View Poll Results: Which Quantum Interpretation do you think is correct?  
Copenhagen Interpretation  36  22.78%  
GRW ( Spontaneous Collapse )  2  1.27%  
Consciousness induced Collapse  12  7.59%  
Stochastic Mechanics  3  1.90%  
Transactional Interpretation  4  2.53%  
Many Worlds ( With splitting of worlds )  13  8.23%  
Everettian MWI (Decoherence)  18  11.39%  
deBroglie Bohm interpretation  18  11.39%  
Some other deterministic hidden variables  16  10.13%  
Ensemble interpretation  14  8.86%  
Other (please specify below)  22  13.92%  
Voters: 158. You may not vote on this poll 

#73
Apr2311, 06:51 PM

P: 661

This poll doesn't include consistent histories, which is by far the most sensible interpretation.
I believe most of the interpretations will be at least partially consistent with the final model of reality, since you can bend an "ontological probability" into all sorts of nonsense, but if your puny evolved mind can accept an "ontological probability" then you might find the whole shebang has a surprisingly simple description. 



#74
Apr2311, 07:47 PM

P: 381

epistemic is a representation of an observer’s knowledge of reality rather than reality itself. heisenberg: a system is completely described by a wave function ψ, representing an observer's subjective knowledge of the system. "The laws of nature which we formulate mathematically in quantum theory deal no longer with the particles themselves but with our knowledge of the elementary particles. ... The conception of objective reality ... evaporated into the ... mathematics that represents no longer the behavior of elementary particles but rather our knowledge of this behavior." . 



#75
Apr2311, 07:58 PM

P: 375





#76
Apr2311, 11:49 PM

P: 789

I never really understood all of Ken G's objections to this scenario, but every time I did come to understand what he was saying, he seemed to be correct. He is a CI supporter, so there was never any introduction of untestable assumptions, such as "ontological reality", many worlds, etc., which was a major reason why we could go as far as we did. 



#77
Apr2411, 12:01 AM

P: 275

I don't know if this is really true. Anyway. Supposed the cat is left alone in the box and completely isolated without any thing beside him. Then he is a complete system, here I wonder if it can be in pure state. Also what if one uses the Heisenberg Interpretation where everything *actually* happens. Here the wave function exists independently in the cat and geiger counter without the existence of the observer outside which doesn't need any encoding of knowledge or the concept of wave function as mere calculational tool. In such a case, can we say the cat is in pure state using Heisenberg ontological interpretation. Hope Jesse or Ken or other experts can assist here. 



#78
Apr2411, 11:13 AM

P: 381

thanks gordon, you are welcome. Heinsenberg, February 2, 1960 ..."The act of recording, on the other hand, which leads to the reduction of the state, is not a physical, but rather, so to say, a mathematical process. With the sudden change of our knowledge also the mathematical presentation of our knowledge undergoes of course a sudden change."... Jammer, M., 1974, . 



#79
Apr2411, 11:48 AM

P: 789





#80
Apr2411, 03:12 PM

P: 160





#81
Apr2411, 03:28 PM

P: 172

The ensemble interpretation doesn't really interpret anything tho.
Your still left with the same questons, why does the cat die or live? 



#82
Apr2411, 05:16 PM

P: 275

"The probability function combines objective and subjective elements. It contains statements about possibilities or better tendencies ('potentia' in Aristotelian philosophy), and these statements are completely objective, they do not depend on any observer; and it contains statements about our knowledge of the system, which of course are subjective in so far as they may be different for different observers." Complete context in: http://www.marxists.org/reference/su...e/heisenb3.htm 



#83
Apr2411, 07:35 PM

P: 275

Ken wrote: "But that's what I'm saying isn't true even if we start with pure states for each component of the system, when we couple them, the only pure state is now a combined system. The cat is now a substate of that system, and substates don't evolve according to the Shroedinger equation, so they don't evolve unitarily and they don't become superposition states. There is really no such thing as the state of a part of a system, but we as physicists can make correct predictions by using the concept of a mixed state to treat such substates, or in some special circumstances, we have enough information to treat a substate as a pure or superposition state. That ability is quickly lost for the cat in the box, even if it starts out in an impossibletoknow pure state." If true, it means that Wigner friend inside the box with a box of cat is pure state as a combined system. But Wigner friend is a substate of that system and substrates don't evolve according to the Schroedinger equation. so there is no superposition of any kind state. The paradox doesn't happen. I need confirmation if this is true. If true. Schrodinger cat can never be in superposition of dead and alive even in principle in the boring world of the Copenhagen. But it is all possible in Many worlds because here the cat and universe can be in pure state by principle. 



#84
Apr2411, 09:13 PM

Sci Advisor
P: 8,470





#85
Apr2411, 09:41 PM

P: 275

"So my point is, whether we start with a putative (but impossible) purestate cat, or if we adopt a mixture of pure states with some statistical distribution, doesn't matter for the cat paradox because correct quantum mechanics says that once we couple that cat to the mechanism that can kill it, there is no longer any such thing as the state of the cat in quantum mechanics. There is only a projection of the full state onto the cat degree of freedom, but that isn't a quantum mechanical state, it is a classical treatment of a quantum mechanical state. It makes no difference to the quantum mechanics if we now assert that the cat "really is" alive or dead and we have no way of knowing which, or if we assert that we have chosen to treat it that way in our mathematics the correct quantum mechanics is completely moot on the point, there is no catstate wavefunction so there is no superposition of alive or dead." So you mean decoherence is the explanation why when we couple the cat to the mechanism that can kill it, there is no longer any such thing as the state of the cat in quantum mechanics? I'ts been 75 long years since the Schrodinger Cat. Let's settle it once and for all as far as Copenhagen interpretation is concerned. We know in many worlds, cat can be both dead and alive.. but we are just focusing on pure Copenhagen for now. 



#86
Apr2411, 10:45 PM

Sci Advisor
P: 8,470





#87
Apr2411, 11:43 PM

P: 275

Your Wigner friend example can be modelled with a simple illustration Supposed you have a 430 atom buckyball emitted. Since you believe superposition has no ontological reality. Then you think the buckyball will take classical trajectory to the screen? Copenhagen is pragmatic in that it doesn't want to commit to any picture of what happens. If you believe the 430 atom buckyball has classical trajectory and only after a number of trials can give you the interference patterns, then you follow the belief of ensemble or statistical interpretations where it is only meaningful after a number of runs? This is similar to Wigneg friend and the box of cat and another scientist outside the box. Only the calculations make sense and everything is classical from the beginning. Pure state then is just there is something to calculate about. So you believe in the statistic interpretation instead of pure Copenhagen (where imagining what occurs inside is outlawed) ? I believe it is possible though that superposition is literal, so the buckyball is literally in superpositon of positions. It's like the 430 atom buckyball lost out the classical form and become an apparison or ghost in between emission and detection. Your Wigner friend example can refute this but it can't happen in the first place because of decoherence which makes the substates unable to use the Schroedinger equation and there is no quantum mechanics at all. On the other hand, those who believe in Many Worlds believe the buckyball gets duplicated in many branches. Bohmian believes in classical trajectory but they were "push" by the wave function and pilot wave. 



#88
Apr2511, 10:09 AM

P: 789





#89
Apr2611, 07:39 AM

Sci Advisor
PF Gold
P: 1,942





#90
Apr2611, 08:11 AM

P: 275

But what's weird is that in Many World, the cat can be in pure state even without measuring it. Maybe you are trying to imagine a cat in Many worldlike setting. I wonder why a cat can be in pure state in Many worlds while impossible in Copenhagen. Rap or anyone? 


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