Interpretations of Quantum Mechanics (is there a general consensus?)

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The discussion centers on the interpretation of the wave function in quantum mechanics, with participants questioning whether it represents a real field that possesses energy and momentum. There is no consensus among scientists, with many adhering to a pragmatic approach of "Shut Up And Calculate," focusing on calculations rather than interpretations. Some argue that the wave function is not a physical field like the electric field, as it exists in configuration space rather than real space, complicating its characterization as "real." The conversation also touches on various interpretations of quantum mechanics, including transactional and decoherence interpretations, highlighting the ongoing debate about the nature of quantum states. Ultimately, the wave function's role remains a complex and contentious topic in the field of quantum mechanics.
  • #61
bhobba said:
Ok - a question then. According to Copenhagen when the position of a quantum particle is measured prior to that it may not even have the property of position - it is the interaction with the measurement apparatus that gives it the property of position. I can't quite follow how something could not have been said to happen to the quantum particle as a result of the measurement.
Something does happen, the particle's position is measured. But given no prior measurement we cannot say for example that the act of measurement did or did not change the particle. In the sense of a change we cannot say something did or did not happen to the particle during measurement.

However in the case of two immediate position measurements we will according to QM measure the same position the 2nd time and so we can positively say no change occurred during the 2nd measurement. So after the 1st measurement we collapse our description to express this fact.

The Ensemble interpretation says its simply a statistical observation like tossing a dice and is silent on what happens to the particle - but Copenhagen seems to be saying something happened to it caused by interaction with the measurement apparatus.
The Ensemble interpretation and Copenhagen interpretation are not very different. The EI says the wave-function (or hilbert space vector) represents an ensemble of systems while the CI says it represents a class of systems. Both EI and CI and all other QM interpretations assert something happens or may happen during measurement. Measurement is a two-way interaction not a God-like peaking at the state without disturbing of the system.

For example in EI if you have a stream of photons with vertical polarization and you measure oblique polarization (with a polaroid film) you will end up with a reduced number of oblique photons. The photons which survive have been changed and the photons which didn't likewise since they are absorbed. In CI you replace "reduced number" with a (classical) probability distribution but you are still representing an attenuation of either probability or number.

The problem with EI is if you presuppose objective states prior to measurement you fail to get Bell inequality violation. Current EI doesn't assume this it just refuses to apply QM to single systems.
 
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  • #62
jambaugh said:
CI invokes wave function collapse but the wave function itself is understood to represent knowledge about the system, not to represent the reality of the system.

That is said very often, but I don't think that is the case in CI. The wave function represents the state of the system, not knowledge.
 
  • #63
martinbn said:
That is said very often, but I don't think that is the case in CI. The wave function represents the state of the system, not knowledge.

"...many physicists and philosophers see the reduction of the wave function as an important part of the Copenhagen interpretation. But Bohr never talked about the collapse of the wave packet. Nor did it make sense for him to do so because this would mean that one must understand the wave function as referring to something physically real. Bohr spoke of the mathematical formalism of quantum mechanics, including the state vector or the wave function, as a symbolic representation." from http://plato.stanford.edu/entries/qm-copenhagen/

This characterizes Bohr's view and I generally mean Bohr CI when I speak of CI. This may be improper. The view of a unified CI is something of a myth.

" The Copenhagen Interpretation denies that the wave function is anything more than a theoretical concept, or is at least non-committal about its being a discrete entity or a discernible component of some discrete entity.
The subjective view, that the wave function is merely a mathematical tool for calculating the probabilities in a specific experiment, is a similar approach to the Ensemble interpretation.
There are some who say that there are objective variants of the Copenhagen Interpretation that allow for a "real" wave function, but it is questionable whether that view is really consistent with logical positivism and/or with some of Bohr's statements. Bohr emphasized that science is concerned with predictions of the outcomes of experiments, and that any additional propositions offered are not scientific but meta-physical. Bohr was heavily influenced by positivism. On the other hand, Bohr and Heisenberg were not in complete agreement, and they held different views at different times. Heisenberg in particular was prompted to move towards realism."[/color] - from http://en.wikipedia.org/wiki/Copenhagen_interpretation

If you like, I'm a "Bohr-ist", call it BCI, vs. a Heisenberg-ist HCI.

[EDIT] And I believe when you read about CI being the historical consensus view among physicists, that statement is referring to the pragmatic/positivistic Bohr version.
 
  • #64
jambaugh said:
"...many physicists and philosophers see the reduction of the wave function as an important part of the Copenhagen interpretation. But Bohr never talked about the collapse of the wave packet. Nor did it make sense for him to do so because this would mean that one must understand the wave function as referring to something physically real. Bohr spoke of the mathematical formalism of quantum mechanics, including the state vector or the wave function, as a symbolic representation." from http://plato.stanford.edu/entries/qm-copenhagen/

This characterizes Bohr's view and I generally mean Bohr CI when I speak of CI. This may be improper. The view of a unified CI is something of a myth.

" The Copenhagen Interpretation denies that the wave function is anything more than a theoretical concept, or is at least non-committal about its being a discrete entity or a discernible component of some discrete entity.
The subjective view, that the wave function is merely a mathematical tool for calculating the probabilities in a specific experiment, is a similar approach to the Ensemble interpretation.
There are some who say that there are objective variants of the Copenhagen Interpretation that allow for a "real" wave function, but it is questionable whether that view is really consistent with logical positivism and/or with some of Bohr's statements. Bohr emphasized that science is concerned with predictions of the outcomes of experiments, and that any additional propositions offered are not scientific but meta-physical. Bohr was heavily influenced by positivism. On the other hand, Bohr and Heisenberg were not in complete agreement, and they held different views at different times. Heisenberg in particular was prompted to move towards realism."[/color] - from http://en.wikipedia.org/wiki/Copenhagen_interpretation

If you like, I'm a "Bohr-ist", call it BCI, vs. a Heisenberg-ist HCI.

[EDIT] And I believe when you read about CI being the historical consensus view among physicists, that statement is referring to the pragmatic/positivistic Bohr version.

I was complaining about the statement that the wave function represents the knowledge about the system. In these quotes there is nothing about knowledge. I also think that Bohr was not a positivist.
 
  • #65
martinbn said:
I was complaining about the statement that the wave function represents the knowledge about the system. In these quotes there is nothing about knowledge. I also think that Bohr was not a positivist.

No Bohr was an operationalist. But that's down on the positivistic side of the spectrum.
(positivism is another of those loaded words with multiple versions of definition)

But how can a "tool used to calculate probabilities" be other than a representation of knowledge about the system, said knowledge is express by the predictions of behavior i.e. transition probabilities and not metaphysical assertions about the reality of the system as is done e.g. in Bohmian pilot waves or MW? CI is NOT a metaphysical interpretation. It is exactly that which Einstein objected to in the famous debates and why he asserted it and with it QM was incomplete. It failed to give a description of the underlying reality Einstein asserted must exist in a complete theory.

Note Bohr and Heisenberg were debating this very point too. Heisenberg imagined particle behavior with sudden jumps. Bohr argued that "wave" and "particle" were distinct complementary descriptions. They cannot be distinct descriptions of the same reality if they are (or one of them is) direct representations of reality. They are rather distinct operational descriptions of system behavior. Later Heisenberg accepted complementarity and this is the final component of CI. --see http://www.aip.org/history/heisenberg/p09.htm

CI = complementarity + HUP + statistical interpretation of Schrodinger's wave equation (*and implicitly the interpretation of the wave-function itself as a statistical object, not a physical one...)

I think my (*) is clear in the discussions between Bohr, Heisenberg, and Einstein. The distinct reified wave function view grew from Schrodinger's original wave mechanics which was only natural given its similarity in form to prior classical wave mechanics. It was CI's distinct departure from this view which made it significant and allow the full formulation of QM as not only a new theory but a distinct type of theory from classical mechanics.

If you or anyone has a reference to Bohr, or Heisenberg post 1927 implying in any way that the wave function was to be interpreted as a direct representation of reality, please make it known to me.
 
  • #66
jambaugh said:
This characterizes Bohr's view and I generally mean Bohr CI when I speak of CI. This may be improper. The view of a unified CI is something of a myth.

I think that is one of the problems. You do a search on Copenhagen and all sorts of ideas pop up including what I always believed about it - namely it asserts wave-function collapse is a real thing that occurs out there. You find guys like Ballentine in his critique makes reference to its problems in that area. Now if guys like that who are experts in Quantum interpretation do that - well it really does make it hard for the rest of us.

Ballentine in his paper in the Ensemble Interpretation sates it outright - wave function collapse is part of 'orthodox' theory (and he seems to lump Copenhagen in with that) and is a problem for any interpretation that that has it - he doesn't seem to believe Copenhagen says it's merely something that occurs in physicists calculations
http://www.kevinaylward.co.uk/qm/ballentine_ensemble_interpretation_1970.pdf

He readily admits though his objections to not apply to what he calls 'subjective' interpretations favoured by for example Heisenberg where the collapse is like the above. Could that perhaps be the root of his confusion (if indeed it is confusion) - because there is no doubt Heisenberg ascribed to a version of Copenhagen?

Thanks
Bill
 
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  • #67
bhobba said:
I think that is one of the problems. You do a search on Copenhagen and all sorts of ideas pop up including what I always believed about it - namely it asserts wave-function collapse is a real thing that occurs out there. You find guys like Ballentine in his critique makes reference to its problems in that area. Now if guys like that who are experts in Quantum interpretation do that - well it really does make it hard for the rest of us.
I'm still reading Ballentine's paper you referenced. I note that in his introduction he states his principle objection to CI is its assertion that the "the state variable description is the most complete description of an individual quantum system".
Ballentine in his paper in the Ensemble Interpretation sates it outright - wave function collapse is part of 'orthodox' theory (and he seems to lump Copenhagen in with that) ...
Yes, Copenhagen invokes collapse...
...and is a problem for any interpretation that that has it - he doesn't seem to believe Copenhagen says it's merely something that occurs in physicists calculations
http://www.kevinaylward.co.uk/qm/ballentine_ensemble_interpretation_1970.pdf

He readily admits though his objections to not apply to what he calls 'subjective' interpretations favoured by for example Heisenberg where the collapse is like the above. Could that perhaps be the root of his confusion (if indeed it is confusion) - because there is no doubt Heisenberg ascribed to a version of Copenhagen?

Thanks
Bill
I could read what you cite differently. His objection to collapse is that it is invoking the maximal description assertion which he finds unnecessary. But I'll have to finish reading to see. His reference to Heisenberg and 'subjective' interps. would seem to mean he understood CI as I do. Heisenberg got this view from Bohr and was the one to coin the phrase Copenhagen Interpretation.

... reading further. Ah!, Ballentine is a realist! He wants to preserve reality ... near the end of p361 "...in contract the statistical interpretation considers the a particle to always be at some position in space, each position being realized with relative frequency |\psi(r)|^2 in an ensemble of similarly prepared experiments."[/color]

I think he is still in essence invoking collapse in the same way as CI (as I describe it) in that should one, using his interpretation, wish to describe the part of an ensemble that has been measured with a given position, they will of course need to use a "collapsed" wave function. I see nothing qualitatively distinct between asserting "that last electron came from an ensemble with state vector \psi" and saying "that last electron has mode vector \psi". The difference for Ballentine is his religious belief in the position of a particle between acts of measurement. (I say religious, not improper (nor proper) because it is a belief which cannot be empirically checked...by definition.)

I do see what may be a misunderstanding in his characterization of Heisenberg's "intermediate kind of reality," collapsing via measurement "from the possible to the actual." Note this is not saying "collapsing from an unobserved actuality(reality) to another observed actuality(reality)". But it might be read as such leading one to think Heisenberg is speaking of "collapse in actuality". But then the context of his '58 reference may be that this latter is a correct characterization of Heisenberg's view. I'd like to see that reference in context.

I found http://evans-experientialism.freewebspace.com/heisenberg.htm from that same reference which may clarify. (still reading it)

I'll digest it and Ballentine's paper and get back to you.
 
  • #68
Len M said:
But what if the patterns are subject to “rules” that exist within the construct that is our reality?
You said it yourself, "exist within the construct." That makes it quite clear where the "existence" lies, that's what I'm saying about all forms of information. As soon as we see what nature is doing as being some kind of information processor, then immediately the information processor is our brains, not nature. We must see nature as a kind of "mini me", because that is all we understand-- that is the point of physics, to be able to see our thought processes in nature, thereby claiming some understanding. What other form of understanding is there?

By a construct I mean a reality that is not produced from the hardware of a dualistic brain, rather mind emerges from “something” that gives us empirical reality.
And that's the paradox of mind-- we want to imagine that our minds "emerge" from nature, but everything we think we understand about nature comes from our minds. Hence, the "emergence" scenario is one where a mind emerges from itself, like a tiger chasing its tail. It's hard to say what other options we have available, so we get as far as we can, but we should not be surprised when faced with certain difficulties if we choose to ignore the self-referential character of the situation.

Within that reality brains are the same stuff as external objects, everything is a dualist construct from “something”.
Exactly, everything is a construct, including what is purported to be responsible for the construct. Our minds are constructs that are trying to construct themselves. This is the situation, we don't need to imagine otherwise-- everything we can say about our minds, including the definition of what a mind is, and any attempt to understand a mind, ends up being the object of that understanding, not the subject of it. The subject of the understanding is not what we mean by a mind, not in physics anyway.
But within that “whole” surely we can then say that “rules” exist without thought.
That is just the thinking that I reject. To me, the words "rules" and "without thought" are having a little fight in that sentence. If there was any evidence that reality actually obeyed rules, rather than just can be effectively analyzed using the construct of rules (a product of a human mind), then there might be some authority to that claim, but a "rule" is something we make up (it's an anthropomorphism), and how does reality "obey" things anyway? These anthropormorphisms are not just conveniences of language, they are the language. If we could really make the point that our minds were not involved using language that is not anthropomorphic, then maybe we could be making a consistent argument, but there's a reason we never seem able to do that. The goal of understanding is to see ourselves in what we are studying, so anthropomorphism is inescapable, and that's fine, but we should not claim in the same sentence that includes anthropomorphisms that we are not involved.

Imagine a scenario where by nature outside of the “whole” consists of random irreducible elements not “existing” in space or time. We cannot logically think of an exception to this scenario that involves a brain sitting in a corner taking in all of these elements from “something” and creating “rules” – the brain can only be part of a dualistic construct that emerges from this “something”.
Sure, but even so, those "rules" exist in that brain, all the same. This also explains why rules are pretty much made to be broken, in physics, and why the ontologies of physics theories vary radically from century to century with no evidence of any convergence on the horizon.
The molecules do not care about their differences, but those differences involve “rules” that are part of our reality and are used in the emergence of the hardware that is us. Those “rules” will be there whether we discern patterns or not.
The rules are the patterns we discern, I don't think reality has the least idea what a rule is, precisely because reality does not have a mind. Or, if we take the view that reality is itself some kind of great mind, then the point still holds that the rules are a product of the mind, not the other way around. Both the rules, and what we mean in physics by reality itself, are inescapably intertwined with the mind that notices them, constructs them, and evaluates them. One can invoke the phrase "mind independent reality", but one cannot say anything else about it, so physics immediately leaves that notion to philosophy, as that notion has no place in the concept of reality that physics uses.

I believe Bohr hit the nail on the head when he pointed out that physics is not about reality, it is about what we can say about reality. Many people interpret that as Bohr's claim that the wave function is epistemic rather than ontic, but I think he was saying something much deeper that goes way beyond quantum mechanics-- he was saying that physics is a mind trying to see itself in what is around it, and meeting with both substantial success as well as unavoidable limitations.
I just don’t think that you can easily use the dualism of our reality to imply that cognitive thought gives rise to that dualism (unless one considers that dualisms exists as such within mind independent reality).
I don't think you have any choice in the matter-- the dualism does arise from itself, just like the mind does. There isn't any dualism that is "inherent" in some mind independent reality, dualism is just what you get when a mind tries to draw a line and say "in here is me, out there is other." It's pure mental construct, fundamental to the very definition of mind but meaningless without that definition. The tiger is chasing its tail, and that is part of the point of dualism.

It is the construct (the “whole”) that comes first and the cognitive thoughts second – existence comes before knowledge.
That is certainly the common view, but I regard it as untenable when applied to what physics means by "knowledge" and "existence" because there are two flavors of existence. There is what "really exists," which we can say nothing about, but we want to say something about it, so we invent physics and knowledge, and then, only then, can we start to talk about what exists. But then the existence we are talking about is immediately resultant from the knowledge and comes after that knowledge, and is strongly conditioned by the kinds of knowledge we are capable of manipulating. This is not a bug, it's exactly how physics is supposed to work-- physics is supposed to give us a means to talk about existence, and everything we get from physics comes as a result of our minds. There is no physics without physicists, and more, there was never supposed to be. That latter is what I believe Bohr meant by "there is no quantum world" and "physics concerns what we can say about nature."
None of this implies that our senses and brain do not have an effect on what we perceive, but that effect takes place within the construct that is the “whole” and within that “whole” there are rules that manifest themselves in terms of mechanisms that are purposeful and independent of cognitive thoughts.
The problem is when you try to get past the words "the whole", which are suitably vague to be talking about some pre-physics idea (what can be more basic than everything, the "whole"?), and try to get into specifics like talking about "rules." At that point you have left the realm of what we cannot talk about and entered the realm of what we can talk about (rules), which is exactly where you cross over from mind-independent thinking to mind-dependent thinking, and that brings us into contact with useful notions of our minds like rules and information. And if you want to start talking about what our minds are, you have the exact same issue-- you can start with words that don't say anything, like "a mind is whatever it is that connects with our ability to think", but the instant you take the next step, and give that definition some teeth by attributing elements to the mind, you have crossed over into what a mind can say about itself, and the tail chase is on.

Within our reality, (our “whole”) there seems to be purposeful things going on according to “rules”.
Again look at the inescapable anthropomorphisms. "Seems to be"-- seems to whom? To a rock? All we can say is that the "rules" concept is a good one to have in our minds, a useful notion, what more can we say, what more is there any need to say?

It is those “rules” that constitutes physics and we assign lots of interpretations to those “rules” (and thus I see physics as exploring the rules of our reality but not those of mind independent reality). But fundamentally, those “rules” are surely independent of the interpretations or of any cognitive process that fits the “rules” to our perception of things.
Why must the rules be independent of those interpretations? Consider the following "dense" student:
Professor: "gravity is a force that is inversely proportional to the distance to the center of the Earth."
Dense student: "Is that what it is exactly?"
Professor: "No, it's just a useful idealization, we have to make idealizations to do physics."
Dense student: "So what is gravity exactly?"
Professor: "Physics doesn't tell us that."
Dense student: "I don't understand, isn't physics where we get the notion of gravity? Experiment, hypothesis, theory, that whole scientific method business? So why can't it tell us what gravity is exactly, if it is responsible for the word?"
Professor: "Physics can tell us exactly what our approximate models are."
Dense student: "So gravity is a collection of approximate models, that physics tells us exactly what each particular model is?"
Professor: "Yes."
Dense student: "So gravity is a construct of our minds?"
Professor: "Um, well, er..."

There are “rules” that mean if we throw a ball, that same ball will come down.
Take that above dialog, and replace "gravity" with "ball", or with "come down." It's the same issue. "Reality obeys rules" is a statement of our minds that is gibberish without our minds. The ball, that we say is going up and coming down, has no idea what we are talking about.
 
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  • #69
jambaugh said:
... reading further. Ah!, Ballentine is a realist! He wants to preserve reality ... near the end of p361 "...in contract the statistical interpretation considers the a particle to always be at some position in space, each position being realized with relative frequency |\psi(r)|^2 in an ensemble of similarly prepared experiments."[/color]

I'll digest it and Ballentine's paper and get back to you.

Very perceptive. Yes indeed he is a realist, as am I. The ensemble interpretation is not a realist interpretation - it is strictly silent on it - you simply consider any observation as consisting of a preparation procedure then an observation with a very large number of preparations having the different possible observations associated with a preparation. You use the law of large numbers to ensure it is large enough so the proportion has reached a stable limit and what you observe is simply considered as selecting one of them. I hasten to add this does not make it a physical interpretation as someone tried to assert on philosophical grounds - that ensemble resides in one place only - the head of the theorist - the very large number you would need to guarantee the law of large numbers can not be replicated out there in reality.

The thing though with this interpretation is it whispers in your ear - there is more to this - there is some other factors at work that causes a particular element of that ensemble to be chosen and that would be a realist interpretation. Personally I believe some sub-quantum process does that (one candidate would be Primary State Diffusion advocated by Ian Percival although I don't think that's it - QM's secrets are probably not that easily won) but there are issues with the KS theorem that means that process is a theory that has QM as a limit but can't be QM. IMHO that's the reason Einstein liked it because he did not believe QM was fundamental - but Bohr did.

Anyway when you have finished it I would be really interested in what you think.

Oh - one thing I want to mention is I do not agree with Ballentine that other interpretations as bad as he makes out. I know Consistent Histories pretty well and a smattering of others - IMHO they all suck (including the Ensemble interpretation) in their own way and leave you dissatisfied - its just the way they suck is different for each interpretation. The way the Ensemble interpretation sucks is how does it chose the element from the ensemble - the way consistent histories sucks is it looks like you are defining you way out of the problem by saying you can't ask certain types of questions.

Thanks
Bill
 
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  • #70
Ken G said:
Dense student: "So what is gravity exactly?"
Professor: "Physics doesn't tell us that."
Dense student: "I don't understand, isn't physics where we get the notion of gravity? Experiment, hypothesis, theory, that whole scientific method business? So why can't it tell us what gravity is exactly, if it is responsible for the word?"
Professor: "Physics can tell us exactly what our approximate models are."
Dense student: "So gravity is a collection of approximate models, that physics tells us exactly what each particular model is?"
Professor: "Yes."
Dense student: "So gravity is a construct of our minds?"
Professor: "Um, well, er..."

I sort of follow this and yet I don't understand it. I mean there's a difference between unicorns and gravity. Unlike the former, "gravity" (the stuff/something that our model is referring to) affects rocks, humans, squirrels, planets, stars, galaxies, etc. I understand that our present model/theory of gravity is likely not final as we cannot foresee what a future theory of quantum gravity, etc. will be like, but our model is talking about some aspect of an observer independent reality; that is, the mathematical structure of the theory refers to or represents something that there is in the world independently of our theories.
 
  • #71
bohm2 said:
I sort of follow this and yet I don't understand it. I mean there's a difference between unicorns and gravity. Unlike the former, "gravity" (the stuff/something that our model is referring to) affects rocks, humans, squirrels, planets, stars, galaxies, etc. I understand that our present model/theory of gravity is likely not final as we cannot foresee what a future theory of quantum gravity, etc. will be like, but our model is talking about some aspect of an observer independent reality; that is, the mathematical structure of the theory refers to or represents something that there is in the world independently of our theories.

I would say that Ken G considers the mind to be the fundamental framework that encompasses our reality and provides a logical limit to what we can know through science (how can we step outside of the mind to examine its scientific place in “something”?)

So theories do not tell us anything scientific about mind independent reality, rather they can only tell us about consistencies within mind dependent reality. But I believe Ken takes this further – that even the elementary observation that excludes any kind of cognitive analysis of a rock falling to the ground is a product of the mind, the event has no scientific place within mind independent reality only a philosophical one.

I agree with all of that, but I stop short of what seems to me to be a stance of radical idealism. I’m not at all sure that this is a philosophically satisfactory stance; certainly Bernard d’Espagnat (his book “Veiled Reality”) puts forward philosophical arguments that suggest there is an external “something” to phenomena than just constructs of the mind. In this sense I find intersubjective agreement to be perplexing in terms of radical idealism along with the notion that within this stance knowledge comes before existence.

But the basic statement of Ken that says, the only thing we will ever have in our reality in which to establish “knowledge” is the mind, is quite stark and surely true. There appears no means, even in principle, of stepping outside of our minds, ever.
 
  • #72
bohm2 said:
I sort of follow this and yet I don't understand it. I mean there's a difference between unicorns and gravity. Unlike the former, "gravity" (the stuff/something that our model is referring to) affects rocks, humans, squirrels, planets, stars, galaxies, etc. I understand that our present model/theory of gravity is likely not final as we cannot foresee what a future theory of quantum gravity, etc. will be like, but our model is talking about some aspect of an observer independent reality; that is, the mathematical structure of the theory refers to or represents something that there is in the world independently of our theories.
It sounds like your definition of gravity would be something like "whatever it is that exists independently of our theories that makes our theories work." I'm fine with that, but note that this is not the way gravity gets used in physics. Gravity, in physics, is not whatever makes the theories work, it's just the theories, period. This is demonstrable-- we never test what makes the theories work, we test the theories.
 
  • #73
Len M said:
So theories do not tell us anything scientific about mind independent reality, rather they can only tell us about consistencies within mind dependent reality.
Yes, I couldn't have said it better.
But I believe Ken takes this further – that even the elementary observation that excludes any kind of cognitive analysis of a rock falling to the ground is a product of the mind, the event has no scientific place within mind independent reality only a philosophical one.
Yes, the "scientific place" is just what mind-dependent reality is, because the purpose of science is to replace (or represent) a mind-independent reality (if it is believed to exist) with a mind-dependent one (which is not a matter of belief, it is demonstrable).
I agree with all of that, but I stop short of what seems to me to be a stance of radical idealism. I’m not at all sure that this is a philosophically satisfactory stance; certainly Bernard d’Espagnat (his book “Veiled Reality”) puts forward philosophical arguments that suggest there is an external “something” to phenomena than just constructs of the mind.
I actually have no issue with the philosophical stance that there is some reality "out there" that we are interacting with when we form the scientific image of mind-dependent reality. I just don't think it matters to science whether or not such a thing exists, and none of the language of science refers to it. The confusion that comes up is that invariably people ask, "so you think there was no universe out there before humans came along?", but to that I simply say "you cannot make any sense of the phrase 'before humans came along' until you think like a human. So yes, I do think there was a universe out there before humans came along, and the reason I think that is because I think like a human, and so clearly everything I am talking about is the universe that humans think about, not some mind-independent version for which I cannot even define the words I'm using."

In this sense I find intersubjective agreement to be perplexing in terms of radical idealism along with the notion that within this stance knowledge comes before existence.
Yes, physics always leaves us with the question "why does this work at all?", including "why is there any such thing as objectivity or intersubjective agreement?" We don't know the answers to these, they might not even be questions that physics is capable of answering (just as no mathematical structure can be used to understand why its axioms are held to be true). I would say that all we can really say is that we know it does work, for what it works at, and we have no idea why, and even if we ever did get some idea why, it would not be a glimpse into mind-independent reality-- it would just be a deeper glimpse into mind-dependent reality, we would get some insight into how our minds work such that physics works, but we never escape the fact that all we get to know about reality is always the mind-dependent version. This is virtually tautologically true.
But the basic statement of Ken that says, the only thing we will ever have in our reality in which to establish “knowledge” is the mind, is quite stark and surely true. There appears no means, even in principle, of stepping outside of our minds, ever.
Exactly the issue. So instead of bemoaning that we cannot step outside our minds, or pretend that we can, we should simply embrace this truth, stop claiming physics is something it never was, and start accepting what it really is-- as Bohr said, it is what we can say about nature (using our minds).
 
  • #74
I think what you both (Ken G and Len M) are saying is obvious, as I said in other thread about this.

But the thing is that many people don't understand what you are saying at all. I have seen here people criticizing Ken G but showing that they did not understand what he is saying at all.
 
  • #75
Ken G said:
Exactly the issue. So instead of bemoaning that we cannot step outside our minds, or pretend that we can, we should simply embrace this truth, stop claiming physics is something it never was, and start accepting what it really is-- as Bohr said, it is what we can say about nature (using our minds).
I don't think a scientific realist will deny that our cognitive structures puts a limit on how we interpret the world and they do not deny the limitations of our mathematical models available to us to describe the world but I think there is disagreement with respect to this point below:
However, it is important to recognise that there is a very obvious difficulty with the thought that what can be said provides a constitutive contribution to what can be real and that physics correspondingly concerns what we can say about nature. Simply reflect that some explanation needs to be given of where the relevant constraints on what can be said come from. Surely there could be no other source for these constraints than the way the world actually is-it can't merely be a matter of language. It is because of the unbending nature of the world that we find the need to move, for example, from classical to quantum physics; that we find the need to revise our theories in the face of recalcitrant experience. Zeilinger and Bohr (in the quotation above) would thus seem to be putting the cart before the horse, to at least some degree. Schematically, it's the way the world is (independently of our attempted description or systematisation of it) that determines what can usefully be said about it, and that ultimately determines what sets of concepts will prove most appropriate in our scientific theorising. It is failure to recognise this simple truth that accounts, I suggest, for the otherwise glaring nonsequitur in the proposed answer to `Why the quantum?'...Of course, what statements can be made depends on what concepts we possess; and, trivially, in order to succeed in making a statement, one needs to obey the appropriate linguistic rules. But the point at issue is what can make one set of concepts more fit for our scientific theorising than another? For example, why do we have to replace commuting classical physical quantities with non-commuting quantum observables?
Information, Immaterialism, Instrumentalism: Old and New in Quantum Information
http://users.ox.ac.uk/~bras2317/iii_2.pdf
 
  • #76
mattt said:
I think what you both (Ken G and Len M) are saying is obvious, as I said in other thread about this.

But the thing is that many people don't understand what you are saying at all. I have seen here people criticizing Ken G but showing that they did not understand what he is saying at all.
Yes, I think that's all true. The point itself is obvious, but its ramifications are not. Some complain about the point because they reject the ramifications, but it is often because they leap too far into thinking what it implies. Two examples are, the common claims that if all physics language is mind-dependent, then we shouldn't be able to talk about the universe before there were minds (we are only now making sense of what came before), or that we could not all agree on the laws if they weren't independent of us (we are all quite similar, so why wouldn't we agree on laws that come from how we look at things?). So it is the objections based on false ramifications that fall through, not the claims themselves.
 
  • #77
bohm2 said:
I don't think a scientific realist will deny that our cognitive structures puts a limit on how we interpret the world and they do not deny the limitations of our mathematical models available to us to describe the world but I think there is disagreement with respect to this point below:
That argument is a classic example of what I am talking about. They claim to be refuting the idea that physics is entirely 100% what we can say about nature and nothing more, even though it is, by saying that if physics wasn't about something else, it couldn't work. There is no basis for that argument at all. We have no idea why physics works, and hence we also have no idea when it wouldn't work.
 
  • #78
Vectronix said:
Hi :)

I recently read a book that states that most scientists believe the wave function represents a real field (i.e., one that possesses energy and momentum). I think this is part of the transactional interpretation of QM but not sure... can anyone confirm whether the book I read is right about this or not?
Afaik, the conventional/mainstream interpretation of QM is that it's a probabilty calculus. That is, it's a mathematical system designed to calculate the probabilities of instrumental results. It's not a description of reality. And doesn't necessarily inform wrt what's going on wrt the behavior in realms that aren't amenable to our normal sensory apprehension.
 
  • #79
ThomasT said:
Afaik, the conventional/mainstream interpretation of QM is that it's a probabilty calculus. That is, it's a mathematical system designed to calculate the probabilities of instrumental results. It's not a description of reality. And doesn't necessarily inform wrt what's going on wrt the behavior in realms that aren't amenable to our normal sensory apprehension.
What's more, the same statement can be made about all of physics-- there's nothing about quantum mechanics that makes it more true than it always was. Quantum mechanics is simply the place where we are forced to part with our illusions to the contrary. What gets me is, I simply don't see any reason why anyone would hesitate to see physics for exactly what it is, what it does, and what is demonstrable about it. From where comes the need for pretense it is something else? Do the equations work differently if we pretend they correspond to some reality that physics is probing, other than the reality that emerges when we use our minds and senses? What is mind-independent, or sensory-independent, about that interaction? What is mind-independent, or sensory-independent, about anything in physics at all?

What's more, I don't see it as some kind of "bitter pill" to recognize that physics is something we humans participate in. Indeed, quite the contrary-- I think it is quite freeing to recognize that, and I suspect it will be more and more important, going forward into future theories, to continue to bear this in mind. The naivete of the "fly on the wall" physicist is gone forever from our most fundamental theories, vive la difference.
 
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  • #80
Ken G said:
What's more, the same statement can be made about all of physics-- there's nothing about quantum mechanics that makes it more true than it always was. Quantum mechanics is simply the place where we are forced to part with our illusions to the contrary. What gets me is, I simply don't see any reason why anyone would hesitate to see physics for exactly what it is, what it does, and what is demonstrable about it. From where comes the need for pretense it is something else? Do the equations work differently if we pretend they correspond to some reality that physics is probing, other than the reality that emerges when we use our minds and senses? What is mind-independent, or sensory-independent, about that interaction? What is mind-independent, or sensory-independent, about anything in physics at all?

What's more, I don't see it as some kind of "bitter pill" to recognize that physics is something we humans participate in. Indeed, quite the contrary-- I think it is quite freeing to recognize that, and I suspect it will be more and more important, going forward into future theories, to continue to bear this in mind. The naivete of the "fly on the wall" physicist is gone forever from our most fundamental theories, vive la difference.

One (social) concern is to clearly make this point in a way that it cannot be confused by persons not appreciating the issues of the question, who would highjack the authority of science to rationalize their wish-fulfilling mystical beliefs. In short we don't want the magicians saying "See this proves ESP and 'mind over matter' "!

Of course this is an absurd misinterpretation but there are no limits to human absurdity, e.g. http://www.churchofquantumconsciousness.com
 
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  • #81
apeiron said:
What's more, the same statement can be made about all of physics-- there's nothing about quantum mechanics that makes it more true than it always was. Quantum mechanics is simply the place where we are forced to part with our illusions to the contrary.
I hadn't ever thought of it like that. But it makes sense. Ie., due to QM we're forced to face the apparent fact that the mathematical theories aren't precisely corresponding to the qualitative characteristics of an underlying reality. And this goes for classical as well as quantum physics.

apeiron said:
What gets me is, I simply don't see any reason why anyone would hesitate to see physics for exactly what it is, what it does, and what is demonstrable about it. From where comes the need for pretense it is something else?
I suppose that's attributable to some scale/regime specific stuff that QM isn't designed to deal with. That is, human nature.
 
  • #82
jambaugh said:
One (social) concern is to clearly make this point in a way that it cannot be confused by persons not appreciating the issues of the question, who would highjack the authority of science to rationalize their wish-fulfilling mystical beliefs. In short we don't want the magicians saying "See this proves ESP and 'mind over matter' "!

Of course this is an absurd misinterpretation but there are no limits to human absurdity, e.g. http://www.churchofquantumconsciousness.com
This is a good point also, imho. Because people do sometimes, quite incorrectly, misinterpret and adopt stuff from quantum theory to support their social agendas.
 
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  • #83
ThomasT said:
I hadn't ever thought of it like that. But it makes sense. Ie., due to QM we're forced to face the apparent fact that the mathematical theories aren't precisely corresponding to the qualitative characteristics of an underlying reality. And this goes for classical as well as quantum physics.

By qualitative, I'm guessing here you mean intrinsic? If you are, I think I agree but was it any different in classical physics? I think an argument can be given that we were always ignorant of the intrinsic properties of matter. I think this is the point that Russell, Eddington and Stoljar, more recently, has argued; that is, physics can tell us only about the dispositional or relational properties of matter, but since dispositions ultimately require categorical properties as bases, and relations ultimately require intrinsic properties as relata, there must also be categorical or intrinsic properties about which physics is silent. Or so goes the argument. As Van Fraassen points out:
If all the ‘observable’ (in the physicist’s sense) properties of an object can be represented in structural terms, then what is the nature of the ontological residuum?...If there is something to nature besides its structure, but structure is all that science describes or can describe, then what is that something, that undescribed and indescribable something...? But what sense does it make to try and conceive of structure that is not structure of something? Structure of nothing is nothing, isn’t that so?
Structuralism(s) about science: some common problems.
http://onlinelibrary.wiley.com/doi/10.1111/j.1467-8349.2007.00150.x/pdf

So our model of "electrons" presumably is not be based on any sort of direct access to the particle’s intrinsic nature, but rather must be based on information about the particle’s behavior, reflected in the overall configuration of the particles (Jeremy Butterfield). But I still don't think this necessitates an anti-realist view (e.g. that the world does not exist independently of the human mind). For example, chemical facts that were not necessitated by physical facts in the past turned out later to be frustrated by then unknown physical facts (e.g. unification of chemistry with physics didn`t happen until the physics changed via quantum mechanics and then everything made more sense).
 
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  • #84
jambaugh said:
... reading further. Ah!, Ballentine is a realist! He wants to preserve reality ... near the end of p361 "...in contract the statistical interpretation considers the a particle to always be at some position in space, each position being realized with relative frequency |\psi(r)|^2 in an ensemble of similarly prepared experiments."[/color]

Well, it seems to me that one of the points of Bell's analysis of the twin-particle version of the EPR experiment is that a realistic interpretation of that kind is not so easy to make coherent. In the case of position, you can consistently believe that a particle has a position at every moment, but you just don't know what it is. But in the case of spin, is it consistent to believe that the particle simultaneously has a spin in the x-direction, the y-direction and the z-direction, but you just don't know what it is? It seems to me that Bell's argument shows that it's not consistent to believe that (and also believe in locality).
 
  • #85
bohm2 said:
By qualitative, I'm guessing here you mean intrinsic?
By qualitative I mean an apprehension of what's happening wrt our sensory capabilities (this is what understanding refers to). I'm not sure what intrinsic means.

bohm2 said:
If you are, I think I agree but was it any different in classical physics?
No, but it was the disparity between quantum experimental phenomena and the visualizability of the mathematics that accounted for it that made us realize that we really don't, and perhaps can't, maybe ever, have an accurate qualitative apprehension of the reality underlying instrumental behavior.

bohm2 said:
I think an argument can be given that we were always ignorant of the intrinsic properties of matter.
I don't think in terms of intrinsic properties of matter.

bohm2 said:
I think this is the point that Russell, Eddington and Stoljar, more recently, has argued; that is, physics can tell us only about the dispositional or relational properties of matter, but since dispositions ultimately require categorical properties as bases, and relations ultimately require intrinsic properties as relata, there must also be categorical or intrinsic properties about which physics is silent. Or so goes the argument. As Van Fraassen points out:

Structuralism(s) about science: some common problems.
http://onlinelibrary.wiley.com/doi/10.1111/j.1467-8349.2007.00150.x/pdf

So our model of "electrons" presumably is not be based on any sort of direct access to the particle’s intrinsic nature, but rather must be based on information about the particle’s behavior, reflected in the overall configuration of the particles (Jeremy Butterfield). But I still don't think this necessitates an anti-realist view (e.g. that the world does not exist independently of the human mind). For example, chemical facts that were not necessitated by physical facts in the past turned out later to be frustrated by then unknown physical facts (e.g. unification of chemistry with physics didn`t happen until the physics changed via quantum mechanics and then everything made more sense).
I wouldn't say that thinking that the world exists independently of the human mind characterizes the realist view. It seems to me that all physical sciences, including quantum physics, assume that the world exists independently of the human mind. But standard quantum theory is certainly not realistic. Is it?
 
  • #86
ThomasT said:
I'm not sure what intrinsic means.

A simple and obvious example is subjectivity/inner experience/qualia. We all seem to have special "access" to it that we have to nothing else. No matter how detailed the physics/molecular biology/neuroscience gets, even if we knew all the neural correlates of consciousness, a scientist will never be able to see/feel/experience/know your thoughts/inner experience/phenomenology. So it's argued that a brain (as presently understood) is not a mind, although the former seems to provide the structure/mechanisms for the latter. The same argument goes with other "material" objects in physics. Russell writes:
Physics is mathematical, not because we know so much about the 'physical world’ (and here he means the non-mental, non-experiential world) but because we know so little: it is only its mathematical properties that we can discover. For the rest, our knowledge is negative...The physical world is only known as regards certain abstract features of its space-time structure — features which, because of their abstractness, do not suffice to show whether the physical world is, or is not, different in intrinsic character from the world of mind.
 
  • #87
I can not even prove there are other "minds" out there besides my own "mind".

I know I can think/feel/perceive and have to suppose other "things" I perceive as "people" can think/feel/perceive as well, that "they" have a "mind" too.

So if I can not prove that there are other minds out there, neither I can prove there are "anything independent of my mind" (whatever it may mean).

But be it whatever it may be, the thing is that I have perception/sensory inputs, and all Science do is to organize rationally all that "sensory/experimental data" avoiding innecesary dogmas.

Be aware that all that perception/sensory data that I know I have, could be made by some kind of Matrix (you know, the film). In that case, all Science do again is to organize rationally all that "sensory/experimental data" avoiding innecesay dogmas, so that I can have the only one rational and consistent organization of all that data, even if the "world" that data "produce" is the one Matrix show me (and could have nothing to do with "the other world outside Matrix").

So ALL I could ever say about "this world" is "mind-dependent" in exactly that sense.

If all these galaxies, planets, physics, all I can perceive and think of, is "the world Matrix shows me" or just any other thing altogether, is a metaphysical question that Science can not treat.

But again, be it whatever ("trascendentally or mind-independent") it may be, Science is the only rational and consistent way of organizing all the perception/sensory data that constitute my "mind-dependent world" (the only one I will ever have access to).

EDIT: I am just learning English, so probably I didn't use the proper words to express what I wanted.
 
  • #88
jambaugh said:
One (social) concern is to clearly make this point in a way that it cannot be confused by persons not appreciating the issues of the question, who would highjack the authority of science to rationalize their wish-fulfilling mystical beliefs. In short we don't want the magicians saying "See this proves ESP and 'mind over matter' "!

Of course this is an absurd misinterpretation but there are no limits to human absurdity, e.g. http://www.churchofquantumconsciousness.com
Yes, that is a difficult distinction to make for people who are used to black-and-white thinking (either empirical science is the final truth or truth can be anything I want it to be, so any cool person in the armor of the first is an excuse for the second!). Frankly, I don't really care what anyone chooses to believe if it jazzes them to do so, but I do feel sorry for people looking for guidance about where to put their faith such that it will generate empirical returns! To them I just say, if you want empirically meaningful outcomes, stick to empirically established evidence. If you just think something is "cool" to believe, it's a free country.
 
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  • #89
ThomasT said:
I hadn't ever thought of it like that. But it makes sense. Ie., due to QM we're forced to face the apparent fact that the mathematical theories aren't precisely corresponding to the qualitative characteristics of an underlying reality. And this goes for classical as well as quantum physics.
I think that was actually me you quoted, and I agree with you-- the relationship between mathematics and reality is even harder to understand than the relationship between physics and reality! Physics is fairly straightforward-- we make observations and build mathematical models that make sense of how we interact with what we are observing. But what then is the meaning of a mathematical proof, and why do we care what can be proven rather than what can be tested? It's a place to get into the Godel theorems.
 
  • #90
Ken G said:
[...] Frankly, I don't really care what anyone chooses to believe if it jazzes them to do so, but I do feel sorry for people looking for guidance about where to put their faith such that it will generate empirical returns! To them I just say, if you want empirically meaningful outcomes, stick to empirically established evidence. If you just think something is "cool" to believe, it's a free country.

Yea, freedom is necessarily freedom to make mistakes. And I'm just as ambivalent about what others choose to believe privately. What gets my goat is public misrepresentations about what science says. I've cringed and yelled too many times when Sci. Fi. show X has the line "Quantum theory predicts __[insert nonsense here]__". Yes I know its a plot device and its just TV. BUT the same people who hear this nonsense and buys it, vote for representatives who control e.g. research appropriations, and education funding, and curriculum policy in public schools. When people either believe the nonsense, or knowing its nonsense believe that legitimate scientists believe the nonsense, then this will affect their social and political behavior. There's a growing movement away from the trust in science that we had in the 40's 50's and into the 60's. A rise in belief in mystic nonsense and confusion about what science actually is. I see a "proper" interpretation of QM as the culmination of true science (and what I consider "silly nonsense interpretations" as total anti-scientific mysticism). But the lesson is lost in the drone of nonsense.

Well I'm ranting and I'll cease. It's the teacher in me, both the desire to lecture and the lament at a lost opportunity for people to understand.
 

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