|Nov30-12, 11:28 PM||#86|
Does Decoherence Solve the Measurement Problem Completely
For convenience, here's some articles I found on PMT's:
Also I still have a copy of a paper that a friend and I scribbled some notes on the back of the printed pages (some of which isn't readily legible to me now), but couldn't find a link to a free copy for you to download (I could scan and post it for you, but that would be illegal):
Photometric Error Analysis. IX: Optimum Use of Photomultipliers. by A.T. Young
Of course you might be familiar with these and other explanations of PMT behavior and are still not satisfied that you understand it. If you have other, better articles then please post them here.
|Dec1-12, 01:19 AM||#87|
|Dec1-12, 08:29 AM||#88|
This: http://philsci-archive.pitt.edu/4224/1/scriptie.pdf is a very comprehensible analysis of decoherence, especially in the everettian context
|Dec2-12, 10:12 AM||#89|
I think in general it would be very material dependant and so on, But if we could isolate the essential process that is involved in it and to talk about it in a material indepentant manner, it would be nice.
I will point to some quotes that are of interest to me,
“We and our measuring instruments are part of nature and so are, in principle, described by an amplitude function satisfying a deterministic equation. Why can we only predict
the probability that a given experiment will lead to a definite result? From what does the uncertainty arise? Almost without a doubt it arises from the need to amplify the effects of single atomic events to such a level that they may be readily observed by large systems.”
". . . In what way is only the probability of a future event accessible to us, whereas the certainty of a past event can often apparently be asserted?. . . Obviously, we are again involved in the consequences of the large size of ouselves and of our measuring equipment. The usual separation of observer and observed which is now needed in analyzing measurements in quantum mechanics should not really be necessary, or at least should be even more thoroughly analyzed. What seems to be needed is the statistical mechanics of amplifying apparatus"
He empasises on the large sizes of ourselves and our measuring equipment.
"Observation must involve the concept of amplification which must expend free energy"
-N Bohr(slightly misworded but its alright)
He talk about the free energy cost involved in the measurement. I think is a generally correct in all situations, however currently only a heuristic principle, Clearly it is closely related to the landauer's principle who said that to measure one bit of information KT Log 2 amount of energy must be expended.
As I was thinking along these lines, I was led to believe that one can use the change in temprature of cold heat bath to measure the energy levels of a quantum mechanical system. In this particlar case, The cold heatbath can be arranged in an experimental setup, while we cannot monitor the precise state of the heat bath, its Tempratue is what is available to us. Therefore coupling a cold heat bath to a state in superposition can allow us to measure its energy.
While what is happening is far from clear to me, I think the general picture fits closely with The fact that one uses caloriemeter's as particle detectors, an essential component of a photomultiplier tube must involve a voltage difference which must involve expended work, or the fact that measurement using bubble/ vapour chambers involve thermodynamic Transition.
The general fact that we have to take into account in all of this is that we cannot arrange the "universal wavefunction" so it is not fully to talk about, In any situation out experimental appratus must consist of a large number of degrees of freedom, whose state we can only talk about approximately, or in the theromodynamic approximation. We also must accept the restriction that we cannot talk the change in the state of the measurement appratus in the thermodynamic approximation. While it is far from clear, I would love to listen to your comments and opinions.
|measurement, quantum mechanics|
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