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Author Topic:   Quantum physics: Copenhagen vs decoherence interpretations
cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 16 of 57 (468968)
06-02-2008 5:15 PM
Reply to: Message 15 by randman
06-02-2008 4:32 PM


Re: Your reason for presenting this information?
we are discussing the varying interpretations of quantum mechanics in respect to non-locality....such as whether observation is mere decoherence, the Many Worlds hypothesis and the transactional hypothesis, and exactly what the Copenhagen interpretation is.
I think you would need to understand something of these interpretations in general before trying to talk about non-locality. And then you would discover that the type of non-locality inherrent in QM is essentially idendepent of interpretation except in certain cases (that you don't mention.)
On causality, it's clear that causality or local realism are violated by QM or perhaps both.
Interesting. It is clear that local realism is violated. It is not clear at all that causality is violated; quite the opposite. Why would you try to claim otherwise? You have no evidence at all that causality is violated. You say that this is off-topic for your current thread but your comment suggests a level of disconnect enough to make me realise that any further conversation here, on-topic or off-topic, will be a waste of my time. If I have any time to spare for QM here, it will be to go back to Coleman's lecture and try to make it accessible, as Percy requested a while back.

This message is a reply to:
 Message 15 by randman, posted 06-02-2008 4:32 PM randman has replied

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 Message 17 by randman, posted 06-02-2008 5:29 PM cavediver has not replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 17 of 57 (468969)
06-02-2008 5:29 PM
Reply to: Message 16 by cavediver
06-02-2008 5:15 PM


Re: Your reason for presenting this information?
It is clear that local realism is violated. It is not clear at all that causality is violated; quite the opposite. Why would you try to claim otherwise?
Just repeating verbatim what quantum physicists state, something I have showed you over and over again. It's either local realism or causality or perhaps both. In fact, you have stated yourself that in "Standard quantum mechanics", causality is violated. I am just saying it may be possible that it is but that local realism is definitely violated.
As far as not addressing the thread topic or posting here, if you are not interested, that's fine by me. I'd rather have someone post that is interested in discussing the topic and not simply trying to make accusations and insinuations which are not accurate.
Edited by randman, : No reason given.

This message is a reply to:
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 Message 18 by Son Goku, posted 06-02-2008 6:14 PM randman has replied

  
Son Goku
Inactive Member


Message 18 of 57 (468973)
06-02-2008 6:14 PM
Reply to: Message 17 by randman
06-02-2008 5:29 PM


Re: Your reason for presenting this information?
randman writes:
In fact, you have stated yourself that in "Standard quantum mechanics", causality is violated.
In that context, cavediver was discussing nonrelativistic quantum mechanics, which is certainly not causal because it doesn't take relativity into account. Nonrelativistic QM lives in Newton's space and time, not the spacetime of Einstein's special theory of relativity.
However quantum field theory, which is basically quantum mechanics made relativistic, does obey causality. This isn't anything to do with quantum mechanics in particular, any theory which doesn't take relativity into account is "acausal".
It's not that local realism or causality or both is violated by QM. It's locality or realism or both. Causality being violated in a theory with no relativistic content is a very vague statement.

This message is a reply to:
 Message 17 by randman, posted 06-02-2008 5:29 PM randman has replied

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 Message 19 by randman, posted 06-02-2008 6:23 PM Son Goku has replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 19 of 57 (468979)
06-02-2008 6:23 PM
Reply to: Message 18 by Son Goku
06-02-2008 6:14 PM


Re: Your reason for presenting this information?
In that context, cavediver was discussing nonrelativistic quantum mechanics, which is certainly not causal because it doesn't take relativity into account. Nonrelativistic QM lives in Newton's space and time, not the spacetime of Einstein's special theory of relativity.
However quantum field theory, which is basically quantum mechanics made relativistic, does obey causality.
Yep, been there already and realize that's what cavediver said. Doesn't really change the fact, contrary to his claims, quantum physicists are indeed wrestling with the issue of non-locality and hence or partly hence, the many creative interpretations of QM.

This message is a reply to:
 Message 18 by Son Goku, posted 06-02-2008 6:14 PM Son Goku has replied

Replies to this message:
 Message 22 by Son Goku, posted 06-02-2008 6:50 PM randman has replied

  
Son Goku
Inactive Member


Message 20 of 57 (468980)
06-02-2008 6:26 PM


The Kochen-Specker Theorem
It may be more useful to have a read of this:
The Kochen-Specker Theorem
At least the non-mathematical parts.
The Kochen-Specker Theorem is one of the deepest results in the foundations of QM. It'll give you a good idea of the wierdness Qm requires.
As a side note nonlocality, e.t.c. don't have anything to do with the Copenhagen interpretation (where by Copenhagen interpretation, I mean what Bohr and co. actually thought) and the Many-Worlds interpretation. They're related to a seperate issue.
Edited by Son Goku, : Forgot the link

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randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 21 of 57 (468982)
06-02-2008 6:32 PM
Reply to: Message 20 by Son Goku
06-02-2008 6:26 PM


Re: The Kochen-Specker Theorem
My understanding is Bohr and the Copenhagen interpretation doesn't consider a particle until "observation" however that is defined, in any definite position or location at all. In other words, it exists as a probability, and so in that sense you could think an entangled particle is not really affected long distance since it's not in a specific state until the observation event.
However, from our perspective, the entangled particles still do act as one, non-local system in that when one takes on specific form and properties within our vantage point of space-time, which can depend on the question "asked of it" so to speak, the other must take on it's pairing.
Thanks btw for the suggestion on the paper. It may be a few days as I will need to take a break from posting and this topic this evening to travel for a few days on business.
Edited by randman, : No reason given.

This message is a reply to:
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Son Goku
Inactive Member


Message 22 of 57 (468989)
06-02-2008 6:50 PM
Reply to: Message 19 by randman
06-02-2008 6:23 PM


Interpretations
randman writes:
Doesn't really change the fact, contrary to his claims, quantum physicists are indeed wrestling with the issue of non-locality and hence or partly hence, the many creative interpretations of QM.
There are few issues here.
Firstly any theory which aims to match the same set of experimental evidence as QM must first, due to Bell's Theorem, incorporate nonlocality.
However due to the Kochen-Specker theorem any theory must also drop one of the following three:
(1)Value realism: Any measurable constructed out of things I've already measured should be measurable. Example, if energy is observable, then energy squared is observable.
(2)Value definiteness: All observables defined for a QM system have definite values at all times.
(3)Noncontextuality: A system possesses a property independently of how it is measured. Example, measurement of energy doesn't depend on you measuring it with position based equipment or momentum based equipment.
So even if we've incorporated nonlocality and dropped one of (1),(2),(3) we still don't have to use orthodox QM, those are simply the conditions a theory must obey to match orthodox QM.
However if you take orthodox QM at face value you are then lead into the interpretational issues, which is separate from nonlocality. You are then asking what does collapse mean. Is it real?
This is what the Copenhagen and Many-Worlds interpretations are about. Although in both the Many-Worlds and the historical Copenhagen interpretation collapse isn't real. It's only modern Copenhagen (which is vastly different from the original) that it is "real".
In short:
Nonlocality is an issue you see when discussing alternatives to orthodox QM. The interpretations involve taking orthodox QM at face-value.

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 Message 19 by randman, posted 06-02-2008 6:23 PM randman has replied

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 Message 23 by randman, posted 06-02-2008 11:36 PM Son Goku has not replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 23 of 57 (469016)
06-02-2008 11:36 PM
Reply to: Message 22 by Son Goku
06-02-2008 6:50 PM


Re: Interpretations
Son Guku, I'll respond maybe this weekend or next week. This topic takes a little more thought than some others, and I've been immersed in some business stuff and will be so for a few days after tonite. Thanks for your responses. Hope to continue the discussion in a few days.

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Son Goku
Inactive Member


Message 24 of 57 (472144)
06-20-2008 4:43 PM


Many Worlds
I just wanted to add something about one of the more misunderstood interpretations of Quantum Mechanics. The Many Worlds scenerio comes from assuming that quantum mechanics as it is currently formulated (or any quantum theory) applies at all levels. In case people think it sounds like some off the wall idea, it is actually the direct prediction of QM if you allow it to be applicable even at our macroscopic scale.

Replies to this message:
 Message 25 by Straggler, posted 06-20-2008 5:58 PM Son Goku has replied

  
Straggler
Member
Posts: 10333
From: London England
Joined: 09-30-2006


Message 25 of 57 (472152)
06-20-2008 5:58 PM
Reply to: Message 24 by Son Goku
06-20-2008 4:43 PM


Cats in Boxes
Hi
I am not sure that non-locality is really what Randman is interested in. I may be wrong but it seems to me he is actually more interested in the possible role of the observer, consciousness etc in QM and the various interpretations that here are with respect to this.
I just wanted to add something about one of the more misunderstood interpretations of Quantum Mechanics. The Many Worlds scenerio comes from assuming that quantum mechanics as it is currently formulated (or any quantum theory) applies at all levels. In case people think it sounds like some off the wall idea, it is actually the direct prediction of QM if you allow it to be applicable even at our macroscopic scale.
With this in mind what is the current predominant interpretation of the Schrodinger's cat scenario? What do most physicists (well the ones that consider such things) subscribe to as the meaning of the collapse of the wave function in such a scenario? Is there a role for conscousness or not?
Is the many worlds inerpretation widely accepted? On what basis is one interpretaion preferred over another and are there firm scientific reasons for these or are they just personal preferences at root?
For thse unfamiliar with Schrodinger's cat Schrdinger's cat - Wikipedia

This message is a reply to:
 Message 24 by Son Goku, posted 06-20-2008 4:43 PM Son Goku has replied

Replies to this message:
 Message 26 by Son Goku, posted 06-21-2008 12:23 PM Straggler has replied

  
Son Goku
Inactive Member


Message 26 of 57 (472250)
06-21-2008 12:23 PM
Reply to: Message 25 by Straggler
06-20-2008 5:58 PM


Foundational QM
Straggler writes:
Is there a role for consciousness or not?
This question is much easier to answer than the others so I'll deal with it first. Basically, the answer is no. Most would think this is not a question of consciousness. In fact the view that consciousness is involved was always a very a minor one, proposed originally by Wigner. However even he lost interest in it very quickly.
Straggler writes:
With this in mind what is the current predominant interpretation of the Schrodinger's cat scenario? What do most physicists (well the ones that consider such things) subscribe to as the meaning of the collapse of the wave function in such a scenario?
Big question, so if there is anything unclear in what follows don't hesitate to ask.
First let's get the pragmatists out of the way, as you have said. Although I should say that this position has gone from being very common in past decades to uncommon today. This is due to a post 2000 revival in interest in the foundations of QM. For the purpose of what follows I will call the "I don't care" interpretation the Dirac interpretation.
Now I'll explain my notation. If a cat is definitely dead I will denote it: |Dead>. If it is definitely alive then: |Alive>. In Schrodinger’s cat experiment we have that the state is |Dead> + |Alive>. Now my symbols above can contain more information. For instance the state of the Cat being dead and me off in Budapest is:
|Cat is dead and I’m off in Budapest>
Any of these |Insert phrase> things are what may be called a wavefunction.
Here is low down of what the most common interpretations say:
Many Worlds:
Quantum Mechanics applies at all levels. This means even large scale objects like you and I can be in superposition. So what happens in this model is that the state of the universe goes from:
|State of World> =
|I haven’t looked at the cat yet and the cat is alive> + | I haven’t looked at the cat yet and the cat is dead>
To
|State of World> =
|The cat is alive and I see him alive> + |The cat is dead and I see him dead>
There is no collapse here because the first state can evolve smoothly into the second in the standard formalism of quantum mechanics. One should also note that Many-Worlds is totally deterministic.
Bayesian interpretation:
The wavefunction only represents our knowledge of the system. Hence collapse is simply when we learn more. That is upon seeing the cat alive, we know the cat is alive and hence there is no probability for anything else. Collapse is therefore not a real event.
Historical Copenhagen/ Bohr Interpretation:
We are classical thinking things. Hence the quantum world makes no sense to us. The formalism of QM is the closest we will get to understanding it. It is a formalism for explaining our big classical world’s interaction with the small quantum world. Collapse is a part of that formalism. Like all of QM though we must not try to understand what it really is/means. That is all.
Modern Copenhagen:
This is actually the only model with collapse in it. Basically we have:
|State of World> =
|I haven’t looked at the cat yet and the cat is alive> + | I haven’t looked at the cat yet and the cat is dead>
Goes to:
|The cat is alive and I see him alive>
Or
|The cat is dead and I see him dead>
With a 50:50 chance of each. This is collapse, because there is no way to go from the first state to either of the second two, in the standard formalism, without an instant jump.
Dynamical collapse:
Basically Modern Copenhagen with attempts at modelling what process causes collapse.
QM is incomplete, there is another theory underlying it:
Fairly obvious. Not so much an interpretation really.
Now as to which interpretation is the standard/dominant one, it depends on the area of physics and the period of history you’re talking about. In the 30s it was definitely either the Dirac Interpretation or Historical Copenhagen. After the 40s until 90s-00s it was Modern Copenhagen or Dirac. Recently all the interpretations have been kind of levelling off to have even numbers of proponents. However in certain areas different interpretations dominate. For instance in quantum computing many-worlds dominates. In particle physics it’s still Dirac which dominates.
Is the many worlds interpretation widely accepted? On what basis is one interpretation preferred over another and are there firm scientific reasons for these or are they just personal preferences at root?
The Many-Worlds is definitely widely accepted. For a brief period in the 90s, due to the arrival of quantum computation, it may have been the most widely held. Today it’s probably roughly even with others. Usually one interpretation is preferred in a given circumstance because it allows easier intuition of the physics. For quantum computation many-worlds definitely seems to make things easier. For Measurement Theory, which is the applied science of what goes on when several hundreds of quantum mechanical measurements are made and how we may use them in engineering, Modern Copenhagen is significantly more useful.
Currently the preferences are rooted in reasons like these, however that’s not to say the interpretations differ only in a philosophical sense. For instance if QM is incomplete the new theory will probably make new predictions. If dynamical collapse is true we should see evidence for the mechanism of collapse. To falsify Many Worlds we’d just need to find some scale where QM does not apply.
Just to mention something of interest. A lot of the "QM is incomplete" people have attempted to make theories which replace it and are deterministic. The funny thing is in a lot of these theories when you try to model what the subatomic world looks like when viewed by a large classical observer, you get an effective theory of the universe from their point of view and this effective theory is basically QM. So in these "QM is incomplete" models, historical Copenhagen ends up being partially correct in the sense that QM is (in these models) a formalism for explaining a big classical objects interaction with the small quantum world.
Edited by Son Goku, : Spelling error.

This message is a reply to:
 Message 25 by Straggler, posted 06-20-2008 5:58 PM Straggler has replied

Replies to this message:
 Message 27 by Son Goku, posted 06-22-2008 6:44 AM Son Goku has not replied
 Message 28 by Straggler, posted 06-22-2008 10:25 AM Son Goku has replied

  
Son Goku
Inactive Member


Message 27 of 57 (472410)
06-22-2008 6:44 AM
Reply to: Message 26 by Son Goku
06-21-2008 12:23 PM


Re: Foundational QM
I should also mention something about the meaning of states such as |Dead> + |Alive>. The exact meaning of it depends on the interpretation.
In almost all of the interpretations mention aboved it means being simultaneously dead and alive. However in the Bayesian Interpretation |Dead> + |Alive> means "could be dead or alive, but we don't know".
Also a warning if anybody decides to read up on this stuff, the word "Copenhagen Interpretation" is desperately lacking a standardisation. Several texts or articles will say it and they could be referring to either (what I have called) Historical Copenhagen or Modern Copenhagen. Even worse some people pick and mix between Historical and Modern, switching back and forth between them or fusing them together. In fact sometimes people don't realise they disagree on their interpretation of QM since they both just use "Copenhagen" for their opinion.
Wikipedia, sensibly, calls Historical Copenhagen, the Copenhagen interpretation and calls Modern Copenhagen, Objective collapse.
Also the Bayesian interpretation is occasionally called the ensemble/statistical interpretation.
Most of the interpretations I haven't mentioned are extensions/modifications of ones I have. (For instance Many-Minds is a modifcation of Many worlds and Consistent Histories is a extension of/attempt to clarify Historical Copenhagen). Although quite often the more advanced interpretations stray into modifying things so much that they may be a new theory rather than an interpretation of QM.
Finally, obviously a lot of people who hold to Modern Copenhagen end up drifting to Dynamical Collapse since they want to actually have a description of collapse.

This message is a reply to:
 Message 26 by Son Goku, posted 06-21-2008 12:23 PM Son Goku has not replied

  
Straggler
Member
Posts: 10333
From: London England
Joined: 09-30-2006


Message 28 of 57 (472421)
06-22-2008 10:25 AM
Reply to: Message 26 by Son Goku
06-21-2008 12:23 PM


Re: Foundational QM
Firstly thankyou for this clear and informed explanation.
Now I'll explain my notation. If a cat is definitely dead I will denote it: |Dead>. If it is definitely alive then: |Alive>. In Schrodinger’s cat experiment we have that the state is |Dead> + |Alive>. Now my symbols above can contain more information. For instance the state of the Cat being dead and me off in Budapest is:
|Cat is dead and I’m off in Budapest>
Any of these |Insert phrase> things are what may be called a wavefunction.
Each of the |state> terms is the probability of that particular state being the eventual observed state. Is that right? Thus the sum of all the |state> terms = 1 (e.g. |Dead cat> + |Alive cat> = 1). Is that correct?
Would each |state> be a term in the Schrodinger equation? Or are the staes as you have described them independent of time and thus not part of the Schrodinger equation?
Many Worlds:
Quantum Mechanics applies at all levels. This means even large scale objects like you and I can be in superposition. So what happens in this model is that the state of the universe goes from:
|State of World> =
|I haven’t looked at the cat yet and the cat is alive> + | I haven’t looked at the cat yet and the cat is dead>
To
|State of World> =
|The cat is alive and I see him alive> + |The cat is dead and I see him dead>
There is no collapse here because the first state can evolve smoothly into the second in the standard formalism of quantum mechanics. One should also note that Many-Worlds is totally deterministic.
In the case of many worlds dowe consider splitting worlds at the amcroscopic level (i.e. dead cats and alive cats) or the subatomic level or both? Presumably both?
So from any instant in time there are literally as many worlds branching off as ther are posible states for subatomic particles in the universe? Is that correct? If so the number of 'worlds' created at every instant must be vast beyond comprehension even in cosmological terms.
Bayesian interpretation:
The wavefunction only represents our knowledge of the system. Hence collapse is simply when we learn more. That is upon seeing the cat alive, we know the cat is alive and hence there is no probability for anything else. Collapse is therefore not a real event.
Historical Copenhagen/ Bohr Interpretation:
We are classical thinking things. Hence the quantum world makes no sense to us. The formalism of QM is the closest we will get to understanding it. It is a formalism for explaining our big classical world’s interaction with the small quantum world. Collapse is a part of that formalism. Like all of QM though we must not try to understand what it really is/means. That is all.
Are these two not essentially the same? Both suggest that more knowledge/perception is the answer even if they disagree as to how possible that may be in practise.
Modern Copenhagen:
This is actually the only model with collapse in it. Basically we have:
|State of World> =
|I haven’t looked at the cat yet and the cat is alive> + | I haven’t looked at the cat yet and the cat is dead>
Goes to:
|The cat is alive and I see him alive>
Or
|The cat is dead and I see him dead>
With a 50:50 chance of each. This is collapse, because there is no way to go from the first state to either of the second two, in the standard formalism, without an instant jump.
Dynamical collapse:
Basically Modern Copenhagen with attempts at modelling what process causes collapse.
Are there any theories as to what the mechanism of collapse might be?
Do you personally subscribe to any of the interpretations that you have outlined above?

This message is a reply to:
 Message 26 by Son Goku, posted 06-21-2008 12:23 PM Son Goku has replied

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 Message 29 by Son Goku, posted 06-22-2008 2:41 PM Straggler has not replied

  
Son Goku
Inactive Member


Message 29 of 57 (472464)
06-22-2008 2:41 PM
Reply to: Message 28 by Straggler
06-22-2008 10:25 AM


Re: Foundational QM
Each of the |state> terms is the probability of that particular state being the eventual observed state. Is that right? Thus the sum of all the |state> terms = 1 (e.g. |Dead cat> + |Alive cat> = 1). Is that correct?
If I'm being totally correct I should write:
(1/2)|Alive> + (1/2)|Dead>.
The square of the number in front of the state is the chance of that state eventually being observed. If the squares of these numbers are summed it should equal 1.
(If anybody is wondering, in case the html style formatting for square root is unclear, 1/2 is 1 over the square root of 2.)
Would each |state> be a term in the Schrodinger equation? Or are the staes as you have described them independent of time and thus not part of the Schrodinger equation?
They would be a term in Schrodinger's equation. Specifically they are what you solve Schrodinger's equation to obtain. However, looking back it may have been better to refer to (1/2)|Decayed> + (1/2)|Undecayed>, refering to the atom whose decay determines the death of the cat. This is because only the Many-Worlds accepts that something macroscopic like a Cat can be in a superposition like (1/2)|Alive> + (1/2)|Dead>.
In the case of many worlds dowe consider splitting worlds at the amcroscopic level (i.e. dead cats and alive cats) or the subatomic level or both? Presumably both?
So from any instant in time there are literally as many worlds branching off as ther are posible states for subatomic particles in the universe? Is that correct? If so the number of 'worlds' created at every instant must be vast beyond comprehension even in cosmological terms.
The answer to all these questions is yes. Superposition occurs at both levels, there are as many worlds as there are possible subatomic states and the number of worlds is massive.
Are these two not essentially the same? Both suggest that more knowledge/perception is the answer even if they disagree as to how possible that may be in practise.
Yes they are quite similar. The funny thing is that Einstein was a Bayesian and Bohr was a historical Copenhagener. The great debates concerning QM in the 20s and 30s where actually between these two, seemingly similar, interpretations.
Usually a Bayesian person is implying that QM is a statistical approximation to something underneath. However a Historical Copenhagener (from here on a HCer) thinks there is absolutely nothing underneath and the quantum world is fundamentally unknowable since all we can ever have are our experimental equipment and its interactions. The best way to phrase the difference between them is this:
Bayesian: QM is an approximate theory of atomic systems themselves.
HCer: QM is a totally accurate theory of the interaction of our equipment with atomic systems. There can not be a theory of atomic systems themselves, even an approximate one.
I hope this kind of makes the distinction clearer, since the way I've phrased it previously makes it sound like they're both just sound like "I don't what atomic systems are doing". The big difference is that a HCer says that it makes no sense to talk about an atom itself, only an atom and some equipment which will measure it.
To take specific state:
(1/2)|Alive> + (1/2)|Dead>
A Bayesian would say this means (apologies for repetition) "could be alive or dead, but I don't know". A HCer however interprets this as some fundamentally incomprehensible statement about what statistical spread of results our equipment will obtain when it and the atomic system meet.
If I'm still being too vague, please say so.
Are there any theories as to what the mechanism of collapse might be?
Yes. Penrose for example thinks it is gravity which causes it. Others think it has something to do with interactions with the environment and thermal properties like entropy. (That is, due to the subatomic system and the measuring equipment both being in a room with highly disordered thermal air or the disordered thermal nature of the equipment itself.)
Do you personally subscribe to any of the interpretations that you have outlined above?
Currently, I wouldn’t subscribe to any of them as the truth. For instance Many-Worlds makes the least assumptions and modifications, literally taking QM as is and applying to both the subatomic and macroscopic world. On the other hand its implications sound crazy. They all suffer from this, being very convincing and difficult to argue against from one specific angle and yet sounding deficient from another. I should clearly say my main problem is that I find all of them convincing. Whenever I read something about one of them I always half-think “Yeah, there is something to this”. They all have very good points and not many bad ones.
However when I’m thinking/visualising QM I definitely picture Modern Copenhagen. That is I actually do think of atoms as doing stuff by themselves somewhere away from equipment, like in outer space. (Something Bohr specifically said you should not do.) I also picture something suddenly jumping to a specific state when measured, but I never mentally picture a process behind this.
To be honest I really don’t know what to think, it’s a very difficult issue. However I think possibly we need more theorems about the ontological structure of QM like the Kochen-Specker Theorem. I wouldn’t underestimate insights from those who are working with the practical consequences of quantum measurement, so there may also be insights from Quantum Computation and the recently introduced Measurement theory.

This message is a reply to:
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Replies to this message:
 Message 30 by PaulK, posted 06-22-2008 3:43 PM Son Goku has replied

  
PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 30 of 57 (472471)
06-22-2008 3:43 PM
Reply to: Message 29 by Son Goku
06-22-2008 2:41 PM


Re: Foundational QM
Randman holds that arbitrary actions can - somehow radically change the past based on the "delayed-choice" experiments. My understanding is that these experiments would only narrow down the possible past states.
Could you please explain how delayed choice experiments fit into the various interpretations ? (I think that I could work it out, but I'd rather it was done by someone more qualified).

This message is a reply to:
 Message 29 by Son Goku, posted 06-22-2008 2:41 PM Son Goku has replied

Replies to this message:
 Message 31 by Son Goku, posted 06-28-2008 7:40 AM PaulK has replied

  
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