Copenhagen interpretation of Quantum Theory

[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.

 

[GreenPenInc]

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

It seems a little rich to associate Gell-Mann with Many Worlds, since he helped develop the Consistent Histories formalism.

EDIT: Just noticed how old the poll was. Still, though, it's worth noting that he's evidently changed his views significantly.

 

[shapke]

know this thread is damn old but anyway...
none of you guys remembered to mention 1997 poll where Copenhagen won and minor 2000 one when MWI was last

 

[i8pieyay]

for everyhting else i do not know but i do know that the part about matter well electrons effecting other across the universe is possible its known as "string theory"

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.

 

[i8pieyay]

also i beliave in the many worlds theory but the many minds theory I am not sure about its true we all exist on a certain level of consciousnees but could they be altered or many for that matter who knows

 

[Dmitry67]

Interesting... In MWI, or "pure" QM + decoherence any measurement, in principle, can be "undone" (even it is difficult to do). Hence, it can be experimentally proven that CI is wrong.

 

[Ilja]

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

Wrong. Nothing in this paper shows any problem for pilot wave theories or other non-local interpretations.

 

[Ilja]

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.

Delayed choice experiments are no problem for Copenhagen, because in Copenhagen a measurement is only a measurement after macroscopic amplification. Once the choice is delayed, we conclude that the measurement in the Copenhagen sense is delayed too.

Ilja

 

[Minich]

Any theory or interpretation can be valid forever, if it is not limited by the number of assumptions.
Ptolemeus geocentryc system can be valid now if we admit ANY number of epycircles and other parameters.
Copenhagen interpretation can be valid forever, if it is not limited by the number of assumptions.

 

[Dmitry67]

Good point... Copenhagen is a total mess of epycircles :)
Macroscopic systems built from microscopic particles. At the same time properties of these microscopic particles are defined based on the macroscopic measurements. Dead recursion, no hope for any axiomatisation. Fuzzy definitions for 'what is macroscopic'? 'what is a measurement'? what is a 'knowledge?' Epycircles everywhere :)

 

[Dmitry67]

BTW questions for the proponents of the CI
What flavor of CI do you prefer?
Based on http://en.wikipedia.org/wiki/Interpretation_of_quantum_mechanics#Comparison there are 3 different versions of CI

 

[Gear300]

The Copenhagen Interpretation is a "for-all-practical-purposes" interpretation (and an interpretation nonetheless). It simply takes into account that if we don't have the experiment or other sustainable proof for it, then it is left to interpretation; and for the most part, since the Quantum Theory works out very well, "for-all-practical-purposes" we may leave the question to interpretation for the time being.

 

[Minich]

As i know there are many other interpretations.
For example Plank - De Broigle interpretation (zpe/zpf: see Google search). Even Shroedinger equation can be deduced from this interpretation (De Broigle wave is Doppler shift of vibrating particle in zpf).

I always interpreted spontaneous emission as induced emission in zpf and it was very useful for quantum calculations :)

And by now Copenhagen and ZPF interpretations give equal numbers :)

 

[SixNein]

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

I thought that MWI caused problems with quantum computation because of quantum decoherence?

Doesn't this research show an objective reality? Also doesn't MWI reject an objective reality?
http://www.sciencedaily.com/releases/2009/03/090304091231.htm

 

[Dmitry67]

On the contrary, MWI is one of few interprettions where wefunction is REAL
Regarding Hardy's experiment there is nothing new except the experimetal part of it
About "I thought that MWI caused problems with quantum computation because of quantum decoherence?" - I don't know what you are talking about, but there is no known way to tell one interpretation from another, so if it would 'cause problems' then there will be a way to do it -> Nobels prize :)

 

[Pollock]

I don't accept that the MWI is a necessarily favoured alternative to the Copenhagen interpretation,and I would like to hear how others view Cramer's Transactional interpretation and also the Bohm alternative.