhagen, no ?

Imagine that the Heisenberg cut comes in for objects heavier than 200 tonnes. In other words, systems of more than 200 tonnes are classical systems and obey a superselection rule that only allows them to be in nearly classical states, and not in superpositions of these, and this is done by the projection postulate. How does quantum computing prove this statement wrong ? And if it does, if we now put the Heisenberg cut at 10^10 kg objects ?

the experimental evidence of quantum computation- specifically independant CNOT operations carried out in parallel on single photons- physically demonstrates the MWI- and demonstrates that non-multiverse interpretations are unphysical- according to the leaders of the field-

I fail to see how, for instance, Bohmian mechanics would give different observable results than MWI-QM. Now of course, I am also sensitive to the argument that Bohmian mechanics has some MWI flavor to it

Qunatum Mechanics IS the physics of parallel universes

Well, I also find this the most obvious interpretation of the formalism, but on purely formal grounds. I don't see how one can experimentally PROVE this view, given that it is empirically equivalent to Copenhagen with the Heisenberg cut far enough away, or to Bohm. It is for formal ugliness that I don't like these interpretations, not for their empirical falsifiation.


In fact, the experiment that "proves" to me MWI up to a point is an EPR experiment, but unfortunately, one needs another hypothesis for that, which was historically the first to be "tested" by these experiments.

The reason is that in order to get an indication of the validity of MWI, that one needs to put in superposition, and show interference, of VERY MACROSCOPIC systems (ideally, say, a planet).
Now, this is practically impossible to do because of environmental decoherence, which makes the interference invisible... unless one finds a way of making sure that the two branches that have to interfere cannot entangle with the same environment (and hence decohere).
Well, if one takes locality for granted (that's the point of course!), then one can use spacelike separation as a way to avoid environmental decoherence of the overall system (there will be local environmental decoherence, but it will not be the same environment degrees of freedom, and hence preserve the possibility of interference).
If one puts a macroscopic system in this way in a superposition (by having it observe one branch of an entangled system) in the basis of another macroscopic system (by having it observe the other branch of the entangled system in a rotated basis), and one brings then these two macroscopic systems together, one can try to find out if there is interference in their interaction, which would show up as correlations in their measurements. That's exactly what happens in an EPR experiment !

But, caveat: the only "superpositions" have been tiny electronic signals yet, over relatively small distances (50 km or so -> 10s of microseconds). That doesn't have much "gravitational" weight. We haven't really put human beings, or planets or so in superposition that way, for say, an hour or so. And there is still the issue of detection efficiency and the fair sampling hypothesis. So the "proof" isn't there yet that planets and so on can be in superpositions.

I'm focussing on the mass of the system in superposition, because I have to say that I'm sensitive to Penrose's argument. As long as we don't have a verified theory of quantum gravity, the possibility exists that superpositions of gravitationally important systems does not work, which would be the end of MWI. I fail to see how quantum computing proves this wrong.

 

[setAI]

Well, I hate to disturbe a fellow MWI-er, but I fail to see how one can say that quantum computation proves MWI. Honestly, quantum computation is nothing else but the unitary evolution of states of a system, and it is sufficient to put the Heisenberg cut AFTER obtaining the final result to be in agreement with Copenhagen, no ?

not according to Deutsch- the Copenhage interpretation predicts that in Deutsche's experiment the photons would appear at BOTH detectors at the end- MWI predicts just the right detector- and this was experimentally confirmed- also I concur with him that for example Shor's algorithm can only be physically performed if MWI is at least somewhat true- the large amount of empirical research I offered I conjecture at least 'demonstrates' or 'shows' [but does not PROOVE yet] that Deutsch is correct- however Deutsch himself often claims that the MWI is PROVEN and as far as I know there has been no professional challenge to this claim that I have found- Deutsch rather famously convinced Seth Lloyd that the MWI is true and he was the only voice of dissent I am aware of-

Imagine that the Heisenberg cut comes in for objects heavier than 200 tonnes. In other words, systems of more than 200 tonnes are classical systems and obey a superselection rule that only allows them to be in nearly classical states, and not in superpositions of these, and this is done by the projection postulate. How does quantum computing prove this statement wrong ? And if it does, if we now put the Heisenberg cut at 10^10 kg objects ?

I think it is much more complicated than this- and there are important implications of this from the Holographic Principle and the Beckenstein Bound/ the idea of Locality itself/ as well implications of the Simulation Argument- but that is speculation on my part- as for what Quantum Computing shows about this- I would refer to Deutsch's "Pennies and Pounds" comment:
just like the stars and galaxies, the unseen parts of reality are arranged in groups that resemble the seen part. Within one of these groups, which we call a parallel universe, the particles all can interact with each other, even though they barely interact with particles in other universes. They interact in much the same way as the ones in our seen universe interact with each other. That is the justification for calling them universes. The justification for calling them parallel is that they hardly interact with each other, like parallel lines that do not cross. That is an approximation, because interference phenomena do make them interact slightly. So, that is the sequence of arguments that leads from the parallelism, which by the way is much less controversial at the microscopic level than the macroscopic level, right up to parallel universes. Philosophically, I would like to add to that that it simply does not make sense to say that there are parallel copies of all particles that participate in microscopic interactions, but that there are not parallel copies of macroscopic ones. It is like saying that someone is going to double the number of pennies in a bank account without doubling the number of Pounds."

I fail to see how, for instance, Bohmian mechanics would give different observable results than MWI-QM. Now of course, I am also sensitive to the argument that Bohmian mechanics has some MWI flavor to it

I am with you- I see the neo-MWI honed form Quantum Computing as a new and improved version of Bohm's ideas- they say essentially the same thing about parallel universes- only with Bohm it was not as clear what the nature of the Implicate was- with MWI we can say it is parallel states/histories

Well, I also find this the most obvious interpretation of the formalism, but on purely formal grounds. I don't see how one can experimentally PROVE this view, given that it is empirically equivalent to Copenhagen with the Heisenberg cut far enough away, or to Bohm. It is for formal ugliness that I don't like these interpretations, not for their empirical falsifiation.

as I said I think QC shows that the MWI is currently the only known interpretation that is tenable [mainly because quantum factoring easily makes computations that exceed the resources of the observable universe!]- but Deutsch claims PROOF- and his arguments are Nobel-Prize strong- and I haven't seen ANY peer-reviewed challenges against his claim- so as far as I can see this is about the best proven claim in modern physics at the moment-

which is why I am quite shocked to see Zapper's reaction!

to get an indication of the validity of MWI... one needs to put in superposition, and show interference, of VERY MACROSCOPIC systems (ideally, say, a planet)... As long as we don't have a verified theory of quantum gravity, the possibility exists that superpositions of gravitationally important systems does not work, which would be the end of MWI. I fail to see how quantum computing proves this wrong.

Seth Lloyd's Quantum Computational Cosmology focuses on the Quantum Gravity issue directly- and it must be noted that decoherence is not absolute- but a diminishing gradient of interaction that NEVER reaches zero- so it can be said that ALL macroscale objects are at least in a very weak form of superposition from any specified observer at all times- pennies and pounds

 

[ZapperZ]

PEER REVIEWED documentation has already been provided!

here are some of the main papers and their citebase stats-

http://xxx.lanl.gov/abs/quant-ph/9906007
http://www.citebase.org/cgi-bin/citations?id=oai:arXiv.org:quant-ph/9906007

http://xxx.lanl.gov/abs/quant-ph/0104033
http://www.citebase.org/cgi-bin/citations?id=oai:arXiv.org:quant-ph/0104033


http://www.arxiv.org/abs/quant-ph/0210204
http://www.citebase.org/cgi-bin/citations?id=oai:arXiv.org:quant-ph/0210204

FINALLY! And after asking for, what, THREE separate times?

Why did I ask for specific citation? Because it exposes the fact that you have a WRONG conclusion. If you think that these three papers are EXPERIMENTAL verification of MWI and nothing else, then you have no clue on what experimental verification is. Show me where in these papers are there any experimental results, much less results that conclusively "prove" MWI is the only valid interpretation of QM.

here are some of the research programs that are using the observed behavior of this experiment for quantum computation research:
http://www.vcpc.univie.ac.at/~ian/hotlist/qc/research.shtml


this is quite unbelievable and you are abusing this forum with your empty claims that this is not rigorously peer reviewed science- this research has been at the forefront of mainstream quantum mechanics for nearly a decade now- any user of physicsforums claiming to be a mentor should know all of this already- it says in your profile that you are physicist zapper- I guess I am dissapointed that you are not giving us more information about this news and are instead actually arguing against it?!?

I will report any abuses against this peer-reviewed research to Warren-

Your rabid devotion to MWI has caused you to cloud your judgement and made you halucinate things that isn't there. I challenge you to cite exactly where in this thread, or any other thread, where I have dissed MWI and consider it to be an invalid area of physics. This isn't about MWI. It is about YOUR conclusion that (i) MWI is widely accepted and (ii) there are experimental evidence that unambiguously verify MWI and nothing else! This is what I am questioning, NOT MWI. But you seem to have confused those two, and somehow, questioning you implies questioning MWI. Horrors!

If someone comes in here and start bad-mouthing MWI by claiming that there are experimental evidence that invalidates MWI and uses the same trick as what you did, I would have given him/her the SAME smackdown as I did for you.

You have not shown any valid experimental evidence that singly distinguish MWI over other interpretation. Unless you can provide citation otherwise, I strongly suggest you no longer make that kind of conclusion on here.

Zz.

 

[setAI]

how are these MY claims? these are David Deutsch's claims and he has backed them up more so than any scientist in living memory!- and I have given him full credit- I accept his arguments and his empirical evidence [as do most in the field: http://www.edge.org/3rd_culture/prize05/prize05_index.html ]- before I discovered his work I loosely agreed with Bohm's model- so much for me being a 'rabid' proponent of the MWI!

for the record- I provided you [before you asked the 'first' time] with

-a video document of a lecture followed by experiment which claims and then shows the MWI in action

-huge amounts of corroborating PEER-REVIEWED publications predicting the results of this experiment and it's implications

-a huge list of accredited institutions that have reproduced the experiment to perform optical quantum computing

-several quotes from David Deutsch that reinforce his arguments that the MWI is verified and all non-local interpretations are unphysical-


"...you have a WRONG conclusion. If you think that these three papers are EXPERIMENTAL verification of MWI and nothing else, then you have no clue on what experimental verification is. Show me where in these papers are there any experimental results, much less results that conclusively "prove" MWI is the only valid interpretation of QM.
...You have not shown any valid experimental evidence that singly distinguish MWI over other interpretation. Unless you can provide citation otherwise, I strongly suggest you no longer make that kind of conclusion on here."

the above citations demonstrate that this is a false statement on your part- the MWI as the only valid interpretation is demonstrated at length in all of the above [you should be aware that nearly every example of optical quantum computing reproduces the experiment to perform computations- the very existence of these quantum computers verifies the experiment!]- as well as repeatedly and directly by David Deutsch HIMSELF- do you claim then that David Deutsch has the wrong conclusion and that his claim of MWI being verified is somehow flawed?

you have failed to offer a single link to ANYTHING that even tries to challenge David's claims- as far as I know there are no such challenges currently- I certainly haven't found any- I actually have been trying to find some-

 

[Farsight]

Interesting, er, debate.

I looked briefly at the "Lecture 2 worked examples", and what do I see in the first sentence:

Suppose that photons are classical impenetrable spheres.

No, I won't.

And I have to say that as I speak I just don't buy MWI. But I'll enjoy looking at the links, and you never know. Thanks for posting them up setAI.

 

[ZapperZ]

how are these MY claims? these are David Deutsch's claims and he has backed them up more so than any scientist in living memory!- and I have given him full credit- I accept his arguments and his empirical evidence [as do most in the field: http://www.edge.org/3rd_culture/prize05/prize05_index.html ]- before I discovered his work I loosely agreed with Bohm's model- so much for me being a 'rabid' proponent of the MWI!

for the record- I provided you [before you asked the 'first' time] with

-a video document of a lecture followed by experiment which claims and then shows the MWI in action

-huge amounts of corroborating PEER-REVIEWED publications predicting the results of this experiment and it's implications

-a huge list of accredited institutions that have reproduced the experiment to perform optical quantum computing

-several quotes from David Deutsch that reinforce his arguments that the MWI is verified and all non-local interpretations are unphysical-

Again, where is the EXCLUSIVITY in these verifications? In many results, the agreement can be on a number of DIFFERENT scenario! I asked for specifically experimental results that ONLY agrees with MWI, and NOT anything else. All you have claimed that so-and-so agrees with MWI, but then again, a number of interpretations do also!

The paper you cited (at you never gave me SPECIFIC citations till a couple of posts ago) were NOT experimental verifications of anything, and much less, an experimental verification that verified ONLY MWI. If you think they ARE experimental evidence, then you have a strange way of classifying as what is "experimental" results!

"...you have a WRONG conclusion. If you think that these three papers are EXPERIMENTAL verification of MWI and nothing else, then you have no clue on what experimental verification is. Show me where in these papers are there any experimental results, much less results that conclusively "prove" MWI is the only valid interpretation of QM.
...You have not shown any valid experimental evidence that singly distinguish MWI over other interpretation. Unless you can provide citation otherwise, I strongly suggest you no longer make that kind of conclusion on here."

the above citations demonstrate that this is a false statement on your part- the MWI as the only valid interpretation is demonstrated at length in all of the above [you should be aware that nearly every example of optical quantum computing reproduces the experiment to perform computations- the very existence of these quantum computers verifies the experiment!]- as well as repeatedly and directly by David Deutsch HIMSELF- do you claim then that David Deutsch has the wrong conclusion and that his claim of MWI being verified is somehow flawed?

Er... could you show me a quantum computer, please? I'd like to see where this thing exist, and how it somehow ONLY agrees with MWI and nullifies others.

Again, simply by agreeing with MWI results does not imply that other scenarios have been disqualified. This is simple logic. And you have been extremely liberal in your usage of the word "proof" here. There is no such thing as "proof" of any theory in physics. You can tell Deutsch that! However, after reading many of his work, I highly doubt that HE, of all people, would use that word in trying to sell this.

you have failed to offer a single link to ANYTHING that even tries to challenge David's claims- as far as I know there are no such challenges currently- I certainly haven't found any- I actually have been trying to find some-

And again, as you have failed in my last challenge to you to show where in any of my posts was my intention to challenge MWI, why is this about MWI? There have been MANY discussions about MWI in this forum one way or the other. I never once feel any need to challenge any of them because, frankly, there isn't any need for it. I never challenge any of the Bohm's pilot wave scenario either, etc.. etc. So why would I feel the need to offer ANYTHING again MWI? I have NOTHING against it, and this is the point that you somehow cannot get through your head. I am indifferent towards all of these "interpretation" of QM because they do NOTHING for me.

However, when someone comes in here and start making such outlandish claim, then I asked for VALID CITATION, something you could have given me right after my very first post, rather than pointing to some website and having me hunt all over it. I gave you a specific citation of Tony Leggett's paper as an example of where nothing about MWI was used, EVEN when I have cited that paper numerous times and could have easily asked you to go hunt for it. But noooooo... I carefully made a complete reference to the paper just in case you wanted to go look at it and double check my claim. I was hoping that you'd at least extend the same curtosey and provide exact reference to back up your claim. It was like pulling teeth!

And then what did I get? No experimental papers!

Zz.

 

[vanesch]

not according to Deutsch- the Copenhage interpretation predicts that in Deutsche's experiment the photons would appear at BOTH detectors at the end- MWI predicts just the right detector- and this was experimentally confirmed-

This is what I don't understand: as I said, if you put the Heisenberg cut in Copenhagen/von Neumann far enough back (say, at the level of the person looking at the result of the quantum computation), then both are equivalent in their predictions, so I don't see how "Copenhagen" can predict anything different from MWI, UNLESS it is a specific version of Copenhagen where certain systems are declared being "classical" which turn out not to be so.

But the point is: MWI cannot be "somewhat" true. If it is "true up to a certain level of macroscopicity" then it is a form of Copenhagen !

Let us not forget that there are as many "Copenhagen" flavors (with DIFFERENT empirical predictions) as there are ways to put the Heisenberg cut (meaning: different ways of defining what are "measurement apparatus").
If you say that photons are "measurement apparatus" then you have a version of Copenhagen that is easily falsified because any interference experiment would do so.
If you say that "atoms" are measurement apparatus, but not photons, then optical interference is predicted, but not, say, Stern-Gerlach experiments.
If you say that not atoms and photons are measurement apparatus, but only buckeyballs, or golf balls, or humans or ... then you make these "Copenhagen" flavors come closer and closer to MWI predictions.

So when you say something about "Copenhagen predicts this, and MWI that", it is necessary to say WHAT FLAVOR of Copenhagen predicts this (in other words, what has been declared "measurement apparatus" in the given flavor). And it is sufficient to remove the culpable object from the list of "measurement apparatus" to find out that we have now a *different* prediction of Copenhagen.

In fact, von Neumann said that we have to put the Heisenberg cut "far enough" so that it doesn't make any difference anymore: if you do so, you will NEVER find a disagreement with MWI's predictions.

 

[ZapperZ]

Hey vanesch,

Would you consider the Penrose proposal[1] of superposition using mirrors involving 10^14 atoms as a "macroscopic" interference and thus, extending this cut off? Or is this cut off not defined by the scale of coherence but rather the "interacting" system?

Zz.

[1] W. Marshall et al., PRL 91, 130401 (2003).

 

[Schrodinger's Dog]

as the reference to the poll indicates- it is MWI- since this poll the MWI has been experimentally verified http://www.quiprocone.org/Protected/Lecture_2.htm - since around the year 2000 the Everett interpretation has been confirmed as the only EXPERIMENTALLY VALID interpretation of QM- all other [non multiverse[ interpretations no longer fit with observations- as a result we now have the field of quantum computers- which are only predicted and described by the Everettian MWI-

I read this out to my colleague at work and he laughed? Which I'm glad about because frankly, I've always seen MWI as a complete cop out, with no real way of obtaining proof of alternate realities, I find it hard to believe someone has, who knows I may read the link later so I can really giggle myself hoarse.

I'll also have to remember that becasue of MWI the researchers can get to grips with quantum computing, there's me thinking it was because of mainstream physics? I may have a basic understanding of physics and the various interpritations but I certainly favour the two slit proofs over some science fiction novelists wet dream. Tell you what get me to send myself a postcard from the other universes and if I get it I'll believe this hocus pocus.:tongue:

 

[vanesch]

Hey vanesch,

Would you consider the Penrose proposal[1] of superposition using mirrors involving 10^14 atoms as a "macroscopic" interference and thus, extending this cut off? Or is this cut off not defined by the scale of coherence but rather the "interacting" system?

Zz.

[1] W. Marshall et al., PRL 91, 130401 (2003).

Didn't read your reference (I'm pretty busy for the moment). I take it you allude to one or other variant of the Felix experiment.

The point Penrose was trying to make was: from the moment that gravity becomes an appreciable interaction (even ever so tiny), "collapse" would occur. Mind you that we don't have any counter example! Even in "macroscopic" quantum phenomena such as superconduction, with a big number of involved degrees of freedom, the gravitational difference between the different terms in the superposition is entirely neglegible.

Now, the problem I see is that from the moment we try to put something in a superposition, such that the contributing terms are gravitationally different, we usually have already so many other interactions going on that the different terms decohered, and no quantum interference is possible.

So Penrose wanted to put an object (the mirror) in a quantum-mechanical superposition of positions, such that it would count for a tiny gravitational difference, and in such a way that no decoherence occurs otherwise. Not much of course! Probably not even measurable. A mirror in superposition would reflect a photon differently than a mirror in a mixture, and his experiment is designed in such a way as to find out the difference between the two kinds of reflection, by showing an optical interference pattern or not.

But I'm somewhere affraid that - apart from the difficulty of doing the experiment in such a way that no decoherence happens by "trivial" means, I'm affraid that his setup misses the point. Because if it is true that the two different mirror configurations in the superposition have different gravitational contributions, then THROUGH GRAVITATIONAL INTERACTION, they will get entangled with other stuff (say, some air molecule or something). Now, as one cannot "shield" gravitational interaction, I don't see how one can avoid this entanglement to take place, and hence how decoherence TRHOUGH GRAVITY will be avoided.

Now, Penrose's a much smarter guy than I am, so he must have thought of this. But I never saw an account that dealt with the problem.

It is a bit as if one wanted to show that EM charge destroys superposition, and one wants to put a 1 microCoulomb object in a superposition of two positions at 10 cm apart. It is almost sure that no interference effect will be observed, because I don't know how you can avoid a 1 microcoulomb charge not to interact (and hence entangle) with something else. And there's more hope for the charge, because there's maybe a shielding technique using superconductors or so ; something that is not available for gravitational interaction.

 

[Max_Sukharev]

2setAI,

just so you know - THERE ARE NO EXPERIMENTS, which confirmed "mutliverse" interpretation.

 

[DrChinese]

I'm sorry guys. You lost me ages ago. Are there major conclusions about QM that all the interpretations agree on?

I think most of them would match your #2: That no greater description of reality is possible in principle. This covers Copenhagen and MWI, as well as the Relational and Transactional interpretations at this time. There are attempts being made to identify experimental opportunities to distinguish these. You can see from the comments above that there has not been any breakthrough to date that is generally accepted.

 

[DaTario]

1. The VERY FACT that one can conduct A POLL on this means that the acceptance of some form of interpretation of QM means it is still A MATTER OF TASTE! Real physics isn't done this way. You cannot simply adopt something and call it physics when all you can base it on is PREFERENCE! So by the very act that you are citing A POLL of OPINIONS shows CONCLUSIVELY that this is NOT a done deal! Don't you see this?

If you don't believe me, show me any other part of accepted physics that is done via such a popularity contest. Did the acceptance of BCS Theory of Superconductivity done via such a similar poll? Or was it simply based on an astounding body of evidence?

I believe that some part of the physics procedure is governed by preferences. Looking at reality is not an action which has only one way. Reality is constructed by our way of looking at it instead of captured simply.

Some examples may be pointed out as for example, the pseudo vectorial character of some electrical concepts.

 

[Tipi]

The reason is that in order to get an indication of the validity of MWI, that one needs to put in superposition, and show interference, of VERY MACROSCOPIC systems

Hi vanesh,

I miss your point in this quote. Could you help me with a little precision?

Also, I don't understand some things about the MWI. I'm sure you will easily help me.

First, I'm not sure it is a universe of what that split under a measurement. Is it a universe of matter? Is it a universe of possibility? Is it a universe of experimental prediction, of phenomenon, of events? What is the definition of a universe in the MWI?

Secondly, my understanding of the MWI make me think that a proponent of it has choosen between these two possibilities:
1. We add a universe (of something) in our theory in order to eliminate the measurement problem.
2. We remove a part of the wave function (the collapse) in order to explain the experimental fact.

I'm interested, if these two points are not stupid, in an argument that point towards number 1. I don't know why, but at this moment, I prefer to choose to remove the little part instead of adding the gigantic one...



Thank you very much for your help, and the help of anyone else interested,


Tipi

 

[Tipi]

Ok, I have read your (very nice) posts https://www.physicsforums.com/showpost.php?p=1012700&postcount=9".

Some points are clearer, but I still don't get what is a universe. Suppose (like in Bohmian Mechanics) that we have more than one point in the configuration space, each point representing the state of the object under consideration and the state of the observer corresponding. Since we have different point, we have different "observations". These different observations come from different what?

Do I have many body, one corresponding to each point? Do I have only one body and many-minds, one mind for each point? Or do I have only one body and one mind, but many universe, one corresponding to each point?

Are these choices only a matter of taste?

Thanks,

Tipi

 

[kvantti]

I have a question that I'm confused with. It's about the delayed quantum eraser experiment [http://www.bottomlayer.com/bottom/kim-scully/kim-scully-web.htm].

According to Copenhagen interpretation, wouldn't the superposition of the second photon collapse at every interaction it has with the measuring apparatus? That would be, with the PS, BSA, BSB and the "eraser" BS. And yet, if the quantum information of the which path information is lost, it would seem to us that the photon went thru both slits; even tho it had to interact with the beam splitters to get to the eraser.

The result is consistent with the HUP, but for me this seems to be a failure of the copenhagen interpretation... unless I'm confusing something.