Copenhagen Interpretation of Sleep / Unseen brain?

[bhobba]

I know that some % of experts do in fact regard consciousness as causing the wavefunction collapse.

Its a very very small percentage. It originated from an argument Von Neumann made in his highly influential Mathematical Foundations Of Quantum Mechanics. But since then we understand decoherence a lot better and its now realized his argument no longer holds water. Personally I believe the very small percentage that do haven't thought about the issue carefully enough.

Otherwise what initiates a "measurement" ?

Interaction causing entanglement.

Why does not a particle's expanding wavefunction

Wavefunctions do not in general expand - instead they get entangled with the environment.

Thanks
Bill

 

[themaea]

It doesn't explain why you do. Technically it's why an improper mixed state is a proper one.
http://philsci-archive.pitt.edu/5439/1/Decoherence_Essay_arXiv_version.pdf

Thanks
Bill

atyy, bill.. I think there is a mistake inside the paper above.. specifically in section 1.2.3 where:

"However, note that even though 2 = 3, their physical interpretation is not
quite the same. System 2 is in a definite deterministic physical state, whereas
system 3 is part of a composite superposition state. Its physical state is truly
undetermined, as long as no measurement is performed on \part B" of system
3 (that we removed from our control). System 2 is said to be a proper mixture,
versus system 3 which is in a improper mixture. When a measurement
is performed on the discarded part B of system 3, but we are not told of the
outcome (ignorance), system 3 reduces to a proper mixture, and systems 2 and
3 are then physically identical."

The mistake is for system 3 to reduce to a proper mixture.. there is a collapse somewhere.. whereas in system 2.. there is no issue of collapse.. so how can they be physically identical?

 

[bhobba]

The mistake is for system 3 to reduce to a proper mixture.. there is a collapse somewhere.. whereas in system 2.. there is no issue of collapse.. so how can they be physically identical?

Because there is no way observationally to tell the difference.

They are INTERPRETATIONALY different however - remember collapse is an interpretational thing.

Thanks
Bill

 

[atyy]

atyy, bill.. I think there is a mistake inside the paper above.. specifically in section 1.2.3 where:

"However, note that even though 2 = 3, their physical interpretation is not
quite the same. System 2 is in a definite deterministic physical state, whereas
system 3 is part of a composite superposition state. Its physical state is truly
undetermined, as long as no measurement is performed on \part B" of system
3 (that we removed from our control). System 2 is said to be a proper mixture,
versus system 3 which is in a improper mixture. When a measurement
is performed on the discarded part B of system 3, but we are not told of the
outcome (ignorance), system 3 reduces to a proper mixture, and systems 2 and
3 are then physically identical."

The mistake is for system 3 to reduce to a proper mixture.. there is a collapse somewhere.. whereas in system 2.. tere is no issue of collapse.. so how can they be physically identical?

System 2 is already a proper mixture, so you can think of it as already collapsed.

 

[ynon]

1977ub: I like to think my approach to QM is commonsensical though common sense may not always apply to QM at this time. I don't know the transition between QM and classic reality or if there even is one but I don't think consciousness has anything to do with it. The principles of QM were operating many years before consciousness.There should be some transiton I would think.

Think of wave-particle duality. Recently controversial. Experiments " prove it is a particle". Other experiments "prove it is a wave". It could be both and we simply see different views of the same phenomena. For an analogy think of a quarter spinning on a table.You see heads and tails superimposed, the quarter collapses and you see heads or tails. It decided on tails or heads before you observed it as heads or tails. .

.You see a fallen tree laying on the ground, you didnt see it fall. Observation causing it to be fallen means you caused it to fall in the past. Unlikely.However without an observer to hear it fall it would not produce sound because sound is what is heard. A lady was bragging about her new hearing aid. Her friend asked what kind it was. She replied, " 12:30".

A large % of experts do regard consciousness as causing the wavefunction collapse .Some dont. It would explain some things but that is no proof. . Also MWI is just conjecture and is nice for Sci-fi story lines but the fact that it would explain some things isn't much of a proof. There being a God would explain many, many things but is no proof. My humble opinions at this time.

 

[rootone]

A large % of experts do regard consciousness as causing the wavefunction collapse .

Um, source please?

 

[ynon]

rooton: Sorry about that . My source was 1977ub. I incorrectly remembered him saying large % instead of small and didnt notice as I was discounting them altogether anyway. I will double up on the ginko biloba. Works if you remember to take it. I don't believe consciousness causes wave function collapse. .. It is unfortunate that any believe this. Makes for great Sci-fi though.

 

[bhobba]

Think of wave-particle duality. Recently controversial.

Not recently.

It was chucked in the bin in 1926 when Dirac came up with his transformation theory - likely sooner.

Please don't get hung up on this. We spend far too much time here arguing about this point. Its in beginner texts but not advanced ones. If you want to develop a modern understanding of QM forget about it.

Thanks
Bill

 

[Derek Potter]

The mistake is for system 3 to reduce to a proper mixture.. there is a collapse somewhere.. whereas in system 2.. there is no issue of collapse.. so how can they be physically identical?

I think he means they end up the same, not that they are the same from the beginning.

Hensen's mistake, if any, is in System 2 where he glosses over the fact that we choose a state at random from a "reservoir". Remember, this choice is part of the physical preparation of the system, it is not the mathematician's trick of choosing a typical member of an ensemble. In a quantum universe the choice is quantum and thus system 2 is an entanglement of A with the chooser and therefore identical to system 3 which is defined as improper!

As Kirkpatrick says "The proper mixture cannot be created".

I suspect system 2 can be rescued if you postulate wavefunction collapse so that the entanglement is broken. This is exactly what happens to system 3 - the measurement on B is assumed to result in a definite outcome, which implies wavefunction collapse.

I am convinced the distinction between proper and improper mixtures is an artifact that only appears under the assumption of collapse. Since the latter is optional - or as bhobba says, interpretational - it would appear to be a distinction without a difference.

 

[ynon]

Bhobba: I guess I felt the controversy recent because of older texts on the matter I do agree it is best not to get hung up on it though.Funny how people interpret things differently.Is a glass half full or half empty? A car accident can elicit many different but honest versions of the same incident. To me Dirac transformation seemed to validate wave-particle duality.All I have been crudely saying is what Wikipedia says below.For an analogy of the appearances I think of a quarter spinning on a table.You see heads and tails superimposed, the quarter collapses and you see heads or tails.Head or tail, same quarter. Only an analogy of course. .
I see what you mean, we are only talking about apparent aspects as it were. Not true waves or particles. I did know that but didnt specify.. A matter of semantics.
As the Beatles said, " and nothing to be hung about".I am wadeing through the Hilbert space thingy now.. Thank you.

"The term transformation theory refers to a procedure and a "picture" used by P. A. M. Dirac in his early formulation of quantum theory, from around 1927.[1]
(The term further sometimes evokes the wave-particle duality, according to which a particle (a "small" physical object) may display either particle or wave aspects, depending on the observational situation. Or, indeed, a variety of intermediate aspects, as the situation demands.)"Wikipedia

 

[bhobba]

"The term transformation theory refers to a procedure and a "picture" used by P. A. M. Dirac in his early formulation of quantum theory, from around 1927.[1](The term further sometimes evokes the wave-particle duality, according to which a particle (a "small" physical object) may display either particle or wave aspects, depending on the observational situation.

Wikipedia is usually solid - in this case it isn't.

Here is the correct historical context:
http://www.lajpe.org/may08/09_Carlos_Madrid.pdf

The transformation theory shifted QM to the state as the fundamental object - not matrices as in matrix mechanics, or wave as in wave mechanics.

Thanks
Bill

 

[Derek Potter]

Thanks
Boill

New sig, bhobba? :)

 

[ynon]

Bhobba: Thank you. I seek clarification and see why the term wave-particle is outdated. Still in lab at U of H and SWT light appeared to behave like waves or particles whether they were or were not. Maybe wave-appearing / particle-appearing duality would be more appropriate.Is there a word to call this characterist of light that is more succinct than: " MM and WM must always yield the same empirical decisions".?
"
Wikipedia needs your or someones input on this to include a more recent interpretation or definition with what they wrote.

It's still ham no matter how it is sliced. The word " matter" has different meanings depending on the context.Slice is one thing to a butcher and another thing to a golfer. "Pressure" has different meanings to a psychologist or gas station attendant. Define "is" . A defense used by a former president.

 

[bhobba]

Hi Ynon

You will find many threads discussing the issue - it will not be appropriate to rehash them. They tend to be long and simply go around in circles because ideas said in many beginning texts/popularisations are challenged and they are challenged by more advanced material the beginner may not understand the details of, so have to take the word of others.

But if you want to read about it here is a good article:
http://arxiv.org/abs/quant-ph/0609163

Also see our FAQ:
https://www.physicsforums.com/threads/is-light-a-wave-or-a-particle.511178/

Note,, while the paper above specifically states it, please keep in mind what it refers to as a wave is shorthand for wave-fuction, which is different to a wave eg waves are not complex values nor invariant to phase changes.

Here is a much much better foundation for QM than waves particle duality:
http://www.scottaaronson.com/democritus/lec9.html
http://arxiv.org/pdf/quant-ph/0101012.pdf

Thanks
Bill

 

[Feeble Wonk]

I'm actually not fond of Schlosshauer's description. I prefer the classic how to have quantum mechanics without a fundamental status for observers.

I'm not sure how you meant this. Are you saying that "classical" (I'm assuming that the same as "standard") Copenhagen interpretation still places a fundamental status on the role of the observer?

 

[Feeble Wonk]

Or maybe a better way of asking... Are you saying that the "measurement problem", as still viewed by Copenhagen, ultimately suggests a fundamental role of the observer?

 

[bhobba]

Or maybe a better way of asking... Are you saying that the "measurement problem", as still viewed by Copenhagen, ultimately suggests a fundamental role of the observer?

You have to understand observer in QM is not necessarily an organic conscious observer. In modern times its anything that causes decoherence ie is an interaction. With that in mind in Copenhagen observer is absolutely fundamental.

Thanks
Bill

 

[Feeble Wonk]

Thanks. That had been my understanding. I just wasn't certain that's what Atyy had actually meant.