Freethought & Rationalism Archive

Answerer · 10-04-2002, 02:23 AM

Yeah, I feel that Axiom was right, the hidden local variable theory was disproved long time since the invention of Bell theorem. And the experiment, which disproved the hidden local variable theory, had in turn confirmed the fact that nature is fundamentally nonlocal. Therefore since we can't have a local realism picture of the sub-atomic, thhere is not much point in searching for realism at all.
Anyway, I feel that(particle + wave = string) string theory could provide us a brand new picture of the sub-atomic rather than holding onto old and classical concepts such as particle, wave, etc.

Liquidrage · 10-04-2002, 08:15 AM

Hidden variables is not the majority viewpoint but it is still supported by many. A simple seach on yahoo can find the opponenets and proponents of the theory and some of the new flavors it comes in.

Non-causality is not the majority viewpoint by any means. It was at one time but isn't from what I can discern at the moment. When I buy books read literature on the subject I do so without knowing if the author(s) believes in determinism or not. Yet overwhelmingly I find that most believe Quantum Uncertainty is a result of a yet unknown process that is itself not uncertain.

Edit:
Took me a while but finally found the link I was looking for
<a href="http://fergusmurray.members.beeb.net/Causality.html" target="_blank">http://fergusmurray.members.beeb.net/Causality.html</a>
It sums up nicely a majority of what I've read on the matter. There there are many schools of thought on the issue and many different valid (as of now) interpretations.

Which brings us back to the incompleteness of QM and why I used the word "believed" when talking about the majority viewpoint on causality.

[ October 04, 2002: Message edited by: Liquidrage ]

Answerer · 10-04-2002, 11:27 PM

Well, it seems that old and common concepts are hard to be rid of.

Jesse · 10-05-2002, 02:19 AM

Axiom of Choice:
Since we don't see the predicted probabilities of the hidden variable theory, there aren't any hidden variables. So certain events in the universe are indeed uncaused by anything.

Not necessarily--hidden variables are still possible, but only if you allow superluminal signalling between particles (as in Bohm's interpretation of QM). Also, the many-worlds interpretation is a wholly deterministic interpretation which is compatible with the EPR results, although it's never been completely clear how to recover the ordinary classical notion of "probabilities" from the universal wavefunction of the MWI.

Axiom of Choice:
You are certainly right about our thinking on the wave particle duality though. It is a artifact of the mathematics used to describe them: we use wave equations sometimes, and equations for particles other times.

I think the wave-particle duality is more problematic than that. There are other physical theories that use complicated non-intuitive mathematical formalism, but they are not as strange as QM. The reason is that in classical theories, no matter how crazy the math is you still have a picture of an objective universe whose behavior is self-contained and does not depend on interactions with outside observers--any "observer" within the universe would be just another physical system whose behavior could be explained by the theory. In QM, though, you must use a deterministic wavefunction to calculate a system's evolution between observations, but then to actually get physical predictions you have to add the additional postulate that each observation "collapses" the wavefunction into an eigenstate, with probability proportional to the square of the amplitude of the wavefunction. The "observer" need not be a conscious system, of course, but the point is that if we also try to understand the behavior of the observing system and why it interacted with the first system at that particular time, we must model the observing system using a wavefunction too, but then we would seem to need a higher-order observing system to get any physical predictions from that wavefunction. It seems to lead to an infinite regress--we don't understand how to turn quantum mechanics into a self-contained theory of the whole universe with no "outside" system to act as an observer, due to this mysterious wave-particle duality. Thus the wave-particle duality seems to present a problem for those of us who believe that there must be an objective reality that exists independently of our measurements (several interpretations of QM present ways in which we could recover this idea, but they lead to bizarre consequences of their own).

[ October 05, 2002: Message edited by: Jesse ]

Liquidrage · 10-05-2002, 05:31 AM

I hate to do this as it always seems to end up here when we get into QM and uncertainty.

But the biggest reaseon we have the infinite regression of the collapse that Jesse mentioned is none other then true "free will".
If one does not assume free will of the observer then one can rightfully claim that the collapse is predetermined and there is not infinite regression needed.
It sounds like it's too trivial to be, but yet it is exactly the reason.

From Ghost in the Atom, and yes, this is the John Bell.

BBC Interviewer: "Of course one person who was somewhat
disbelieving was Einstein, and he made the famous remark that God
does not play dice with the universe. Would you say that after
this experiment, (Alain Aspect's, 1982,) and after your work,
you're convinced that God does indeed play dice with the
universe?"

John Bell: " No, no, by no means. But I would also like to
qualify a little bit this 'God does not play dice' business. This
is something often quoted, and which Einstein did say rather early
in his career, but afterwards he was more concerned with other
aspects of quantum mechanics than with the question of
indeterminism. And indeed, Aspects' particular experiment tests
rather those other aspects, specifically the question of no action
at a distance."

BBC Interviewer: " You don't think it tells us anything about the
determinism or indeterminism of the physical world?"

John Bell: " To say it tells nothing, that would be going to far.
I think that it is very difficult to say that any one experiment
tells you about any isolated concept. I think that it's a whole
world view which is tested by an experiment, and if the experiment
does not verify that world view, it is not so easy to identify
just which part is suspect and has to be revised. Certainly the
experiment says that Einstein's world view is not tenable."

BBC Interviewer: " Yes, I was going to ask whether it is still
possible to maintain, in the light of experimental experience, the
idea of a deterministic universe?"

John Bell: " You know, one of the ways of understanding this
business is to say that the world is super-deterministic. That
not only is inanimate nature deterministic, but we, the
experimenters who imagine we can choose to do one experiment
rather than another, are also determined. If so, the difficulty
which this experimental result creates disappears."

BBC Interviewer: " Free will is an illusion - that gets us out of
the crisis, does it?"

John Bell: " That's correct. In the analysis it is assumed that
free will is genuine, and as a result of that one finds that the
intervention of the experimenter at one point has to have
consequences at a remote point, in a way that influences
restricted by the finite velocity of light would not permit. If
the experimenter is not free to make this intervention, if that
also is determined in advance, the difficulty disappears."

[ October 05, 2002: Message edited by: Liquidrage ]

Starboy · 10-05-2002, 06:20 AM

His point of view seems to imply that the way the universe works depends on if there is someone there to observe it. Something I have a hard time accepting.

Starboy

Liquidrage · 10-05-2002, 06:35 AM

Are you referring to John Bell?
I do not believe he supports the Copenhagen Interpretation and in fact his work is the foundation for alternate theories including the non-local hidden variables mentioned earlier by Jesse.

ishalon · 10-05-2002, 04:54 PM

Quote:

Originally posted by RJS:


I likely have an issue with the whole concept of since we cant know the exact position or momentum of a given particle at a given time, then its movements are uncaused. Seems like a leap of faith to me

And I certainly am not qualified to debate it! Heck, if Einstein had issues with it for many years, what can I expect

??

If we don't know the exact position/momentum of a particle at an instant, aren't its movements caused by chance?

Answerer · 10-05-2002, 06:27 PM

I remember that some books spoke of the collapse of wavefunction of the particle due to its interaction with some marco-scopic system. Although this explanation doesn't really explain anything fundamentally, at least it aviods the notation and usage of 'human consciousness'.

Jesse · 10-06-2002, 02:26 AM

Answerer:
I remember that some books spoke of the collapse of wavefunction of the particle due to its interaction with some marco-scopic system. Although this explanation doesn't really explain anything fundamentally, at least it aviods the notation and usage of 'human consciousness

Yeah, I think you're talking about <a href="http://www.decoherence.de/" target="_blank">decoherence</a>...decoherence does allow us to dispense with the notion that "observation" has to be associated with consciousness, but as you say it does not fundamentally clear up the problem because you still get the "infinite regress" issue I mentioned when you try to translate wavefunctions into probabilities in a self-contained universe.

10-04-2002, 08:15 AM	#22
Liquidrage Veteran Member Join Date: Dec 2001 Location: Tallahassee Posts: 1,301	Hidden variables is not the majority viewpoint but it is still supported by many. A simple seach on yahoo can find the opponenets and proponents of the theory and some of the new flavors it comes in. Non-causality is not the majority viewpoint by any means. It was at one time but isn't from what I can discern at the moment. When I buy books read literature on the subject I do so without knowing if the author(s) believes in determinism or not. Yet overwhelmingly I find that most believe Quantum Uncertainty is a result of a yet unknown process that is itself not uncertain. Edit: Took me a while but finally found the link I was looking for <a href="http://fergusmurray.members.beeb.net/Causality.html" target="_blank">http://fergusmurray.members.beeb.net/Causality.html</a> It sums up nicely a majority of what I've read on the matter. There there are many schools of thought on the issue and many different valid (as of now) interpretations. Which brings us back to the incompleteness of QM and why I used the word "believed" when talking about the majority viewpoint on causality. [ October 04, 2002: Message edited by: Liquidrage ]</p>

10-05-2002, 02:19 AM	#24
Jesse Moderator - Science Discussions Join Date: Feb 2001 Location: Providence, RI, USA Posts: 9,908	Axiom of Choice: Since we don't see the predicted probabilities of the hidden variable theory, there aren't any hidden variables. So certain events in the universe are indeed uncaused by anything. Not necessarily--hidden variables are still possible, but only if you allow superluminal signalling between particles (as in Bohm's interpretation of QM). Also, the many-worlds interpretation is a wholly deterministic interpretation which is compatible with the EPR results, although it's never been completely clear how to recover the ordinary classical notion of "probabilities" from the universal wavefunction of the MWI. Axiom of Choice: You are certainly right about our thinking on the wave particle duality though. It is a artifact of the mathematics used to describe them: we use wave equations sometimes, and equations for particles other times. I think the wave-particle duality is more problematic than that. There are other physical theories that use complicated non-intuitive mathematical formalism, but they are not as strange as QM. The reason is that in classical theories, no matter how crazy the math is you still have a picture of an objective universe whose behavior is self-contained and does not depend on interactions with outside observers--any "observer" within the universe would be just another physical system whose behavior could be explained by the theory. In QM, though, you must use a deterministic wavefunction to calculate a system's evolution between observations, but then to actually get physical predictions you have to add the additional postulate that each observation "collapses" the wavefunction into an eigenstate, with probability proportional to the square of the amplitude of the wavefunction. The "observer" need not be a conscious system, of course, but the point is that if we also try to understand the behavior of the observing system and why it interacted with the first system at that particular time, we must model the observing system using a wavefunction too, but then we would seem to need a higher-order observing system to get any physical predictions from that wavefunction. It seems to lead to an infinite regress--we don't understand how to turn quantum mechanics into a self-contained theory of the whole universe with no "outside" system to act as an observer, due to this mysterious wave-particle duality. Thus the wave-particle duality seems to present a problem for those of us who believe that there must be an objective reality that exists independently of our measurements (several interpretations of QM present ways in which we could recover this idea, but they lead to bizarre consequences of their own). [ October 05, 2002: Message edited by: Jesse ]</p>

10-05-2002, 05:31 AM	#25
Liquidrage Veteran Member Join Date: Dec 2001 Location: Tallahassee Posts: 1,301	I hate to do this as it always seems to end up here when we get into QM and uncertainty. But the biggest reaseon we have the infinite regression of the collapse that Jesse mentioned is none other then true "free will". If one does not assume free will of the observer then one can rightfully claim that the collapse is predetermined and there is not infinite regression needed. It sounds like it's too trivial to be, but yet it is exactly the reason. From Ghost in the Atom, and yes, this is the John Bell. BBC Interviewer: "Of course one person who was somewhat disbelieving was Einstein, and he made the famous remark that God does not play dice with the universe. Would you say that after this experiment, (Alain Aspect's, 1982,) and after your work, you're convinced that God does indeed play dice with the universe?" John Bell: " No, no, by no means. But I would also like to qualify a little bit this 'God does not play dice' business. This is something often quoted, and which Einstein did say rather early in his career, but afterwards he was more concerned with other aspects of quantum mechanics than with the question of indeterminism. And indeed, Aspects' particular experiment tests rather those other aspects, specifically the question of no action at a distance." BBC Interviewer: " You don't think it tells us anything about the determinism or indeterminism of the physical world?" John Bell: " To say it tells nothing, that would be going to far. I think that it is very difficult to say that any one experiment tells you about any isolated concept. I think that it's a whole world view which is tested by an experiment, and if the experiment does not verify that world view, it is not so easy to identify just which part is suspect and has to be revised. Certainly the experiment says that Einstein's world view is not tenable." BBC Interviewer: " Yes, I was going to ask whether it is still possible to maintain, in the light of experimental experience, the idea of a deterministic universe?" John Bell: " You know, one of the ways of understanding this business is to say that the world is super-deterministic. That not only is inanimate nature deterministic, but we, the experimenters who imagine we can choose to do one experiment rather than another, are also determined. If so, the difficulty which this experimental result creates disappears." BBC Interviewer: " Free will is an illusion - that gets us out of the crisis, does it?" John Bell: " That's correct. In the analysis it is assumed that free will is genuine, and as a result of that one finds that the intervention of the experimenter at one point has to have consequences at a remote point, in a way that influences restricted by the finite velocity of light would not permit. If the experimenter is not free to make this intervention, if that also is determined in advance, the difficulty disappears." [ October 05, 2002: Message edited by: Liquidrage ]</p>

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10-04-2002, 02:23 AM	#21
Answerer Veteran Member Join Date: Feb 2002 Location: Singapore Posts: 3,956	Yeah, I feel that Axiom was right, the hidden local variable theory was disproved long time since the invention of Bell theorem. And the experiment, which disproved the hidden local variable theory, had in turn confirmed the fact that nature is fundamentally nonlocal. Therefore since we can't have a local realism picture of the sub-atomic, thhere is not much point in searching for realism at all. Anyway, I feel that(particle + wave = string) string theory could provide us a brand new picture of the sub-atomic rather than holding onto old and classical concepts such as particle, wave, etc.

10-04-2002, 11:27 PM	#23
Answerer Veteran Member Join Date: Feb 2002 Location: Singapore Posts: 3,956	Well, it seems that old and common concepts are hard to be rid of.

10-05-2002, 06:20 AM	#26
Starboy Banned Join Date: Jun 2002 Location: Tallahassee, FL Reality Adventurer Posts: 5,276	His point of view seems to imply that the way the universe works depends on if there is someone there to observe it. Something I have a hard time accepting. Starboy

10-05-2002, 06:35 AM	#27
Liquidrage Veteran Member Join Date: Dec 2001 Location: Tallahassee Posts: 1,301	Are you referring to John Bell? I do not believe he supports the Copenhagen Interpretation and in fact his work is the foundation for alternate theories including the non-local hidden variables mentioned earlier by Jesse.

10-05-2002, 06:27 PM	#29
Answerer Veteran Member Join Date: Feb 2002 Location: Singapore Posts: 3,956	I remember that some books spoke of the collapse of wavefunction of the particle due to its interaction with some marco-scopic system. Although this explanation doesn't really explain anything fundamentally, at least it aviods the notation and usage of 'human consciousness'.

10-06-2002, 02:26 AM	#30
Jesse Moderator - Science Discussions Join Date: Feb 2001 Location: Providence, RI, USA Posts: 9,908	Answerer: I remember that some books spoke of the collapse of wavefunction of the particle due to its interaction with some marco-scopic system. Although this explanation doesn't really explain anything fundamentally, at least it aviods the notation and usage of 'human consciousness Yeah, I think you're talking about <a href="http://www.decoherence.de/" target="_blank">decoherence</a>...decoherence does allow us to dispense with the notion that "observation" has to be associated with consciousness, but as you say it does not fundamentally clear up the problem because you still get the "infinite regress" issue I mentioned when you try to translate wavefunctions into probabilities in a self-contained universe.

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