Re: Is State Vector Reduction a 'Process'?
- From: "Seratend" <ser_monmail@xxxxxxxx>
- Date: Sat, 28 May 2005 09:14:29 +0000 (UTC)
Aaron Bergman a =E9crit :
> In article <1117095659.166639.149930@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
> Seratend <ser_monmail@xxxxxxxx> wrote:
>
> >
> > I understand you seem to adopt the copenhagen interpretation.
>
> I don't believe in any 'interpretation' of quantum mechanics. I'm just
> confused by all of it. As I said elsewhere, in my ideal world, there
> would be a physical collapse process leading to the emergence of a
> classical world. Unfortunately, I'm not sure I believe that's likely.
>
Ok, I also prefer to leave interpretation to philosophy : ).
I have another question: what do you call a classical world. Frankly I
do not understand that. QM deals only with statitistics of outcomes
and, in my opinion, outcomes are the "classical world" (what we "see").
Therefore, it is relatively difficult for me to understand people who
want to demonstrate that there is a physical collapse leading to the
outcomes.
I can only understand this sentence as the quest for a deterministic
(causal) description of outcomes compatible with the statistics of QM.
If this is the case, we already have such a description, bohmian
mechanics for the position eigen basis (and equivelent formulations in
different eigenbasis).
As in classical probability, I can work with the statistical
description it provides whenever its results are more practical than
the ones of a deterministic description explaining the outcomes. I have
a mathematical separation in the desciption of outcomes: statistical or
deterministic. Both are ok. Choosing one versus the other is only a
matter of taste rather than a necessity.
Hence my non understanding of the quest of a physical collapse behing
the outcomes of QM.
This subject as you have already noticed is different from the problem
of the preferred eigenbasis and the decoherence (the analog of the law
of large numbers in QM).
> I'm not sure I understand what you're asking. Let me try to answer
> something, then. The question of what why we observe what we observe is
> completely unanswered by quantum mechanics.
So you are saying that QM theory does not explain the preferred basis.
> This, however, is a different issue of the existence of the basis for o=
bservation.
I do not understand you. To describe the observation of something I
need a basis. For example, in the deterministic world, a signal s(t) is
well described by s(t) or its fourier transform ^s(w). However, I
usually see the values of the signal at every time (s(t) and not the
values at a given frequency).
> As you seem to agree, the diagonalization of the density matrix in a gi=
ven
> experimental setup determines a preferred basis.
No, I just say that we obtain a basis. I just question, if it is
another postulate. As if I take QM postulates, I may apply the collapse
postulate to this local state in any basis I want (especially one
different from the eigenbasis:
for any diagonal density matrix I have: rho=3D sum_i pi|ai><ai|
Choosing another basis:
|ai>=3D sum cij|bj>
=3D> rho=3D sum_i pi.cij.cik* |bj><bi|
rho is no more diagonal. Both eigen basis are possible for the
measurement outcomes as expressed by the QM postulates.
> The connection between this basis and our perception of reality is too =
hard a question for me,
> but it seems to be right.
>
Well if you accept decoherence, you may accept the situations where the
interaction between the environment and the system is so weak, that in
a first approximation, no entanglment as occured. In this case, what
eigenbasis do we select?
> [...]
>
> > My question regarding this theory remains: does QM theory explain the
> > preferred basis or not?
>
> QM (ie, decoherence) explains how preferred bases arise in experiments.
> It does not explain why we perceive what we perceive.
>
If I take 2 experiments: the observation of double slits interference
and the emission of radiation of an hidrogen gas. In one case I see,
the position (an interference) and in the second case the energy
eigenstate of the H atoms. Frankly, I see no common preferred basis and
the last observer is the human (the projector) in this example.
How decoherence is able to explain/solve this difference in this
preferred eigen basis observation?
Seratend.
.
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