Layman's Question on Quantum Mechanics

[quantumcarl]

If no human has observed the moon or been able to calculate its existence through studying its physical effects.... does the moon exist under the terms and formulations of quantum mechanics? Please be kind!!!:bugeye:

[abszero]

Can anything be said to "exist" if you can't, in principle, observe its effects or it directly?

[zekise]

Absolutely - the moon will exist if you dont observe it or if humanity ceases to observe it or if it never had observed it. There are many astronomical objects that have never been seen before but get discovered by humans. It is illogical to believe that they did not exist prior to observation. There is no force in nature that has been discovered, or could even be conceived, that can bring a planet into existence once it is observed by humans for the first time. For one thing this force will have to defy relativity. If anybody is claiming this, then they should provide proof of such a force, and as long as they are unable to do so, such claims are not worth a dime a dozen.

This meme that something must be observed by a conscious being in order for it to exist is simply a creation of some people's imagination, who have difficulty accepting that there is an objective reality out there irrespective of their own existence.

Now if the object was a quantum particle, again the answer is an emphatic no. For a quantum particle to get realized, all that has to happen is for its wavefunciton to decohere. This is as simple as the wavefunction collapsing on an atom and the particle getting absorbed or knocking off an electron. Again, there is NO OBSERVATION, NO MEASUREMENT, NO CONSCIOUSNESS, and NO HUMANITY involved.

What you are referring to are certain myths pushed by religionists, mystics and other obfuscators who, unlike scientists, have no idea how reality works, who cannot accept that their self is utterly insignificant in the grand scheme of things, and who are beholden to their own subjective emotions and petty rationalizations.

[vanesch]

What you are referring to are certain myths pushed by religionists, mystics and other obfuscators who, unlike scientists, have no idea how reality works, who cannot accept that their self is utterly insignificant in the grand scheme of things, and who are beholden to their own subjective emotions and petty rationalizations.

I don't think the origin of the view that there is a potential relationship between the "existance" (which should be defined of course) finds its sole origin in religionists and mystics. I count myself amongst the people that think that consciousness MIGHT have something to do with the claim to existence, but this is NOT based upon my desire for religion (I'm not religious) nor mysticism (I have no desire for any mysticism). In fact, my personal opinion grew out of the study of the FORMALISM of quantum theory (which means that from the moment that the formalism will change, the view will change). There is a fundamental incompatibility between the "real world" you describe and the world description that results if you take the formalism of quantum theory seriously. That formalism states that ALL physical interaction is given by a strictly unitary operator - which unavoidably leads to a world where all possibilities are realised - while clearly what we subjectively observe does NOT correspond to such a world. So there are two outcomes to this: this strict unitarity does not hold (very well possible, but this is NOT what the current formalism says), OR we consciously only observe PART of the state of the universe (ONE branch, or world). Now, once you enter into these waters, and the link between subjective experience and objective world is not the trivial relation anymore you are advocating, one should take into account the philosophical reflexions that have been made in these issues.

Again, I'm not claiming that "the moon isn't there when you don't look at it" (in the necessary secondary degree). I'm only claiming that this is what quantum theory as we know it today, tells you, when you take it seriously as an ontological description of "reality", and that the origin of this is not some desire for mysticism, but is a hard statement in the quantum formalism, namely the requirement for unitarity.

[quantumcarl]

Can anything be said to "exist" if you can't, in principle, observe its effects or it directly?

As a kind of addendum to my question:

the idea that there is a "potential" for a moon to exist, even without observation or awareness of its existence, seems like it could be part of the quantum way of analyzing existence.

Is the potential for a moon to exist, the potential for humans to observe a moon to exist and other potentials like of no moon existing etc... part of a quantum equation with regard to the "existence" of the moon or matter in general? Remember that matter is simply a configuration of energy, wave function etc...

[ZapperZ]

As a kind of addendum to my question:
the idea that there is a "potential" for a moon to exist, even without observation or awareness of its existence, seems like it could be part of the quantum way of analyzing existence.
Is the potential for a moon to exist, the potential for humans to observe a moon to exist and other potentials like of no moon existing etc... part of a quantum equation with regard to the "existence" of the moon or matter in general? Remember that matter is simply a configuration of energy, wave function etc...

But at some point, there is a "transition" from quantum behavior to the classical behavior that we all know and love. You must make such a distinction or else you will get into the mystical world of mumbo-jumbo.

Treat a classical entity as it should, and treat a quantum entity as it should. But don't mix them up or you'll get absurdities. When you apply a set of rules that were never meant to be applied to that particular situation, you get quackeries.

Zz.

[quantumcarl]

But at some point, there is a "transition" from quantum behavior to the classical behavior that we all know and love. You must make such a distinction or else you will get into the mystical world of mumbo-jumbo.
Treat a classical entity as it should, and treat a quantum entity as it should. But don't mix them up or you'll get absurdities. When you apply a set of rules that were never meant to be applied to that particular situation, you get quackeries.
Zz.

What you have written here constitutes a warning. We could heed your warning if we had a definition for "mumbo-jumbo" and "quackeries". A reason why we need to avoid them would come in handy as well... is this a yellow or orange alert with regard to in-coming absurdities?

I have no wish to indulge in the dog-chase-tail-chase-dogma religiousities that so many entrepreners have milked when it comes to quantum physics.

I am simply interested in the objective views of quantum mechanics and how they may apply to awareness. You will please notice I am trepedaciously avoiding the word "consciousness" because it seems this word has been trade-marked, patented and copyrighted by every guru and swami on the planet... and for no good reason other than to sound "universal".

If it is true that quantum theorys and the classic, relativity theorys are like an oil and water scenario, there is still something emulsifying the two and that is what we are experiencing... at this moment. Surely one system supports the other... or, even more probable, one system gives rise to the other. There must be common elements in both systems that can be or have been observed. Is this true?

[Sherlock]

If no human has observed the moon or been able to calculate its existence through studying its physical effects.... does the moon exist under the terms and formulations of quantum mechanics? Please be kind!!!:bugeye:

Conjectured objects that have never been observed might exist, but we have no way of knowing for sure. Conjectured events that have never been observed might have happened, but we have no way of knowing for sure. If no human had ever observed the moon, and if there also were no observed events ("physical effects") that would lead to the conjecture that there is a moon orbiting the earth, then we could feel justified in the belief that the earth has no moon --- and neither quantum theory nor any other physical theory would contradict this view. However, humans have been observing and tracking the moon for millenia, so the belief that it's there even during intervals when no one on earth happens to be observing it seems justified --- and neither quantum theory nor any other physical theory contradicts this belief.

As far as I know (which isn't that far ... I'm just a student of this stuff), the "terms and formulations" of QM don't deal with moons. Moons and, say, photons are different. The main difference has to do with the scale of compositional and interactional complexity ... I think. :rolleyes:

Anyway, there are no unambiguous physical referents for photons other than the symbolic representations and the experimental events which define them.

Do the math symbols on some piece of paper and the materials and instruments in some experimental setup exist when no one is looking at them? Yes ... at least that's the standard working assumption --- which is firmly grounded wrt our collective experience and pertains to any and all objects amenable to our direct sensory perception.

Do the photons that you might expect your experiment to produce exist if your experiment doesn't produce them? No ... at least not in any physical form other than their mathematical representation.
In other words, the, eg., click of the PMT isn't caused by the photon ... the click is the photon.

So ... what is quantum theory? It's a basic algorithm (employing various mathematical models) for predicting the results of quantum experiments. What does it tell us about our world, about existence? It tells us that a certain instrument (or set of instruments) has a certain probability of being in some three-dimensional configuration (amenable to our direct sensory perception) at a certain time wrt a certain experimental preparation.

Does the quantum mechanical algorithm mirror an underlying reality, an underlying quantum world? That's not its purpose. It was designed as, and functions as, an instrumental theory. It's about mathematically organizing and relating the data wrt the materials and instruments which are associated with the data --- and so far the only thing that this tells us about an underly quantum world is that it apparently can't be understood in terms of the persistent images from the world of our sensory perceptual experience. (I personally think that it tells us that nature is fundamentally waves, but, as I mentioned earlier, I don't know very much yet.)

In a letter in the October 2005 PHYSICS TODAY (pp. 15-16), Aage Bohr, Ben R. Mottelson, and Ole Ulfbeck write:
In his Reference Frame column "What's Wrong With This Quantum World?" (PHYSICS TODAY, February 2004, page 10), David Mermin comments on a statement attributed to Niels Bohr by his associate Aage Petersen:
When asked whether the algorithm of quantum mechanics could be considered as somehow mirroring an underlying quantum world, Bohr would answer
"There is no quantum world. There is only an abstract quantum physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature."[1]

Mermin's column describing different physicist's reactions to the statement touches on issues that remain central to the understanding of quantum mechanics.

Although "quantum world" was not part of Bohr's terminology, we can imagine that he might have responded as indicated to the question posed. We see the statement in relation to his basic view that the algorithm of quantum mechanics is a purely symbolic formalism accounting for observations that are obtained under specified conditions. That view is illustrated by his advocacy that the word "phenomenon" be used exclusively to refer to "an observation obtained under specified circumstances, including an account of the whole experimental arrangement. In such a terminology, the observational problem is free of any special intricacy, since, in actual experiments, all observations are expressed by unambiguous statements referring, for instance, to the registration of the point at which an electron arrives at a photographic plate."[2]

Interpreted in this manner, the dismissal of a quantum world leaves the particle as an object capable of directly producing the basic event of observation, such as the registration of an electron arriving at a photographic plate or a click produced in a counter. As is evident in the conflicting reactions that Mermin reports, the issue of which world these objects belong to remains controversial.

Mermin asks, What's wrong with this quantum world? Our answer is that the rejection of it in the form described does not go far enough. As we have recently argued,[3] the perceived need to explain the click as being caused by a particle is a remnant from classical imagery, which has obscured the full implications of fortuitousness and thereby the principle underlying quantum mechanics. Thus all experimental evidence is consistent with a complete break with causality in that the click comes without any cause, as a genuinely fortuitous event. The event is recognized as a macroscopic discontinuity in the counter. Thus genuine fortuitousness unavoidably eliminates the particles. Although fortuitousness has been a central innovation of quantum physics, a complete break with causality was beyond the horizon of the pioneers of quantum mechanics. Indeed, if there were no particles producing the clicks, what would the theory be all about?

Perhaps surprisingly, the very notion of genuine fortuitousness is powerful in its implications. With particles excluded, only geometry is left on the stage, and the symmetry of spacetime itself, through its representations, provides the mathematical formalism of quantum mechanics. Once that point is recognized, quantum mechanics emerges from the principle of genuine fortuitousness combined with the embodiment of spacetime symmetry, without any reference to degrees of freedom of particles or fields. The theory, exclusively concerned with probability distributions of genuinely fortuitous clicks, thus differs from previous physical theories in that it does not deal with objects to be measured -- which eliminates the issue of a quantum world.

References
1. A Petersen, Bull. At. Sci. 19, 8 (1963).
2. N. Bohr, Essays 1933-1957 on Atomic Physics and Human Knowledge, Ox Bow Press, Woodbridge, CT (1987), p. 64.
3. A. Bohr, B.R. Mottelson, O. Ulfbeck, Foundations of Physics 34(3), 405 (2004).

[ZapperZ]

What you have written here constitutes a warning. We could heed your warning if we had a definition for "mumbo-jumbo" and "quackeries". A reason why we need to avoid them would come in handy as well... is this a yellow or orange alert with regard to in-coming absurdities?
I have no wish to indulge in the dog-chase-tail-chase-dogma religiousities that so many entrepreners have milked when it comes to quantum physics.
I am simply interested in the objective views of quantum mechanics and how they may apply to awareness. You will please notice I am trepedaciously avoiding the word "consciousness" because it seems this word has been trade-marked, patented and copyrighted by every guru and swami on the planet... and for no good reason other than to sound "universal".
If it is true that quantum theorys and the classic, relativity theorys are like an oil and water scenario, there is still something emulsifying the two and that is what we are experiencing... at this moment. Surely one system supports the other... or, even more probable, one system gives rise to the other. There must be common elements in both systems that can be or have been observed. Is this true?

Let me give you a very clear example of such a discontinuity that you have ALREADY accepted - phase transition.

If you look at the thermodynamics description of the properties of water, just because you have understood it doesn't mean you can make a smooth transition when you lower its temperature until it becomes ice. Several state variables become discontinuous at the phase transition temperature. You now have to shift gears and use a different set of description. This hasn't bothered anyone yet.

QM has many features that merge into the classical properties, especially at high quantum number, high temperatures, or large interactions (decoherence). But this doesn't mean that using QM description for classical, macroscopic system is any more valid than using classical physics for QM systems. There are a bunch of things we still don't quite know at the mesoscopic scale where these two extremes clash their heads. All we know right now is that one should not simply adopt QM's "world view" on classical systems. It will produce absurd conclusions.

Zz.

[Schrodinger's Dog]

Think this question belongs in the philosophy Section under existentialism:wink:

I'm hoping that there is no oil and water thing between quantum and classical worlds, that there is an underlying unifier we're missing, but then I've always been a dreamer:smile:

Personally I think we're missing something somewhere, whether it's misinterpreting data or being ill equiped or too technologicaly backward to really understand what it is we're attributing to the quantum world and all it's vagueries; I don't know but there's just a nagging suspicion there, I can't quite put my finger on.

Schrodinger himself longed for the time that quantum mechanics shuffled off it's mortal coil and was replaced by a better theory, just as Newtons gravitational laws we're superceeded by Einsteins relativity. His dying regret was that he wouldn't be alive to see it. Who knows maybe we will:smile:

[ZapperZ]

As long as the discussion is physics based, with concrete physics examples, then it belongs here. I have tried to stick by that by bringing in actual physics examples to illustrate my arguments. However, if it degenerates into semantics, hand-waving, unsubstantiated, or "pure-logic" arguments that totally ignores actual physics examples, then it will be moved to the philosophy forum.

Zz.

[quantumcarl]

Conjectured objects that have never been observed might exist, but we have no way of knowing for sure. Conjectured events that have never been observed might have happened, but we have no way of knowing for sure. If no human had ever observed the moon, and if there also were no observed events ("physical effects") that would lead to the conjecture that there is a moon orbiting the earth, then we could feel justified in the belief that the earth has no moon --- and neither quantum theory nor any other physical theory would contradict this view. However, humans have been observing and tracking the moon for millenia, so the belief that it's there even during intervals when no one on earth happens to be observing it seems justified --- and neither quantum theory nor any other physical theory contradicts this belief.
As far as I know (which isn't that far ... I'm just a student of this stuff), the "terms and formulations" of QM don't deal with moons. Moons and, say, photons are different. The main difference has to do with the scale of compositional and interactional complexity ... I think. :rolleyes:
Anyway, there are no unambiguous physical referents for photons other than the symbolic representations and the experimental events which define them.
Do the math symbols on some piece of paper and the materials and instruments in some experimental setup exist when no one is looking at them? Yes ... at least that's the standard working assumption --- which is firmly grounded wrt our collective experience and pertains to any and all objects amenable to our direct sensory perception.
Do the photons that you might expect your experiment to produce exist if your experiment doesn't produce them? No ... at least not in any physical form other than their mathematical representation.
In other words, the, eg., click of the PMT isn't caused by the photon ... the click is the photon.
So ... what is quantum theory? It's a basic algorithm (employing various mathematical models) for predicting the results of quantum experiments. What does it tell us about our world, about existence? It tells us that a certain instrument (or set of instruments) has a certain probability of being in some three-dimensional configuration (amenable to our direct sensory perception) at a certain time wrt a certain experimental preparation.
Does the quantum mechanical algorithm mirror an underlying reality, an underlying quantum world? That's not its purpose. It was designed as, and functions as, an instrumental theory. It's about mathematically organizing and relating the data wrt the materials and instruments which are associated with the data --- and so far the only thing that this tells us about an underly quantum world is that it apparently can't be understood in terms of the persistent images from the world of our sensory perceptual experience. (I personally think that it tells us that nature is fundamentally waves, but, as I mentioned earlier, I don't know very much yet.)
In a letter in the October 2005 PHYSICS TODAY (pp. 15-16), Aage Bohr, Ben R. Mottelson, and Ole Ulfbeck write:
In his Reference Frame column "What's Wrong With This Quantum World?" (PHYSICS TODAY, February 2004, page 10), David Mermin comments on a statement attributed to Niels Bohr by his associate Aage Petersen:
When asked whether the algorithm of quantum mechanics could be considered as somehow mirroring an underlying quantum world, Bohr would answer
"There is no quantum world. There is only an abstract quantum physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature."[1]
Mermin's column describing different physicist's reactions to the statement touches on issues that remain central to the understanding of quantum mechanics.
Although "quantum world" was not part of Bohr's terminology, we can imagine that he might have responded as indicated to the question posed. We see the statement in relation to his basic view that the algorithm of quantum mechanics is a purely symbolic formalism accounting for observations that are obtained under specified conditions. That view is illustrated by his advocacy that the word "phenomenon" be used exclusively to refer to "an observation obtained under specified circumstances, including an account of the whole experimental arrangement. In such a terminology, the observational problem is free of any special intricacy, since, in actual experiments, all observations are expressed by unambiguous statements referring, for instance, to the registration of the point at which an electron arrives at a photographic plate."[2]
Interpreted in this manner, the dismissal of a quantum world leaves the particle as an object capable of directly producing the basic event of observation, such as the registration of an electron arriving at a photographic plate or a click produced in a counter. As is evident in the conflicting reactions that Mermin reports, the issue of which world these objects belong to remains controversial.
Mermin asks, What's wrong with this quantum world? Our answer is that the rejection of it in the form described does not go far enough. As we have recently argued,[3] the perceived need to explain the click as being caused by a particle is a remnant from classical imagery, which has obscured the full implications of fortuitousness and thereby the principle underlying quantum mechanics. Thus all experimental evidence is consistent with a complete break with causality in that the click comes without any cause, as a genuinely fortuitous event. The event is recognized as a macroscopic discontinuity in the counter. Thus genuine fortuitousness unavoidably eliminates the particles. Although fortuitousness has been a central innovation of quantum physics, a complete break with causality was beyond the horizon of the pioneers of quantum mechanics. Indeed, if there were no particles producing the clicks, what would the theory be all about?
Perhaps surprisingly, the very notion of genuine fortuitousness is powerful in its implications. With particles excluded, only geometry is left on the stage, and the symmetry of spacetime itself, through its representations, provides the mathematical formalism of quantum mechanics. Once that point is recognized, quantum mechanics emerges from the principle of genuine fortuitousness combined with the embodiment of spacetime symmetry, without any reference to degrees of freedom of particles or fields. The theory, exclusively concerned with probability distributions of genuinely fortuitous clicks, thus differs from previous physical theories in that it does not deal with objects to be measured -- which eliminates the issue of a quantum world.
References
1. A Petersen, Bull. At. Sci. 19, 8 (1963).
2. N. Bohr, Essays 1933-1957 on Atomic Physics and Human Knowledge, Ox Bow Press, Woodbridge, CT (1987), p. 64.
3. A. Bohr, B.R. Mottelson, O. Ulfbeck, Foundations of Physics 34(3), 405 (2004).

I admit my question raises a potential for esoteric "quackery" and I apologise for this if it is deemed an oppoprium. I have brought it to the quantum physics section because of the idea of location-nonlocality that has been observed on the extreme sub-atomic level and because it has been postulated that the observation of activity at this level changes the activity in question.

These observations, hypothetically, appear to suggest that awareness and observation had or have a fundamental role in the behaviour of energy/matter.

I see here that Sherlock and ZapperZ are refering to scale and how congruence of results is inconsistent as observations traverse the vast differences of scale. And, as a layman, I can only accept this as the stumbling block to finding a unifyer between Quantum and Relative theories. However, again, as a layman, let me offer another example that may help in this regard and suggest that applying fractal geometry or fractal theory to bridge the gap between a sub-atomic quantum reality and the classic, relative macroscopic reality we all "know and love".

At any rate, please let me thank you for the cool posts to date!

[ZapperZ]

I admit my question raises a potential for esoteric "quackery" and I apologise for this if it is deemed an oppoprium. I have brought it to the quantum physics section because of the idea of location-nonlocality that has been observed on the extreme sub-atomic level and because it has been postulated that the observation of activity at this level changes the activity in question.
These observations, hypothetically, appear to suggest that awareness and observation had or have a fundamental role in the behaviour of energy/matter.

Exactly what "observation" are you talking about? And putting a hand-waving statement about a "fundamental role in the behavior of energy/matter" only adds to the ambiguity of whatever it is you're trying to get across. Remember, if you can't use a clear, exact, physics example, this goes to the philosophy forum.

There is a very clear definition of what is meant by an "observable" in QM. We spend hours and hours in school being taught the meaning of a hermitian operator, its properties, its commutation relation, etc., not for nothing. Maybe that would be something you need to look into before making the connection of "observation" in QM.

I see here that Sherlock and ZapperZ are refering to scale and how congruence of results is inconsistent as observations traverse the vast differences of scale. And, as a layman, I can only accept this as the stumbling block to finding a unifyer between Quantum and Relative theories.

Er... are you not aware that Special Relativity has been incorporated within QM already? Dirac pioneered this work a long time ago.

Besides, what are "Relative theories"?

However, again, as a layman, let me offer another example that may help in this regard and suggest that applying fractal geometry or fractal theory to bridge the gap between a sub-atomic quantum reality and the classic, relative macroscopic reality we all "know and love".
At any rate, please let me thank you for the cool posts to date!

Wolfram has tried this in his book. Yet, when questioned at Brookhaven during his talk if he has produced any new physics, he said no. When asked if his approach can derive emergent phenomena such as superconductivity, he said no.

So before you suggest that such a thing can "bridge" the gap between QM scale and classical scale, maybe you need to show that it can, first and foremost, already able to do what we already know within such a scale. Derive the QM emergent phenomena first, and then we can put some confidence in such assertion.

Zz.

[Schrodinger's Dog]

Are you guys checking out the Skepticism and debunking : Heim theory thread? A step in the right direction perhaps? I'd asy ask Niel armstrong if the moon exists personally; oh no wait a minute we nver actually went there it was all a cold war propoganda excersise.

Seriously though I think the gravitational evidence alone is compelling. I don't wake up every morning and wonder if the sun exists because the warmth from the light on my face is concrete enough under my criteria, OK it may not be scientifically concrete but if I only believed things that were concrete, I'd believe very little. I don't need QM or Relativity to prove or disprove the existence of the sun or the moon, or the planets etc,etc. Frankly I have better things to do with my time than prove the obvious.:wink: if it turns out I'm wrong and the sun and moon don't exist then mah ignorance is bliss.:biggrin:

QM relativity are simply a matter of scale on a small scale the quantum effects overcome the relativistic effects and on a macro scale the contrary is true. Working out why this is the case is simply a matter of understanding why gravity dominates the macro and strong/weak etc the very small. I think it would be interesting if in the Heim theory, the macro world Gravity and Electromagnetism rule and in the micro strong and weak rule. strong increases with distance gravity decreases as does electromagnetism which is now unified as Elecro gravity. Maybe that's all the answers we need?

[ZapperZ]

Are you guys checking out the Skepticism and debunking : Heim theory thread? A step in the right direction perhaps? I'd asy ask Niel armstrong if the moon exists personally; oh no wait a minute we nver actually went there it was all a cold war propoganda excersise.
Seriously though I think the gravitational evidence alone is compelling. I don't wake up every morning and wonder if the sun exists because the warmth from the light on my face is concrete enough under my criteria, OK it may not be scientifically concrete but if I only believed things that were concrete, I'd believe very little. I don't need QM or Relativity to prove or disprove the existence of the sun or the moon, or the planets etc,etc. Frankly I have better things to do with my time than prove the obvious.:wink: if it turns out I'm wrong and the sun and moon don't exist then mah ignorance is bliss.:biggrin:
QM relativity are simply a matter of scale on a small scale the quantum effects overcome the relativistic effects and on a macro scale the contrary is true. Working out why this is the case is simply a matter of understanding why gravity dominates the macro and strong/weak etc the very small. I think it would be interesting if in the Heim theory, the macro world Gravity and Electromagnetism rule and in the micro strong and weak rule. strong increases with distance gravity decreases as does electromagnetism which is now unified as Elecro gravity. Maybe that's all the answers we need?

Hint: there is a reason that discussion is in S&D forum and NOT in the physics forum.

Zz.

[Schrodinger's Dog]

Disprove it or prove it that's all I'm asking for.

If it's tosh fair enough but I'd so love it to be true:wink:

[quantumcarl]

What Bohr said about the idea of a quantum world seems to be the best answer to my question. Credit to Sherlock for the quote.

= Bohr
"There is no quantum world. There is only an abstract quantum physical description.

It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature."

Is Bohr a well accomplished physicist?

[quantumcarl]

Exactly what "observation" are you talking about? And putting a hand-waving statement about a "fundamental role in the behavior of energy/matter" only adds to the ambiguity of whatever it is you're trying to get across.
Zz.

The perception of reality by biosystems is based on different, and in certain respects more effective principles than those utilised by the more formal procedures of science. As a result, what appears as random pattern to the scientific method can be meaningful pattern to a living organism. The existence of this complementary perception of reality makes possible in principle effective use by organisms of the direct interconnections between spatially separated objects shown to exist in the work of J.S. Bell.

This is from the website address:
http://www.tcm.phy.cam.ac.uk/~bdj10/papers/bell.html

and also seems to address my question. I'm not ascerting any theory I've conccocted. I am simply exploring supportive and non-supportive objective analysis's with regard to awareness and the extent to which it plays a role in determining the constructs of nature. That's why part of the question involves whether or not the power of awareness is fundimental to the existence of matter.

My mention of fractal geometry was just my apparently misguided way of giving back in return for the generous assistance I am receiving in answer to my question.

Here is another example of the type of observation I am talking about and whether or not observation/awareness changes the behaviour of an observed field/wave/particle.

Quantum eraser: A proposed photon correlation experiment concerning observation and "delayed choice" in quantum mechanics
Marlan O. Scully and Kai Drühl
Max-Planck Institut für Quantenoptik, D-8046 Garching bei München, West Germany
Institute for Modern Optics, Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131
Received 2 April 1981
We propose and analyze an experiment designed to probe the extent to which information accessible to an observer and the "eraser" of this information affects measured results. The proposed experiment could also be operated in a "delayed-choice" mode.
©1982 The American Physical Society

From:
http://prola.aps.org/abstract/PRA/v25/i4/p2208_1


And another example of what I'm talking about:

[\"The running of the universe and the quantum structure of time'

Amongst its virtues, quantum mechanics is pre-occupied with what goes on in the laboratory and the notion of observer is based on the actions of real physicists as they prepare states and then perform tests on them. the problem arises because physicists are themselves emergent phenomena. This has led to an unsatisfactory mixture of classical and quantum concepts resulting in the measurement problem in quantum mechanics. In this paper a more fundamental, mechanistic view of the observer is taken

From:
http://arxiv.org/pdf/quant-ph/0105013


this is a very cool source and thank you for motivating me to look for it!

[ZapperZ]

Again, I will point out the idea of a "measurment" in QM that you need to understand FIRST before going into something as in-depth as the quantum eraser. You should expect to be able to deciper something that involved, when you haven't fully understood the idea of linear operators in QM. This is a recipe for disaster based on all my years at looking people trying to tackle QM without understanding the fundamental mathematics.

You may also want to do a search on the tons of postings that I have made regarding "emergent phenomena", especially in my journal entry. As a condensed matter physicist, I've done nothing but work with emergent phenomena, and superconductivity in particular. So before you buy wholesale of the stuff you're cutting and pasting, be VERY aware that these concepts in physics have underlying mathematical definition, and that you MAY be understanding the stuff you're endorsing differently than the way they are being meant! Do not use the pedestrian definition of these words and phrases and think you've understood what they are. Would you buy the spiel if I tell you that fractional quantum hall effect is an "emergent phenomenon"? Would you be able to explain why it is so?

Zz.

[quantumcarl]

Again, I will point out the idea of a "measurment" in QM that you need to understand FIRST before going into something as in-depth as the quantum eraser. You should expect to be able to deciper something that involved, when you haven't fully understood the idea of linear operators in QM. This is a recipe for disaster based on all my years at looking people trying to tackle QM without understanding the fundamental mathematics.

You may also want to do a search on the tons of postings that I have made regarding "emergent phenomena", especially in my journal entry. As a condensed matter physicist, I've done nothing but work with emergent phenomena, and superconductivity in particular.

So before you buy wholesale of the stuff you're cutting and pasting, be VERY aware that these concepts in physics have underlying mathematical definition, and that you MAY be understanding the stuff you're endorsing differently than the way they are being meant! Do not use the pedestrian definition of these words and phrases and think you've understood what they are. Would you buy the spiel if I tell you that fractional quantum hall effect is an "emergent phenomenon"? Would you be able to explain why it is so?
Zz.

I don't "endorse" any of the material I have copied and pasted or linked here. I am supplying, as requested, what I perceive to be examples of what I'm asking with regard to the function of awareness as concerned with matter and the nature of nature.

I welcome you're recommendations, however, since you claim to be and appear to be clearly more qualified than I am in decifering the complex and seemingly unreachable concepts of quantum mechanics. I know its frustrating to look back on people who want to understand a concept like quantum physics but who have also not spent the time doing the math or the experiments that formulate the foundations of the concept(s).

The fact that one person has "suffered through" the training and discovery of a complex discipline or concept can either help them or hinder them in their effort to teach less experienced people what they have learned. The choice between helping or hindering is in the hands of the experienced person.

I'll put this thread to rest-mass or to a "non-local" rather than see it shuffled off to the nebulous, hand-wavey and non-commital philosophy section once I determine that there are no other contributions that support or don't support the idea that without biological observation and awareness of nature, nature does not exist.

The last paper I sited goes into some detail in that regard covering what they term as "consciousness" and the "quantum computer"..... which may be running a program, metaphorically speaking, of "awareness" to keep tabs on its progress. "QUACKERIE":surprised

Would you buy the spiel if I tell you that fractional quantum hall effect is an "emergent phenomenon"? Would you be able to explain why it is so?

Here's what I dug up... mind you... I haven't done the hands on work or the calculations and measurments as you have recommended ... so I still don't buy any of the speil or the wholesale goods until I grow them and handle them myself (as per your suggestion)!

Superfluidity, like the fractional quantum Hall effect, is an emergent phenomenon (or, in other words {editor}) a low-energy collective effect of huge numbers of particles that cannot be deduced from the microscopic equations of motion in a rigorous way and that disappears completely when the system is taken apart. (Anderson, 1972).

[Sherlock]

I admit my question raises a potential for esoteric "quackery" and I apologise for this if it is deemed an oppoprium. I have brought it to the quantum physics section because of the idea of location-nonlocality that has been observed on the extreme sub-atomic level and because it has been postulated that the observation of activity at this level changes the activity in question.
These observations, hypothetically, appear to suggest that awareness and observation had or have a fundamental role in the behaviour of energy/matter.
I see here that Sherlock and ZapperZ are refering to scale and how congruence of results is inconsistent as observations traverse the vast differences of scale.

I'm just a layman, and a casual student of QM. ZapperZ is a working physicist -- I think he's currently at Argonne National Laboratory. Neils Bohr was one of the original developers of quantum theory.

I don't think there's anything necessarily wrong with speculating about the possible makeup and behavior of an underlying reality in terms of imagery from our ordinary experience. But that's not how QM was developed or what QM means, afaik.

If QM is about experimental setups and results (which it is), and not a description of an underlying quantum reality (which, afaik, it isn't), then the existence of nonlocal propagations in nature, or the idea that the existence of some object or event in nature depends on our consciousness of it, isn't entailed by QM.

QM books often weave metaphysical (using classical analogs/imagery) language with the physical, instrumentalist/mathematical language in a way that makes it sort of unclear that, say, the word 'particle' as it's used in QM has only a mathematical (and instrumental) existence and meaning. Phrases like, "the probability that the particle will be found ...", used in contexts involving detector clicks or dots on a screen tend to obscure the fact that it's the detector clicks or dots on a screen, and their probability of occurance wrt specified experimental setups, that are being talked about mathematically and not some underlying quantum world of particles and waves.

It's not that anybody is denying the possibility, or existence, of an underlying quantum world. But how are you going to talk about it unambiguously? This was one of the main problems that the developers (including Niels Bohr, who you've asked about) of quantum theory were faced with. Whatever it might be, it's not amenable to our direct sensory perception and can only be approximately tracked by instruments. So, QM is about what can be unambiguously stated wrt the various experimental results that have historically defied classical explanation -- that is, QM is all about the experimental results not their possible underlying causes. It's a purely correlational theory, not a causal one.

Of course the underlying quantum world, whatever it might be, is presumed to be a bit more sensitive to observational probing than the moon is.

However, the existence of quantum phenomena in the physical forms of experimental preparations and results, and the math which describes these, (which are the only physical forms in which quantum phenomena can be unambiguously said to exist) doesn't depend on our consciousness of them any more than the existence of the moon depends on our consciousness of it.


I am simply exploring supportive and non-supportive objective analyses with regard to awareness and the extent to which it plays a role in determining the constructs of nature. That's why part of the question involves whether or not the power of awareness is fundamental to the existence of matter.

The physical fact that the experimental preparations and the math have the specific forms that they do has of course something to do with the conscious decisions that went into their construction. But those conscious decisions were preceded by sensory apprehensions of the physical world which didn't just pop into existence because we wanted or willed them to be there. The physical facts are what they are -- and to the extent that all people with normal (and sober) sensory capabilities see the same physical facts, then they're considered to be objective (not just subjective, ie., not just in your or my imaginings) and part of our physical world.

The working assumption in all of the physical sciences is that the world of our objective sensory experience exists whether you or I or anybody is paying attention to it.

And there's nothing in either quantum theory or quantum experiments which contradicts this view ... at least as far as I'm aware.

In order to really understand what Bohr and ZapperZ and others are saying it's necessary to put down the QM popularizations and actually start learning the theory -- and then a fascinating (not just the physical/experimental phenomena themselves, but also the ingenious ways that physicists have devised to produce them) world of discovery will be revealed to you.

[ZapperZ]

I don't "endorse" any of the material I have copied and pasted or linked here. I am supplying, as requested, what I perceive to be examples of what I'm asking with regard to the function of awareness as concerned with matter and the nature of nature.

But that is exactly what I am questioning, where you actually understood the significance of the example you're citing. I've seen many people citing stuff in which the perceived to understand, and yet got it completely wrong. QM isn't a series of words - it's a series of mathematical formulation. That is what makes learning QM so difficult for a lay person.

Here's what I dug up... mind you... I haven't done the hands on work or the calculations and measurments as you have recommended ... so I still don't buy any of the speil or the wholesale goods until I grow them and handle them myself (as per your suggestion)!

I can do better. Look in my journal entry under "Theory of Everything?". There's a series of appers by Laughlin (and citing Anderson) on this subject. You'll realize how ironic it is for you to indicate TO ME what an emergent phenomenon is.

Zz.

[Schrodinger's Dog]

Sorry I've diverted this post enough. But had to say there are some fascinating insights into scientific method here. I'm as guilty of anyone of not understanding the finer points of the maths, but then I haven't studied much of it yet. I came into Physics by way of popualrist material and thus have yet to fully apreciate any theory which is why I wouldn't know where to start in commenting on the maths behind the science, and which is why I'll wait 'till I've studied the math before I make any comments that are pertainent.

Having said that I do know this, our perception is derived from our environment, evolution has geared us in a way to percieve the world that increases the chances of our surviving/formulating survival strategies and aquiring what we need. Whether this is in fact the objective truth is a subject for philosophy and has no real place in science as such, although it is a valid point to say, what you percieve is not necessarily the truth. An objective reality has it's limitations place on it by the environment you exist in. Is it what's really there? God knows:wink:

If we could build a computer to percieve the world as it really is it wouldn't work, because we don't know what it is we're looking for and wouldn't know it if we saw it.

[ZapperZ]

Rather than repeat everything that I have written down, I will be downright tacky and simply point to the essay that I've previously written and posted in a number of places.

http://www.physicspost.com/science-article-208.html

[Thanks to Greg for putting this on Physics Post, even though I didn't get any credit for it] :)

Zz.

[vanesch]

But at some point, there is a "transition" from quantum behavior to the classical behavior that we all know and love. You must make such a distinction or else you will get into the mystical world of mumbo-jumbo.
Treat a classical entity as it should, and treat a quantum entity as it should. But don't mix them up or you'll get absurdities. When you apply a set of rules that were never meant to be applied to that particular situation, you get quackeries.
Zz.

As ZapperZ noted in his journal entry "A theory of everything?", there is indeed at the basis a difference in philosophy (between him and me) and the "quantum quackeries" are indeed only a reason to worry for people like me. The fundamental distinction is essentially the "belief in reductionism" which he cites in his journal entry and to which I adhere and to which some others don't - this is probably because both attitudes reflect different (successful) working attitudes in different domains.

However, I don't agree 100% with ZapperZ's definition of "reductionism". Reductionism (at least, how I understand it) does NOT have to mean that many-particle effects are simply the addition of few-particle interactions. Reductionism (as I understand it) simply holds that there is supposed to be a single, coherent, mathematical description of ALL what happens in nature. In other words, that there is a 1-1 mapping between a certain mathematical structure, and all physical aspects of the universe. That doesn't mean that we think that we KNOW of such a structure, but we assume that such a structure exists and we try to discover aspects of it. Another way of stating that is that there exist universal physical laws that apply to everything. It has always been my idea that this was the very working hypothesis of physics, and as such am surprised that there are physicists (good ones even, like those ZapperZ cites, and ZapperZ himself :approve: ) claiming the opposite.

Of course, the simplest ways (in the mind of a reductionist) to find hints of that structure is to explore the most "elementary" interactions, in the few-particle case. (and that's probably why most adherents of this view are particle physicists)
Their idea is that, from these basic laws, once we know them, we can in principle mathematically deduce what will happen in more complicated settings, with gazillions of particles - under the hypothesis that we found the correct behaviour for ANY set of particles, starting from the study of a few, and good mathematical and esthetic intuition for building a theory.
Now, condensed matter physicists (like ZapperZ) have of course a different approach. They observe certain phenomena in the lab, and try to build models of those phenomena, finding out sometimes general laws of behaviour that way. And some take on the attitude that each phenomenon can have its own different laws, INDEPENDENT of what lies underneath. This is then a holistic approach: the whole follows laws that are independent of the laws followed by the underlying constituents.

I would first like to point out that "emergent phenomena" are, in themselves, NOT a proof that the holistic view is correct. Indeed, there are a lot of toy examples of simple laws governing constituents that give rise to "special" behaviour of a whole set of those constituents. Phase transitions included. The school example of the Ising model comes to mind of course. The problem is more with real-world situations, where 1) deriving the special behaviour of the constituents and 2) solving for the behaviour of the entire system is mathematically so hopelessly complicated that it is much more PRODUCTIVE to use the condensed matter people approach, and build directly a model around the observed properties, without bothering with the underlying constituents and their laws.

But the whole discussion is:
is this "model building approach" (practical holism) just a matter of getting results in a feasible way, or is this fundamental ? It is the discussion between reductionism and holism.

I have, however, an argument, that, to me, goes strongly against holism. It goes as follows. Any possible measurement we could make on a many-constituent system, and from which holistic models could be build, will have some (statistical or definite) regularity. In the reductionist vision, it will hence correspond to a property of the mathematical structure that maps onto the many-constituent system, as built up by the rules given by the theory that ALSO governs the few-constituent systems and for which the theory is supposed to be known. The mathematical property that corresponds to the measurement on the macroscopic theory will hence have a (at least Platonic) existance. It may be practically intractable, but it is supposed to exist (as in "existence proofs" in mathematics).
Now, there are two possibilities: or this mathematical property corresponds to the effectively measured property, in which case holism is not necessary (we DEDUCED the property from the fundamental laws of the constituents, exactly as reductionism claims), OR this mathematical property does NOT correspond to the measured property, in which case the theory of the fundamental interactions has been falsified, and there is a CLASH between the fundamental laws from which a certain prediction is derived, and the observations.
But in no case, we can have living happily together, a holistic vision, and a theory of interactions of fundamental constituents.

To make the above statement more concrete: imagine we are looking at the evaporation of water (a phase transition). We can measure, for instance, the bending of a light beam through a bottle of water, when we heat it by sending a current through a resistance in the water, and observe that when the water is evaporated, then the index of refraction has changed and the spot of the beam changes position. The position of the light beam corresponds to the "possible measurement" I was talking about in the abstract, above, and, *in principle* it corresponds to a clear property of the EM field (beam left or beam right), which is a property of the mathematical structure of the entire field structure of the whole experimental setup (including the matter fields of the electrons, protons,... in the water, the wire, the resistor, the battery, the light source...). No matter how mindbogglingly complicated this setup is, there is no reason why this mathematical structure doesn't exist: there are rules for setting up, say, the Hilbert space of 10^30 particles. Even though it cannot be done in practice, by a human, or a humanly designed computer, mathematically, this structure exists. As such, there will, in this mathematical structure describing the entire setup starting from fundamental principles, be an observable that corresponds to the measurement of the position of the beam after the resistor has been heating the water. It might be a probabilistic answer, but no matter, there will be *A* response to the question: is the beam here or there ?
This answer can be, or cannot be, in agreement with what is observed. But it is not INEXISTANT. The reductionist answer to a potentially holistic phenomenon EXISTS (in a mathematical sense). In most cases it is hopeless to FIND it, but nevertheless it exists.

In the case that there is agreement, we've then simply shown that (for the case at hand) no holism is involved: this aspect of the boiling of water is entirely contained in the elementary interactions of its constituents.
In the case that there is disagreement, well, we've falsified the theory of behaviour of the constituents of water in this case (because IF they were all following the proposed laws, then there wouldn't be any disagreement). But you cannot have that the constituents follow individually certain laws, and the whole follows OTHER laws, without there being a clash at some point.

What has all this to do with the OP ?
The point is of course that QM "pretends" to be a universal theory. So in the reductionist view, well, that means that it should make just as well sense to talk about the Hilbert space of states of a human being as it makes sense to talk about the hilbert space of states of the electron and proton in a hydrogen atom. Everybody agrees that it is for sure NOT PRACTICAL to talk about the hilbert space of states of a human being, but reductionists say: well, if that's to be the case for a set of atoms, it is also the case for a BIG set of atoms (unless my theory says that it only works for less than exactly N atoms). And then you run in a few difficulties. Bohr resolved the issue in the "holistic" way, by simply saying that there is some kind of "phase transition" between a classical world of humans and so, and the "weird microscopic world" of atoms. If you take on that view, there is no difficulty. The Born rule and the projection postulate simply TELL you how to link both theories. The totally unanswerable question in this view is then: WHEN do we apply the Born rule ? Because if there were a precise answer, that would be in reductionist terms!

There is of course a kind of "intermediate" view between the holistic and reductionist view. The mathematical structure of reality (the theory of everything) MIGHT not reveil all its aspects by only studying elementary interactions ; or, in other words, the laws we deduce from studying elementary interactions MAY of course be approximations to the "true" laws, which are so very good in the case of elementary interactions that we do not have data with enough accuracy to notice the approximation. As such, reductionists, with their misplaced arrogance, will only deduce "tangent laws" to the true mathematical structure of nature, and then claim that they know everything, if only they could solve the mathematical problem of many particle interactions. But that is not a blow to reductionism as such. It is only a blow to the hope that we can deduce the mathematical structure of reality from JUST elementary interactions. It might be then, indeed, that condensed matter experiments are more sensitive to the approximations made. We are now in the case of "disagreement" in the above explanation. But it has not undone the belief that there EXISTS a single mathematical description of all of nature. It only showed that there were limits to the structure we derived from our elementary interactions. If this is the case, however, our hopes of EVER deriving the true mathematical structure of nature may be totally hopeless, and as such, a practical form of holism is itself an emergent property of reductionism :rofl:

As far as I know, the above situation has never been found (that there is a clear prediction of a macroscopic behaviour from elementary laws, and that observation is in contradiction with it). That's of course cheap, because of the mathematical difficulty in DERIVING the predictions for big systems, the test has not been conducted very often (predict interesting condensed-matter properties ab initio).

cheers,
Patrick.

[ZapperZ]

There is no evidence one way or the other (i.e. microscopic laws can derive, via addition of complexities, the emergent phenomena and the argument that microscopic laws cannot, via addition of complexities, derive the emergent phenomena). However, Laughlin in his book cited several examples that includes the fractional quantum hall effect on why there are indications that it can't! I find those arguments to be very compelling, and I haven't seen anyone, even Weinberg, tried to put a counter argument.

Again, as I've mentioned before, the main issue here isn't to cite "proofs" that reductionism works or don't. My main concern to to make sure that people are aware that there is a very large school of thought that many are not aware of that disagrees with such a view, and this school of thought happens to be the largest sector of practicing physicists.

Zz.

[Locrian]

As far as I know, the above situation has never been found (that there is a clear prediction of a macroscopic behaviour from elementary laws, and that observation is in contradiction with it).


In a way there is - there are lots of examples where people have thought they derived macroscopic behaviour from elementary laws only to find themselves wrong. Of course, you can always go back and just say - they did it wrong! This misses the point though.

I used to think the field I worked in (diamond growth) lacked for good theory, but over time I've realized that all the theorizing has just never produced any useful information. The theory is sometimes wrong, sometimes so specific as to not be useful, and every now and then produces a little information anyone actually running experiments already knew.

Trying to use elementary laws to produce macroscopic ones is very useful in one important way - it teaches what a damned waste of time such a philosophy is.

[vanesch]

Again, as I've mentioned before, the main issue here isn't to cite "proofs" that reductionism works or don't. My main concern to to make sure that people are aware that there is a very large school of thought that many are not aware of that disagrees with such a view, and this school of thought happens to be the largest sector of practicing physicists.


We already had this discussion, and it sounds to me as quite shocking (although I believe what you say).
However, what exactly does this crowd think ? Do they think that, "yes, individual systems follow exactly the microscopic laws in all situations, but macroscopic systems just follow different laws" (1), or do they think "the microscopic laws derived from elementary interactions are probably (good) approximations to the true laws of nature, but who show other aspects to emerge when many-particle systems are involved, which do NOT follow from the APPROXIMATIVE laws of individual interactions" (2) ?

Although I can have some sympathy for (2) - though if true, it makes finding the "true laws of nature" a quite hopeless business - I tried to outline why I think that (1) is self-contradictory, in that from the microscopic laws FOLLOWS the existance of a prediction for the macroscopic behaviour, so this is OR in agreement, or in disagreement with what really happens. In the second case, the microscopic laws CANNOT be exact, and in the first case, well, we are back to reductionism all right so there are no "different laws for macroscopic systems" after all.
To give a caricatural example: the microscopic laws cannot say that each individual atom of the apple will go to the left, while the apple will go to right (through some "emergent macroscopic law") without there being a CLASH between the microscopic laws and the macroscopic law.

[vanesch]

In a way there is - there are lots of examples where people have thought they derived macroscopic behaviour from elementary laws only to find themselves wrong.

Yes, but usually this is by making a lot of approximations and extra hypothesis. The true holistic (anti-reductionist) approach is that EVEN IF YOU WERE TO USE THE EXACT MICROSCOPIC LAWS OF NATURE without any approximation, you would not be able to derive certain macroscopically observed phenomena. I think that that claim is self-contradictory, in that if the microscopic laws are exact (meaning, the DETERMINE how the individual constituents will behave), then this RESULTS automatically in the existance of a prediction of the behaviour of the overall macroscopic system in said situation, and can as such NOT be different, as dictated by a "macroscopic law".

For instance, if we have conservation of momentum at microscopic scale, then we can DERIVE conservation of momentum at macroscopic scale, exactly. Now, if there is going to be a macroscopic law that says that in this particular macroscopic case, there is NOT going to be conservation of momentum, there is a CLASH. But you cannot have that microscopic conservation of momentum is an EXACT microscopic law, and that there is an "emergent property" which violates conservation of momentum at macroscopic scale, happily existing together. If violation of conservation of momentum is observed, this only means that conservation of momentum is microscopically not EXACT (although in individual collisions, say, it may be such a good approximation that we cannot observe any deviation from it).

Now, in the case of conservation of momentum, the mathematically precise prediction from microscopic laws is easy to do. For most other properties, it is an almost intractable mathematical problem in practice, but that doesn't mean that the prediction (the exact mathematical prediction) does not EXIST (in the Platonic sense).

[ZapperZ]

We already had this discussion, and it sounds to me as quite shocking (although I believe what you say).
However, what exactly does this crowd think ? Do they think that, "yes, individual systems follow exactly the microscopic laws in all situations, but macroscopic systems just follow different laws" (1), or do they think "the microscopic laws derived from elementary interactions are probably (good) approximations to the true laws of nature, but who show other aspects to emerge when many-particle systems are involved, which do NOT follow from the APPROXIMATIVE laws of individual interactions" (2) ?
Although I can have some sympathy for (2) - though if true, it makes finding the "true laws of nature" a quite hopeless business - I tried to outline why I think that (1) is self-contradictory, in that from the microscopic laws FOLLOWS the existance of a prediction for the macroscopic behaviour, so this is OR in agreement, or in disagreement with what really happens. In the second case, the microscopic laws CANNOT be exact, and in the first case, well, we are back to reductionism all right so there are no "different laws for macroscopic systems" after all.
To give a caricatural example: the microscopic laws cannot say that each individual atom of the apple will go to the left, while the apple will go to right (through some "emergent macroscopic law") without there being a CLASH between the microscopic laws and the macroscopic law.

Write down all you know about the elementary interactions. Now, using just those and adding more and more complexities, there is nothing in what you are doing that will produce the emergent behavior.

Now, you can argue "But how does one know that since no one has done it for a gazillion interactions?" This is why we are having this debate, because if one has and can, we would have known one way of the other. The ONLY thing we can go by is (i) by looking at what CAN and HAS been done, which hasn't produced the emergent behavior and (ii) the novel results and measurements that are seen at the emergent scale that DEFY being explained simply using the elementary interactions (i.e. how does the smallest detected value of charge in emergent phenomena is LESS than the charge on a single charge carrier?).

These things have been ignored for way too long, especially among many who are being seduced into elementary particles and String theory. In Anderson's review of Laughlin's book in an issue of Physics Today, he managed to give a backhanded slap to Brian Greene and string theorists for not even considering these emergent phenomena. Yet, they couldn't even muster a rebuttal to Anderson's direct criticism.

Zz.

[ZapperZ]

Yes, but usually this is by making a lot of approximations and extra hypothesis. The true holistic (anti-reductionist) approach is that EVEN IF YOU WERE TO USE THE EXACT MICROSCOPIC LAWS OF NATURE without any approximation, you would not be able to derive certain macroscopically observed phenomena. I think that that claim is self-contradictory, in that if the microscopic laws are exact (meaning, the DETERMINE how the individual constituents will behave), then this RESULTS automatically in the existance of a prediction of the behaviour of the overall macroscopic system in said situation, and can as such NOT be different, as dictated by a "macroscopic law".
For instance, if we have conservation of momentum at microscopic scale, then we can DERIVE conservation of momentum at macroscopic scale, exactly. Now, if there is going to be a macroscopic law that says that in this particular macroscopic case, there is NOT going to be conservation of momentum, there is a CLASH. But you cannot have that microscopic conservation of momentum is an EXACT microscopic law, and that there is an "emergent property" which violates conservation of momentum at macroscopic scale, happily existing together. If violation of conservation of momentum is observed, this only means that conservation of momentum is microscopically not EXACT (although in individual collisions, say, it may be such a good approximation that we cannot observe any deviation from it).
Now, in the case of conservation of momentum, the mathematically precise prediction from microscopic laws is easy to do. For most other properties, it is an almost intractable mathematical problem in practice, but that doesn't mean that the prediction (the exact mathematical prediction) does not EXIST (in the Platonic sense).

No, that is not what is meant by emergent behavior. It has nothing to do with the violation of any physical concept. It is the SHORTCOMMING of the model at the microscopic scale. Your elementary description is INSUFFICIENT to produce the large scale order. It has nothing to do with conservation laws being violated.

Look at the tight-binding band structure. I could easily only consider the nearest-neighbor interactions and get a bunch of characteristics that agree with experimental measurement. But I also have a few shortcoming that can't be reconcilled with experiments. So then I include the next-nearest neighbor interactions. That agrees more, but I can still find something not quite right. I then add MORE interactions.

In none of these are there any question about conservation laws not working. It is the shortcoming of the MODEL.

Zz.

[vanesch]

Write down all you know about the elementary interactions. Now, using just those and adding more and more complexities, there is nothing in what you are doing that will produce the emergent behavior.


But this is what I mean. Take an experiment which explicitly tests for some emergent behaviour (like I tried to do with the boiling water). If the emergent phenomenon takes place, the light goes on, and if not, the light will not go on. Now, take the ENTIRE system, including the experimental apparatus, and consider, within a certain theoretical microscopic framework, the description of this entire system. For instance, make the product hilbert space for each of the individual particles and relevant field modes, as described by quantum theory. In the end, there will be an observable that corresponds to "the light goes on", and the mathematical outcome of that observable exists (even though we have no clue of how to derive that in practice without approximation, given the mindboggling complexity of the mathematical problem at hand).

We'll have a probability for the light going on or not, and this mathematically existing answer (although we don't know it) IS JUST AS HARD A "CONSERVATION LAW" for the system at hand as the (much easier) derivation of the conservation of momentum. It follows just as exactly. So if the observation in practice is in contradiction with this answer, then this is JUST AS MUCH A CLASH with microscopic physics as would be an observation of the violation of conservation of momentum, or a violation of the first or second law of thermodynamics.

I don't say that this can't happen, but to me this would only indicate the inadequacy of the microscopic laws that we know about, and NOT the failure of reductionism as such ; though it may - as I said - lead us to some practical holism emerging from reductionism because of the hopelessness of the task to derive the true laws of nature.

[vanesch]

No, that is not what is meant by emergent behavior. It has nothing to do with the violation of any physical concept. It is the SHORTCOMMING of the model at the microscopic scale. Your elementary description is INSUFFICIENT to produce the large scale order. It has nothing to do with conservation laws being violated.
Look at the tight-binding band structure. I could easily only consider the nearest-neighbor interactions and get a bunch of characteristics that agree with experimental measurement. But I also have a few shortcoming that can't be reconcilled with experiments. So then I include the next-nearest neighbor interactions. That agrees more, but I can still find something not quite right. I then add MORE interactions.
In none of these are there any question about conservation laws not working. It is the shortcoming of the MODEL.
Zz.

I agree fully here. But the tight-binding model with nearest-neighbour interactions is already a very "rough" approximation to the exact microscopic laws. So any failure of this approximation to the full problem is of course not, in itself, anything fundamental. The question is: does the solution of the exact microscopic laws, applied to the system at hand, agree with the observed phenomena or not ? And in the case that the answer is no (as you seem to suggest for the fractional quantum hall effect - I don't know anything about it, but I certainly agree with you that this should be of utmost importance!), it would mean only, to me, that the microscopic laws we thought of being exact, weren't, after all.

It would only be in the case that one can show that ALL thinkable laws of nature that are in agreement with microscopic few-particle interactions are in fundamental contradiction with observed macroscopic phenomena, that I would be willing to accept holism - and as such, accept the end of physics. This would be some kind of "Bell theorem" for reductionism - and in my eyes, would mean the end of physics, which is the quest to derive the fundamental mathematical structure of the laws of ALL of nature (and are, as such, reductionist in nature).

However, that wouldn't mean much to the practicing physicist, which ALREADY applies a kind of practical holism (except for elementary particle physicists, until recently: now, indeed, the standard model is often ALSO seen as just a phenomenological set of laws). But the problem with the generalisation of this view is that "physics" has as such, LOST ALL POSSIBLE FORCE OF PREDICTION. Indeed, the difference between fundamental holism and practical holism is that practical holism follows from the fact that ab initio calculations are often impractical, so one ressorts to phenomenology to compensate for one's lack of mathematical skill to solve the ab initio problem. But IN THOSE CASES where we CAN do ab initio calculations (like in the case of deriving conservation of momentum!), we *trust* the results. In fundamental holism, however, it is not because we can with good certainty calculate things AB INITIO (on any level!) that the entire system will behave that way: a NEW law can always emerge. So we've lost ALL predictability of physics. Fundamental physics becomes unfalsifiable. That's what I call the "end of physics". We're back to stamp collecting :bugeye:

[ZapperZ]

But this is what I mean. Take an experiment which explicitly tests for some emergent behaviour (like I tried to do with the boiling water). If the emergent phenomenon takes place, the light goes on, and if not, the light will not go on. Now, take the ENTIRE system, including the experimental apparatus, and consider, within a certain theoretical microscopic framework, the description of this entire system. For instance, make the product hilbert space for each of the individual particles and relevant field modes, as described by quantum theory. In the end, there will be an observable that corresponds to "the light goes on", and the mathematical outcome of that observable exists (even though we have no clue of how to derive that in practice without approximation, given the mindboggling complexity of the mathematical problem at hand).

But this CANNOT be done! That's why we're having this debate! If it can, either I or you would have to shut up.

The closest anyone ever tried in doing such a thing is in N-body problems. Even there, one can only do this with a certain geometry that contains many types of symmetry. I see no indication of any form of emergent behavior there. Can you?

What you have described above is a hypothetical guess. I have no clue, and neither do you, that such a description that you present can or cannot produce the emergent property. I can, however, point out that so far, no one and no method has using the elementary interactions as the starting point. And I can point out that there are many emergent behavior in which even hand-waving arguments from a reductionist standpoint fall short in trying to reconcile the experimental observations.

To say that once I have ALL of the elementary interaction, then I have the "Theory of Everything" is very audacious. It is also useless to condensed matter physicist. That's like giving us a tool that we cannot possibly use, because knowing such a thing does NOTHING to describe practically ALL of the stuff we work with in condensed matter. And unfortunately, many people buy such claims of a "theory of everything", resulting in books proclaiming the "End of Physics" once such a thing is found. This is bogus. I get royally pissed by such claims because they clearly and glaringly ignore the field of condensed matter as IF it doesn't even exist. My journal entry is to combat such ignorance.

No matter what is claimed at the elementary interaction level, the ONE thing that is of no dispute right now is that knowing all of such interactions, one has no ability at the moment to derive emergent behavior. Whether this inability is inherent in the model, or simply because we lack the capability to deal with such large interactions, is still disputed. But this really is irrelevant to the issue that I brought up originally. Even when we know all the interactions, we presently cannot use it can CM physicist, nor can we make use of it to predict other yet-undiscovered emergent behavior. My training as an experimentalist is rearing its ugly head again. I'm asking "yeah, so? What can I do with it?"

Currently, nothing.

Zz.

[ZapperZ]

I agree fully here. But the tight-binding model with nearest-neighbour interactions is already a very "rough" approximation to the exact microscopic laws. So any failure of this approximation to the full problem is of course not, in itself, anything fundamental. The question is: does the solution of the exact microscopic laws, applied to the system at hand, agree with the observed phenomena or not ? And in the case that the answer is no (as you seem to suggest for the fractional quantum hall effect - I don't know anything about it, but I certainly agree with you that this should be of utmost importance!), it would mean only, to me, that the microscopic laws we thought of being exact, weren't, after all.

But you need to remember my argument in this particular posting, that I'm showing you that it has nothing to do with conservation laws.

And I have no answer to your second question because we have no ability to do that. All I have is that fact that such a microscopic description has not produced emergent behavior. Period. Is it simply because we cannot do all the complexities? Or is it because there is a built-in shortcoming in the model that simply neglect some "long-range, collective order" that will only emerge once one crosses over some scale? These are questions no one can answer. But because of that, it is also wrong to assume that a "Theory of Everything" is everything! Elementary particle physicist may get multiple orgasms when they find it, but CM physicists will simply ask "Is that all there is?" We can't use it, and it isn't useful.

Zz.

[vanesch]

But this really is irrelevant to the issue that I brought up originally. Even when we know all the interactions, we presently cannot use it can CM physicist, nor can we make use of it to predict other yet-undiscovered emergent behavior. My training as an experimentalist is rearing its ugly head again. I'm asking "yeah, so? What can I do with it?"
Currently, nothing.
Zz.

Sure, I'm not disputing that. It's what I call "practical holism". And indeed many phenomena are difficult/impossible to practically calculate ab initio.

But you seem to make no distinction between "the answer exists (the "there exists" symbol in logic)" and "I know how I can find the answer". I'm claiming that "there exists" an answer for any measurable quantity related or not to an emerging property, and that there are only two possibilities: it agrees (the microscopic laws predict the property) or it doesn't agree (clash between the laws and the observation).
Of course if I cannot KNOW the answer, I cannot find out in which case I am, but it is not because I don't KNOW the answer that it doesn't exist (Fermat's last theorem was true, even before the proof was discovered).
And this means that there CANNOT be a peaceful coexistance between microscopic laws and macroscopic laws predicting emergent properties UNLESS the macroscopic properties are all in agreement (in the above sense) with the microscopic laws, which is all which the reductionist view requires.

[vanesch]

Is it simply because we cannot do all the complexities? Or is it because there is a built-in shortcoming in the model that simply neglect some "long-range, collective order" that will only emerge once one crosses over some scale? These are questions no one can answer. But because of that, it is also wrong to assume that a "Theory of Everything" is everything! Elementary particle physicist may get multiple orgasms when they find it, but CM physicists will simply ask "Is that all there is?" We can't use it, and it isn't useful.

I agree with you of the sole spiritual value of this and total lack of practical use, except for the multiple orgasm: see, it WAS useful to some :approve: :rofl:

But I could formulate the reductionist-holist debate in another way, which is probably more meaningful.

Suppose that I have some microscopic laws, and that I CAN derive SOME macroscopic properties WITH mathematical certainty from these microscopic laws (such as conservation of momentum! But there might be others) ab initio, without making extra assumptions and approximations. COULD IT HAPPEN that there are specific "macroscopic" laws that contradict these ab initio predictions, while nevertheless the microscopic laws are supposed to be "correct" ? THIS is, to me, the essence of the holistic viewpoint, and, in my not so humble opinion, self-contradictory. If the answer to the above question is "no" then that, to me, is the essence of the reductionist viewpoint.

But that's a far cry from the indeed arrogant claim that if we know the fundamental microlaws, we know "all of physics". I will not hide that this was my initial motivation to go into particle physics, but one ends growing up :grumpy:

[selfAdjoint]

Patrick, given your test of holism, how would you rank broken symmetries, as found in the standard model for example. The usual account of these is that the ab initio physics predicts - e.g. - zero mass quarks, but "interactions" produce mass. Is this emergent in your view? Is it an example of emergent physics contradicting micro physics?

[ZapperZ]

Sure, I'm not disputing that. It's what I call "practical holism". And indeed many phenomena are difficult/impossible to practically calculate ab initio.
But you seem to make no distinction between "the answer exists (the "there exists" symbol in logic)" and "I know how I can find the answer". I'm claiming that "there exists" an answer for any measurable quantity related or not to an emerging property, and that there are only two possibilities: it agrees (the microscopic laws predict the property) or it doesn't agree (clash between the laws and the observation).
Of course if I cannot KNOW the answer, I cannot find out in which case I am, but it is not because I don't KNOW the answer that it doesn't exist (Fermat's last theorem was true, even before the proof was discovered).
And this means that there CANNOT be a peaceful coexistance between microscopic laws and macroscopic laws predicting emergent properties UNLESS the macroscopic properties are all in agreement (in the above sense) with the microscopic laws, which is all which the reductionist view requires.

You will note that my objection to reductionst approach isn't just based on the argument that we have not found an example or an answer. It is also based on indications, such as the examples in Laughlin book, of why there are many observations in which even Weinberg cannot come up with even hand-waving arguments to explain how such phenomena can emerge out of an elementary description. These are not slam-dunk proofs, but rather compelling evidence.

Take a lot of identical balls. Now shoot them through a hole. At the hole, you have a detector that measures the number of balls going through the hole at any given instant. Now make the hole smaller... and smaller... and smaller. At some point, only ONE ball at a time can pass through the hole. This is the SMALLEST number (other than none) that will pass through, carrying the entity equivalent to ONE ball.

This is NOT what happens in fractional charges/QHE. I can get an equivalent to 1/5 of a ball!! The SMALLEST entity under such emergent phenomenon is SMALLER than the smallest entity at the microscopic scale. This is what I point out as compelling evidence on why elementary interactions have even conceptual problems (forget about mathematical formalism) of accounting for this.

I'm not using this to discuss the phenomenon. I'm using this to show you that I'm not simply using the "there are no answers" and the sole argument.

Zz.

[quantumcarl]

I'm just a layman, and a casual student of QM. ZapperZ is a working physicist -- I think he's currently at Argonne National Laboratory. Neils Bohr was one of the original developers of quantum theory.
I don't think there's anything necessarily wrong with speculating about the possible makeup and behavior of an underlying reality in terms of imagery from our ordinary experience. But that's not how QM was developed or what QM means, afaik.
If QM is about experimental setups and results (which it is), and not a description of an underlying quantum reality (which, afaik, it isn't), then the existence of nonlocal propagations in nature, or the idea that the existence of some object or event in nature depends on our consciousness of it, isn't entailed by QM.
QM books often weave metaphysical (using classical analogs/imagery) language with the physical, instrumentalist/mathematical language in a way that makes it sort of unclear that, say, the word 'particle' as it's used in QM has only a mathematical (and instrumental) existence and meaning. Phrases like, "the probability that the particle will be found ...", used in contexts involving detector clicks or dots on a screen tend to obscure the fact that it's the detector clicks or dots on a screen, and their probability of occurance wrt specified experimental setups, that are being talked about mathematically and not some underlying quantum world of particles and waves.
It's not that anybody is denying the possibility, or existence, of an underlying quantum world. But how are you going to talk about it unambiguously? This was one of the main problems that the developers (including Niels Bohr, who you've asked about) of quantum theory were faced with. Whatever it might be, it's not amenable to our direct sensory perception and can only be approximately tracked by instruments. So, QM is about what can be unambiguously stated wrt the various experimental results that have historically defied classical explanation -- that is, QM is all about the experimental results not their possible underlying causes. It's a purely correlational theory, not a causal one.
Of course the underlying quantum world, whatever it might be, is presumed to be a bit more sensitive to observational probing than the moon is.
However, the existence of quantum phenomena in the physical forms of experimental preparations and results, and the math which describes these, (which are the only physical forms in which quantum phenomena can be unambiguously said to exist) doesn't depend on our consciousness of them any more than the existence of the moon depends on our consciousness of it.
The physical fact that the experimental preparations and the math have the specific forms that they do has of course something to do with the conscious decisions that went into their construction. But those conscious decisions were preceded by sensory apprehensions of the physical world which didn't just pop into existence because we wanted or willed them to be there. The physical facts are what they are -- and to the extent that all people with normal (and sober) sensory capabilities see the same physical facts, then they're considered to be objective (not just subjective, ie., not just in your or my imaginings) and part of our physical world.
The working assumption in all of the physical sciences is that the world of our objective sensory experience exists whether you or I or anybody is paying attention to it.
And there's nothing in either quantum theory or quantum experiments which contradicts this view ... at least as far as I'm aware.
In order to really understand what Bohr and ZapperZ and others are saying it's necessary to put down the QM popularizations and actually start learning the theory -- and then a fascinating (not just the physical/experimental phenomena themselves, but also the ingenious ways that physicists have devised to produce them) world of discovery will be revealed to you.

I tend to agree with you here. Your explaination is akin to the differences between the two schools of "emotionalism" and "detached objectivism". An example would be where we see two observers viewing the painting of the Mona Lisa by Da Vinci. One viewer only sees the emotional content, the smile, the reticent attitudes and garments the subject in the painting is shown to exhibit and the other viewer sees the techniques and the materials the painter used to depict an "emergent phenomenon" that apparently no longer exists with the exception of the painted record.

The terminologies of physics and quantum physics can be confusing and mis-leading for the general public. For instance the words "photon" and "graviton" simply describe a quantum measurement of an area of a wave... as far as I can decifer. Yet many, many people take these words as factual descriptions of existing and tangable particles. They see gravity as a kind of collection of little undecernable "gravitons" spewing off a mass and exherting an attractive force. Similarily with the idea of photons, people actually think they can feel little particles called "photons" hitting them when a light wave reaches their location.

This ambiguity that's been set up by the terminology of physics, which is really exclusively meant to clarify various theories of physicists alone, can tend to bleed over into terms and conditions of molecular physics where again, we cannot easily discern molecules in our daily lives yet we are told that all matter is comprised of these quanta. What is also confusing is that some of us are told that the ideas of molecules and atoms are also simply convenient ways of describing waves and energy packettes.

So, perhaps what I am asking about nature (after Bohr) is this:.. at what point do we "emerge" from the micro-microscopic, non-solid condition that quantum physics proports to be able to (physically) measure and what are the catylists or the conditions that make it possible to distiguish between the two seemingly contradictory states?

I realise that to imagine awareness to be fundamental to the condition of solid matter is pushing anthropomorphism to its outer limits. But, it is also hard to prove that there is any other fundamental basis for waves of energy to be perceived as solid matter.

[quantumcarl]

I can do better. Look in my journal entry under "Theory of Everything?". There's a series of appers by Laughlin (and citing Anderson) on this subject. You'll realize how ironic it is for you to indicate TO ME what an emergent phenomenon is.
Zz.

Quite to the contrary, you asked me the question with regard to whether or not the quantum hall effect is an example of an emerging phenomenon. It is more ironic that you would ask me, a lay person to quantum physics and physics in general, the question. I simply had to google the proposition and hope it was an approximate to what you were asking. I didn't do the math and I didn't do the quantum trough or hall effect experiments.

Is it true that when light colides with light (at this point carrying only relative mass or rest mass, I forget which) that particles like sigmas and others are formed, constituting something we are able to observe and classify as matter?

[ZapperZ]

Quite to the contrary, you asked me the question with regard to whether or not the quantum hall effect is an example of an emerging phenomenon. It is more ironic that you would ask me, a lay person to quantum physics and physics in general, the question. I simply had to google the proposition and hope it was an approximate to what you were asking. I didn't do the math and I didn't do the quantum trough or hall effect experiments.

No, look again. I asked you if you actually understood what "emergent phenomena" were when you "cut-and-paste" something that Anderson did. I questioned your understanding of the things you're using to either illustrate your point, or to use as an argument point. Instead, when I asked you this, you were trying to point to me what emergent behavior is. This is what I find ironic.

Is it true that when light colides with light (at this point carrying only relative mass or rest mass, I forget which) that particles like sigmas and others are formed, constituting something we are able to observe and classify as matter?

Light doesn't need to collide with light to produce matter (we have no photon colliders at the moment.). Pair production does this very often and it is the source of many positrons. But why is this even relevant here?

Zz.

[quantumcarl]

No, look again. I asked you if you actually understood what "emergent phenomena" were when you "cut-and-paste" something that Anderson did. I questioned your understanding of the things you're using to either illustrate your point, or to use as an argument point. Instead, when I asked you this, you were trying to point to me what emergent behavior is. This is what I find ironic.


OK I see what your angle was with the question... and now I have a .000301 percent better understanding of the concept of emergent property... and that's probably an over-estimate. Still, I appreciate the motivation to study an idea I have never actually heard of...


Light doesn't need to collide with light to produce matter (we have no photon colliders at the moment.). Pair production does this very often and it is the source of many positrons. But why is this even relevant here?
Zz.


In my reply to Sherlock I explained that I don't understand what the threshold, the catylist or the condition is where waves of energy become observed and classified as matter. This is in keeping with my original question concerning matter and its fundamental origin. I explained that, as far as I know, photons and gravitons are convenient units of measurement used in quantifying a light wave/frequency or a field of gravity and that these units are not particles or considered to have a real mass and stuff like that.

Then I mentioned the contradictory notion that matter is also considered to be a result of waves and frequencies of energy and that terminology like "atoms" and "molecules" could also be considered units of measurement being used to describe densities of energy... (I'm sure you have a better description of this). This is when I remembered reading in PF Physics Section that collisions of photons, at the early stages of the universe produced something like sigmas, hadrons(?) and other (things i don't have a name for suchas quarks or top quarks or something(??)).


With your experience in these "matters" would you say that photon units of a light wave are also an emergent phenomena and so would not be considered fundamental to the existence of matter? Or would simply tell me to... "do the math boy?!!!"

[Sherlock]

So, perhaps what I am asking about nature (after Bohr) is this:.. at what point do we "emerge" from the micro-microscopic, non-solid condition that quantum physics proports to be able to (physically) measure and what are the catylists or the conditions that make it possible to distiguish between the two seemingly contradictory states?

The point of Bohr's spiel was that instead of speculating about another level (or other levels) of physical reality (instead of building metaphysical constructions to account for quantum phenomena), the quantum theory, in order to have a clear meaning (an unambiguous formulation) and thereby to progress, had to concern itself only with what happens at the instrumental level -- that is, as far as the science of physics can be concerned, there isn't any other level. (Sure, there might be some sort of imagery attached to this or that mathematical model, but it would be a mistake to take that literally as some sort of reference to the composition or behavior of an underlying reality. Quantum theory isn't an ontology of an underlying quantum world.)

The concern is then to what experimental phenomena does quantum theory solely apply, to what experimental phenomena can a semi-classical formulation be applied, and to what experimental phenomena can a purely classical formulation be applied.


I realise that to imagine awareness to be fundamental to the condition of solid matter is pushing anthropomorphism to its outer limits. But, it is also hard to prove that there is any other fundamental basis for waves of energy to be perceived as solid matter.
I think of human awareness or consciousness as the physical body monitoring (detecting, sensing) stuff impinging on it from outside, and also monitoring stuff that's happening inside it. Eventually, stimuli of sufficient magnitude become electro-chemical changes in the brain -- at which point we are aware or consicous of something or other, or, more usually, many things at once. We as well as other organisms are, then, just more or less complex, mobile detecting and adapting devices, which, through many generations of adaptation and alteration are, additionally, able to reproduce within species using only our self-contained biological components (and perhaps some wine and mellow music).

Waxing metaphysical, whoops, we're just a particular bounded complex (a manifestation of several different scales) of wave interactions.

A particular consciousness, then, arises out of a particular material configuration -- not the other way around. This general conception of consciousness avoids the usual anthropomorphizing.

At this point, I think you should present your consciousness-matter considerations to the metaphysics or philosophy forums (if you haven't already) in order to work out any semantic inconsistencies that might be present or that might arise -- because QM, per se, doesn't address this sort of thing -- and anyway there are people frequenting those forums who have thought a lot about the meaning of consciousness, etc.

I'll no doubt join in the discussion there at some point, as I love to speculate about such matters.

As for your latest questions (I just noticed your last post), maybe one of the mentors can answer some of them in a way that satisfies you, but to really understand what physics has to say it's necessary to learn it in steps. I could outline a program of self-study for you, but you're probably better off getting it from one of the mentors.

[vanesch]

Patrick, given your test of holism, how would you rank broken symmetries, as found in the standard model for example. The usual account of these is that the ab initio physics predicts - e.g. - zero mass quarks, but "interactions" produce mass. Is this emergent in your view? Is it an example of emergent physics contradicting micro physics?

I tried to point out that "emergent phenomena" (meaning, special behaviour seen in large collection of constituents which does not directly seem to occur in small collections of said constituents) are not, by themselves, any indication of "holism" (the way I understand it, namely the negation of reductionism, and reductionism in my book means: there is a UNIQUE set of laws of nature (a mathematical structure, say) which describe ALL of nature). For sure there are emergent phenomena. But you know that you can have emergent phenomena too in computer simulations (from Conway's game of life to many other funny things people have thought up). And these computer simulations are OF COURSE reductionist: the program describes the individual interactions of the constituents. So the program (which is the computer equivalent of the "physical laws on microscale") IS capable of generating "emergent behaviour" such as little conglomerates which walk across the screen and so on.
I would even think that the very name of "emergent" phenomena meant exactly this: they EMERGE from the playing together of the microscopic components following their microscopic laws.

The school example is the Ising model: http://en.wikipedia.org/wiki/Ising_model

which shows a phase transition emerging from the microscopic interaction between vertices.

What I thought was at stake here, was that there are several (according to ZZ, a majority) of physicists which think that the laws of nature on microscopic scale ARE NOT RESPONSIBLE for certain macroscopic phenomena (which are hence not *emerging* from the microlaws but "appear out of the blue"). So you have the validity of the microlaws for the constituents, but nevertheless, a large set of constituents shows behaviour which is NOT emerging from the workings of these microlaws.

As I tried to point out, this view, on a purely conceptual side, looks to me self-contradictory. Because any measurable quantity that shows us the appearance of the new phenomenon has - in principle - a predicted value based on the microlaws. If that predicted value INDICATES US the "new phenomenon" (so there is agreement), then after all, the new phenomenon WAS emerging from the microlaws, and it was NOT a new phenomenon. And if the predicted value does not indicate us the "new phenomenon" then there is a CONTRADICTION between the microlaws and the macroscopic behaviour observed, which FALSIFIES the microlaws.
My silly example was: if the microlaws say that the atoms of the apple all go to the left, this can not be in coexistance with a macrolaw saying that the apple as a whole goes to the right.
The only way of reconciling both would be if the microlaws DID NOT MAKE ANY DEFINITE PREDICTION of the measurable quantity ; but this cannot happen, because the microlaws already define the behaviour of the constituents entirely.

[quantumcarl]

The point of Bohr's spiel was that instead of speculating about another level (or other levels) of physical reality (instead of building metaphysical constructions to account for quantum phenomena), the quantum theory, in order to have a clear meaning (an unambiguous formulation) and thereby to progress, had to concern itself only with what happens at the instrumental level -- that is, as far as the science of physics can be concerned, there isn't any other level. (Sure, there might be some sort of imagery attached to this or that mathematical model, but it would be a mistake to take that literally as some sort of reference to the composition or behavior of an underlying reality. Quantum theory isn't an ontology of an underlying quantum world.)
The concern is then to what experimental phenomena does quantum theory solely apply, to what experimental phenomena can a semi-classical formulation be applied, and to what experimental phenomena can a purely classical formulation be applied.
I think of human awareness or consciousness as the physical body monitoring (detecting, sensing) stuff impinging on it from outside, and also monitoring stuff that's happening inside it. Eventually, stimuli of sufficient magnitude become electro-chemical changes in the brain -- at which point we are aware or consicous of something or other, or, more usually, many things at once. We as well as other organisms are, then, just more or less complex, mobile detecting and adapting devices, which, through many generations of adaptation and alteration are, additionally, able to reproduce within species using only our self-contained biological components (and perhaps some wine and mellow music).
Waxing metaphysical, whoops, we're just a particular bounded complex (a manifestation of several different scales) of wave interactions.
A particular consciousness, then, arises out of a particular material configuration -- not the other way around. This general conception of consciousness avoids the usual anthropomorphizing.
At this point, I think you should present your consciousness-matter considerations to the metaphysics or philosophy forums (if you haven't already) in order to work out any semantic inconsistencies that might be present or that might arise -- because QM, per se, doesn't address this sort of thing -- and anyway there are people frequenting those forums who have thought a lot about the meaning of consciousness, etc.
I'll no doubt join in the discussion there at some point, as I love to speculate about such matters.
As for your latest questions (I just noticed your last post), maybe one of the mentors can answer some of them in a way that satisfies you, but to really understand what physics has to say it's necessary to learn it in steps. I could outline a program of self-study for you, but you're probably better off getting it from one of the mentors.

I see your point. My question was raised in the "hand-waving, tree-hugging" philosophy section through my initial ascertation that awareness (the neurophysicist's term for the more ambiguous term of "conscousness") is fundamental to the bio-specific experience of (solid) matter. This is not a question of metaphysics but one of biological perception and adaption with regard to survival and a biological unit's ability to function in an environment it perceives itself to be a part of.

Our environment also includes our thoughts and our beliefs (which may or may not be truths irregardless of how collectively they are experienced) and these beliefs are formed in what is termed a classical environment by people who are "emergent phenomena". Doesn't this constitute a kind of bias on the part of the observer with regard to the results of quantum measurements, etc...?

[vanesch]

This is NOT what happens in fractional charges/QHE. I can get an equivalent to 1/5 of a ball!! The SMALLEST entity under such emergent phenomenon is SMALLER than the smallest entity at the microscopic scale. This is what I point out as compelling evidence on why elementary interactions have even conceptual problems (forget about mathematical formalism) of accounting for this.
I'm not using this to discuss the phenomenon. I'm using this to show you that I'm not simply using the "there are no answers" and the sole argument.
Zz.

I looked up a bit on the fractional quantum hall effect:
http://www.pha.jhu.edu/~qiuym/qhe/qhe.html

as far as I can make up anything from the explanation (by Laughlin) of the FQHE:
http://www.pha.jhu.edu/~qiuym/qhe/node5.html#SECTION00050000000000000000

I would say that this is entirely a reductionist approach, no ? He's putting together wavefunctions for electrons in such a way that the FQHE is explained.

Of course I'm not a condensed matter physicist, and probably many subtleties escape me totally here. But I don't see the shocking contradiction between the reductionist view (for instance, claiming that electrons have to be described by a wavefunction in hilbert space), and the FQHE. I guess that if Weinberg has problems with it, I'm no party !

[ZapperZ]

I looked up a bit on the fractional quantum hall effect:
http://www.pha.jhu.edu/~qiuym/qhe/qhe.html
as far as I can make up anything from the explanation (by Laughlin) of the FQHE:
http://www.pha.jhu.edu/~qiuym/qhe/node5.html#SECTION00050000000000000000
I would say that this is entirely a reductionist approach, no ? He's putting together wavefunctions for electrons in such a way that the FQHE is explained.
Of course I'm not a condensed matter physicist, and probably many subtleties escape me totally here. But I don't see the shocking contradiction between the reductionist view (for instance, claiming that electrons have to be described by a wavefunction in hilbert space), and the FQHE. I guess that if Weinberg has problems with it, I'm no party !

No, the ground state wavefunction is not the wavefunction of a "free" charge carrier. It's the ground state of a "quasiparticle". So this already is a wavefunction of a many-body system.

Zz.

[vanesch]

No, the ground state wavefunction is not the wavefunction of a "free" charge carrier. It's the ground state of a "quasiparticle". So this already is a wavefunction of a many-body system.
Zz.


Ok, but we know how these effective quasi-particles appear as "helpful bookkeeping devices" of the stationary states of a many-particle system with periodic potentials, so this is not impossible to obtain "ab initio" (again: in principle, though it may be intractable in practice).

As such, constructing wavefunctions of quasiparticles is nothing else but exploring the zoo of ab initio solutions of the many-body problem, in a smart way (by first making superpositions that correspond to "quasiparticles" - call them stationary states of the hamiltonian, or good approximations of it), and then again making superpositions of these quasiparticle states. So, as such, using wavefunctions of quasiparticles does not clash, in my eyes, with any reductionist view.

Of course, the precise modelling of the interaction terms (that is, the matrix elements of the neglected parts of the hamiltonian that we are now putting in in the "quasiparticle states") is probably more guesswork than ab initio deduction, and it requires a great deal of physical intuition, guesswork, good luck, insight and whatever to DO what people like Laughlin did, but I fail to see the shock with the principle of reductionism. That's - I admit this freely - probably more due to my naivity than my ability to outsmart Weinberg :rolleyes:. It might very well be that there are subtle reasons that would seriously make you expect that this kind of wavefunction should NOT be obtained ab initio and that I fail to see the difficulty because I fail to know about these reasons.
But if it is only based upon the usually NAIVE explanation of quasiparticles acting like normally charged particles, behaving classically (as is usually explained the hall effect in a first course), and that in this naive picture, we now have to use fractionally charged "bullets" to find agreement with the FQHE, then this argument doesn't have much weight in my eyes. The picture, in all likelihood, is simply wrong for this case.

So, in my great naivity, I fail to see how one can conclude that the FQHE is not - in principle - obtainable from the exact solution to the quantum mechanical problem of the many-electron system, though I concede, and I repeated this often, that this may be practically totally unfeasable and that it is indeed MUCH SMARTER to do what condensed matter physicists are doing and to model phenomenologically.

[ZapperZ]

Ok, but we know how these effective quasi-particles appear as "helpful bookkeeping devices" of the stationary states of a many-particle system with periodic potentials, so this is not impossible to obtain "ab initio" (again: in principle, though it may be intractable in practice).

I'm not sure what you mean by "ab initio" here. It certainly doesn't HAVE to mean "start from elementary interactions". The ab initio starting point in condensed matter physics has always been the many-body hamiltonian.

The confusion comes in when condensed matter uses the phrase such as "single-particle" excitation. This does NOT mean it is starting with elementary particle and adding the interactions one at a time. A single particle spectral function ALREADY comes in with a baggage load of many-body interactions absorbed within the self-energy term inside the many-body Green's function. This is what allows us to treat this as if it is a one-body problem.

Now, while you can "turn off" the many-body interactions and regain the "bare particle", the problem is not tractable if you instead decides to change the problem from a many one-body problem (which is what Landau did) to a single, many-body problem. You can't solve this. So by doing what appears to be only a one-body problem, you are already commited to an emergent entity - the quasiparticle that arises out of the many-body interactions.

This is why I said that the starting point is the many-body ground state. The "electrons" that you measure in a conductor is already a many-body normalized quasiparticle, not the bare electrons. And if Anderson and Laughlin are correct, ALL of our elementary particles are emergent particles arising out of some field excitations, including the quarks.

Zz.

[quantumcarl]

Out of respect of the learned people who have contributed to this thread and to help me clarify my question I'd like to thank you all for entertaining it and me and my ineptitude with the study of the nature of quantum physics, mechanics and physics in general.

Since there has been such an open attitude toward disclosing everyone's level of understanding of physics I'll include my own background with the topic. As a medical illustrator for many years with a well established cancer treatment centre I was fortunate enough to be exposed to varied amounts of knowledge about every discipline that goes into the treatment of cancer. My favorite group to spend well over 4620 coffee breaks and lunch breaks with was the medical physicists.

One man in particular became a sort of mentor for me who originally immigrated from China, became a dishwasher and supported himself through university and became a PhD medical physicist. That is the extent of my informal training in physics... with the exception of this incredible forum, the Physics Forum.

Before I completely blow this thread out of quantum physics into philosophy or get my knuckles wrapped by a mentor I'll just say that I have completely enjoyed the responses I've received to my question.
I realise now that physicists really can't progress in their studies if they are continually questioned or in doubt about niggling little philosophical questions concerning the nature of their work. It would be like stopping Wayne Gretsky every five minutes during a hockey game and asking him if he really exists! Totally inappropriate.. and absurd!

I am actually satisfied with the "speil' from Bohr that suggests "physics is not about what nature is but more about what physicists can say (with regard to their observations) about nature. Thank you very much Dr. Bohr and everyone else here that has done and is doing the math!

[vanesch]

I'm not sure what you mean by "ab initio" here. It certainly doesn't HAVE to mean "start from elementary interactions". The ab initio starting point in condensed matter physics has always been the many-body hamiltonian.


Well, start with "real" electrons (in the framework of non-relativistic quantum mechanics, sufficient for most of condensed matter physics), and real nucleae. Consider the crystal structure as a given (if you want to discuss this, go to the Born-Oppenheimer approximation of the many body problem which allow you to treat the electron system and the nucleae system - in most cases - separately) and consider hence the many-electron system in a periodic potential. Then realise that stationary solutions for the many-body system without interactions can be classified using a Fock space approach, and call the bookkeeping state countings "quasi particles". We have now a "free quantum field theory" of quasiparticles. Next, add in the interactions of the individual real particles, but modelled as interactions of quasi-particles. It is usually here where we totally leave the ab-initio approach and start guessing reasonable effective interactions of quasi particles ; but in order to be right, these should be the matrix elements of the up hereto neglected interaction hamiltonian in the real many-body problem, but between the Fock basis states, and not between the real-single-particle states. It is only to be hoped that the guessed-at effective interaction term corresponds to this matrix element, but in the case it is, we are still "in parallel" with an approximation to an ab initio calculation.
The point I'm trying to make is that if I were some god-mathematician with a brain a billion times the size of the visible universe, I WOULD be able to do all these calculations ab initio. Because some of us are lesser mortals :smile: we have to ressort to intuition and guesswork.


The confusion comes in when condensed matter uses the phrase such as "single-particle" excitation. This does NOT mean it is starting with elementary particle and adding the interactions one at a time. A single particle spectral function ALREADY comes in with a baggage load of many-body interactions absorbed within the self-energy term inside the many-body Green's function. This is what allows us to treat this as if it is a one-body problem.


I understand that, but I'm claiming that the idea behind it is still ab initio, but not from calculations, but from intuition and guesswork, because of the limited size of our brains. It does not mean that the ab initio approach is going to FAIL. It is simply untractable by us, lesser mortals. And maybe the smarter we get, the more cases we will find where we CAN, within some approximation, do the true ab initio calculation.


Now, while you can "turn off" the many-body interactions and regain the "bare particle", the problem is not tractable if you instead decides to change the problem from a many one-body problem (which is what Landau did) to a single, many-body problem. You can't solve this. So by doing what appears to be only a one-body problem, you are already commited to an emergent entity - the quasiparticle that arises out of the many-body interactions.
This is why I said that the starting point is the many-body ground state. The "electrons" that you measure in a conductor is already a many-body normalized quasiparticle, not the bare electrons. And if Anderson and Laughlin are correct, ALL of our elementary particles are emergent particles arising out of some field excitations, including the quarks.
Zz.

I understand that, but I don't find that an argument against reductionism. The quasi particles EMERGE from the underlying microphysics - or at least, we conceptually think of it that way (and in some toy models, we can even do it explicitly). I'm not arguing against "emergent properties" at all. I'm arguing against the idea that we can have microphysical laws which are "correct" and apply to the microphysics, and that we have INDEPENDENT and co-existing macrophysical laws, which have nothing to do, even in principle, with these microphysical laws. I'm claiming that as a matter of principle, these microphysical laws make a definite statement concerning the macrolaws ; and if they are in agreement, all the better, and if they are in contradiction, the microlaws are simply FALSIFIED. But I don't buy that they can INDEPENDENTLY exist next to eachother.

However, I totally agree that the above statement is only one of principle (available to said god-mathematician with said brain) and that we have to realise our mortal limitations, and as such, that the said approach is a total waste of time in a great many number of cases, and that you indeed BETTER do as if you are discovering (almost) independent laws: you'll get faster to a useful theory.

So you can tell me: well, if you know that it is the only practical method, what the hell are you blathering about ? I think that there IS a fundamental difference. We get smarter as time goes on. We learn new mathematical techniques, and we get smarter machines. We get more and more experience with how these many-body systems behave. This means that there is some hope that we can do more and more ab-initio-like calculations, or at least derive general properties of the kinds of solutions we can hope to obtain ab initio. And in the reductionist approach, these derivations and properties make sense ; while in the true holistic approach, this is a total waste of time.

As I said, I think that reductionism together with the hypothesis of the existence of an objective world are the two founding principles of physics. I'm not willing to give them up so easily.

[Schrodinger's Dog]

Really walking a fine line between explaining your method and philosophy, here I'll step over that line.

all good stuff. But accepting that there is an objective reality and accepting there is no objective reality only a subjective one are different sides of the same coin . Neither has any proof and neither is more credible than the other? This maybe a philosophical point, but it does at least raise one important issue? What if what we see is not objectively real? What if we are merely seeing it that way because that is how we evolved to see it, evolutionaly speaking the reality of photons properties are less beneficial to survival than seeing them the way we do now? Yeah I know you can dismiss such questions as specualtion and philosophy.

But if I had a machine that did 1000 experiments which all got the same results. And you did the experiment and got 1000 slightly different results. You'd check the machine and see that those results where caused by an error brcause of reason A. But what if the machine is right and your perception is wrong? We cannot simply dismiss the idea that what we see experimentaly is the absolute truth any more than we can dismiss that it is all delusion. With that in mind, we have to be really careful about what we say is true from our perspective, getting 1 million peope to corroborate results is sciences way of mitigating the subjectivity but barring meeting an alien that tells us QM is all tosh because of Reason B or that QM is all right because of reason A, we will never truly know what objectivity is. With this in mind all we can do is experiment and hope that everything exists that we say does and that QM isn't just some bizarre fantasy, because the alternative doesnt bear thinking about:wink:

Yep total philosophy I agree, but I still think it's a point.... Like I said before if we're wrong then we'll never know it 'till someone teaches us how to percieve reality properly:smile:

I must say though that this thread is one of the best I've read in my short time on here. You'd be hard pressed to come up with a better suming up of scientific ideals and methodology; bravo gentlemen:smile:

I think I agree with Vanech and ZZ, I'm just hoping I'm not wrong:wink:

[ZapperZ]

Well, start with "real" electrons (in the framework of non-relativistic quantum mechanics, sufficient for most of condensed matter physics), and real nucleae. Consider the crystal structure as a given (if you want to discuss this, go to the Born-Oppenheimer approximation of the many body problem which allow you to treat the electron system and the nucleae system - in most cases - separately) and consider hence the many-electron system in a periodic potential. Then realise that stationary solutions for the many-body system without interactions can be classified using a Fock space approach, and call the bookkeeping state countings "quasi particles". We have now a "free quantum field theory" of quasiparticles.

But these aren't "quasiparticles". They ARE particles. Their non-interactions make them to be "ideal gasses", and statistically, we can deal with that.

Next, add in the interactions of the individual real particles, but modelled as interactions of quasi-particles. It is usually here where we totally leave the ab-initio approach and start guessing reasonable effective interactions of quasi particles ; but in order to be right, these should be the matrix elements of the up hereto neglected interaction hamiltonian in the real many-body problem, but between the Fock basis states, and not between the real-single-particle states. It is only to be hoped that the guessed-at effective interaction term corresponds to this matrix element, but in the case it is, we are still "in parallel" with an approximation to an ab initio calculation.

Actually, this is not true all the time. In Landau's Fermi Liquid theory, it is ONLY in the weak coupling limit (i.e. the interaction is weak enough that you can use mean field approximation) that will produce a 1-to-1 correspondence to the "bare", many one-body scenario. Crank up the coupling, and you lose everything! It is why strongly-correlated systems are such a fundamental and hot topic in condensed matter physics. We LOSE quasiparticles here! We have no well-defined entity to call a "quasiparticles" (see the normal state of an underdoped high-Tc superconductor). So no, there's nothing "parallel" here. At some point, your well-defined entity goes away.

And not only that, if you do this in 1-dimension, even the smallest correlation can produce a fractionalization of the spin and charge degree of freedom - they go their own separate ways with their own dispersion. There's nothing to match anything with the "non-interacting" case here - bluntly put, a "quasiparticle" is no longer "a good quantum number".

The point I'm trying to make is that if I were some god-mathematician with a brain a billion times the size of the visible universe, I WOULD be able to do all these calculations ab initio. Because some of us are lesser mortals :smile: we have to ressort to intuition and guesswork.

But as I've said, if this is OBVIOUS, we won't be having this discussion. It is NOT obvious, at least not to me, and certainly not to Anderson and Laughlin. You could be looking all you want at the individual dots on a piece of paper, but you will never been able to deduce from the local arrangement of those dots that it forms a picture. The long-range pattern is just not there for you to see it. It is why such interactions at that microscopic scale tells us nothing about the larger ensemble. Only when you step back and consider the whole thing as a clumb do you see the emergent behavior.

Zz.

[Rade]

The true holistic (anti-reductionist) approach is that EVEN IF YOU WERE TO USE THE EXACT MICROSCOPIC LAWS OF NATURE without any approximation, you would not be able to derive certain macroscopically observed phenomena. I think that that claim is self-contradictory...This is not a correct understanding of holism, at least as understood by the science of cybernetics. If the state conditions of two black boxes (A,B) are given, and each is studied in isolation until its "canonical representation" is established and if they are then coupled in a known pattern by known linkages, then it must follow logically that the behavior of the whole [A-B] is determinate, and can be predicted. Thus such a "holistic" system will show no emergent properties since there is a 1:1 canonical transformation (U) linking A --> B. Likewise, there must be a 1:1 inverse of U (V) which may be also U^-1 for B --> A (= unitary transformation of a QM system).
Now the concept of "reducibility" and its relationship to "holism" in general system theory is such that a holistic system [(A)-(B) from above example] has immediate effects on each other as thus shown [ (A) <-----> (B) ] or perhaps one way only [ (A) -----> (B). The "reductionist" representation is only obtained when the two parts are functionally independent, thus [ (A) (B) ].
Now, in cases where the "parts" are at a range of size greatly different than the "whole", then the fundamental properties of the whole can be very different indeed from the parts, and what is "true" at one end (the reduced state) may not be true at the other (the holistic state). For example, consider the concept "taste" as relates to the atoms carbon (C), hydrogen (H), oxygen (O). If we treat these as black boxes each has a fundamental taste property (= no taste). However, when we couple to form a large molecule H-C-O (a sugar) we find a new property of taste has "emerged" (= sweet) that could not be predicted from the parts via any formalism of QM.
And I take it that this is what ZapperZ is articulating when he states:
[ZapperZ: "QM has many features that merge into the classical properties, especially at high quantum number, high temperatures, or large interactions (decoherence). But this doesn't mean that using QM description for classical, macroscopic system is any more valid than using classical physics for QM systems. There are a bunch of things we still don't quite know at the mesoscopic scale where these two extremes clash their heads. All we know right now is that one should not simply adopt QM's "world view" on classical systems. It will produce absurd conclusions."]

[quantumcarl]

You could be looking all you want at the individual dots on a piece of paper, but you will never been able to deduce from the local arrangement of those dots that it forms a picture. The long-range pattern is just not there for you to see it. It is why such interactions at that microscopic scale tells us nothing about the larger ensemble. Only when you step back and consider the whole thing as a clumb (clump) do you see the emergent behavior.
Zz.

Sorry to bother you again. This sounds like a fundamental requirement to observing matter. You have to exist at a similar scale to the scale of other emergent phenomena... or "step{ped} back" to see the emergent behaviours of energy.

It is boggling for me to figure out how physicists do the opposite and reduce their observations to the scale of energy fields or EM energy.

Do the Quantum Physicists consider themselves as one of the instruments in an experiement? Or as one of the conditions?

By the way, "how salty is spring tension (Zapper z)?!!" :rofl: (ref:"How big is a photon..." thread, PF)

[ZapperZ]

Sorry to bother you again. This sounds like a fundamental requirement to observing matter. You have to exist at a similar scale to the scale of other emergent phenomena... or "step{ped} back" to see the emergent behaviours of energy.

Please note that when I said "observe", it has NOTHING to do with "I have to exist" requirement. This makes the rest of your point in that post moot.

You are more than welcome to start a new thread in the Philosophy section to discuss what is obvously the main thing you are so interested in. I just don't have the patience to deal with such issues.

Zz.

[vanesch]

This is not a correct understanding of holism, at least as understood by the science of cybernetics. If the state conditions of two black boxes (A,B) are given, and each is studied in isolation until its "canonical representation" is established and if they are then coupled in a known pattern by known linkages, then it must follow logically that the behavior of the whole [A-B] is determinate, and can be predicted. Thus such a "holistic" system will show no emergent properties since there is a 1:1 canonical transformation (U) linking A --> B. Likewise, there must be a 1:1 inverse of U (V) which may be also U^-1 for B --> A (= unitary transformation of a QM system).


Ah, that's a much more restricted definition of "reductionism" which makes even no sense in the frame of QM, in that the QM state space of the system [A-B] is BIGGER than the state space of [A] and the statespace of [B] (entangled states).

I understood "reductionism" as: all macroscopic behaviour is *in principle* determined by the laws (in casu QM) gouverning the microsystems (and holism as the negation of reductionism). This means that the laws governing the microsystem have mathematically fixed (even if you don't know how to *derive* it in practice) the emergent properties.




Now the concept of "reducibility" and its relationship to "holism" in general system theory is such that a holistic system [(A)-(B) from above example] has immediate effects on each other as thus shown [ (A) <-----> (B) ] or perhaps one way only [ (A) -----> (B). The "reductionist" representation is only obtained when the two parts are functionally independent, thus [ (A) (B) ].


Well, in physics, that's simply called: 'interacting systems'. Of course we allow the constituents to interact...


Now, in cases where the "parts" are at a range of size greatly different than the "whole", then the fundamental properties of the whole can be very different indeed from the parts, and what is "true" at one end (the reduced state) may not be true at the other (the holistic state). For example, consider the concept "taste" as relates to the atoms carbon (C), hydrogen (H), oxygen (O). If we treat these as black boxes each has a fundamental taste property (= no taste). However, when we couple to form a large molecule H-C-O (a sugar) we find a new property of taste has "emerged" (= sweet) that could not be predicted from the parts via any formalism of QM.


That's because "taste" is not a well-defined measurement observable (it's in fact a qualium). As I tried to point out, one needs to describe an *experiment* that measures a "holistic" quantity. The microscopic description of the experiment, in the reductionist version, should then also give the correct outcome for the experimental measurement. That's what I tried to do with the description of the measurement of the index of refraction of water, that evaporates. The phase-transition introduces a change in refractive index, and that gives rise to a change in the configuration of the EM field, something that "makes microscopic sense". So considering the entire physical microdescription of all the particles and fields involved, if reductionism holds (meaning: if the microdescription determines mathematically the macroproperties) then this microdescription determines also this change in the configuration of the EM field.



And I take it that this is what ZapperZ is articulating when he states:
[ZapperZ: "QM has many features that merge into the classical properties, especially at high quantum number, high temperatures, or large interactions (decoherence). But this doesn't mean that using QM description for classical, macroscopic system is any more valid than using classical physics for QM systems. There are a bunch of things we still don't quite know at the mesoscopic scale where these two extremes clash their heads. All we know right now is that one should not simply adopt QM's "world view" on classical systems. It will produce absurd conclusions."]

I agree with ZapperZ statement as such, but we both interpret this differently. I see this as a statement that QM might need a modification, while he can - apparently - accept this situation happily and doesn't see any contradiction in it.
In a reductionist view, there can only be ONE theory of the universe. Now, it could be that classical and QM theories we have now are only approximations, in certain limits, of this one theory.
Nevertheless, I think there IS a view of QM as a world view which does NOT produce absurd (although weird, agreed) results as such, and that is a "many world" view. So it is not the argument of the absurdness which is for me sufficient to conclude that QM does not work at macroscopic scales. The more difficult aspect is its relationship to GR. This, to me, is the only compelling reason to think there might be something wrong with QM - apart of course from an eventual clear experimental deviation of its predictions.

[quantumcarl]

Please note that when I said "observe", it has NOTHING to do with "I have to exist" requirement. This makes the rest of your point in that post moot.
You are more than welcome to start a new thread in the Philosophy section to discuss what is obvously the main thing you are so interested in. I just don't have the patience to deal with such issues.
Zz.

Right on. I'll consider your recommendation and if I follow it I can only hope to see a contribution there from the objectivistic quarter of the equation.

All the best in your endeavors.

[ZapperZ]

Right on. I'll consider your recommendation and if I follow it I can only hope to see a contribution there from the objectivistic quarter of the equation.
All the best in your endeavors.

Sorry. I avoid physics discussion in the philosophy forum like a plague.

Zz.

[Sherlock]

I understood "reductionism" as: all macroscopic behaviour is *in principle* determined by the laws (in casu QM) gouverning the microsystems (and holism as the negation of reductionism). This means that the laws governing the microsystem have mathematically fixed (even if you don't know how to *derive* it in practice) the emergent properties.

The sort of reductionism that eg. the standard (particle theory) model represents is an ontological analysis into smaller and smaller constituent parts. Whether the rules defining the experimental production of the particles are actually abstractions of general rules governing the behavior of phenomena on any and all scales is questionable, and apparently, wrt meso and macro scale observations, not the case. This sort of reductionism seems to be at odds with a holistic approach.

Then there is the sort of reductionism that refers solely to the abstraction of the truly general principles governing the behavior of phenomena on any and all scales. This is an epistemological rather than an ontological reductionism, and it seems to me to be a holistic approach, in any sense that I can now think of using the term, holistic.


In a reductionist view, there can only be ONE theory of the universe. Now, it could be that classical and QM theories we have now are only approximations, in certain limits, of this one theory.

It seems reasonable to assume that the currently standard theories will undergo modifications with advances in technology. It also seems at least somewhat reasonable to me to assume that the sort of reductionist approach underlying the currently standard particle model is just the wrong approach if the goal is to get at the truly general principles which apply to any and all scales of behavior.


I think there IS a view of QM as a world view which does NOT produce absurd (although weird, agreed) results as such, and that is a "many world" view.

The adoption of the Many Worlds Interpretation of QM requires taking at least some parts of the QM algorithm and mathematical models employed as more or less accurate representations of what is happening in real 3D space independent of observation. But I think it's reasonable to view this (the MWI prerequisite that the QM formalism is, in some/any sense, a description of the physical reality between emitters and detectors) as a perversion of the meaning and application of QM.

Or am I just wrong about what I'm supposing to be prerequisite to the MWI view?

There is a view of QM which doesn't produce absurd continuations. It just requires accepting that the theory is not intended as, and doesn't function as, a description of an underlying quantum world.

[selfAdjoint]

The sort of reductionism that eg. the standard (particle theory) model represents is an ontological analysis into smaller and smaller constituent parts.
This is the way it's presented in popularizations, but the quarks and gluons are actually quanta of the gauge field, which is a large scale phenomenon. The size of the experimental spaces at the colliders, at which the SM is applied are actually quite large on a human scale. Rather than "smaller" perhaps "prior" would be a better word.
Whether the rules defining the experimental production of the particles are actually abstractions of general rules governing the behavior of phenomena on any and all scales is questionable, and apparently, wrt meso and macro scale observations, not the case.
I don't know what you mean by this. Ab initio calculation of, say, chemical reactions is difficult because of computational complexity, but much progress has been made and there is no bar in principle to deriving all chemistry, biology, and indeed the whole experienced world, from particle physics.
This sort of reductionism seems to be at odds with a holistic approach.
Well, weak emergence (as gas pressure emerges from the conservation of particle momentum) is envisioned. But holism as it is usally presented simply seems to be almost content-free to me. What does it predict?

[Sherlock]

This is the way it's presented in popularizations, but the quarks and gluons are actually quanta of the gauge field, which is a large scale phenomenon. The size of the experimental spaces at the colliders, at which the SM is applied are actually quite large on a human scale. Rather than "smaller" perhaps "prior" would be a better word.

The experimental spaces are large because of the energies and instrumental complexity required to produce the particles. But the particles that are experimentally produced (or theoretically hypothesized) are neither large nor complex wrt the human scale.

I'm only barely at the level of semi-sophisticated popularizations of the standard particle model. Maybe my characterization of the enterprise as "an ontological analysis into smaller and smaller constituent parts" was wrong -- or at least a possibly misleading way to describe it. Maybe it's meaningless to rank the particles that high energy physics has been able to produce (or which it has hypothesized) on a scale of 'size'. But if it isn't, then the upper limit on the size of quarks and gluons (100 attometers ?) is certainly smaller than the particles which confine them. However, I was thinking (most heuristically, for which I might apologize if it weren't for this feeling that if the fundamental laws of nature apply to all scales of behavior, then there is evidence of them at the level of our ordinary sensory perception ) more along the lines of scales of complexity (a hierarchy of 'media' ?) rather than size, per se.

I'm not sure what you mean in suggesting that, eg. quarks, are 'prior' (some sort of temporal hierarchy?). According to what parameter scale might the particles of the standard theory be ranked?

Recent experimental data and the size of the quark in the constituent quark model
http://www.edpsciences.org/articles/epjc/pdf/2002/11/100520277.pdf

Quarks, diquarks, and pentaquarks
http://physicsweb.org/articles/world/17/6/7/1


Ab initio calculation of, say, chemical reactions is difficult because of computational complexity, but much progress has been made and there is no bar in principle to deriving all chemistry, biology, and indeed the whole experienced world, from particle physics.

It isn't known if there's "no bar in principle to deriving ... the whole experienced world from particle physics". It is known that it can't be done from the current standard model. The current standard model isn't fundamental in the sense that fundamental refers to behavioral laws which apply to any and all scales of interaction. While the standard model is certainly an abstraction, it apparently isn't an abstraction of what's truly fundamental wrt nature.


The Theory of Everything
http://www.pnas.org/cgi/content/full/97/1/28


... holism as it is usally presented simply seems to be almost content-free to me. What does it predict?

Holism, like reductionism, is an approach to (ostensibly eventually) understanding what's fundamental wrt the behavior of anything and everything in our universe. Since modern physics has taken an analytical reductionist approach rather than a holistic reductionist approach, then the latter hasn't produced much theoretical content.

The weak and strong forces, electromagnetism, and gravity (and who knows what else the analytical reductionist approach might tack on) --- maybe these aren't truly fundamental. Even with it's success in quantitatively accounting for many phenomena, considering the problems facing the standard model, it seems at least worth considering that maybe it's just the wrong way to go about getting at what's fundamental wrt all phenomena.

What's fundamental must be operating (evident) at the level of our sensory perception and wrt more or less everyday phenomena, not just wrt quantum experimental phenomena -- so there's no reason why we shouldn't, eventually, be able to express the fundamental principles of our universe in familiar terms. Maybe it just hasn't been looked at carefully enough, or sorted out according to the right paradigm. Of course, the standard model (or any model for that matter) isn't wrong wrt what it's able to predict. It just isn't telling us what's fundamental in the sense of universal physical principles.

Anyway, my main reason for entering the holism-reductionism discussion in the first place was to get vanesch to expound in more detail on his reasons for becoming an MWI er (or ist). But thanks for your comments, selfAdjoint, and I welcome any criticism of my comments.

[vanesch]

There is a view of QM which doesn't produce absurd continuations. It just requires accepting that the theory is not intended as, and doesn't function as, a description of an underlying quantum world.

Yes, I know, the "shut up and calculate" view. I call that a non-view :biggrin:. It is maybe the most accurate interpretation of QM :rofl: . But it leaves you with a problem: how do you identify the mathematical objects you're manipulating with things in the lab ? Which you need to do in order to give some sense to the numbers you're calculating in the first place. This means no matter, that you DO implicitly identify certain objects in the lab with certain mathematical structures. Now why can you do that for those things that suit you, and why do you obstinately refuse to do so with the rest of the mathematical formalism - just because it bothers your intuition ?

However, I'm much less hostile to this view than you might think. It is a bit like the Mendelian theory of genetics before the recognition of DNA: the theory worked, used certain concepts but didn't really correspond to a representation of reality. Once DNA and several cellular mechanisms were discovered, Mendelian genetics could be EXPLAINED on the basis of these biological mechanisms.

Maybe QM does the same, and is some statistical mechanism that has no correct representation of reality in it, but nevertheless arrives at correct predictions. The analogy can be continued: one should then look for an underlying representation of reality that explains the success of the formalism. But there are serious sea monsters in that ocean!
My point of view is that one should row with the tools one has, and in as much that the formalism of QM DOES allow for a representation of reality, take the opportunity to use it (were it only to devellop an intuition for the formalism!) - even if you want to keep in mind that it MIGHT not be the correct representation of reality. And then, it might be, too.

[ZapperZ]

Yes, I know, the "shut up and calculate" view. I call that a non-view :biggrin:. It is maybe the most accurate interpretation of QM :rofl: . But it leaves you with a problem: how do you identify the mathematical objects you're manipulating with things in the lab ?

You don't! You adopt a "working" view to deal with the formalism which you know isn't necessary kosher but works. By the time you actually make a measurement, these are then classical concepts. You measure energy, position, momentum, etc. So there's no problem with interpretation of what you observe in the lab.


Zz.

[vanesch]

You don't! You adopt a "working" view to deal with the formalism which you know isn't necessary kosher but works.

You mean, let's take a modest attitude, we haven't gotten *a clue* how nature "really" works, but we've noticed that in certain domains, certain formalisms give good results, and that's all we can say ?

[ZapperZ]

You mean, let's take a modest attitude, we haven't gotten *a clue* how nature "really" works, but we've noticed that in certain domains, certain formalisms give good results, and that's all we can say ?

On the contrary, we DO have a clue, and in fact, more than a clue. The clue here is that our classical concepts are having loads of weird properties when applied to where they shouldn't be applied. But this doesn't mean we're clueless, or else we will have no useful information.

Zz.

[selfAdjoint]

On the contrary, we DO have a clue, and in fact, more than a clue. The clue here is that our classical concepts are having loads of weird properties when applied to where they shouldn't be applied. But this doesn't mean we're clueless, or else we will have no useful information.
Zz.

It has always seemed to mr that science progresses mostly by showing things that aren't true, rather than things that are. The earth isn't flat; it isn't at the center of the solar system,...., and nature isn't classical!

[vanesch]

Anyway, my main reason for entering the holism-reductionism discussion in the first place was to get vanesch to expound in more detail on his reasons for becoming an MWI er (or ist). But thanks for your comments, selfAdjoint, and I welcome any criticism of my comments.

I've done that already a few times, but probably the time to find back the original posts is just as long as typing it here again.

My reason for taking on the MWI viewpoint is this:
1) QM is seen as a "universal" theory (is supposed to describe what happens in the universe). This can be correct or wrong, but it is what QM claims. The axioms of QM do not include a domain of applicability.
2) QM contains precise rules of how composite systems, build up from smaller systems, are supposed to work (namely: the tensor product of hilbert spaces). There is no postulated limit to this, and as such, I can construct, if I want, the hilbert space of all particles in my body, and in the lab's instruments, and ...
3) The superposition principle is a basic postulate of QM
4) The unitary time evolution is a basic postulate in QM (it's time derivative is the hamiltonian).
5) All relevant physical interactions (except gravity, acknowledged) are known how to be represented by this unitary time evolution.

As such, there is, from the postulates,
1) a natural description of the measurement apparatus, including the body of the observer, as a vector in hilbert space (follows from the build-up as tensor products of hilbert spaces of the constitutents)
2) the unitarity of the time evolution operator acting upon this state

and from these two points, invariably, the body state of the observer ends up entangled with the different possible outcomes of measurements WITHOUT CHOOSING ONE of them (as is said in the projection postulate). As such, it almost naturally follows that, if we are going to require that we only observe ONE outcome (and not all of them in parallel, as do our bodies), we can only be aware of one of these terms, with a certain probability. Once we accept that we only observe ONE of our body states, a classical awareness can emerge.

This is the essence of MWI. There are variations on the theme. It follows from taking the postulates of QM seriously ; there's no escaping from this view if you accept the axioms of QM and apply them universally. The objection can be that we are using the quantum formalism way outside of where it was somehow *intended* to work, but in absence of a theory that tells us WHY this formalism doesn't work the way it does (in other words, an underlying theory explaining QM), this is what the current formalism of QM says, by itself. And although very weird, it is not self-contradictory (and, as I often tried to show here, gives even a natural frame to view certain "bizarre" results, such as EPR situations, quantum erasers, and other such things). The real problem doesn't reside in the weirdness, the real problem resides with gravity. I think that given this difficulty, all bets are still open.

Nevertheless, I still advocate the MWI view for practical reasons (can sound bizarre): it helps elucidate EPR paradoxes and other weird quantum phenomena. It is a great TOOL for understanding the QM formalism.

[ZapperZ]

It has always seemed to mr that science progresses mostly by showing things that aren't true, rather than things that are. The earth isn't flat; it isn't at the center of the solar system,...., and nature isn't classical!

But is there a difference between showing something is "true" and showing something is "valid"? Newton's laws are valid to be used to construct a building. Even if more fundamental description of the universe is found, Newton's laws will STILL be valid to build a house.

At some point, the extreme Popper's view of science is no longer useful.

Zz.

[Sherlock]

I've done that already a few times, but probably the time to find back the original posts is just as long as typing it here again.
My reason for taking on the MWI viewpoint is this:
1) QM is seen as a "universal" theory (is supposed to describe what happens in the universe). This can be correct or wrong, but it is what QM claims. The axioms of QM do not include a domain of applicability.
2) QM contains precise rules of how composite systems, build up from smaller systems, are supposed to work (namely: the tensor product of hilbert spaces). There is no postulated limit to this, and as such, I can construct, if I want, the hilbert space of all particles in my body, and in the lab's instruments, and ...
3) The superposition principle is a basic postulate of QM
4) The unitary time evolution is a basic postulate in QM (it's time derivative is the hamiltonian).
5) All relevant physical interactions (except gravity, acknowledged) are known how to be represented by this unitary time evolution.
As such, there is, from the postulates,
1) a natural description of the measurement apparatus, including the body of the observer, as a vector in hilbert space (follows from the build-up as tensor products of hilbert spaces of the constitutents)
2) the unitarity of the time evolution operator acting upon this state
and from these two points, invariably, the body state of the observer ends up entangled with the different possible outcomes of measurements WITHOUT CHOOSING ONE of them (as is said in the projection postulate). As such, it almost naturally follows that, if we are going to require that we only observe ONE outcome (and not all of them in parallel, as do our bodies), we can only be aware of one of these terms, with a certain probability. Once we accept that we only observe ONE of our body states, a classical awareness can emerge.
This is the essence of MWI. There are variations on the theme. It follows from taking the postulates of QM seriously ; there's no escaping from this view if you accept the axioms of QM and apply them universally. The objection can be that we are using the quantum formalism way outside of where it was somehow *intended* to work, but in absence of a theory that tells us WHY this formalism doesn't work the way it does (in other words, an underlying theory explaining QM), this is what the current formalism of QM says, by itself. And although very weird, it is not self-contradictory (and, as I often tried to show here, gives even a natural frame to view certain "bizarre" results, such as EPR situations, quantum erasers, and other such things). The real problem doesn't reside in the weirdness, the real problem resides with gravity. I think that given this difficulty, all bets are still open.
Nevertheless, I still advocate the MWI view for practical reasons (can sound bizarre): it helps elucidate EPR paradoxes and other weird quantum phenomena. It is a great TOOL for understanding the QM formalism.
Thanks ... I'm still thinking about this. Just read an article by A.J. Leggett, Reflections on the quantum measurement paradox, in Quantum Implications, Essays in Honor of David Bohm.

I have a question: what does the term, macroscopic, mean when used to refer to quantum states? I've always thought of macroscopic as meaning that something could be seen with the naked eye ... an unamplified (by instruments) visual phenomenon. So, what exactly is being seen in macroscopic quantum superpositions?

[quantumcarl]

Thanks ... I'm still thinking about this. Just read an article by A.J. Leggett, Reflections on the quantum measurement paradox, in Quantum Implications, Essays in Honor of David Bohm.
I have a question: what does the term, macroscopic, mean when used to refer to quantum states? I've always thought of macroscopic as meaning that something could be seen with the naked eye ... an unamplified (by instruments) visual phenomenon. So, what exactly is being seen in macroscopic quantum superpositions?

Don't mind me, I'm just maintaining an awareness of this thread. I found this to do with classical/macroscopic and quantum/microscopic scales.

I will use the example of a droplet of water. If I’m investigating the properties of the whole droplet, I obviously will consider the droplet as the physical entity. However, if I conduct an investigation in the atomic realm, I must consider the protons, neutrons, electrons, etc. as physical entities because in this case the properties of these minute entities are of interest to me. For differentiation purposes, I will call entities such as the droplet macroscopic entities or classical entities. I will call protons, neutrons, electrons, photons etc. microscopic entities or quantum entities. There is some problem in equating “classical” with “macroscopic” and “quantum” with “microscopic” because the distinction between classical and quantum is process dependent; and there are cases where the quantum scales could be very large. But since “macroscopic” and “microscopic” are popular terms and their meanings in most cases do correspond to “classical” and “quantum”, I will respect tradition and try to hang on to them.

From: http://www.thinhtran.com/heisenberg.html

And if this helps you that would be nice.. but, for me....:uhh:


Quantum superposition is the application of the superposition principle to quantum mechanics. The superposition principle is the addition of the amplitudes of waves from interference. In quantum mechanics it is the amplitudes of wavefunctions, or state vectors, that add. It occurs when an object simultaneously "possesses" two or more values for an observable quantity (e.g. the position or energy of a particle).

More specifically, in quantum mechanics, any observable quantity corresponds to an eigenstate of a Hermitian linear operator. The linear combination of two or more eigenstates results in quantum superposition of two or more values of the quantity. If the quantity is measured, the projection postulate states that the state will be randomly collapsed onto one of the values in the superposition (with a probability proportional to the square of the amplitude of that eigenstate in the linear combination).

The question naturally arose as to why "real" (macroscopic, Newtonian) objects and events do not seem to display quantum mechanical features such as superposition. In 1935, Erwin Schrödinger devised a well-known thought experiment, now known as Schrödinger's cat, which highlighted the dissonance between quantum mechanics and Newtonian physics.

In fact, quantum superposition does result in many directly observable effects, such as interference peaks from an electron wave in a double-slit experiment.

If two observables correspond to noncommutative operators, they obey an uncertainty principle and a distinct state of one observable corresponds to a superposition of many states for the other observable.

From: http://en.wikipedia.org/wiki/Quantum_superposition

I think the crux of my question here in this thread is this: "is energy presented in the macroscopic form of matter even when it is not being observed?"

The idea of the question places a great deal of importance on the power of observation that I instictively don't agree with but cannot prove either way because all experiments involve an observation at some point along the way.

The information that is transmited over distance from remote instruments suggests that hard, macroscopic matter does not depend upon being observed to be in the form of matter. And when the information is viewed some time after being gathered... that makes matter seem all that much more of a separate and independent state. I guess you'd call it a Classical state.

I wonder if there is any proof that shows the nature of the quantum microcosim to be absolutely fundamental to the classical macrocosim. Would this not constitute a unifier?

[vanesch]

Thanks ... I'm still thinking about this. Just read an article by A.J. Leggett, Reflections on the quantum measurement paradox, in Quantum Implications, Essays in Honor of David Bohm.
I have a question: what does the term, macroscopic, mean when used to refer to quantum states? I've always thought of macroscopic as meaning that something could be seen with the naked eye ... an unamplified (by instruments) visual phenomenon. So, what exactly is being seen in macroscopic quantum superpositions?

Well (damn, we're getting metaphysical again... guess ZapperZ is going to get nervous at me :tongue:), let us first ask what it means, in a classical context, when "something is seen with the naked eye". Clearly, at the end of the day, what counts is a certain state of the particles and fields in your brain. So what corresponds to the (subjective) notion of "I see a red ball on the left side of the table", is a certain physical configuration of your brain. Which can, physiologically, be traced back to certain nerves in the visual nerve firing, which can be traced back to a certain image impinging on your retina, which can be traced back to EM radiation being emitted from a thermal light bulb, scattering off the red ball. But at the end of the day, it is the state of your brain which makes you have your subjective experience "I see a red ball on the left side of the table". We're so much used to doing this tracing back, that we do not even realise it, and associate immediately to the subjective experience "I see a red ball on the left side of the table" that there *IS* a red ball on the left side of the table. This is what one could call the very reasonable hypothesis of an objective world which corresponds to our subjective experiences. But it is good to keep in mind that this is nothing else but a good working hypothesis, stimulated by that tracing back as described above, and which works in a lot of everyday situations. And in classical physics, indeed, the relationship is so evidently 1-1, that it is - by a lot of physicists - considered a total waste of time to even think about it.

Well, quantum mechanically, it is not so different, but the 1-1 relation is gone. Of course, in all quantum interpretations where you switch to classical physics at some point, after the switch, you're back in the above scenario and we can stop the discussion. But if we insist on an MWI viewpoint, so that we DO HAVE a quantum state in hilbert space of the ball and all that, including our brains, the above "useless" relationship between subjective experience and hypothesis of objective world saves the day, so to say. Indeed, we take it that it is the STATE OF THE BRAIN which determines subjective experiences. But now we have an apparent (?) difficulty:

Imagine that we have the state:
|red ball left on table>|brainstate1> + |green ball right on table> |brainstate 2>

If you analyse these brainstates carefully, you'd do exactly as in the above explanation: you'd find that brainstate1 corresponds to the classical state in the case we would have had a classical red ball on a classical table, and brainstate 2 corresponds to a classical green ball on the table etc...
So if you take this literally, you should have to say that you should be aware of BOTH situations. This clearly isn't the case, so an EXTRA RULE is needed: you can only be aware of ONE classical brainstate. Your subjective experiences can only be related to ONE TERM in the above expansion, and this will be assigned RANDOMLY (through the Born rule).
Maybe another "subjective you" will experience the complementary term, I don't know. What matters, is your subjective experience, to you, only.

So we could say that we have to work "in the basis of classical brain states which correspond to subjective experiences". There are good indications that this needs not to be forced, and that decoherence naturally leads to a coarse-grained Schmidt decomposition which has these states for your brain states. There are people who claim that they can derive the Born rule and do not need to postulate it (I don't believe them, but that's something else). So there are differences in the details: what some think you have to postulate (like I do), others think they can derive somehow naturally (Deutsch, Zurek...). But this is just a matter of esthetics of the axiomatic structure of the theory. It simply, in practice, comes down that you end up having your subjective experiences LINKED TO ONE classically-looking brainstate in the overall quantum state, and that the probability for such a state to be picked is given by the Born rule.

And now, decoherence is nice, in that whatever you will do afterwards, you will only be effectively interacting with the states of the systems around you in the same term. You will not notice the existence of the other terms, because the in-product <other terms | your term> will always be effectively 0 because of the complexity of the environment states, which will always be "classically different" (at least one particle of the environment in the other term will be at a different position, say, than in "your" term). One says that these terms "decohered". As such, it seems to you (in all your successive subjective experiences) that the world really looks much like a classical term. For instance, if you did end up having your subjective experiences derived from "brainstate1" (and not from 2), things really look to you as if the world were classical and reduced quantum-mechanically to: |red ball left on table>|brainstate1>

That doesn't mean that the other term "disappeared magically", but you will almost be in the impossibility to ever detect something of the second term, because of this inproduct being effectively zero from the moment that ONE particle (or one field mode) is in a sufficiently different position. As this is essentially uncontrollable once there has been a contact with a thermal bath or so, this second term will remain undetectable for ever.
You can just as well consider that the state of the world REDUCED to:

|red ball left on table>|brainstate1>

and from that you will be able to derive all your future subjective experiences. Hence you can apply the projection postulate in practice. But that means that you can apply it from the moment that "irreversible entanglement" with the environment took place, which explains why we can *usually* apply the projection postulate already early in the "chain" (usually after a physical interaction we call "measurement") and treat the rest classically. It doesn't alter the final classical situation which corresponds to the quantum state which will explain our subjective experiences, EVEN THOUGH the true state of the world remains:

|red ball left on table>|brainstate1> + |green ball right on table> |brainstate 2>

So this slightly alters our 1-1 concept of the link between "subjective experiences" and the "hypothesis of an objective world".
If we take the above stuff for real, the "truely objective state" of the world remains:

|red ball left on table>|brainstate1> + |green ball right on table> |brainstate 2>

your subjective experience "now" derives from |brainstate1>,

and the term |red ball left on table>|brainstate1> is sufficient to derive every possible future subjective experience, so in a way you could say that WHAT YOU CONCERNS, the semi-objective state of the world is simply:

|red ball left on table>|brainstate1>

which justifies the use of the projection postulate for all practical purposes.

I said: we can *usually* apply the projection postulate early, from the moment we have a "measurement". But there are a few exceptions to this rule. One such exception is when we perform an EPR experiment. I posted several times a symbolic treatment of such an experiment in MWI view, and then, no "spooky action at a distance" is needed at all: this spooky action is only required when we ERRONEOUSLY have applied the projection postulate too early. In the MWI view, the projection postulate is a SHORTCUT (not something that "really happens") when we are SURE that all quantum-mechanical interference with other terms is definitely excluded. And this is what goes wrong in EPR situations: an interference term appears when Alice and Bob come together to compare their notes. If the projection postulate, applied too early, excluded this interference term, you end up with some puzzling aspects.

[Sherlock]

Well (damn, we're getting metaphysical again... guess ZapperZ is going to get nervous at me ), let us first ask what it means, in a classical context, when "something is seen with the naked eye". Clearly, at the end of the day, what counts is a certain state of the particles and fields in your brain. So what corresponds to the (subjective) notion of "I see a red ball on the left side of the table", is a certain physical configuration of your brain. Which can, physiologically, be traced back to certain nerves in the visual nerve firing, which can be traced back to a certain image impinging on your retina, which can be traced back to EM radiation being emitted from a thermal light bulb, scattering off the red ball. But at the end of the day, it is the state of your brain which makes you have your subjective experience "I see a red ball on the left side of the table".
We're so much used to doing this tracing back, that we do not even realise it, and associate immediately to the subjective experience "I see a red ball on the left side of the table" that there *IS* a red ball on the left side of the table.

I think that "clearly, at the end of the day" what counts is what we have seen, or felt, or heard, or smelled, or tasted. We're not aware of most of the components of the correlational/causal chain, this tracing back, as we navigate our way through the macroscopic world of our sensory perceptions. That's why it is what we perceive that is the primary basis for evaluating hypotheses about the physical world. That is, what is seen by us to happen in the macroscopic world is the final arbiter of statements about it --- and that's what my question was about: what is it that's actually seen in the macroscopic world that verifies the existence of so-called macroscopic quantum superpositions? We can see macroscopic superpositions, as they happen, in water and other media. But of course these aren't macroscopic quantum superpositions. Is it maybe that the term, macroscopic, has a technical and different meaning wrt quantum experiments than it does in ordinary language?

This is what one could call the very reasonable hypothesis of an objective world which corresponds to our subjective experiences. But it is good to keep in mind that this is nothing else but a good working hypothesis, stimulated by that tracing back as described above, and which works in a lot of everyday situations. And in classical physics, indeed, the relationship is so evidently 1-1, that it is - by a lot of physicists - considered a total waste of time to even think about it.

I don't think it's a waste of time to think about it, but the idea that there is an objective world that is revealed to us via (as opposed to being created by) our senses, and that it exists whether we happen to be sensing it or not, is the only way of thinking about it that makes any ... sense. It's the basis of physical science. I also keep in mind that everything is rendered in macroscopic form, it's just that wrt quantum experimental phenomena the results (macroscopic though they be) can't be accounted for using the mathematical constructions of classical physics.

Well, quantum mechanically, it is not so different, but the 1-1 relation is gone. Of course, in all quantum interpretations where you switch to classical physics at some point, after the switch, you're back in the above scenario and we can stop the discussion. But if we insist on an MWI viewpoint, so that we DO HAVE a quantum state in hilbert space of the ball and all that, including our brains, the above "useless" relationship between subjective experience and hypothesis of objective world saves the day, so to say. Indeed, we take it that it is the STATE OF THE BRAIN which determines subjective experiences. But now we have an apparent (?) difficulty:
Imagine that we have the state:
|red ball left on table>|brainstate1> + |green ball right on table> |brainstate 2>
If you analyse these brainstates carefully, you'd do exactly as in the above explanation: you'd find that brainstate1 corresponds to the classical state in the case we would have had a classical red ball on a classical table, and brainstate 2 corresponds to a classical green ball on the table etc...
So if you take this literally, you should have to say that you should be aware of BOTH situations.

You can take the QM formalism literally as being in 1-1 correspondence with an underlying quantum world, but how would you know? So, for good reason, what is taught is that, as far as anybody knows, the QM formalism is not in 1-1 correspondence with an underlying quantum world.
You can take the QM formalism literally as being in 1-1 correspondence with the macroscopic world, but the difference here is that we actually experience the macroscopic world. So, for good reason, what is taught is that when the formalism says that a pointer is in a superposition of pointing at 1 and pointing at 2 for some specific preparation, then we interpret this to mean that it will either be pointing at 1 or pointing at 2 at the end of each trial, and that the probability assigned to each unique result refers to the mean average of a certain number of trials. The various pointer positions are the possible, mutually exclusive, results of individual measurements ... that's what the formalism means -- not that these things are happening simultaneously in each trial.
Anyway, the superposition principle is employed because quantum theory is essentially a theory of wave mechanics. Waves of what ... where? The frequency distributions produced by the detectors. But what relationship do these waves have with the underlying quantum reality? Nobody knows exactly. But waves in any medium are still waves ... frequency distributions ... and, apparently, whatever is happening in the medium or media of the underlying quantum world is somewhat similar to the data waves produced by the detectors. That is, it seems that a wave is a wave is a wave --- no matter what medium it happens to be propagating in.

This clearly isn't the case, so an EXTRA RULE is needed: you can only be aware of ONE classical brainstate.

We're only aware of one classical brainstate at a time in the first place. Well it isn't actually the brainstate that we're aware of, is it ? We're aware that eg. an instrument pointer is pointing in some specific direction, not all possible directions, at a certain time. The EXTRA RULE is the interpretational one that MWI adds which says that the expansion refers to simultaneously existing, mutually exclusive macroscopic states. Since this "clearly isn't the case" we don't take QM literally as a hi-fidelity representation of physical reality, and thus dismiss the MWI approach. It's what is seen that is the primary evaluational basis, not what is metaphysically postulated or mathematically formulated.

Your subjective experiences can only be related to ONE TERM in the above expansion, and this will be assigned RANDOMLY (through the Born rule).
Maybe another "subjective you" will experience the complementary term, I don't know. What matters, is your subjective experience, to you, only.

My subjective experiences, and afaik everybody else's (unless they're all lying), ARE only related to ONE TERM in the above expansion for each trial.
Another subjective me experiencing the complementary term ? I see what you mean by your statement at the beginning of the post --- yes, I agree, this MWI approach is truly metaphysical.

So we could say that we have to work "in the basis of classical brain states which correspond to subjective experiences". There are good indications that this needs not to be forced, and that decoherence naturally leads to a coarse-grained Schmidt decomposition which has these states for your brain states. There are people who claim that they can derive the Born rule and do not need to postulate it (I don't believe them, but that's something else). So there are differences in the details: what some think you have to postulate (like I do), others think they can derive somehow naturally (Deutsch, Zurek...). But this is just a matter of esthetics of the axiomatic structure of the theory. It simply, in practice, comes down that you end up having your subjective experiences LINKED TO ONE classically-looking brainstate in the overall quantum state, and that the probability for such a state to be picked is given by the Born rule.
And now, decoherence is nice, in that whatever you will do afterwards, you will only be effectively interacting with the states of the systems around you in the same term. You will not notice the existence of the other terms, because the in-product <other terms | your term> will always be effectively 0 because of the complexity of the environment states, which will always be "classically different" (at least one particle of the environment in the other term will be at a different position, say, than in "your" term). One says that these terms "decohered". As such, it seems to you (in all your successive subjective experiences) that the world really looks much like a classical term. For instance, if you did end up having your subjective experiences derived from "brainstate1" (and not from 2), things really look to you as if the world were classical and reduced quantum-mechanically to: |red ball left on table>|brainstate1>
That doesn't mean that the other term "disappeared magically", but you will almost be in the impossibility to ever detect something of the second term, because of this inproduct being effectively zero from the moment that ONE particle (or one field mode) is in a sufficiently different position. As this is essentially uncontrollable once there has been a contact with a thermal bath or so, this second term will remain undetectable for ever.
You can just as well consider that the state of the world REDUCED to:
|red ball left on table>|brainstate1>
and from that you will be able to derive all your future subjective experiences. Hence you can apply the projection postulate in practice. But that means that you can apply it from the moment that "irreversible entanglement" with the environment took place, which explains why we can *usually* apply the projection postulate already early in the "chain" (usually after a physical interaction we call "measurement") and treat the rest classically. It doesn't alter the final classical situation which corresponds to the quantum state which will explain our subjective experiences, EVEN THOUGH the true state of the world remains:
|red ball left on table>|brainstate1> + |green ball right on table> |brainstate 2>

I think that physical science takes the "true state of the world" to be what is seen, and what is seen is that either there is a red ball left on table or there is a green ball right on table at a certain time. A certain way of interpreting the QM formalism will require you to 'explain' why you only see one or the other at a certain time, but that way of interpreting the formalism is not required and in light of everything else that is known that pertains to this consideration it is, prima facie, a bad way of interpreting it. Just my current opinion.

So this slightly alters our 1-1 concept of the link between "subjective experiences" and the "hypothesis of an objective world".

It doesn't quite do it for me. I'm looking at my keyboard now. Pondering which key to hit. Is my brainstate in a superposition of all the possible continuations -- and does that mean that when I hit a key then I've actually hit all of the keys but because of the branching I'm only subjectively aware of hitting one key ?? .... naaahh

If we take the above stuff for real, the "truely objective state" of the world remains:
|red ball left on table>|brainstate1> + |green ball right on table> |brainstate 2>
your subjective experience "now" derives from |brainstate1>,
and the term |red ball left on table>|brainstate1> is sufficient to derive every possible future subjective experience, so in a way you could say that WHAT YOU CONCERNS, the semi-objective state of the world is simply:
|red ball left on table>|brainstate1>
which justifies the use of the projection postulate for all practical purposes.

I don't know that that's a good way to approach understanding the adoption and retention of the projection postulate. It came, afaik, from considerations of how formulas and models from classical wave optics might be applied in the quantum theory, and it's retained because it works.

I said: we can *usually* apply the projection postulate early, from the moment we have a "measurement". But there are a few exceptions to this rule. One such exception is when we perform an EPR experiment. I posted several times a symbolic treatment of such an experiment in MWI view, and then, no "spooky action at a distance" is needed at all: this spooky action is only required when we ERRONEOUSLY have applied the projection postulate too early. In the MWI view, the projection postulate is a SHORTCUT (not something that "really happens") when we are SURE that all quantum-mechanical interference with other terms is definitely excluded. And this is what goes wrong in EPR situations: an interference term appears when Alice and Bob come together to compare their notes. If the projection postulate, applied too early, excluded this interference term, you end up with some puzzling aspects.

The probabilities calculated using QM are only physically meaningful wrt to statistical ensembles. The probabilistic interpretation of QM, which is the standard one because it's the one that makes the most sense, doesn't have any problem with "spooky action at a distance" --- which, iirc, you have written a nice exposition of.
I'm going back through Heisenberg's The Physical Principles of the Quantum Theory now. No doubt he's rolling over in his grave from this MWI stuff.
Thanks for the lengthy reply. I'm not convinced yet that the MWI approach makes good sense. And, I'm still wondering what it is that is actually seen superposed in the experiments that purport to produce macroscopic quantum superpositions. I just haven't had time to find and read any of the experimental papers yet. There's probably some technical definition for macroscopic that I haven't learned yet.
I would like to see a thread where the foundations of the MWI are discussed (by you and the other people who have written or are writing papers on it) at length. I could well be missing some important subleties in my current bewilderment regarding why such a metaphysical approach is being entertained by so many obviously smart people. It seems to me that there is a much less problematic way to interpret quantum theory, and if adopting the MWI approach is, ultimately, really just a matter of taste ... then, I wonder ... why pursue it ?

[Sherlock]

From: http://www.thinhtran.com/heisenberg.html
And if this helps you that would be nice.. but, for me....

Thanks quantumcarl ... I only just briefly glanced at the article, but saved it and will read it. I didn't know there was a problem with the uncertainty relations ... but it's always a good thing to consider other perspectives.

From: http://en.wikipedia.org/wiki/Quantum_superposition

This doesn't really answer my question either.
Now, to your question ...

I think the crux of my question here in this thread is this: "is energy presented in the macroscopic form of matter even when it is not being observed?"

The "macroscopic form of matter" is the objects and events that we see with our visual perception. The kinetic energy of an object has to do with its mass (for practical purposes, its weight) and its velocity. The answer to your original question about whether, according to QM, the moon exists when we're not looking at it was yes.
So yes, "energy is presented in the macroscopic form of matter even when it is not being observed."

The idea of the question places a great deal of importance on the power of observation that I instictively don't agree with but cannot prove either way because all experiments involve an observation at some point along the way.

Trust your instincts on this one. Even though there's no way to 'prove' that, say the moon, exists when we're not observing it --- assuming that it does is the only way of thinking about it that makes any sense, as far as I can tell. This assumption is an integral part of our ordinary language and is a basic assumption of the physical sciences, including quantum theory.

The information that is transmited over distance from remote instruments suggests that hard, macroscopic matter does not depend upon being observed to be in the form of matter. And when the information is viewed some time after being gathered... that makes matter seem all that much more of a separate and independent state. I guess you'd call it a Classical state.

Well, ultimately, things have to be amplified (rendered big enough or complex enough for us to see) to the macroscopic level in order to be able to say anything meaningful about them.

I wonder if there is any proof that shows the nature of the quantum microcosim to be absolutely fundamental to the classical macrocosim. Would this not constitute a unifier?

From sub-submicroscopic stuff to super-duper macroscopic stuff, from the very simple to the very complex, it's all going along for the same ride. What's fundamental is the behavioral laws that objects, events, evolutions on any scale in any medium must obey.
I guess that doesn't answer your question ... ok, I don't know.
But I think your question(s) about the relationship between consciousness (awareness) and matter (other than the material brain states which define consciousness) have been answered. Our sensory perception of the world isn't an act of creation. On the other hand, the experimental production of quantum phenomena is an act of creation. Before the moon was formed it didn't exist. Once brought into existence, our observations of it don't appreciably alter its existence and it doesn't pop into and out of existence each time we look at it and look away. The same with photons and electrons. Once the data has been produced by the instruments it exists, whether we're looking at it and whether we like it, or not.

[vanesch]

what is it that's actually seen in the macroscopic world that verifies the existence of so-called macroscopic quantum superpositions?


No, I think you have it backwards about the reasons to consider macroscopic quantum superpositions. Macroscopic quantum superpositions are simply part of the mathematical formalism of quantum theory. Maybe they don't exist, which then only means that the postulates of quantum theory are of limited use. As I tried to point out, macroscopic quantum superpositions appear naturally in the formalism of quantum theory. You have to do something to the formalism of quantum theory if you DON'T want to obtain them, and that something usually is quite "ugly", like introducing non-locality, and an unphysical interaction based upon a non-well defined concept which is "measurement".
Macroscopic superpositions are unavoidable (in the formalism) if you take the axioms of quantum theory seriously to be valid universally. There's really nothing more to it !

It is when you take your (quite understandable) "naah ! Too crazy to be true" viewpoint that you must conclude that macroscopic superpositions are, after all, not possible, and AS A CONSEQUENCE, that the postulates of quantum theory are not universally applicable. THIS IS VERY WELL POSSIBLE, I'm not denying that. But then we're left with a riddle: if the axioms of quantum theory are NOT universally valid, then what is ? Each time we do that (by introducing some "objective" mechanism of collapse, or by introducing other things, like in Bohm's theory) we seem to have a serious clash with locality, an other cherished principle.
This is why I take the viewpoint: can we not "save the day" for the axioms of quantum theory, and really take them as universally valid ? And then, what should we require ? We know that the consequence of taking the axioms of quantum theory as universally valid, is the existance of macroscopic superpositions *as theoretical constructions*. This is unavoidable in the formalism. And this clashes with your "naah, too crazy to be true". But cannot this macroscopic superposition NEVERTHELESS EXPLAIN OUR SUBJECTIVE EXPERIENCES ? The point is that if there's a way to view these superpositions as nevertheless explaining our subjective experiences, at the end of the day that's good enough for a physical theory. If that theory describes an objective world state, from which one can *derive* subjective experiences that *correspond to what we actually experience*, then this theory is good enough as a physical theory. Of course, a theory in which the subjective experiences correspond directly to the objective world state (as in classical physics) is probably intuitively more acceptable. But imagine the following situation: you're in the lab of a brain surgeon, which implants a few electrodes in your brain, and by sending certain signals in the electrodes, he can make you see pink elephants. What is now the most appropriate theory ? That there *are* pink elephants, or that the true state of the world is a manipulated brain from which we can derive that you should *experience the presence* of pink elephants ? In this case, it is probably evident that the last theory is the most useful. Which is a naive attempt, on my part, of trying to make you see that a theory that can explain all your subjective experiences is all you can require, finally, of a physical theory.

And that is what MWI does. It saves the universality of the QM postulates, it needs to postulate a non-trivial relationship between the world state and your subjective experience, but if you do so, it *explains* perfectly well those subjective experiences, and why you *have the impression* that the world is classical, and why you do not manifestly subjectively observe macroscopic objects in superposition.

The gain is the following: there is no ambiguity as to the difference between a physical phenomenon and a "measurement" (as is necessary in all collapse views) ; there is no need for non-locality and no clash with SR, and we can take the quantum state (the vector in hilbert space) as the true, objective description of the state of the world.



I don't think it's a waste of time to think about it, but the idea that there is an objective world that is revealed to us via (as opposed to being created by) our senses, and that it exists whether we happen to be sensing it or not, is the only way of thinking about it that makes any ... sense. It's the basis of physical science.


Yes, I agree with that. It is because I agree with that, that I think that one should take the "state description" of quantum theory seriously. And if you take the wavefunction as something "really out there", it cannot "disappear" at a certain macroscopic scale. Hence the necessity of the reality of macroscopic superpositions. Unless quantum theory is really fundamentally misguided (as I said, that's an option, but, in the current state of affairs, not a very helpful one).


You can take the QM formalism literally as being in 1-1 correspondence with an underlying quantum world, but how would you know?


Because it is the only coherent formalism that we have ! As I said, it is the starting point for an MWI view. I think that if you want to interpret a formalism of a physical theory, the least you can do is to take the formalism seriously.


So, for good reason, what is taught is that, as far as anybody knows, the QM formalism is not in 1-1 correspondence with an underlying quantum world.
You can take the QM formalism literally as being in 1-1 correspondence with the macroscopic world, but the difference here is that we actually experience the macroscopic world. So, for good reason, what is taught is that when the formalism says that a pointer is in a superposition of pointing at 1 and pointing at 2 for some specific preparation, then we interpret this to mean that it will either be pointing at 1 or pointing at 2 at the end of each trial, and that the probability assigned to each unique result refers to the mean average of a certain number of trials. The various pointer positions are the possible, mutually exclusive, results of individual measurements ... that's what the formalism means -- not that these things are happening simultaneously in each trial.


I'm sorry but that is NOT what the formalism says. It is what a certain interpretation of the formalism says (the Bohr view), and as such it denies any descriptive value to quantum theory. This comes about because people said "naah, too crazy!".

So what's best ? A theory that DOES give you a precise description of what physically happens, and how what physically happens relates to what you subjectively experience as a consequence of it (MWI), or a theory that DOESN'T SAY ANYTHING OF WHAT'S HAPPENING, but allows you to calculate some probabilities of outcomes without explaining any underlying mechanism ?


Anyway, the superposition principle is employed because quantum theory is essentially a theory of wave mechanics. Waves of what ... where? The frequency distributions produced by the detectors. But what relationship do these waves have with the underlying quantum reality? Nobody knows exactly. But waves in any medium are still waves ... frequency distributions ... and, apparently, whatever is happening in the medium or media of the underlying quantum world is somewhat similar to the data waves produced by the detectors. That is, it seems that a wave is a wave is a wave --- no matter what medium it happens to be propagating in.


This is not true. Quantum theory started off as a kind of wave mechanics, but we're now far beyond that POV. The so-called waves are now to be seen as superpositions of position states: as a point being at different places in the same time. Spin superpositions cannot be seen as "waves".


Well it isn't actually the brainstate that we're aware of, is it ? We're aware that eg. an instrument pointer is pointing in some specific direction, not all possible directions, at a certain time.


Just as you are aware of the pink elephants when you were in the brain churgeon's room...


The EXTRA RULE is the interpretational one that MWI adds which says that the expansion refers to simultaneously existing, mutually exclusive macroscopic states. Since this "clearly isn't the case" we don't take QM literally as a hi-fidelity representation of physical reality, and thus dismiss the MWI approach.


Many people do this, but it is clearly based only upon "gut feeling". I would agree with you that a theory that *introduces* parallel macroscopic worlds just for the sake of it, would do an overkill. However, when the mathematical formalism shows them, then the overkill, to me, is to artificially remove them in certain, very unwell defined cases, and as such violate basic principles of the axiomatic structure (such as locality, unitarity, the superposition principle).


It's what is seen that is the primary evaluational basis, not what is metaphysically postulated or mathematically formulated.


Oops, then the world is still a flat disk ! I think that if you want to interpret physically a mathematical formalism, you should give priority to the mathematical structure. If it allows you to deduce what you *should see* (although that is not what "is out there"), then that's good enough for me.


My subjective experiences, and afaik everybody else's (unless they're all lying), ARE only related to ONE TERM in the above expansion for each trial.


Eh, yes, that's exactly what is postulated that you SHOULD see.


I think that physical science takes the "true state of the world" to be what is seen, and what is seen is that either there is a red ball left on table or there is a green ball right on table at a certain time.


It is difficult to let that notion go, I know. The pink elephant is really there. In fact, the notion of "what is seen is what is there" is indeed the pillar of classical physics. But I'm trying to point out that this is maybe a too strong requirement for a physical theory: if the theory tells you what you are supposed to see, and that's what you see, is that not good enough ? If the price of clinging to the requirement that what you see is the true state of the world leads to a lot of FORMAL difficulties and apparent paradoxes, isn't it perferable to go for the lesser requirement of only having the formalism to explain what you ought to see, even if there is something else is out there ?


I'm looking at my keyboard now. Pondering which key to hit. Is my brainstate in a superposition of all the possible continuations -- and does that mean that when I hit a key then I've actually hit all of the keys but because of the branching I'm only subjectively aware of hitting one key ?? .... naaahh


Apart from the intuitive strangeness, what's wrong with it ? If the same crazy theory also allows you to find out that everything will now appear to you *as if* you only hit one key ?


I don't know that that's a good way to approach understanding the adoption and retention of the projection postulate. It came, afaik, from considerations of how formulas and models from classical wave optics might be applied in the quantum theory, and it's retained because it works.


No, that's not the point. The EPR experiments relate only to optical experiments because of experimental possibilities. But the EPR situation can be set up for just any quantum system: atoms, electrons... take your pick.


The probabilities calculated using QM are only physically meaningful wrt to statistical ensembles.


This is a positivist viewpoint to which I don't subscribe, because it *completely gives up on any attempt to describe physical reality at all*. In fact, such a viewpoint is even more "metaphysical" than the MWI viewpoint, because at least, in the MWI viewpoint, there IS a description of physical reality (the wavefunction), even though it doesn't correspond 1-1 to your subjective experience and an extra rule is required to deduce the subjective experience. But in the positivist viewpoint, there IS NO REALITY AT ALL apart from your subjective experience!


The probabilistic interpretation of QM, which is the standard one because it's the one that makes the most sense, doesn't have any problem with "spooky action at a distance" --- which, iirc, you have written a nice exposition of.


It cannot have any problem with spooky action at a distance because there IS no description of physical reality in that viewpoint! The only thing that "exists" are your observations. So I find it strange that one can adhere to a viewpoint that there IS NO REALITY AT ALL, and make objections to a theory that gives you a certain description of reality, and a deduction of what are your subjective experiences from it.

Unless, of course, you take the viewpoint that there IS a reality, but that QM is simply not describing it correctly. As I said, that's a possibility. But is it fruitful to adhere to such a viewpoint if we don't have a correct description that can replace it ?


And, I'm still wondering what it is that is actually seen superposed in the experiments that purport to produce macroscopic quantum superpositions.


If you take the viewpoint that quantum theory does not describe reality (but only in some way is capable of producing right statistical descriptions), then *nothing* corresponds to "superposition". It is just part of the calculational algorithm of probabilities of your observations. This is the problem (in my opinion) of the positivist viewpoint.
Nothing in the formalism corresponds to anything "out there", it is just an algorithm. It is very difficult (in my view) to devellop a "physical intuition" for such a formalism - while the MWI viewpoint allows you exactly that: to devellop a physical intuition of the formalism (a strange intuition all right, but the funny thing is that you get used to it!). To me, the positivist viewpoint reduces quantum theory to a kind of black box that spits out numbers that are probabilities. As such, it is a "non-interpretation" of the theory. It doesn't interpret the elements of the formalism as physical things.


It seems to me that there is a much less problematic way to interpret quantum theory, and if adopting the MWI approach is, ultimately, really just a matter of taste ...

Up to a point, of course it is a matter of taste and intellectual entertainment. But I think one has to make the choice between the following fundamental viewpoints:

A) there exists an objective reality that can be described by a physical theory

B) there doesn't exist such an objective reality.

Ok, there is a bizarre possibility,

C) there exists an objective reality, but it is not compatible with any mathematical theory (most religions somehow fit into this class)

Now, if we split this up further:

A)
1) quantum theory describes this objective reality

2) quantum theory does not describe this objective reality

B)
Quantum theory (as any theory) does not describe the non-existing objective reality

C)
As objective reality is not describable by a mathematical theory, the quantum formalism will not describe it either.

Your point of view is compatible with A2) and with B) and with C).
MWI is (I think) the only viewpoint that is compatible with A1). I'm open to A2), but I don't know of any formulation that doesn't have big problems in one or another way. I'm not open to B: I think that before giving up all together on an objective reality, we should think again. I don't even understand very well C because it means that we are living in an a-logical universe, maybe dictated by the will of the gods or whatever.

I'm only pointing out that A1) is perfectly possible - something which seems to be dismissed out of hand because of the outlandishness of the concept (and not because of the contradiction with observation). Given that it is *possible* to assume that quantum theory describes physical reality, I'd argue that the best interpretation of the formalism is exactly that. If it leaves you with the gut feeling "naaah!", then I find that not a sufficient argument.

People have tried hard to think of A2, but I don't find any approach as yet promising ; the local realists deny EPR situations, and Bell's theorem dictates that if you accept the quantum predictions also in EPR situations, that you will have big difficulties with locality and the principle of relativity.

Of course, from the day that a nice theory explains us why quantum theory seemed to work the way we thought, we'll know more, and we could then possibly dismiss this "subjective experience' viewpoint. But I'm pointing out that we don't HAVE such a formalism yet, so it is a bit difficult to take it as an interpretation of a theory we DO HAVE. Because one should be open to the possibility that the formalism we have is ultimately right, too and that this desired-for theory does not exist.

Nevertheless, I stick with my claim that the MWI view gives you the best possible *intuition* about the formalism (whether it ultimately will prove right or wrong doesn't matter). I tried several times to show how naturally one can interpret "weird experimental results" using this view. That by itself, I find already sufficient reason to consider it.

It is a bit as if discussions about free will would interfere with the (evident) interpretation of classical deterministic physics. I think that assuming determinism is part of the interpretational scheme of classical physics, and pointing out the "evident" problem of free will with such a scheme doesn't really help you devellop a feeling for the formalism of classical physics. In the same way, I view the MWI viewpoint as the most natural one sticking to the formalism of quantum theory ; and pointing out evident problems of "naah! Too crazy" doesn't help you in anything understanding the formalism and getting a feeling for it.

[Sherlock]

Ok vanesch, thanks. I just very quickly scanned your last post and it seems very clearly laid out. More so than anything I've read anywhere else so far. I must take some more time to think about your points ...

[nrqed]

Well, quantum mechanically, it is not so different, but the 1-1 relation is gone. Of course, in all quantum interpretations where you switch to classical physics at some point, after the switch, you're back in the above scenario and we can stop the discussion. But if we insist on an MWI viewpoint, so that we DO HAVE a quantum state in hilbert space of the ball and all that, including our brains, the above "useless" relationship between subjective experience and hypothesis of objective world saves the day, so to say. Indeed, we take it that it is the STATE OF THE BRAIN which determines subjective experiences. But now we have an apparent (?) difficulty:
Imagine that we have the state:
|red ball left on table>|brainstate1> + |green ball right on table> |brainstate 2>
If you analyse these brainstates carefully, you'd do exactly as in the above explanation: you'd find that brainstate1 corresponds to the classical state in the case we would have had a classical red ball on a classical table, and brainstate 2 corresponds to a classical green ball on the table etc...
So if you take this literally, you should have to say that you should be aware of BOTH situations. This clearly isn't the case, so an EXTRA RULE is needed: you can only be aware of ONE classical brainstate. Your subjective experiences can only be related to ONE TERM in the above expansion, and this will be assigned RANDOMLY (through the Born rule)

Hi Patrick... fascinating stuff.
But why would the brain play such a special role? It seems to me that already before the light reaches your eyes, the "collapse" to the red ball should have occurred. Why should such a special status be assigned to the brain? (other than making EPR type experiments easier to swallow:smile: ).
(I also enjoyed the discussion oh holism and reductionism with ZapperZ...except that it felt to me like Zapper was going back and forth from "practical holism" to "fundamental holism" and not really caring as much about the distinction between the two, which must have caused you some frustration. The way I saw it, you were arguing against fundamental holism while saying that practical holism was, of course, a useful approach (indeed, there is no way around it for most calculations!). On the other hand, Zapper would be defending the use of *practical* holism while at the same time dropping hints of believing in *fundamental* holism, but then going back to practical holism and so on....It must have felt like trying to hit a moving target. I do think that when ZapperZ said that most practicing physicists believe in holism (he said it differently, but it was the gist of it), he meant in *practical* holism. That is not surprising. Even a die hard reductionist would say that it would be fool hardy to study superfluidity, say, ab initio. In that sense, *nobody* would disagree that practical holism is a useful (and necessary) scientific tool. The real discussion is whether *fundamental* holism can even be envisioned and debated. *That* is the more exciting discussion. ZapperZ made some comments and brought some arguments but would go back to saying that it is unanswerable and then switching back to defending practical holism.)
Pat

[ZapperZ]

(I also enjoyed the discussion oh holism and reductionism with ZapperZ...except that it felt to me like Zapper was going back and forth from "practical holism" to "fundamental holism" and not really caring as much about the distinction between the two, which must have caused you some frustration. The way I saw it, you were arguing against fundamental holism while saying that practical holism was, of course, a useful approach (indeed, there is no way around it for most calculations!). On the other hand, Zapper would be defending the use of *practical* holism while at the same time dropping hints of believing in *fundamental* holism, but then going back to practical holism and so on....It must have felt like trying to hit a moving target. I do think that when ZapperZ said that most practicing physicists believe in holism (he said it differently, but it was the gist of it), he meant in *practical* holism. That is not surprising. Even a die hard reductionist would say that it would be fool hardy to study superfluidity, say, ab initio. In that sense, *nobody* would disagree that practical holism is a useful (and necessary) scientific tool. The real discussion is whether *fundamental* holism can even be envisioned and debated. *That* is the more exciting discussion. ZapperZ made some comments and brought some arguments but would go back to saying that it is unanswerable and then switching back to defending practical holism.)
Pat

Welp, having had my name resurrected again under this topic, I will have to address this, especially what is perceived to be my waffling back and forth on this so-called "fundamental holism".

We all know my view on "practical holism", so let's leave that there. When vanesch asked me if I think that if we have all the infinite computing power in the world and can really do a computation for a gazilion particles exactly, shouldn't we, IN PRINCIPLE, be able to derive ALL of the emergent phenomena?

I have replied that at best, I don't know, but my haunch is, no, you can't. I will explain why I believe so.

When you look at the liquid state (water, let's say), and you write down ALL the possible interactions of every single water molecules, do you think that by looking at the dynamics of the system that you could predict a phase transition at certain temperatures, even in principle? No you can't. Why? The transition between liquid and solid, for example, involves a broken symmetry. This is a symmetry that does NOT exist in one phase or the other. So it isn't JUST a matter of being able to write down ALL of the interactions of a system, because at SOME point, there is symmetry principle that one needs to introduce into the system, maybe to get an ordered state that wasn't initially there.

We can take this even further by looking at a quantum phase transition. You do NOT have a quantum critical point in a system even when you could compute all of the interactions. There isn't an a priori way for you to model that so that it drops onto your lap naturally.

All of the condensed matter phenomena that I have listed, involved such transition. The emergence of superconductivity out of a sea of charge carriers involves a broken symmetry (many even claim it is a 2nd order phase transition). One has no way in extrapolating such dynamics simply by looking at how it looks like in one state.

So, not only is reductionism not useful in giving anything meaningful about emergent phenomena, but in my opinion, based on what we already know, that it is entirely possible that it can't, even in principle, derive those phenomena.

Now, was I still waffling about this issue in this post?

Zz.

[nrqed]

Welp, having had my name resurrected again under this topic, I will have to address this, especially what is perceived to be my waffling back and forth on this so-called "fundamental holism".

My sincerest apologies if my comments may have appeared offensive. They were not meant to be. My main point was that my impression was that Vanesch wanted to focus exclusively on discussing arguments (for or against) for "fundamental holism", whereas I had the impression that this was a much less relevant issue, that the relevant issue is that *practical* holism was necessary (which, I think, can't be denied).
My apologies again. I will shut up and go back to lurking mode :smile:



Now, was I still waffling about this issue in this post?
Zz.

No, you attacked it up front. I see a lot of interesting directions this argument could go and I will be watching with interest in the lurking mode.


Thank you and my apologies, once more.

Pat

[ZapperZ]

My sincerest apologies if my comments may have appeared offensive. They were not meant to be. My main point was that my impression was that Vanesch wanted to focus exclusively on discussing arguments (for or against) for "fundamental holism", whereas I had the impression that this was a much less relevant issue, that the relevant issue is that *practical* holism was necessary (which, I think, can't be denied).
My apologies again. I will shut up and go back to lurking mode :smile:
No, you attacked it up front. I see a lot of interesting directions this argument could go and I will be watching with interest in the lurking mode.
Thank you and my apologies, once more.
Pat

Oh no, you may have read it wrong. I wasn't the least bit offended at all. I was just a bit amused that it is being resurrected all over again.

Zz.

[vanesch]

Hi Pat !

Nice to see you here again!

Hi Patrick... fascinating stuff.
But why would the brain play such a special role? It seems to me that already before the light reaches your eyes, the "collapse" to the red ball should have occurred. Why should such a special status be assigned to the brain? (other than making EPR type experiments easier to swallow:smile: ).


You're implicitly assuming that there *is* actual collapse, but this time of "brain states" (von Neumann had this argument in fact in his book ; I typed it over here once, and will try to find it back). But the point is that there is NO "objective" collapse, not even of brain states.
The thing that is supposed to happen is that the RELATIONSHIP BETWEEN BRAINSTATES AND SUBJECTIVE EXPERIENCE is the one that "does the picking of a term" (without changing the physical state, which remains in superposition).
In classical physics, it is assumed that the entire brain state (the positions and momenta of all particles in your brain, and the amplitudes and phases of all relevant field modes in your brain) "generates" a subjective experience which is what "you are aware off". In MWI, it is not so different ; only it is not the ENTIRE brainstate (which is entangled with several states of the environment), but just ONE, NONENTANGLED state which generates a subjective experience. If it is postulated (or derived, as some claim, though I think they're wrong, because of circularity or hidden assumptions) that your subjective experience can only derive from ONE brain state in the sum of states, then for your subjective experience it will appear as if this term is the only one that exists. Of course, as long as interference effects with the "neighbouring" terms are non-zero, this would give very strange-looking results (and IMO, this is exactly what happens in EPR setups). But once the different terms are entirely decohered, we'll "never hear again of these other terms" because our subjective experiences are only derived from the brain state in ONE of these terms.
So, what your subjective experiences are concerned, collapse occured.
Nevertheless, the other brainstates, in other terms, are still there. You are simply not subjectively aware of them.

I think that this is the essence of any MWI view.
(and as I said, those parallel worlds are not *introduced* because I have been smoking some crack, they *appear naturally* when you apply the axiomatic structure of quantum theory)


(I also enjoyed the discussion oh holism and reductionism with ZapperZ...except that it felt to me like Zapper was going back and forth from "practical holism" to "fundamental holism" and not really caring as much about the distinction between the two, which must have caused you some frustration.


I could indeed not make up indeed what was the claim!

[vanesch]

When vanesch asked me if I think that if we have all the infinite computing power in the world and can really do a computation for a gazilion particles exactly, shouldn't we, IN PRINCIPLE, be able to derive ALL of the emergent phenomena?
I have replied that at best, I don't know, but my haunch is, no, you can't. I will explain why I believe so.


So I take it that you claim that, if we have that computing power, we would predict DIFFERENT outcomes for the observables that are supposed to measure those phase transitions than what is really observed. Like, when calculating the refractive index (or a suitable observable that corresponds to it, such as the position of the spot of a light beam that is refracted by the sample), which is nothing else but a hermitean operator that works upon the (very big) hilbert space of particles and relevant field modes of all the constituents of the sample and measurement environment, as a function of an ensemble of initial states that correspond, say, to the microcanonical ensemble or whatever (being a relatively suitable initial condition of the real experiment at temperature T), clearly I WILL find a distribution of probability of the position of the light spot on the screen which will give me a probability distribution of the observed refractive index. I expect this distribution to be rather peaked around one value, btw. Now, you claim that this spot will NOT be in the right position as a function of T ?

I find this strange, because this IS what is done in toy models like the Ising model, where observables DO show phase transitions.
For instance:
http://www.physics.cornell.edu/sethna/teaching/sss/ising/intro.htm

http://scienceworld.wolfram.com/physics/IsingModel.html

Of course, this is a toy model, but it shows you how phase transitions can occur from microdynamics "ab initio". The complexity of real-world systems is of course way too big to even be able to find out, but I don't buy the argument that phase transitions cannot be, a priori, calculated ab initio if we know the microdynamics.

[ZapperZ]

So I take it that you claim that, if we have that computing power, we would predict DIFFERENT outcomes for the observables that are supposed to measure those phase transitions than what is really observed. Like, when calculating the refractive index (or a suitable observable that corresponds to it, such as the position of the spot of a light beam that is refracted by the sample), which is nothing else but a hermitean operator that works upon the (very big) hilbert space of particles and relevant field modes of all the constituents of the sample and measurement environment, as a function of an ensemble of initial states that correspond, say, to the microcanonical ensemble or whatever (being a relatively suitable initial condition of the real experiment at temperature T), clearly I WILL find a distribution of probability of the position of the light spot on the screen which will give me a probability distribution of the observed refractive index. I expect this distribution to be rather peaked around one value, btw. Now, you claim that this spot will NOT be in the right position as a function of T ?
I find this strange, because this IS what is done in toy models like the Ising model, where observables DO show phase transitions.
For instance:
http://www.physics.cornell.edu/sethna/teaching/sss/ising/intro.htm
http://scienceworld.wolfram.com/physics/IsingModel.html
Of course, this is a toy model, but it shows you how phase transitions can occur from microdynamics "ab initio". The complexity of real-world systems is of course way too big to even be able to find out, but I don't buy the argument that phase transitions cannot be, a priori, calculated ab initio if we know the microdynamics.

Ah, but look at the Ising model closely. You have to put in, BY HAND, not ab initio, the interaction strength.

It is because of this that many people still claim that we don't quite fully understand the cause of magnetism in matter. The Heisenberg coupling that can determine if something is going to be a ferromagnet or antiferromagnet, for examp;le, has to be put in by hand.

So no. Such a model is not fully ab initio. It requires you to make an a priori input to make it mimick whatever system you are trying to get.

Zz.

[vanesch]

Ah, but look at the Ising model closely. You have to put in, BY HAND, not ab initio, the interaction strength.


Naah, that's not what I mean. That's when you use the Ising model to model another (real-world) system, like ferromagnetism or so. Then it becomes indeed a *phenomenological model*.

But if you would consider a universe where the Ising hamiltonian is exact and the interaction strength is a fundamental constant of that universe, then the Ising model is "ab initio" in that universe. And you have phase transitions ab initio in that universe, which proves that it is possible to obtain phase transitions, ab initio, from microscopic physics, at least in the quantum physics of a toy universe. Which goes against the claim that phase transitions cannot be derived ab initio. It can, at least in some toy universes.

Of course when we want to apply this Ising model to a real world situation, it is not ab initio, it is one of those typical phenomenological modelisations which are so common in condensed matter physics, and which illustrate indeed, only *some aspects* of the physics, and in which we have to do some (educated or not) guesses on the interaction model and parameters.

[ZapperZ]

But if you would consider a universe where the Ising hamiltonian is exact and the interaction strength is a fundamental constant of that universe, then the Ising model is "ab initio" in that universe. And you have phase transitions ab initio in that universe, which proves that it is possible to obtain phase transitions, ab initio, from microscopic physics, at least in the quantum physics of a toy universe. Which goes against the claim that phase transitions cannot be derived ab initio. It can, at least in some toy universes.

But this is what I claim to be something input by hand. I've done such a modeling, although not very extensively. I had to know the interaction strength, and how many neighbors to take into account. I play around with those "free parameters" till I could get the ordered state, or whatever state I was looking for. Was the Hamiltonian exact? Sure! Did I let everything run by itself? Sure! Did it require an input from me? DEFINITELY! So *I* was the "source" for the phase transition or any ordered state.

ZZ.

[vanesch]

But this is what I claim to be something input by hand. I've done such a modeling, although not very extensively. I had to know the interaction strength, and how many neighbors to take into account. I play around with those "free parameters" till I could get the ordered state, or whatever state I was looking for. Was the Hamiltonian exact? Sure! Did I let everything run by itself? Sure! Did it require an input from me? DEFINITELY! So *I* was the "source" for the phase transition or any ordered state.


If what you put in "by hand" is now declared "fundamental microphysics" (of the toy universe), then we are both right :approve:

Did Maxwell put the terms into his equations by hand ? Sure. But that cannot be what you mean, right ?

Now, I think I know what you mean: in the Ising case, it's all made up *in order to* generate things like a phase transition. But I read this differently: I read it that the Ising Hamiltonian could, in a specific toy universe, be derived from some microscopic law, obtained by "scattering" individual spins (in other words, study few-constituent systems). The "particle physicists" of the toy universe could have studied several few-spin systems, and have derived their "fundamental laws of microphysics" of the toy universe. Condensed-matter physicists in that toy universe could then apply those fundamental laws of microphysics to much larger systems, and DERIVE AB INITIO the phase transition ; as such, the phase transition would NOT have to be phenomenologically modelled, but is really derived from the supposed exact microphysical laws they learned from their peers ; and this time they COULD do the math. So there is all right an "emergent phenomenon" of phase transition in large systems of spin, but it is entirely contained and derivable from the microphysics of the toy universe.

Imagine now that the parameters of the microphysical laws in the toy universe are determined by the particle physicists to have certain values, and imagine now that the condensed-matter physicists use these laws to derive a phase transition ; and imagine that they observe that the phase transition DOES NOT occur as predicted by the microphysical laws. What would now be the conclusion ? I think that the conclusion would simply be that they would go and see their particle physicist peers, and tell them that they must have messed up!
But is it really thinkable that the particle physicists tell them that, well, the laws they have are exactly true for the microphysics, but that, when there are a lot of spins, there can be emergent phenomena, and that they better not do their derivation from microphysics ? But that this is all right ? Nothing to worry about ?

How can the individual spins be supposed to follow exactly the laws of microphysics, while the derivable consequence for the behaviour of a lot of them is not true ? It is just "emergent" ?

Honestly, the only conclusion I could draw from such a situation is that
1) the microlaws are not exact (although maybe such a good approximation that one cannot notice experimental derivation from them in few-spin situations) as such, the condensed-matter experiment has a higher sensitivity to the deviations than the few-component interaction experiments; or:
2) in the derivation, an extra assumption has been made without noticing, which invalidates the deduction.

I cannot conceive logically the possibility that the individual constituents (spins) follow ALL the exact laws, but that the deduced conclusion about the behaviour of a lot of them is not correct if there is no error in the deduction.

The only difference with real-world situations (instead of situations in this toy universe) is that we cannot do the derivation in practice, today.

[ZapperZ]

If what you put in "by hand" is now declared "fundamental microphysics" (of the toy universe), then we are both right :approve:
Did Maxwell put the terms into his equations by hand ? Sure. But that cannot be what you mean, right ?

Depends on what you mean "by hand" in your case. In fact, I claim that Maxwell Equations ARE phenomenological. One does not, for example, derive from First Principles, the Coulomb's Law.

Now, I think I know what you mean: in the Ising case, it's all made up *in order to* generate things like a phase transition. But I read this differently: I read it that the Ising Hamiltonian could, in a specific toy universe, be derived from some microscopic law, obtained by "scattering" individual spins (in other words, study few-constituent systems). The "particle physicists" of the toy universe could have studied several few-spin systems, and have derived their "fundamental laws of microphysics" of the toy universe. Condensed-matter physicists in that toy universe could then apply those fundamental laws of microphysics to much larger systems, and DERIVE AB INITIO the phase transition ; as such, the phase transition would NOT have to be phenomenologically modelled, but is really derived from the supposed exact microphysical laws they learned from their peers ; and this time they COULD do the math. So there is all right an "emergent phenomenon" of phase transition in large systems of spin, but it is entirely contained and derivable from the microphysics of the toy universe.

But if this is true, we would have solved magnetism already. Instead, the Ising model for such a system STILL has to make use of the same approximation that we have to use in many-body approximation - the mean-field potential is a very popular one.

The problem here is that the "toy model" requires you to know what to put in. You arrive at an ordered phase because... well, you KNOW this is what you want and you tweak the interactions. How many nearest neighbors, next nearest neighbors, next-next nearest neighbors that you consider is NOT derived ab initio. What coupling strenth do you put in for each of those interactions? To say that you can "derive" a phase transition from such manipulation isn't entirely kosher. You can show your toy system undergoes a phase transition, but you have no idea why it does that with your parameters - meaning that you DON'T have a "Theory of Everything" in principle.

Imagine now that the parameters of the microphysical laws in the toy universe are determined by the particle physicists to have certain values, and imagine now that the condensed-matter physicists use these laws to derive a phase transition ; and imagine that they observe that the phase transition DOES NOT occur as predicted by the microphysical laws. What would now be the conclusion ? I think that the conclusion would simply be that they would go and see their particle physicist peers, and tell them that they must have messed up!

I have 2 ways to address that. First, we have already established that we can't do First Principle calculations of a gazillion interacting particles. So we have already agreed that, in the practical sense, microscopic interactions are of no use in predicting and describing emergent phenomena. This is what Laughlin described in his Nobel Lecture as his bad trick onto his graduate students. So off hand, there is no way to verify what you suggested above, because if it doesn't work, we don't know if it's because of our computational shortcoming, or we're missing something fundamental. Secondly, even if it works, we don't know if it is the SAME mechanism because we're extrapolating.

But is it really thinkable that the particle physicists tell them that, well, the laws they have are exactly true for the microphysics, but that, when there are a lot of spins, there can be emergent phenomena, and that they better not do their derivation from microphysics ? But that this is all right ? Nothing to worry about ?
How can the individual spins be supposed to follow exactly the laws of microphysics, while the derivable consequence for the behaviour of a lot of them is not true ? It is just "emergent" ?
Honestly, the only conclusion I could draw from such a situation is that
1) the microlaws are not exact (although maybe such a good approximation that one cannot notice experimental derivation from them in few-spin situations) as such, the condensed-matter experiment has a higher sensitivity to the deviations than the few-component interaction experiments; or:
2) in the derivation, an extra assumption has been made without noticing, which invalidates the deduction.
I cannot conceive logically the possibility that the individual constituents (spins) follow ALL the exact laws, but that the deduced conclusion about the behaviour of a lot of them is not correct if there is no error in the deduction.
The only difference with real-world situations (instead of situations in this toy universe) is that we cannot do the derivation in practice, today.

You are missing the 3rd option: that the so-called "fundamental" microlaws are THEMSELVES emergent! If one can envision that the property that we consider as "mass" to be nothing more than an excitation out of the Higgs field, then I can certainly speculate that ALL of our fundamental particles are emergent, "quasiparticles" out of some fields, and the fundamental "force" carriers are no different than the collective particles like phonons, spinons, chargons, polarons, etc. In that case, your "micolaws" are not "fundamental" and certainly subject to fluctuations and are themselves many-body excitations.

I know I'm extrapolating, but that is what you are doing with your toy model. So it's fair game.

Zz.

[vanesch]

You can show your toy system undergoes a phase transition, but you have no idea why it does that with your parameters - meaning that you DON'T have a "Theory of Everything" in principle.


Well, if the derivation from the premise is "understood", then you do have an idea !


I have 2 ways to address that. First, we have already established that we can't do First Principle calculations of a gazillion interacting particles. So we have already agreed that, in the practical sense, microscopic interactions are of no use in predicting and describing emergent phenomena. This is what Laughlin described in his Nobel Lecture as his bad trick onto his graduate students. So off hand, there is no way to verify what you suggested above, because if it doesn't work, we don't know if it's because of our computational shortcoming, or we're missing something fundamental.


Honestly, this sounds like claiming that we don't know if natural numbers with more than 10^500 digits can be written as a unique product of prime factors or not, no ? Because there's no way to verify if it is because of a computational shortcoming or if we're missing something fundamental.

Before taking the option of "something fundamental" (and as such throw overboard the entire number theory, and even mathematical logic), I'd say that the obvious point is that we're having computational shortcomings. The funny thing is that probably, 2 centuries ago, one would have said the same about numbers with a few hundred digits. Well, we now know that it was a matter of computational shortcoming: numbers with a few hundred digits can be written as a unique product of prime factors.

So, we might make progress with what can be computed!


You are missing the 3rd option: that the so-called "fundamental" microlaws are THEMSELVES emergent! If one can envision that the property that we consider as "mass" to be nothing more than an excitation out of the Higgs field, then I can certainly speculate that ALL of our fundamental particles are emergent, "quasiparticles" out of some fields, and the fundamental "force" carriers are no different than the collective particles like phonons, spinons, chargons, polarons, etc.

Oh, but that's almost for sure the case! But there's no problem here! The problem I have is with the claim that, when we know the behaviour of constituents exactly (even if this behaviour is "emergent" from an underlying theory) - or at least with sufficient accuracy, and that we make systems compound of many of these constituents, that we suddenly should NOT be able - even in principle - to deduce the behaviour of the compound system, even though we're supposed to know what each individual compound is going to do. THAT is difficult to accept conceptually to me.

[ZapperZ]

Honestly, this sounds like claiming that we don't know if natural numbers with more than 10^500 digits can be written as a unique product of prime factors or not, no ? Because there's no way to verify if it is because of a computational shortcoming or if we're missing something fundamental.
Before taking the option of "something fundamental" (and as such throw overboard the entire number theory, and even mathematical logic), I'd say that the obvious point is that we're having computational shortcomings. The funny thing is that probably, 2 centuries ago, one would have said the same about numbers with a few hundred digits. Well, we now know that it was a matter of computational shortcoming: numbers with a few hundred digits can be written as a unique product of prime factors.

But all I did was described what you called "practical holism" or something to that nature, did I not? I thought we agreed on this already?

So, we might make progress with what can be computed!
Oh, but that's almost for sure the case! But there's no problem here! The problem I have is with the claim that, when we know the behaviour of constituents exactly (even if this behaviour is "emergent" from an underlying theory) - or at least with sufficient accuracy, and that we make systems compound of many of these constituents, that we suddenly should NOT be able - even in principle - to deduce the behaviour of the compound system, even though we're supposed to know what each individual compound is going to do. THAT is difficult to accept conceptually to me.

It isn't for me mainly because I am not convinced that a toy model that I manipulated by hand that happened to mimick large-scale phenomena is accurate. I haven't seen one that is able to, for example, mimick every aspect of an antiferromagnetic phase, for example, all the way up to producing a spin-density wave. All you get is a resemblance to one part of the picture. To get the resemblance to another part, you construct ANOTHER toy model, because the previous one just can't do it.

So what we have here are examples where (i) you claim you can show a toy model system resembling a phase transition seen in a larger system and (ii) me showing you other examples where such toy models don't work - in fact, I claim that there are many more examples in this category than there are in the first. If this is true, then it is just a matter of taste on if this is a convincing evidence one way or the other. My taste runs on it being not convincing.

Now, with that in mind, my point on the 3rd option that you missed would not matter either way. I brought it up simply in relations to the claim of the possibility of TOE. Disregarding the fact that the knowledge of all the "fundamental interactions" are useless in predicting and describing emergent phenomena, it means that even when one obtains complete knowledge of all of our current fundamental interactions, one can STILL end up with nothing more a set of emergent phenomena. We would have known more, but we certainly do not know everything.

Zz.

[vanesch]

It isn't for me mainly because I am not convinced that a toy model that I manipulated by hand that happened to mimick large-scale phenomena is accurate.


That was not the point of course. The point was that toy models can show emergent phenomena such as phase transitions to occur in toy universes (where they are supposed to be "fundamental").
As such, the argument that emergent phenomena *prove* that the reductionist approach is bound to fail in principle is shown to be false as a general argument, because we have a counter example (in a toy universe).

This leaves you with the hope that the same can in principle be done in the real universe: that it is CONCEIVABLE that phase transitions and other fancy emergent stuff MIGHT BE derivable from the microphysics, if only we had enough brains.


I haven't seen one that is able to, for example, mimick every aspect of an antiferromagnetic phase, for example, all the way up to producing a spin-density wave. All you get is a resemblance to one part of the picture. To get the resemblance to another part, you construct ANOTHER toy model, because the previous one just can't do it.
So what we have here are examples where (i) you claim you can show a toy model system resembling a phase transition seen in a larger system and (ii) me showing you other examples where such toy models don't work - in fact, I claim that there are many more examples in this category than there are in the first. If this is true, then it is just a matter of taste on if this is a convincing evidence one way or the other. My taste runs on it being not convincing.


Well, I find it convincing, from the moment that there is ONE example in the bin (i), because that shows that there is no fundamental reason why all the things in bin (ii) could not eventually be moved to bin (i). Bin (i) is not empty. That leaves us with some hope. The hope that the universe is running on a mathematical model. A single one.


it means that even when one obtains complete knowledge of all of our current fundamental interactions, one can STILL end up with nothing more a set of emergent phenomena. We would have known more, but we certainly do not know everything.


Sure. The issue is if this "turtling down" is infinite, or will stop. If we take it that the universe is running on a certain mathematical model, then it should stop, the day we find that mathematical model, no ?
And if it is NOT running on a mathematical model, then anything goes, right ?

That said, we will of course never KNOW if we have it or not (because we cannot do every conceivable experiment). Maybe that's your point.

[nrqed]

Oh no, you may have read it wrong. I wasn't the least bit offended at all. I was just a bit amused that it is being resurrected all over again.
Zz.

Ah ok. Thanks a lot for posting this, I genuinely felt bad. I did not mean to sound rude but in rereading my post I realized that I did come out rude and without tact. I am sincerely glad you were not offended because you would have had good reasons to be.

Thanks again!

Pat

[quantumcarl]

I was wondering, (as a layperson to the study of quantum physics), if the phenomenon of non-location (and all those related events) is a result of the observer, or the instruments of the observer, being unable to discern what actually takes place at a microscopic level.

Perhaps whatever is non-local moves so fast it appears to us as though its in two different places at the same time. Could it be occilating between two locations at a rate which is undetectable to an instrument or observer in our scale and position in the classical environment?

For instance, we are at a scale of x times that of the quantum. The mechanisms that support us as observers, and our instruments, are far removed from the mechanisms and the scale and the speed at which events unfold... microscopically.

Can the physicist be sure his or her perception and the readings their instruments dictate are "up to speed" with the microscopic scale of a quantum field?

[ZapperZ]

I was wondering, (as a layperson to the study of quantum physics), if the phenomenon of non-location (and all those related events) is a result of the observer, or the instruments of the observer, being unable to discern what actually takes place at a microscopic level.

Perhaps whatever is non-local moves so fast it appears to us as though its in two different places at the same time. Could it be occilating between two locations at a rate which is undetectable to an instrument or observer in our scale and position in the classical environment?

For instance, we are at a scale of x times that of the quantum. The mechanisms that support us as observers, and our instruments, are far removed from the mechanisms and the scale and the speed at which events unfold... microscopically.

Can the physicist be sure his or her perception and the readings their instruments dictate are "up to speed" with the microscopic scale of a quantum field?

See, the problem here has more to do with your understanding of a more general principle of superposition. Being in "two locations" is an example of such principle. Now couple that with what QM defines as non-commutative operators as observables, we have a situation where one really cannot learn QM only in bits and pieces.

The principle of superposition is well-verified. This is because, while one cannot see a superposition of locations, for example, one can detect the CONSEQUENCES of it by doing an indirect measurement. One can measure an observable that doesn't commute with the position operator. Such act does not cause a complete collapse of the position superposition. Thus the value that one obtains would reflect such superposition.

This has been done and observed many times, and are often known as the Schrodinger Cat-type states. The existence of the bonding-antibonding bonds in H2 molecule is a prime example. The energy gap measure in the SQUID experiments of Delft and Stony Brook is another. Rather than just repeat everything that has been said many times on here, I'll just copy off an entry in my Journal.


These are the papers that clearly show the Schrodinger Cat-type states (alive+dead, and not alive or dead). All the relevant details are there and anyone interested should read them. Also included is the reference to a couple of review articles which are easier to read, and the reference to two Leggett's papers, who was responsible in suggesting this type of experiments using SQUIDs in the first place. Again, the papers have a wealth of citations and references.

The two experiments from Delft and Stony Brook using SQUIDs are:

C.H. van der Wal et al., Science v.290, p.773 (2000).
J.R. Friedman et al., Nature v.406, p.43 (2000).

Don't miss out the two review articles on these:

G. Blatter, Nature v.406, p.25 (2000).
J. Clarke, Science v.299, p.1850 (2003).

However, what I think is more relevant is the paper by Leggett (who, by the way, started it all by proposing the SQUIDs experiment in the first place):

A.J. Leggett "Testing the limits of quantum mechanics: motivation, state of play, prospects", J. Phys. Condens. Matt., v.14, p.415 (2002).

A.J. Leggett "The Quantum Measurement Problem", Science v.307, p.871 (2005).

This paper clearly outlines the so-called "measurement problem" with regards to the Schrodinger Cat-type measurements.

Zz.

[quantumcarl]

we have a situation where one really cannot learn QM only in bits and pieces.

Yeah, you're right to point that out. I can't ask a coherent question about qm because I haven't studied it from the bottom up.... I don't imagine "suffering fools" is part of the qm curriculum.:uhh: Do I still get some mouse ears for effort? :smile:

[ZapperZ]

Yeah, you're right to point that out. I can't ask a coherent question about qm because I haven't studied it from the bottom up.... I don't imagine "suffering fools" is part of the qm curriculum.:uhh: Do I still get some mouse ears for effort? :smile:

In many cases, the problem here isn't with you. It's more with ME. I see a lot of these questions, and I wish I have more of a patience to write a many-page answer on why there's a huge part of QM that one is missing. This is especially true on questions of quantum entanglement. I see people asking about this and that, and I notice that they haven't actually understood the physics that is the central issue in this phenomenon. You will never realize why it is so "strange" if you don't understand (i) quantum superposition and (ii) the commutation relations of observables. Undergraduate physics majors could spend a whole semester doing nothing but the understanding and applications of these two principles. In fact, the commutation relations of observables is sometime called the First Quantization. It is THAT important.

Physics is a difficult subject because one has to have a mastery of many different, sometime apparently unrelated, areas. And one certainly cannot fully comprehend a particular area by just focusing on one single aspect of it, because that's like looking at the hoof of the animal and trying to deduce what the animal looks like. Realizing the interconnectedness of a particular area is one of the first steps of learning it.

Zz.

[quantumcarl]

In many cases, the problem here isn't with you. It's more with ME. I see a lot of these questions, and I wish I have more of a patience to write a many-page answer on why there's a huge part of QM that one is missing. This is especially true on questions of quantum entanglement. I see people asking about this and that, and I notice that they haven't actually understood the physics that is the central issue in this phenomenon. You will never realize why it is so "strange" if you don't understand (i) quantum superposition and (ii) the commutation relations of observables. Undergraduate physics majors could spend a whole semester doing nothing but the understanding and applications of these two principles. In fact, the commutation relations of observables is sometime called the First Quantization. It is THAT important.

Physics is a difficult subject because one has to have a mastery of many different, sometime apparently unrelated, areas. And one certainly cannot fully comprehend a particular area by just focusing on one single aspect of it, because that's like looking at the hoof of the animal and trying to deduce what the animal looks like. Realizing the interconnectedness of a particular area is one of the first steps of learning it.

Thank you Zapper z.

To begin with I have learned more about QM physics from you and the other contributors to this thread than from anywhere else.

What I have learned has helped me understand that applying QM to philosophy will never be as easy as the people who compiled "What the Bleep..." make it look. In fact... they have only made themselves look rather foolish where they try to analogize QM properities with what you have taught me to regard as "emergent properties".

There is definitely a potential for a unification of classical and quantum physics and the laws governing them... but... there is also a potential for the sculpture of George Washington at Mt. Rushmore to start talking. (That would be an earfull!!)

When I am able to figure out what SQUID and/or KALAMARI have to do with QM, I'll constitute a position of being a better contributor to this section of the illustrious PhysicsForum!!!:rolleyes:

If this means I have to change my name, I'm not doing it. I tried that already and its a big mess. Greg or his adminstrators send out the automated swat team w/dogs when you do.