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Because he did not understood the mechanism of wave-function splitting (now well understood through decoherence).Varon said:If Many worlds has only wave function and no particles. Why didn't Schroedinger discovered it?
Because he did not understood the mechanism of wave-function splitting (now well understood through decoherence).Varon said:If Many worlds has only wave function and no particles. Why didn't Schroedinger discovered it?
Demystifier said:Because he did not understood the mechanism of wave-function splitting (now well understood through decoherence).
Demystifier said:Because he did not understood the mechanism of wave-function splitting (now well understood through decoherence).
Why do you think there would be a problem?Varon said:Any idea how to connect MWI with quantum field theory and particle physics?
Demystifier said:Why do you think there would be a problem?
If you think of many worlds as a "classical theory", then you can extend the whole idea to a many world "classical theory" of QFT. In this theory, neither particles nor fields exist. What exists are certain generalized wave functions which depend on an infinite number of variables.Varon said:Many worlds are classical theory. When you have interacting fields and particles like quantum field theory.. i wonder how you could mix Many worlds in them. Has anyone tried modeling how Many worlds would appear in quantum field theory and whether it would still give the same experimental results and predictions? Most would state that since QM works in QFT, Many worlds should work too.. but it's a classical model. Won't you have trouble when you embed it into QFT or gauge theory?
Fyzix said:I'm pretty sure I read somewhere that Schroedinger realized MWI did not work because of botn probability and the fact that it would violate relativity.
Unfortunately I can't find the source of this claim right now.
MWI is distinguished by two qualities: it assumes realism,[16][17] which it assigns to the wavefunction, and it has the minimal formal structure possible, rejecting any hidden variables, quantum potential, any form of a collapse postulate (i.e., Copenhagenism) or mental postulates (such as the many-minds interpretation makes).
Fyzix said:No, I've already informed you that the Everett-DeWitt account of MWI requires violation of relativity.
Dmitry67 said:Informed about your opinion? Yes
provided any useful info?
We had only one quote about "unzipping the spacetime".
As there is no "unzipping" there is nothing we can discuss.
Do you have anything else?
From another side, as unitary evolution is covariant, MWI *must* be covariant. You did not reply to that either.
Fyzix said:I have written probably 5 pages of information to you, when you have not comprehended the information, I have RE-written it.
When you have argued back, I have thought about it and even inquired others about it to give you as easy to understand explanatino as possible, after doing this 50 times, I have given up.
You believe in MWI because it is infact your religion.
You ignore EVERY obstacle MWI faces because like you said your self "I WOULD BE DEVASTATED IF MWI ISNT TRUE".
You have also admitted here on this forum several times that all problems will be solved by some futuristic theory of consciousness.
When you are willing to take such leaps of faith to defend a flawed hypothesis it is obvious(atleast to me) that a discussion with you will only be a waste of time.
Remember, your view of MWI is wrong.
And based on a link:Fyzix said:Anyways, let's move on to a more "serious" problem facing MWI.
Namely the relativity problem.
After further discussions with Jeffrey Barrett, I've realized that even the decoherence approach suffer from the same fate regarding relativity.
As Barrett himself explains in the Stanford entry.
Reread the passage where he explains exactly the technical difficulties regarding this and tell me how you get around this problem?
http://plato.stanford.edu/entries/qm-everett/
Those who favor a decoherence account of splitting worlds sometimes seem to imagine some sort of “unzipping” of spacetime that occurs along the forward light cone of the spacetime region that contains the measurement interaction. While decoherence effects can be expected to propagate along the forward light cone of the region that contains the interaction event between the measuring device and the object system, and while there is no problem describing the decoherence effects themselves in a way that is perfectly compatible with relativity, there is a problem in imagining that such a splitting process somehow physically copies the systems involved. A strong picture of spacetime somehow unzipping into connected spacetime regions along the forward light cone of the measurement event, would not be compatible with special relativity insofar as relativity presupposes that all events occur on the stage of Minkowski spacetime. And if we give up this assumption, then it is unclear what the rules are for compatibility with special relativity.
If one understands Everett's talk of splitting as in some sense only metaphorical, then one may avoid the problems associated with a strong notion of physical splitting.
rkastner said:to get classical behavior out, one must put it in by choosing what counts as 'system' and what counts as 'environment'.
I don't think it is. It is local, but not manifestly relativistic-covariant. If you still claim it is, can you provide an appropriate reference?Dmitry67 said:From another side, as unitary evolution is covariant,
Then, one seems obliged to conclude about the following inconsistency in the very foundations of the Everett interpretation: the universally valid quantum mechanics
implies the ”splitting” can not occur.
I agree. Nevertheless, I would really like to see a paper which shows that unitary time evolution of the quantum state in QFT or many-particle QM is covariant. It would help me a lot, not only for better understanding of MWI, but also for many other physical issues. In the meanwhile, I still think it isn't covariant.Dmitry67 said:1. "Not manifestly covariant" does not mean "not covariant".
It depends on what one means by "QM".Dmitry67 said:Because a claim that QM is not compatible with SR is a very strong one, right?
Demystifier said:Is there MWI in the Heisenberg picture? I don't think so.
OK, let x denote the space coordinate and t the time coordinate. Consider a 1-particle wave function psi(x,t). If it satisfies the Dirac equation, then it is covariant. Namely, x and t are treated on an equal footing.Dmitry67 said:So there is only Schrodinger picture, and you claim it is non covariant. Could you provide a counter-example to the covariance of such time evolution?
Yes we can, and unitary evolution of such a system is not covariant.Dmitry67 said:Now the question is, can we formulate completely measurement-neutral picture and is that picture covariant?
Another way of saying it is that the number of particles is not covariant. There is a way to avoid this problem by not even talking about particles in QFT, but it does not change the fact that unitary evolution in QFT is not covariant.Dmitry67 said:P.S. And Unruh effect... the number of particles is observer dependent...
Non-covariance is closely related to non-locality (where "nonlocality" is meant in the interpretation-independent sense of nonlocal EPR correlations). In particular, in the classical limit nonlocality disappears and covariance restores.Dmitry67 said:Now I am confused; how apparently covariant behavior comes from the non-covariant equation?
Demystifier said:Non-covariance is closely related to non-locality (where "nonlocality" is meant in the interpretation-independent sense of nonlocal EPR correlations). In particular, in the classical limit nonlocality disappears and covariance restores.
Yes.Dmitry67 said:So, if I insist that wavefunction is real, then covariance becomes not a fundamental property, but an emergent property at the classical limit (it must be proven as a theorem?) , exactly like the 'definite outcomes' and decoherence in general?
Demystifier said:Yes we can, and unitary evolution of such a system is not covariant.
Another way of saying it is that the number of particles is not covariant. There is a way to avoid this problem by not even talking about particles in QFT, but it does not change the fact that unitary evolution in QFT is not covariant.