Does Decoherence Von Neumann Interpretationrefute

[Fredrik]

the latest in neuroscience actually stated our brain neural network only handle the unconscious activities in our mind. The conscious or qualia aspect they still can't find no matter how they probe it. So even though it is possible our conscious/qualia aspect is a result of something external to the brain like some new phenomenon in the vacuum like morphogenetic fields.

What if Paranormal is simply about communications between branes or even worlds.

Please keep the pseudoscience out of this forum. I suggest forums.randi.org.

Do you guys actually believe that an ant choosing two paths (or identical scenerios) can split worlds into many worlds. This is absurdity to the max.

The picture of worlds "splitting" in an objective sense as a result of specific world-splitting events, is an extremely incorrect representation of what I have in mind when I talk about a MWI. (And no, I don't really have time to explain how I think worlds and splits should be defined and described in a MWI).

MWI is almost nonsense.

A lot of the stuff that's been written about "the" MWI is nonsense, and Everett's idea that the Born rule can be thrown out is fundamentally flawed. But that doesn't mean that the idea of many worlds is nonsense. It might be wrong, but it certainly isn't nonsense.

Personally, I think QM looks like a toy theory that someone invented just to show that it's possible to define a theory that assigns non-trivial probabilities (i.e. not always 0 or 1) to results of experiments. I also think that this is a pretty good reason to think that it's nothing more than that, i.e. that it isn't a description of what actually happens to a physical system. But then there's the fact that this toy theory makes absurdly accurate predictions about the results of experiments. How can a toy theory be so accurate? Isn't it possible that the reason is that the most straightforward interpretation of it is an accurate description of what actually happens to a system? I certainly can't dismiss it.

(The first option I mentioned, i.e. that QM is just a set of rules that tells us how to calculate probabilities of possibilities, can be considered even more straightforward and simple. But it probably shouldn't be considered an "interpretation", since it tells us that QM doesn't describe reality, instead of telling us how it describes reality).

Why is that Physicists can embrace such weird thing as MWI yet repulsed by the Paranormal?

Because every argument for the paranormal that we've ever heard is absolutely idiotic, while the MWI is a straightforward interpretation of the most accurate theory in the history of science.

I guess it's more of bias. Our physics and mathematics are not yet in final form so anything is possible.

We're not biased against the paranormal. It's just that we understand the scientific method.

Do you think MWI can be falsified?

No, because it's not a theory. It's an interpretation of QM defined by an additional axiom that doesn't change the predictions of the theory. Since experiments can only tell us how accurate a theory's predictions are, there's no way it can be falsified.

Yes I think MWI can be falsified, by means of physics of the Paranormal.

That actually sounds like a good plan. It's like when people use dowsing rods to find Earth rays. If you want to find something that doesn't exist, you better use a device that doesn't work.

Fredrik, after reading many hours into von Neumann history. I don't think he was saying what you were describing. No. He didn't mention about Many Worlds.. because at that time.. Many Worlds Interpretation have not been proposed yet. Instead. What he was saying is from the context of the Copenhagen where the world are just possibilities. In double slit. The particle never enter both slits as in Many Worlds.. but they are just possibilities. So in von Neumann Interpretation, Macroscopic superposition means every state just exists as possibilities..

I don't think it makes sense to say that the components of a superposition "exist only as possibilities" without explaining what that means. I only see two things that it can mean: 1. |u>+|v> means that the there are (at least) two copies of the system, one of which is in state |u> and the other in state |v>. 2. |u>+|v> doesn't actually represent the properties of the system, but is just a part of a mathematical formalism that can be used to calculate probabilities of possible results of experiments.

The first option is some kind of MWI, regardless of whether von Neumann thought of it in those terms or not.

 

[Fredrik]

I strongly believe that QM (except the high energy corrections + quantum gravity part) is accurate description of the Universe wavefunction, except the formulas, the ideology of it will be the same when TOE will be discovered, so TOE won't solve the measurement problem. After TOE there will be a tricky part – to justify the choice of the basis of decoherence called ‘consiousness’. We will know all the formulas but we won't be able to say why the world behaves this way :)

I don't think a TOE will tell us anything at all about MWI stuff. What I think is missing right now is a formal definition of what a "world" is, and a rigorous proof that there's a set of worlds where the environment's ability to store information about the system is maximized, while the environment in most other worlds is really bad at storing information about the system. Since consciousness involves a memory with well-defined memory states that change with time, consciousness can only exist in worlds where information can be stored. We can then identify the classical worlds with the ones where the environment has the maximum capacity to store information, because in other worlds, no one will be able to remember what just happened.

If I'm right, the solution to the preferred basis problem is that a) there are a lot more worlds than those associated with the preferred basis, and b) the preferred basis just identifies the interesting worlds.

 

[Alfrez]

Please keep the pseudoscience out of this forum. I suggest forums.randi.org.


The picture of worlds "splitting" in an objective sense as a result of specific world-splitting events, is an extremely incorrect representation of what I have in mind when I talk about a MWI. (And no, I don't really have time to explain how I think worlds and splits should be defined and described in a MWI).


A lot of the stuff that's been written about "the" MWI is nonsense, and Everett's idea that the Born rule can be thrown out is fundamentally flawed. But that doesn't mean that the idea of many worlds is nonsense. It might be wrong, but it certainly isn't nonsense.

Personally, I think QM looks like a toy theory that someone invented just to show that it's possible to define a theory that assigns non-trivial probabilities (i.e. not always 0 or 1) to results of experiments. I also think that this is a pretty good reason to think that it's nothing more than that, i.e. that it isn't a description of what actually happens to a physical system. But then there's the fact that this toy theory makes absurdly accurate predictions about the results of experiments. How can a toy theory be so accurate? Isn't it possible that the reason is that the most straightforward interpretation of it is an accurate description of what actually happens to a system? I certainly can't dismiss it.

(The first option I mentioned, i.e. that QM is just a set of rules that tells us how to calculate probabilities of possibilities, can be considered even more straightforward and simple. But it probably shouldn't be considered an "interpretation", since it tells us that QM doesn't describe reality, instead of telling us how it describes reality).


Because every argument for the paranormal that we've ever heard is absolutely idiotic, while the MWI is a straightforward interpretation of the most accurate theory in the history of science.


We're not biased against the paranormal. It's just that we understand the scientific method.


No, because it's not a theory. It's an interpretation of QM defined by an additional axiom that doesn't change the predictions of the theory. Since experiments can only tell us how accurate a theory's predictions are, there's no way it can be falsified.


That actually sounds like a good plan. It's like when people use dowsing rods to find Earth rays. If you want to find something that doesn't exist, you better use a device that doesn't work.


I don't think it makes sense to say that the components of a superposition "exist only as possibilities" without explaining what that means. I only see two things that it can mean: 1. |u>+|v> means that the there are (at least) two copies of the system, one of which is in state |u> and the other in state |v>. 2. |u>+|v> doesn't actually represent the properties of the system, but is just a part of a mathematical formalism that can be used to calculate probabilities of possible results of experiments.

The first option is some kind of MWI, regardless of whether von Neumann thought of it in those terms or not.

I have the book Many Worlds of Schrodinger Rabbits. So I understood the formalism of Many Worlds. I know it splits not because of splitting of world events but quantum choices. No problem on that part. I may review the book again.

About von Neumann. I read more history of him and I think the following is the case.

Copenhagen only focus on the quantum system and measuring device. Since Copenhagen was only von Neumann reference. Neumann only focused on the things that can be measured. So he never state about his idea of macroscopic superposition and what occurred there. Also Neumann even thought QM was just all about calculation, like in option 2 you stated. So naturally he didn't have to mention about macroscopic superposition or bothered with it.
Neumann is a mathematician and didn't bother much about ontology.

So if we have to continue where Neumann left off. And we interpretated the wave function as more than calculating device. Then it means macroscopic superposition is a temporary Many World incident as you described earlier.

And if we have to use the Decoherence Interpretation and connect it with von Neumann incomplete description. Then we can state that macroscopic superposition is maintained by Decoherence and the seeming lack of it is due to the preferred basis. And in the isolated setup where quantum system are being measured (before it decohered), we can say that in the von neumann model, consciousness can bias the decoherence and the results of the measurement. Maybe that is what can be pull out from making sense out of von Neumann incomplete description. von Neumman lived prior to the concepts of Decoherence and Many worlds.
Now since von neumann never stated that mind can bias the results.. but just collapse it. And if Decoherence is true, then decoherence completely invalidates von neumann model, right??
But we can rescue it if we can state that in a neo modern day von neumann model, mind can bias the results of the decoherence (that is, if we don't use the Many Worlds model). If it can't bias it, then Decoherence completely invalidates von Neumann model. Right?

I realized even before reading your reply that you were right that Many World is von Neumann natural consequence in the macroscopic superposition because if it is only possibilities. It means that underneath the ocean where human consciousness is not present, the water only exist as possibilities. This means the weight of the water at the surface can fall down to the limbo region. Since this doesn't happen then it's either Many Worlds or Decoherence that rule von Neumann's model.

 

[Dmitry67]

1
What do you mean by "10 atoms (*) work as 'measurement device', and these 10 - do not", what atoms are you talking about??

2
Also what do you mean by "why optical photon is not 'measured' by glass, when gamma photon is 'measured' by the very same piece of glass". What glass and experimental setup is that?

1 I mean now, in Quantum computing for example, 'devices' are so small that they literally consist of few atoms. And while in the beginning of 20th centruy, when measurement devices were always huge, there was some hope that some 'collapse agent' will be found at some point, now there is no such hope, and the fatal flaw of CI is obvious.

2 You can put a glass or a mirror in double slit experiment, and it won't break an interference pattern, because, dispite the complexity of interaction, neither mirror nor glass 'measure' the photon. At the same time, gamma ray photon would simply leave a track in the very same glass, so it will be definitely 'measured'.

 

[Dmitry67]

Infinity of worlds existing at once?? Come on. It's so bizarre that it's a lot easier to believe in the Paranormal.

It is just a mental block.

People (from Newton!) have no problems in believing in spatial and temporal infinity. Our mind usually don't have any problems with infinite universe. Nobody is saying 'C'mon, galaxies and stars in all directions? are you crazy? it is a lot of extra useless stuff, and it can't be falsified!'

But in MWI when countable (and finite) number of 'worlds' is added coexsiting at the same place, for some reason it is hard to believe.

 

[Dmitry67]

Frederik, I almost agree with you, but why are you saying

"ability to store information about the system is maximized"?

It must be just high enough

 

[Alfrez]

1 I mean now, in Quantum computing for example, 'devices' are so small that they literally consist of few atoms. And while in the beginning of 20th centruy, when measurement devices were always huge, there was some hope that some 'collapse agent' will be found at some point, now there is no such hope, and the fatal flaw of CI is obvious.

2 You can put a glass or a mirror in double slit experiment, and it won't break an interference pattern, because, dispite the complexity of interaction, neither mirror nor glass 'measure' the photon. At the same time, gamma ray photon would simply leave a track in the very same glass, so it will be definitely 'measured'.

Why can't the collapse agent be as small as a few atoms across? About gamma ray leaving tracks, what has this got to do with invalidating Copenhagen Interpretation??

 

[Fredrik]

Frederik, I almost agree with you, but why are you saying

"ability to store information about the system is maximized"?

It must be just high enough

I agree with that. I'm just guessing that we can find the "preferred" basis, let's call it B₀, by solving an optimization problem. This would mean that consciousness can exist in the worlds with the maximum information storage capabilities (i.e. the worlds identified by B₀), and also in the worlds that are the most similar to them. I expect that the information storing capabilities of the worlds identified by basis B will fall very rapidly when B is changed from B₀. This would ensure that almost all other worlds are irrelevant, and more importantly, that our world will be practically indistinguishable from one of the worlds identified by B₀.

 

[Dmitry67]

Thinking about it...
But very cold worlds (like Pluto) are much safer place to preserve information. But they are dead. So we need something more than just "information storage capabilities".

Also, could you clarify, what meaning do you include in the 'world' (hubble spaces, different MWI worlds, different bubble-worlds with different values of Standard Model parameters etc)

 

[Alfrez]

I was reviewing the concept of Decoherence and reading Tegmark article "100 Years of Quantum Mechanics" and a passage confused me. He stated:

"Decoherence explains why we do not routinely see quantum superpositions in the world around us. It is not becuse quantum mechanics intrinsically stops working for objects larger than some magic size. Instead macroscopic objects such as cats and cards are almost impossible to keep isolated to the extent needed to prevent decoherence. Microscopic objects, in contrast, are more easily isolated from their surroundings so that they retain their quantum behavior"

Is he right in saying that if you can isolate the cat or card in say a magnetic bubble containment field and avoid any external contact with surrounding or external heat, photons, etc. it can exist as superposition? But I thought superposition only occurs in simple simple such as double slit experiments where you can isolate the particles from the surrounding and hence maintain the interference. But the cat internal body has many separate stuff like blood flow and body heat. This would prevent the cells from having superposition. However, Tegmark mentioned that if you can somehow isolate the whole cat. It can initiate macroscopic superposition?? How do you define the boundary? Another example, if I can isolate my car in say the containment field, my car would experience macro superposition, however, inside the car the air from the aircon can decohere my body and prevent superposition in my body, so in what sense can you cause macroscopic superposition to the whole car but while inside, there is no superposition in my body??

 

[A. Neumaier]

Von Neumann wrote in a major physics book decades ago that consciousness was what collapse the wave function.. how could he stated this bizaare statement and the facts remain up to this day?

There is nothing bizarre in von Neumann's statements. So there is nothing to refute.
You only need to upgrade your understanding of what the terms mean.

To say that consciousness collapses the wave function is equivalent to say that it takes consciousness to interpret the universe and change the interpretation when new information arrives.

What is he really saying that only consciousness can collapse the wave function? In what context does he meant?

Instead of modeling the system by a superposition in the absence of information, you model it by one of the participating eigenstates if a measurement result becomes known. Clearly, modeling reality (and changing the model) is a conscious activity and requires a consciousness.

This is nothing mysterious, and happens also in classical physics once you have a stochastic dynamics, where the collapse is called conditional probability.

Moreover, it has nothing to do with superluminal changes, since once one changes a molde to describe something, everything in the model changes instantaneously, although the system modeled isn't changed at all.
This already happens when you apply a coordinate transformation in a classical system...

I wonder if it means he believed macroscopic superposition was possible since he believed consciousness can collapse the wave function, and in regions where there is no human like inside the moon, does it mean inside the moon material properties inside exist in superposition and in limbo with no definite particle positions??

What do you mean by ''in limbo''? The inside of the moon has lots of meaningful properties even in the absence of a sharp position (which it doesn't even have classically, by the way). Note that being in a superposition only means that there is no exact value of the position, not that there is no position at all. In particular, there is a mean position and a mean square deviation form this position, which together is adequate for most purposes.

how does the cat blood vessels pump blood when there is no position as it exists in pure limbo.

Blood vessels work quite well without each of their atonms having precise positions to 10^1000 decimals of accuracy.

 

[Alfrez]

I was reviewing the concept of Decoherence and reading Tegmark article "100 Years of Quantum Mechanics" and a passage confused me. He stated:

"Decoherence explains why we do not routinely see quantum superpositions in the world around us. It is not becuse quantum mechanics intrinsically stops working for objects larger than some magic size. Instead macroscopic objects such as cats and cards are almost impossible to keep isolated to the extent needed to prevent decoherence. Microscopic objects, in contrast, are more easily isolated from their surroundings so that they retain their quantum behavior"

Is he right in saying that if you can isolate the cat or card in say a magnetic bubble containment field and avoid any external contact with surrounding or external heat, photons, etc. it can exist as superposition? But I thought superposition only occurs in simple simple such as double slit experiments where you can isolate the particles from the surrounding and hence maintain the interference. But the cat internal body has many separate stuff like blood flow and body heat. This would prevent the cells from having superposition. However, Tegmark mentioned that if you can somehow isolate the whole cat. It can initiate macroscopic superposition?? How do you define the boundary? Another example, if I can isolate my car in say the containment field, my car would experience macro superposition, however, inside the car the air from the aircon can decohere my body and prevent superposition in my body, so in what sense can you cause macroscopic superposition to the whole car but while inside, there is no superposition in my body??

In the inquiry above. Let me add that say in the isolation field, the cat or car has a double slit like setting where two doors are in front. Should the cat or car pass thru both doors or slits and interfere just like a particle in double slit? Or doesn't it happen at all because there are too many microscopic degrees of freedom inside the cat and car body? Scientists now were able to use a buckyball molecule composed of 60 atoms and pass this thru a slit and the macroscopic object interfere. I think the buckyball entire contents are in phase. They also plan a virus in an actual double slit experiment. Should the virus internal part be in phase too before it can cause interference.. or is in phase not required.. meaning a cat can be used in a double slit experment and succeed if the whole setup can be isolated enough like some kind of containment field?? Or is it impossible due to the many microscopic degree of freedom inside the cat body which is not in phase??

 

[Alfrez]

In the inquiry above. Let me add that say in the isolation field, the cat or car has a double slit like setting where two doors are in front. Should the cat or car pass thru both doors or slits and interfere just like a particle in double slit? Or doesn't it happen at all because there are too many microscopic degrees of freedom inside the cat and car body? Scientists now were able to use a buckyball molecule composed of 60 atoms and pass this thru a slit and the macroscopic object interfere. I think the buckyball entire contents are in phase. They also plan a virus in an actual double slit experiment. Should the virus internal part be in phase too before it can cause interference.. or is in phase not required.. meaning a cat can be used in a double slit experment and succeed if the whole setup can be isolated enough like some kind of containment field?? Or is it impossible due to the many microscopic degree of freedom inside the cat body which is not in phase??

Oh, I think the above is another bad example, the de broglie wavelength of the cat is very small so it shouldn't interfere with the slits or doors in a double slit/door experiment supposed the whole setup can be isolated enough. Right?

I think a better example is the original one, the Schroedinger Cat experiment. When Schroedinger proposed it. They didn't know if macroscopic superposition could happen. They didn't know if collapse really occurred or not. But now we have a very sophisticated model of Decoherence and we supposed collapse never happen. So we should go back to the Schroedinger Cat Experiment. Supposed the cat and radioactive substance in the whole setup could be totally isolated in a special containtment field. Could we have superposition of live and dead cat?

As I think I understand it now. To initiate macroscopic superposition, it has to be entangled to any quantum particle or setup which can produce quantum choices.

 

[Dmitry67]

Here you are, there is even a very nice picture!
http://en.wikipedia.org/wiki/Schrödinger's_cat#Many-worlds_interpretation_.26_consistent_histories

 

[Alfrez]

Here you are, there is even a very nice picture!
http://en.wikipedia.org/wiki/Schrödinger's_cat#Many-worlds_interpretation_.26_consistent_histories

Note even such simple thing as double slit experiment can split worlds.. where in one world, the particle passes thru the right slit, in the second word, the particle passes thru the left slit. Now are you saying that after it happened, the 2 worlds continues the independent histories such that in the first world, China will be at war with US in 2020 while in the second world, the Arabs will be at war with US in 2020?? So a simple splitting of the double slit can cause a second world to exist indepedently??

If you believe it. Why not just believe that randomness is intrinsic in QM and where the particle will pass thru, left or right is just a random event without splitting of worlds? The price to pay to avoid randomness is to propose millions of worlds. Isn't this an extreme measure to take??

 

[Alfrez]

There is nothing bizarre in von Neumann's statements. So there is nothing to refute.
You only need to upgrade your understanding of what the terms mean.

To say that consciousness collapses the wave function is equivalent to say that it takes consciousness to interpret the universe and change the interpretation when new information arrives.



Instead of modeling the system by a superposition in the absence of information, you model it by one of the participating eigenstates if a measurement result becomes known. Clearly, modeling reality (and changing the model) is a conscious activity and requires a consciousness.

This is nothing mysterious, and happens also in classical physics once you have a stochastic dynamics, where the collapse is called conditional probability.

Moreover, it has nothing to do with superluminal changes, since once one changes a molde to describe something, everything in the model changes instantaneously, although the system modeled isn't changed at all.
This already happens when you apply a coordinate transformation in a classical system...



What do you mean by ''in limbo''? The inside of the moon has lots of meaningful properties even in the absence of a sharp position (which it doesn't even have classically, by the way). Note that being in a superposition only means that there is no exact value of the position, not that there is no position at all. In particular, there is a mean position and a mean square deviation form this position, which together is adequate for most purposes.



Blood vessels work quite well without each of their atonms having precise positions to 10^1000 decimals of accuracy.

Which one do you believe is the case concerning the possibilities in the components of a quantum superposition and why?

1. |u>+|v> means that the there are (at least) two copies of the system, one of which is in state |u> and the other in state |v>.

2. |u>+|v> doesn't actually represent the properties of the system, but is just a part of a mathematical formalism that can be used to calculate probabilities of possible results of experiments.

Is the latter Copenhagen? I'm not sure if Fredrik means the second is strictly Copenhagen. But the first one can also be Copenhagen, isn't it?

 

[Dmitry67]

Note even such simple thing as double slit experiment can split worlds.. where in one world, the particle passes thru the right slit, in the second word, the particle passes thru the left slit. Now are you saying that after it happened, the 2 worlds continues the independent histories such that in the first world, China will be at war with US in 2020 while in the second world, the Arabs will be at war with US in 2020?? So a simple splitting of the double slit can cause a second world to exist indepedently??

If you believe it. Why not just believe that randomness is intrinsic in QM and where the particle will pass thru, left or right is just a random event without splitting of worlds? The price to pay to avoid randomness is to propose millions of worlds. Isn't this an extreme measure to take??

1 You are still having the same mental block. You see no problem accepting the INFINITY of worlds (in infinite universe) but can't accept the aditional finite, countable number of worlds?

2 Note that no experiment split the whole universe. 'Splitting' is a physical process propagating at v<=c via interaction. Making double slit experiment here you don't split Andromeda galaxy.

3 There are much more than millions worlds, but

4 yes, use truly random (QM) event to decide if you stay at home or go to work. Then definitely 2 copies of you will behave differently. What problem do you see with it except saying that it is "absurd"?

 

[Dmitry67]

If you believe it. Why not just believe that randomness is intrinsic in QM and where the particle will pass thru, left or right is just a random event without splitting of worlds? The price to pay to avoid randomness is to propose millions of worlds. Isn't this an extreme measure to take??

1. Because God does not play dice! (c)
2. Because you can't define randomness without defining what is measurement first. And it appears that measurement is ill-defined concept.
3. I don't see anything extreme in MWI approach.

 

[A. Neumaier]

Which one do you believe is the case concerning the possibilities in the components of a quantum superposition and why?

1. |u>+|v> means that the there are (at least) two copies of the system, one of which is in state |u> and the other in state |v>.

2. |u>+|v> doesn't actually represent the properties of the system, but is just a part of a mathematical formalism that can be used to calculate probabilities of possible results of experiments.

Neither. |u>+|v> actually represents the properties
(i) of the system, according to the Copenhagen interpretation,
(ii) of an ensemble of identically prepared systems, according to the statistical interpretation.
If the uncertainty (root mean square deviation from the mean) is small enough, there is little difference between the two interpretations. This is in particular the case for macroscopic observables, such as the position of the center of mass of the moon.

Is the latter Copenhagen? I'm not sure if Fredrik means the second is strictly Copenhagen. But the first one can also be Copenhagen, isn't it?

None of 1. or 2. is Copenhagen. (i) is.

 

[Fredrik]

I prefer not to use the term "Copenhagen interpretation" if I can avoid it, because every person who uses it seems to mean something different.

 

[Alfrez]

Guys. I have an inquiry about the preferred basis problem in Decoherence which I've been studying the past 5 hours. It is one of the most important and interesting concepts in the latest quantum findings. Rather than create a new thread. I'd put it here to in this thread (so as to conclude it too). My questions are at the bottom after brief quotes to get in the mood:

http://public.lanl.gov/whz/images/decoherence.pdf

"Environment can destroy coherence between the states of a quantum system. This is decoherence. According to quantum theory, every superposition of quantum states is a legal quantum state. This egalitarian quantum principle of superposition applies in isolated systems. However, not all quantum superpositions are treated equally by decoherence. Interaction with the environment will typically single out a preferred set of states. These pointer states remain untouched in spite of the environment, while their superpositions lose phase coherence and decohere. Their name—pointer states—
originates from the context of quantum measurements, where they were originally introduced (Zurek, 1981). They are the preferred states of the pointer of the apparatus.
They are stable and, hence, retain a faithful record of and remain correlated with the outcome of the measurement in spite of decoherence."

.....

My questions.

The environment selects the pointer states or preferred basis which explains why a chair is in classical position of space. Now I'd like to know how what kind of shielding (whether magnetic, plasma, etc.) is possible that can be created such that the chair can be prevented from being Einselected.. meaning the preferred basis wouldn't be classical anymore but composed of say up and down at the same time. What sort of experiments have been proposed that can do this? This is to prove once and for all the Decoherence is real even though we don't know if Copenhagen or Many Worlds or Bohmian, etc. is the physical ontology. But this Einselection Shielding Experiment is invariant to any intepretations because you are to prevent the creation of the preferred basis. The bottom line is this. The preferred basis is chosen because of interaction with a classical environment, now if you shield the chair in a magnetic shield or plasma or other exotic shielding in such a way that it can't get contact with the classical environment, then it can initiate Schroedinger Cat like superposition where the chair can shapeshift to different shapes, something like that. We must make this experiment even on the level of the pioneering Manhattan Project to arrive at more quantum truth which we lack so intimately.

 

[A. Neumaier]

to arrive at more quantum truth which we lack so intimately.

Books on quantum physics are full of quantum truth. Lacking is only a way to make it intelligible to laymen without distorting the truth too much.

Bringing chairs into a nontrivial superposition would not change this. Zeilinger produced superpositions of buckyballs and demonstrated corresponding interference effects, but it gets harder and harder as the particle size grows. All the energy of the universe is probably not enough to do the same for a chair-sized particle.

 

[A. Neumaier]

I prefer not to use the term "Copenhagen interpretation" if I can avoid it, because every person who uses it seems to mean something different.

Still, there is a common intersection: In any of its variants, it assigns a state to each individual system rather than only to an ensemble. This is sensible since there are quantum objects like the sun that cannot be treated in an ensemble fashion but clearly has a quantum state (though we can describe it only in some coarse approximation).

 

[Alfrez]

Books on quantum physics are full of quantum truth. Lacking is only a way to make it intelligible to laymen without distorting the truth too much.

Bringing chairs into a nontrivial superposition would not change this. Zeilinger produced superpositions of buckyballs and demonstrated corresponding interference effects, but it gets harder and harder as the particle size grows. All the energy of the universe is probably not enough to do the same for a chair-sized particle.

But there is a big difference. A buckyball is a quantum object which obviously can interfere with itself. Now in the post-Copenhagen era. Wave function never collapse. Superpositions are still occurring only they are suppressed by Decoherence. However Hilbert space is big. Why is the classical state chosen or preferred. Zurek then claimed it was because the environment classical state got somehow transferred to the object. Now if we can shield this Einselection, then we can for all intent and purposes create macroscopic superposition where the chair can shapeshift into different shapes. Note again that this scenerio is not like the Buckyball where the entire molecule is in quantum coherence. Unless you are saying that the only way the chair can experience macrosuperposition is if its internal parts are in coherence. But Einselection can do the trick since everything is in superposition only we don't observe it because it is decohered. Classical state is just a very tiny bit in the hilbert space and hence classical state should not be the norm (see the pdf where the details are explained in case you are not familiar with the exotic world of Decoherence).

 

[Dmitry67]

Superpositions are still occurring only they are suppressed by Decoherence.

Decoherence does not suppress the superpositions, it just creates an illusion (for complex system A) that system B, which is communicating with system A, is in some definite state.

http://en.wikipedia.org/wiki/Wigner's_friend#Wigner.27s_friend_in_Many_Worlds

May be I am wrong, but based on language you use it appears that you interpret Decoherence as some engine of Objective collapse. But superpositions never end!

 

[Dmitry67]

Why is the classical state chosen or preferred.

based on

http://en.wikipedia.org/wiki/Wigner's_friend#Wigner.27s_friend_in_Many_Worlds

it is a purely mathematical consequence of the observer having many defreees of freedom and it can't be shielded.

Very primitive 'observers', like atoms and molecules, can 'observe' other objects directly in superposition, but they are too simple to be conscious.

 

[Alfrez]

Decoherence does not suppress the superpositions, it just creates an illusion (for complex system A) that system B, which is communicating with system A, is in some definite state.

http://en.wikipedia.org/wiki/Wigner's_friend#Wigner.27s_friend_in_Many_Worlds

May be I am wrong, but based on language you use it appears that you interpret Decoherence as some engine of Objective collapse. But superpositions never end!

What I meant is this. An actual example. My body particles are in trillions of superpositions or being entangled with the environmental particles like photons or air particles. Decoherence simply means it is not in coherence but decohered. Hence Decoherence can suppress the coherence in the superpositions of my body with the environment. Bottom line. Everything is still quantum stuff. The classical states are just a temporary states brought about by Einselection or Environment SuperSelection. If it can somehow be shield. Then we can be any state in the big Hilbert Space.

 

[Dmitry67]

An actual example. My body particles are in trillions of superpositions or being entangled with the environmental particles like photons or air particles. Decoherence simply means it is not in coherence but decohered. Hence Decoherence can suppress the coherence in the superpositions of my body with the environment. Bottom line. Everything is still quantum stuff. The classical states are just a temporary states brought about by Einselection or Environment SuperSelection. If it can somehow be shield. Then we can be any state in the big Hilbert Space.

At first, please clarify what do you mean by YOU or 'MY BODY'
Check the picture:
http://upload.wikimedia.org/wikipedia/en/b/b7/MWI_Schrodingers_cat.png
Do you mean
a. One particular history (frog's view)
b. Ensumble of all histories (the whole 'tree', birds view)

 

[Alfrez]

At first, please clarify what do you mean by YOU or 'MY BODY'
Check the picture:
http://upload.wikimedia.org/wikipedia/en/b/b7/MWI_Schrodingers_cat.png
Do you mean
a. One particular history (frog's view)
b. Ensumble of all histories (the whole 'tree', birds view)

Hmm... you are saying that in this earth, classical state is what we experienced while in other Many Worlds, they can experience a non-classical state that I won't be able to experience?

By shielding Einselection. I just want to experience a state of up-down simulataneously being up-down a legal quantum state.

Unless you are saying I can't experience both up-down state but only up or down one at a time? Hmm...

 

[Alfrez]

To be more distinct. Here's another example. By shielding Einselection in an isolated object. I can view its Ensumble of all histories such that the chair foot can be in superposition of up-down-side, etc. This is the consequence if you can shield Einselection without having to require that the entire chair should be in coherent state. This requirement only exists in pure Copenhagen collapse model. But then if Many Worlds is true, you can see the chair existing in only one state, the other states in other worlds. However, if you can view the chair in many states simultaneously. Then Many World is falsified.