Does Decoherence Solve the Measurement Problem Completely

now there are two options
1) change nature
2) change our ideas about nature
for me 2) is acceptable, but that's a matter of taste ;-)

I am not sure whether you understand what I am saying.

QM tells us a lot about nature; it makes experimentally provable and correct predictions, something that was not the case with classical mechanics! There is no single experiment which tells us that QM (in the sense of its predictions is wrong)!

We should make a clear distinction between
1) QM as a theory of nature = a formalism to predict experimental results
2) our ideas about or philosophy of reality
3) an interpretation of QM and its relation to 2)
4) the language we are using to talk about 1-4)
5) ...

QM has always proven to be "correct" in the sense of (1). The problems appear at the level of (2-4).

Btw.: we never ask the question "why" things work as they do in classical mechanics. Why do we not ask this question? Why do we ask this question in QM? Is it really true that we have a full understanding of these ideas in classical mechanics? I am sure the answer is "no".

Different interpretations quantum theory provide different insights, which are valuable even if the interpretations themselves turn out to be false. For example, the many-worlds interpretation was a key inspiration for the idea of a quantum computer, as proposed by David Deutsch, even though the idea itself does not require that interpretation. Similarly, the tension between de Broglie-Bohm theory and von Neumann's no-go theorem for hidden variables was the main driving force behind Bell's development of his eponymous inequalities. If you like, you can interpret those inequalities in terms of the ability of Alice and Bob to perform better in certain cooperative games using quantum resources than they could with classical resources without ever mentioning hidden variables, as many quantum information theorists are wont to do. However, it is unlikely that Bell's theorem would ever have been discovered were it not for the foundational context in which it first arose. What I was trying to argue in my article, is that the PBR theorem might have a similar status. Whilst it is inspired by the question of the status of the quantum state in a hidden variable theory, it may end up telling us something new about the differences between quantum and classical resources in general. We will never gain these new insights if we close off avenues for understanding quantum theory, even if we regard the foundational programs that they are associated with as unlikely to succeed in the long run.

To take a stand against the milieu, Asher had the idea that we should title our article, “Quantum Theory Needs No ‘Interpretation’.” The point we wanted to make was that the structure of quantum theory pretty much carries its interpretation on its shirtsleeve—there is no choice really, at least not in broad outline. The title was a bit of a play on something Rudolf Peierls once said, and which Asher liked very much: “The Copenhagen interpretation is quantum mechanics!” Did that article create some controversy! Asher, in his mischievousness, certainly understood that few would read past the title, yet most would become incensed with what we said nonetheless. And I, in my naivet´e, was surprised at how many times I had to explain, "Of course, the whole article is about an interpretation! Our interpretation!”

But that was just the beginning of my forays into the quantum foundations wars, and I have become a bit more seasoned since. What is the best interpretive program for making sense of quantum mechanics? Here is the way I would put it now. The question is completely backward. It acts as if there is this thing called quantum mechanics, displayed and available for everyone to see as they walk by it—kind of like a lump of something on a sidewalk. The job of interpretation is to find the right spray to cover up any offending smells. The usual game of interpretation is that an interpretation is always something you add to the preexisting, universally recognized quantum theory. What has been lost sight of is that physics as a subject of thought is a dynamic interplay between storytelling and equation writing. Neither one stands alone, not even at the end of the day. But which has the more fatherly role? If you ask me, it’s the storytelling. Bryce DeWitt once said, “We use mathematics in physics so that we won’t have to think.” In those cases when we need to think, we have to go back to the plot of the story and ask whether each proposed twist and turn really fits into it. An interpretation is powerful if it gives guidance, and I would say the very best interpretation is the one whose story is so powerful it gives rise to the mathematical formalism itself (the part where nonthinking can take over).

The “interpretation” should come first; the mathematics (i.e., the pre-existing, universally recognized thing everyone thought they were talking about before an interpretation) should be secondary.

Exactly.


Is there is clear explanation as to what it means to Record Infromation?
Depends on what you accept as clear. If you mean it explains the why of a particular outcome then no.

Can it explain the behaviour of a photographic plate?
Depends on what you accept as explain - for all practical purposes it does but if you want more than that - sorry - you are out of luck.


Thanks
Bill

I want to understand what is memory?

Then I suggest you study biology and psychology. QM doesn't really say anything about it - its concerned with fundamental physics.

In the past there was a reasonably well known consciousness causes collapse group in QM led by Wigner and Von Neumann. Von Newmann unfortunately and prematurely passed away but when Wigner first heard about decoherence he realised consciousness was no longer required and abandoned it. There is still a few hold outs such as Penrose and Hameroff but it is very much a minority thing now days. However you may find Penrose's views interesting:
http://www.amazon.com/Consciousness-...4230727&sr=1-1

Personally though to me its mystical nonsense - but a person of Penrose's stature can't be dismissed lightly.

I also have to admit I hold views many would put in the mystical nonsense camp in that like Penrose I believe in the literal existence of a Platonic realm where mathematical and fundamental physical truth lies but that is another story - as a warm-up though check out Wigners famous essay on it:
http://www.dartmouth.edu/~matc/MathD...ng/Wigner.html

Thanks
Bill

No I mean it in all seriousness. What is physics underlying the formation of a memory impression on a device.

There is no general answer - it depends on the device.

Thanks
Bill

the reason why we don't in classical mechanics is that classical mechanics fits to our perception whereas QM doesn't; QM was the first physical theory to which no Platonism, Aristotelism, Kantianism or any other XYZism had an answer; QM does not fit to the categories of our perception;

now there are two options
1) change nature
2) change our ideas about nature
for me 2) is acceptable, but that's a matter of taste ;-)

The reason we don't ask why in classical mechanics is because we know it's not fundamental, the answer will always reduce to a more fundamental theory.
So for those who think that QM is *the* fundamental theory, they have to explain why everything occurs really.

I would be happy to understand any one device, A photographic plate, Grieger counter or a PMT

The book to get is Ballentine - Quantum Mechanics - A Modern Development: http://www.amazon.com/Quantum-Mechan.../dp/9810241054

Here you will find QM developed from just two axioms and Schrodengers equation derived (yes derived - not assumed) from its true basis - Galilean Invariance.

Take your time, go through it carefully, and you will come away with a really good understanding.

Thank you for your responses.I could not look at the thread over the past week. I liked some of the answers(esp. tom & nanosiborg) and will over time try to respond to specific answers.

I would like to open some Issues for discussion. There is a usual approach to solution that goes by the name of "Universal Wavefunction". Which at some level posulates that there is an independent reality for the wavefunction which both the system under observation, and the measurement appratus must follow. Decoherence is one such approach, perhaps there are others.

Which if one assumes that measurement appratus exist, What the wavefunction really seems to be doing is it predicts the behaviour of our measurement appratus. One can only describe the experimental outcomes and the wavefunction seems to be predicting probable experimental outcomes. So without the precise experimental arrangement in mind it seems meaningless to talk about wavefunction and amplitudes.

While wavefunctions are an indespensible part of description, since it only tell us about the probability of the outcomes of experimental arrangements, Will a concept such as "Universal wavefunction" have any validity.

I think it is also important to understand that we cannot fully control the state of our appratus. Our limitations to do experiments do not allow us to precisely prepare the state of the appratus, We can only talk about preparation procedure, materials used, and similar concepts.