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Problems by considering that a measurement produce a collapse. (causality violation) 
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#19
Jun2811, 03:55 PM

P: 59

thank you for the reference, but my university have not account with the last one. I will try with a friend in Berkeley to see if he can download, but just in case if you can send me it as attachment to the email please pm.



#20
Jun2811, 07:31 PM

P: 59

I read the first paper and is not what I am seeking for, but thanks anyway. Really i want a paper that can show that special relativity can emerge from a quantum theory and what conditions this quantum theory needs to satisfy it.



#21
Jul111, 07:47 AM

P: 82

Of course we are very concerned by the informations we obtain during our career in the laboratory. But are really the laws of physics concerned by our egocentrism ? The two centuries during which naturalists had to struggle against the dominant animism  of the church, mainly  to obtain the freedom to study nature without the ominous domination of the Noah's Arch, and of the "will of god", merit some respect. But since 1927, under the domination of the Copenhagen pack, the theoritical physics had plunged again in an animism, the animism of Niels Bohr. Our position as macroscopical animals exists, and is respectible, but it remains to be proved that such a point of view has some competence for the centering and the scaling of the physical laws, in the field of microphysics. The impersonnal physical laws are not concerned by our information, nor by the ways we instrumentalize sensors. They are concerned by which quantic reaction absorbs each particular quantons, and how much the thermalization occurs after the capture. Whether we instrumentalize the sensor with amplifiers is our business, not the business of the physical laws in microphysics. And between our scale of macroscopical animals and the scale of microphysic phenomena, there is terrible barrier : the theorem of the requisite Variety, from William Ross Ashby, which put a stop to our panoptical fantasies. 


#22
Jul111, 10:09 AM

P: 59

Seriously I understood nothing of what u were saying. But i will try to made an impression.
Compehagen interepretation was create to safe QM from the attack of differents physicist as Einstein. This interpretation is dying in modern times, but there are also some attempts to keep it alive. (I don't believe in it) There is not a barier between classical mechanics and quantum mechanics (following the ideas of decoherence). Then there is not need to make a reference to scale. There is a different in stuying quantum mechanics of closed system and quantum mechanics of open system and that is the crucial idea. Now the word measurement can be replaced with interaction if you want it and use von neumann premeasurement. The point is that none of these ideas is complete in the sense that doesn't explain why is there nonunitary and non deterministic transformation. In other words the solution of the interaction should be one of the prererred state (this is based on experiments), but how is it selected? That is the question. Then I use the word measurement to include this last step that is experimental verify, but is not clear form the theory. 


#23
Jul111, 11:43 AM

P: 82




#24
Jul111, 12:10 PM

P: 82

... 2. In microphysics, the space is autosimilar at all scales. 3. In microphysics, the space has an infiniteley fine topology, just as the ensemble R used in the classrooms of mathematics. 4 and 5 : idem for the time. 6. As in macrophysics the time is irreversible for statistical reasons, so it is in microphysics, and we are right of exempting us from any experimental validation of this extrapolation. ... 18. It is logical to put the human observer in the center of the picture for every description of quantic or subquantic phenomena. ... (extracted from http://deontoethique.eu/quantic/ind...oltergeist_%3F) 


#25
Jul111, 01:11 PM

P: 59

http://arxiv.org/PS_cache/quantph/p.../0307238v1.pdf Also quantum Darwinism ( the theory of how objective classical reality can emerge from quantum mechanics)have been experimentally verify: http://prl.aps.org/abstract/PRL/v104/i17/e176801 Decoherence is a real effect that have been verify in hundreds of experiments. The ideas of einselection is also a principle that can be used to predict situation and to explain experiments. Then I am not talking about possibilities here. There is not boundary between classical mechanics and quantum mechanics. the difference is that we study in college including graduate courses the quantum mechanics of closed systems. Now when the environment interact with a system a suppression of coherence in some set states occur (have been confirmed experimentally a lot of times) and this effect from a point of view of quantum mechanics is worst than dissipation (faster and more effective). Decoherence have not special postulates is just quantum mechanics of open system and is incredible that if we study the quantum mechanics of open system a set of states start acquiring locally because of the interaction with the environment the properties that we assign to classical states. A nice review paper by Zurek is the following: http://arxiv.org/PS_cache/quantph/p.../0105127v3.pdf Also there are several books of this subject I recommend for person with not enough quantum mechanics background the book of Maximilian A. Schlosshauer (is a great book), for a more advance the book Erich Joos, H. Dieter Zeh, Claus Kiefer, Domenico J. W. Giulini. Also just in case the non unitary and non deterministic result that i mentioned before is true in any experiment. There is no doubt about it, just about it's interpretation. 


#26
Jul111, 01:56 PM

P: 82

Obviously you have not begun to examine the surrepticious postulates your teachers have surrepticiously taught. Ruth Kastner began. Read her at http://www.physicsforums.com/showthread.php?t=380128 Feb2310, 05:41 AM. 


#27
Jul111, 03:18 PM

P: 59

What teacher are you talking about? Did you know the quantum effect of decoherence? How is that is a postulated if an experiment can measured it? Now dissipation is also a postulate?
Also Ruth Kastner is just doing something that people have been doing for more than 70th years. What happen when six or more interpretation of the same theory result in the same postulates, with any mean of seeing a different between them. That is a problem. I think that quantum mechanics doesn't matter the interpretation (mWi, many minds, campehagen, non local hidden theory, vacuum fluctuations, esenmble theory, whatever you can imagine and is not testable theory,..) should recognize the power of quantum mechanics in predict an calculated experiments. If I will try to solve this problem I will use only experimental facts as decoherence (just a pure quantum effect) to attack problems. Quantum mechanics have problems that can be solved by a correct interpretation (but how will ever know, for example WMI what is the point of an interpretation that i can't test). More easy is to solve the problem using what we know of nature and not what we know of quantum mechanics and want nature to be. If you have doubts in the postulates of quantum mechanics and want to know the real problem in each postulates and the possibles alternative to solve it I can recommend a lot of literature is this topics. People have been working in this during decades, nothing new , same ... Why today this is a hot topic, the importance is quantum information and for this the issue have been of importance in applications. Now is the time to experimentally solve this issues, because people want to use quantum mechanics as the new frame of communication and information. For a fundamental physicist like me quantum information is just cool, but a great opportunity to solve this problems (more funds and people working in it). Then I suppose that is time to deal with the ambiguities of quantum mechanics. 


#28
Jul111, 05:24 PM

P: 380

but decoherence does not solve the measurement problem..... .M. Schlosshauer, “Decoherence, the measurement problem, and interpretations of quantum mechanics”, Rev. Mod. Phys. 76, 1267 (2004). .G. Bacciagaluppi, “The Role of Decoherence in Quantum Mechan ics”, http://plato.stanford.edu/archives/f...mdecoherence/ .S. L. Adler,“Why Decoherence has not Solved the Measurement Problem: A Re sponse to P. W. Anderson”, Stud. Hist. Philos. Mod. Phys., 34, 135 (2003). . 


#29
Jul111, 06:32 PM

P: 59

You are right!
Decoherence doesn't solve the measurement problem, but the interpretations of quantum mechanics are not testable (except the local hidden variables and also there is some debate about the experiments) and for that reason are not solutions to the measurement problem. Are just cool stuff to read. The wave function is real? How many people ask about the reality of the Lagrangian in classical mechanics? What secret of the universe is encoded in the Hamilton principle? I never read a post that was dedicated to it. I mean quantum mechanics is nonintuitive and for that reason people star speculating and creating ideas that are out of the reach of science until the day that each one start contradicting each other in a testable way (I am waiting for that day, if it ever happen). Now if I want to attack some of the issue of quantum mechanics I want to keep at the level of experiments. Decoherence for example cannot solve the measurement problem in the sense that i doesn't explain how a pointer state is selected during a measurement. Now what is important of decoherence a the moment to examine the interpretation of quantum mechanics is that decoherence can show that there is not need for a boundary between classical mechanics and quantum mechanics. That mean that any interpretation that start with in the microrealm and in the macrorealm like different stuff will need to incorporate decoherence and it will present a problem. This is an advance in quantum mechanics that can show a new requisite for an interpretation of quantum mechanics, as the same way that bell inequality have been used as a requisite. To show the power of this I want to discuss the nonlocality of quantum mechanics and the locality of special relativity. How can i start? First we need to be sure that both theories are experimentally true in their original context. For example quantum mechanics was developed as a theory of closed system and for that reason the nonlocality can be true in a closed system (not reason to be true in open systems). For the other hand special relativity was discovered in a macro system (following the theory of decoherence in a highly interacting open quantum system and for that reason doesn't need to be true in the quantum mechanics of closed systems). Now if we want to check if special relativity and quantum mechanics are consisted, then I will recommend to use transitions from quantum to classical using decoherence. I will use this transition to understand the requisite that are needed for quantum mechanics to be consisted with classical special relativity. First to check if the correlation of the pointers states are classical (I mean that if for example the bientangled state reduce to a classical correlation (local) when we include the environment. This concept probably is true and is based in quantum discord). Second what kind of interaction (I mean interaction in the sense of dynamics,(potentials, fields, ect.) are permitted in quantum mechanics. The interaction term should be local because decoherence cannot affect for example potential at distance, it can only suppress locally superpositions and this potential at distance will be a problem in the transition for quantum to classical because of the relativistic causality. The I will ask for local interactions. Now in general the idea is that the principle of relativity doesn't need to be true for quantum mechanics, but should be true for the prefered (pointers) state after decoherence if this states represent the emergence of classical world as the experimental evidence show. I found that the only real condition at the moment is locality of interaction (by coincidence a requisite of relativistic quantum field theory). Now covariance in the sense of QFT probably can emerge as a consequence of the pointer states (I am working in it also). That mean I don't need an interpretation here, just to check how the theories were created experimentally and use a connection between them that are experimental. That is to limit our self to data and we can say a lot. 


#30
Jul211, 11:30 AM

P: 380

testing objective collapse models: ongoing experiment. Keith Schwab, Anton Zeilinger, and Markus Aspelmeyer. http://www.fqxi.org/community/articles/display/103  planed: http://arxiv.org/PS_cache/arxiv/pdf/...103.4081v1.pdf O. RomeroIsart, A. C. Pflanzer, F. Blaser, R. Kaltenbaek, N. Kiesel, M. Aspelmeyer, and J. I. Cirac. "Preparing quantum superpositions of even larger objects is considered to be extremely challenging due to the decoherence caused by interaction with the environment [2]. However, succeeding in this task would allow completely new tests of quantum mechanics: this includes experiments in a hitherto unachieved parameter regime where collapse theories predict quantum mechanics to fail [3, 4],or even more general tests of quantum theory against full classes of macrorealistic theories" http://arxiv.org/PS_cache/arxiv/pdf/...103.1236v1.pdf Stefan Nimmrichter, Klaus Hornberger, Philipp Haslinger, and Markus Arndt. "they have the clear advantage that they can be tested in principle. This way they bring back to physics what is otherwise an issue of logical consistency and epistemology. Another motivation to consider the possibility that quantum physics is only an approximation to a deeper underlying theory" . 


#31
Jul211, 07:38 PM

Sci Advisor
PF Gold
P: 5,299




#32
Jul311, 07:03 AM

P: 59

Sincerely my knowledge about experimental techniques and mesophysics is limited, then I didn't follow completely the papers and also I am not familiar with GRW theory and other variations of collapse theories. For this reason i can't argument in favor or against the proposed experiments. Now the results of the experiments can be interesting and can eliminate a vast possibilities of interpretations if it have positive results. Now collapse theories are hard to deal in the sense that they can always find a collapse that can form a loophole in the whole experiment. Like I don't understand the experiments in the sense that I have not study these effects and models before, then I don't know if the experiment is free from this loopholes. Probably you have a better picture than me about this point.



#33
Jul511, 08:42 AM

P: 59

Just to hear some comments. The propagators of a free particle in quantum mechanics and in QFT predicts that there is a probability that a particle can travels faster than light. What it mean from the non locality point of view?



#34
Jul611, 04:24 PM

P: 380

. 


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