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A confusing answer to a simple question: What is quantum theory about?
Thanks! But I mentioned 12 dimensions, which, of course, was from the F-theory.Posted Mar30-12 at 01:47 AM by Demystifier
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A confusing answer to a simple question: What is quantum theory about?
You forgot to mention F-theory.
And some say M is for mother and F for father.
It does become obscure...Posted Mar28-12 at 12:58 PM by MathematicalPhysicist
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Life is an organized disorder
Or you can think of life as a state of genuinely lower entropy, which does not contradict the second law of thermodynamics because it generates more entropy for the thermal bath, i.e. the surrounding environment. For instance, living things emit a lot of entropy-increasing body heat out into space.Posted Mar14-12 at 10:11 PM by lugita15
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Alternatives to quantum nonlocality
Dear Demystifier,Quote:Akhmeteli, can you be so self-critical to point out the major "but" of your approach? As you can see, I have given such a "but" for all the approaches I've mentioned, including my own.
For example, from Sec. 5 of the first paper I suspect that the major "but" of your approach could be the following:[*]... but the theory, unlike QM, predicts that Bell inequalities cannot be violated, provided that both the detection and the communication loopholes are closed.[*]
Would that be correct?
Thank you very much for your comments.
Your statement that I marked with[*][*] is certainly correct. However, I am not sure this is indeed a “but” (let alone “major “but””) of the approach, if “but” means a “drawback”. On the one hand, this prediction has not been proven wrong experimentally so far, as there have been no loophole-free experiments. On the other hand, the proof of violation of the Bell inequalities in QM uses mutually contradictory assumptions: unitary evolution and projection postulate.
Yes, this is certainly a major drawback of the current status of the approach. I’d like to emphasize, however, that an awful lot of experimental data is already described correctly in this approach, as it fully incorporates such realistic models as scalar electrodynamics or spinor electrodynamics. It is not clear though that higher orders of QED are emulated correctly in this approach. Maybe some modifications will be needed to achieve this goal.Quote:Quote by DemystifierOr, from the end of Sec. 4:
"... (but) it remains to be seen whether (the theory is) compatible with experimental data ..."Posted Jan24-12 at 09:11 AM by akhmeteli
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Alternatives to quantum nonlocality
Akhmeteli, can you be so self-critical to point out the major "but" of your approach? As you can see, I have given such a "but" for all the approaches I've mentioned, including my own.
For example, from Sec. 5 of the first paper I suspect that the major "but" of your approach could be the following:
... but the theory, unlike QM, predicts that Bell inequalities cannot be violated, provided that both the detection and the communication loopholes are closed.
Would that be correct?
Or, from the end of Sec. 4:
"... (but) it remains to be seen whether (the theory is) compatible with experimental data ..."Posted Jan24-12 at 03:15 AM by Demystifier
Updated Jan24-12 at 03:47 AM by Demystifier -
Alternatives to quantum nonlocality
I would like to mention my local theory based on elimination of matter field from the equations of electrodynamics and interpretation of the configuration space as an artifact of Carleman linearization - Int'l Journ. Quantum Inf., v.9, Supplement (2011), p. 17 (http://www.akhmeteli.org/akh-prepr-ws-ijqi2.pdf ). See also J. Math. Phys., v.52, p. 082303 (2011) (http://akhmeteli.org/wp-content/uplo...28082303_1.pdf ) and later preprints.Posted Jan23-12 at 08:17 AM by akhmeteli
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Alternatives to quantum nonlocality
- consistent histories - objective reality exists and is local, but classical propositional logic is replaced with a different logic (Griffiths, http://lanl.arxiv.org/abs/1110.0974, http://lanl.arxiv.org/abs/1105.3932 )Posted Jan16-12 at 09:02 AM by Demystifier
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Alternatives to quantum nonlocality
I would agree that the Born rule is the only serious trouble with MWI. Some hold the opinion that the non-existence of reality in the 3-space is even a more serious trouble, but I don't agree with such an opinion.Posted Jan16-12 at 03:14 AM by Demystifier
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Alternatives to quantum nonlocality
If I am reading this right, then MWI only have trouble explaining the Born rule? I was under the impression that it also suffered from the"nonlocality" of all other realist interpretations....Posted Jan5-12 at 06:54 PM by NumeroUno
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Alternatives to quantum nonlocality
The Norsen's theory is not a local theory, as he himself explained to me at one occasion.
Namely, the theory is "local" only in the sense that the wave function in the configuration space is eliminated. But it is still nonlocal in the sense that there is an instantaneous action at a distance between the particles.Posted Dec30-11 at 08:07 AM by Demystifier
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Alternatives to quantum nonlocality
Not sure if this one is on the list but there's this local theory by Travis Norsen:
The Theory of (Exclusively) Local Beables
http://lanl.arxiv.org/PS_cache/arxiv...909.4553v3.pdfPosted Dec29-11 at 04:29 PM by bohm2
Updated Dec30-11 at 02:18 AM by bohm2 -
Posted Jun13-11 at 05:02 AM by DevilsAvocado
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Bohmian trajectories are no longer "hidden variables"
To understand what weak measurement is, the following analogy from everyday life is useful.
Assume that you want to measure the weight of a sheet of paper. But the problem is that your measurement apparatus (weighing scale) is not precise enough to measure the weight of such a light object such as a sheet of paper. In this sense, the measurement of a single sheet of paper is - weak.
Now you do a trick. Instead of weighing one sheet of paper, you weigh a thousand of them, which is heavy enough to see the result of weighing. Then you divide this result by 1000, and get a number which you call - weak value. Clearly, this "weak value" is nothing but the average weight of your set of thousand sheets of papers.
But still, you want to know the weight of a SINGLE sheet of paper. So does that average value helps? Well, it depends:
1) If all sheets of papers have the same weight, then the average weight is equal to weight of the single sheet, in which case you have also measured the true weight of the sheet.
2) If the sheets have only approximately equal weights, then you can say that you have at least approximately measured the weight of a single sheet.
3) But if the weights of different sheets are not even approximately equal, then you have not done anything - you still don't have a clue what is the weight of a single sheet.
But what if you don't even know whether 1), 2) or 3) is true? Then you have different interpretations of your weak measurement. And that is precisely the case with quantum mechanics: We don't know whether particles have even approximately equal velocities at the same position (with the same wave function), so we have different interpretations. Bohmian interpretation says they have exactly equal velocities, which corresponds to the case 1), while Copenhagen interpretation corresponds to the case 3).Posted Jun8-11 at 10:39 AM by Demystifier
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Bohmian trajectories are no longer "hidden variables"
The notion that the statistical ensemble interpretation denies definite trajectories seems a bit more subtle than implied here. If you assume a wave only model of the particle zoo the ensembles may not even refer to these particles, such as photons trajectories, but rather the substructure of them. Yet a trajectory can still be maintained in the way a soliton can have a definable trajectory. It does not even make sense to talk about an ensemble interpretation of photons that self interfere if the photons themselves define the elements of the ensemble. That is empirically ruled out by very basic double slit experiments with particles slowed to one at a time. Ensemble interpretations can only refer to a presumed substructure of photons and other particles.
As Mermin has noted it still implies a classical interpretation of probability, yet that is often the point for many who adhere to it. The bigger question is if such elements exist to define single particles as ensembles where are these elements? Perhaps it has something to do with the fact that between interactions the elements are by definition independent variables. Which by definition cannot be empirically measured directly, or else they would not be independent. Even when an interaction does occur it would only empirically appear as a point-like momentum fluctuation in space rather than revealing a pair of elements. Thus the particle and the wavefunction would be essentially one and the same thing.
This is no claim of how things are, rather it is to illustrate the over-simplicity of assuming the ensemble interpretation refers to standard particles as the singular elements of the ensemble, and the notion of the definable trajectories of such.Posted Jun8-11 at 02:16 AM by my_wan
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Weak measurements in quantum mechanics and 2.6 children in an American family
A minor correction: It should be 2.4 children, not 2.6.Posted Jun3-11 at 09:37 AM by Demystifier
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My favored scientist quotes
"If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet."
Niels Bohr
"If delayed choice quantum eraser shocked you more than the rest of quantum mechanics, you haven't understood the rest of quantum mechanics yet."
Hrvoje NikolicPosted May19-11 at 04:48 AM by Demystifier
Updated May19-11 at 08:20 AM by Demystifier -
Weak measurements in quantum mechanics and 2.6 children in an American family
Weak measurements
Dear members. Forgive if I am on the wrong forum but I have a related paper on Bell's theorem which I think is worth reading.
http://www.m-hikari.com/astp/astp201...17-20-2010.pdf.
In the paper I argue that Bell's theorem is incomplete. From this claim I think I may also state that Hardy's paradox, that is measurement after mutual annihilation, can be explained with classical probability measure theory.Posted Mar16-11 at 07:00 AM by hgeurdes
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Life is an organized disorder
Careful, why do you think that I have a new concept of entropy? What that new entropy would be?Posted Feb4-11 at 04:57 AM by Demystifier
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Life is an organized disorder
But the classical work of Shannon shows that entropy increases if and only if information goes down! So, you have a new concept of entropy or of information.Posted Feb1-11 at 08:27 AM by Careful
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Posted Jan28-11 at 04:30 AM by Demystifier


