Against Realism: Examining the Meaning of Local Realism

[DrChinese]

"Against" Realism

Travis Norsen has written an article entitled "Against Realism". In it, he argues that the phrase "local realism" is not meaningful.

Against Realism (2006)

Abstract:
"We examine the prevalent use of the phrase “local realism” in the context of Bell’s Theorem and associated experiments, with a focus on the question: what exactly is the “realism” in “local realism” supposed to mean? Carefully surveying several possible meanings, we argue that all of them are flawed in one way or another as attempts to point out a second premise (in addition to locality) on which the Bell inequalities rest, and (hence) which might be rejected in the face of empirical data violating the inequalities. We thus suggest that this vague and abused phrase “local realism” should be banned from future discussions of these issues, and urge physicists to revisit the foundational questions behind Bell’s Theorem."

-----

My questions for your consideration:

1. What does realism mean to you?

2. Einstein said: "I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured. I like to think that the moon is there even if I am not looking at it." Is this realism?

3. In your opinion, is "realism" an assumption of Bell's Theorem? If so, where does it arise?

 

[Careful]

My questions for your consideration:

1. What does realism mean to you?

2. Einstein said: "I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured. I like to think that the moon is there even if I am not looking at it." Is this realism?

3. In your opinion, is "realism" an assumption of Bell's Theorem? If so, where does it arise?

Me stupid realist think that such papers are silly. For me realism means the existence of an external world, independent of observation in which correlations between two events are due to processes which satisfy local equations of motion. Einsteins quote is an example of how a realist proposes a model of the world, although it might very well be that particles are not the fundamental degrees of freedom. But I like to think the moon is also there, even if we do not see it. Realism is *not* an assumption of Bell per se, there is a very specific form of realism present (for example, Bell excludes extra dimensions which could be used to define a holographic principle) which together with the screening off condition (which is not a logical consequence of locality) leads to a conflict with the *measurement* postulate of quantum mechanics. There are at least four well known local mechanisms which violate the ``logic'' in this paper : holography, polarizable media, negative ``probabilities'', predeterminsim. That is all the objective content there is to this discussion in my mind. Barely enough to fill an abstract with...

Since you dr Chinese, seem to be so adsorbed with Bell inequalities, why don't you learn a bit more about those approaches which might violate them. You like these negative probabilities and actually I do too : Feynman, Dirac and others have written beautiful papers about this subject in the context of the meaning of quantum mechanics. Feynman once said that ``the only difference between quantum and classical mechanics seems to be that probabilities can go into the negative''. Feynman never doubted the validity of ``traditional'' QM (Schrodinger wave + 100 percent measurement accuracy) but kept on searching for local computer models, very much the right spirit in my mind.

Careful

 

[chronon]

I agree with the paper that the term 'realism' in 'local realism' is pretty much meaningless. See http://www.chronon.org/Articles/localreal.html

 

[Hurkyl]

Me stupid realist think that such papers are silly. For me realism means the existence of an external world, independent of observation in which correlations between two events are due to processes which satisfy local equations of motion.

This is just local hidden variables, is it not? Each point in space-time has some parameters "attached" to it, the outcome of any measurement performed in a region can be completely determined by the values of the parameters appearing within the region, and the value of a parameter at any particular point is completely determined by the values of the parameters in any cross-section of its past light-cone. Is that a fair assessment?

 

[Careful]

This is just local hidden variables, is it not? Each point in space-time has some parameters "attached" to it, the outcome of any measurement performed in a region can be completely determined by the values of the parameters appearing within the region, and the value of a parameter at any particular point is completely determined by the values of the parameters in any cross-section of its past light-cone. Is that a fair assessment?

I would think about this in the first place, but as I explained hundred's of times, that does not imply screening off, non local correlations can be there, neither does it imply dichotomic outcomes, it allows for all possibilities I mentioned previously. One could also allow for laws where the value of x now depends on its nearest elements in the future, that would still be a local spacetime theory. So, it seems to me that the arrow realism -> nonlocality is not logically possible. This is the last thing I say about this unless you have some objections since all this kind of philosophy is turning my stomach. Physics for me is a game of playing around with possible scenario's until the puzzle fits, in such state of mind expressing one's religion leaves a rather silly impression.

 

[selfAdjoint]

For me realism means the existence of an external world, independent of observation in which correlations between two events are due to processes which satisfy local equations of motion.

And that's umm, how many independent premises?
1. External world
2. Independent of observation
3 Correlations due... to equations of motion.

Note that one can hold 3 (quantum equations being specified), without holding 1 or 2. Likewise it's possible to conceive an external world that is contingent on observation (close to Hume's position), or on one in which observation can not give us truly reliable information (not too far from Kant).

Any one or all of these must be considered independently in evaluating quantum correlations, especially in the Bell context, and I agree with the essay that a fast shuffle between them is characteristic of many who would argue from Bell against standard QM (whether Copenhagen, MWI or whatever interpretaion is used). One could illustrate with many past posts on this forum.

Generally speaking, I believe "external reality" is not an operationally meaningful concept. Has anybody seen an experiment that rules out solipsism?

 

[Careful]

Generally speaking, I believe "external reality" is not an operationally meaningful concept. Has anybody seen an experiment that rules out solipsism?

Has anybody seen an experiment to test the premise that I have 100 ghostlike unmaterial eyes which are hanging in China and Japan which unfortunately do not send any signals to my brain (so there is no way to interrogate me to check if I can see beyond my room or not)? SelfAdjoint, honestly, do you not find such kind of reasoning a bit silly ? There have been written plenty of texts by good physicists which explain the necessity of an objective reality as a necessary condition for science to be possible. I still have to wait for the first great physicist to say something positive about solipsism, do not confuse philosophers of physics with physicists. I agree with Norsen concerning the need for realism, I think to have shown on many occasions that it does not exclude a well defined form of local realism. Therefore, I conclude that if his aim is to disprove locality, then well yeh ... on the other hand, it is good that some terminology is settled, although his conclusions about many scientists not knowing what they are talking about when they speak about reality seem to be unfair to say the least.

Careful

 

[RandallB]

As he uses “Metaphysical” it strikes me as redundant and could more easily be disposed of than realism. All forms useful forms of realism should reject the imaginary realism of solipsism.
Also Travis asks we change how we use the word so why didn’t her offer a specific list of how he would see that change being made.

As to 1.) What does realism mean to me
Looks like Naive would describe me best.

2) Einstein’s real means real
Yes I think that is true – otherwise science would need to try show the Dail Lama could reach total spiritual enlighten and discard and destroy reality as he imagined it and then explain what would happen to the reality imaged by those of us remaining – too bizarre for me.

3) "realism" in Bell's Theorem - where does it arise
Maybe you can say that bell addresses a specific type of realism “local realism” of localility. And as it seems to show it may not be true that a different form of realism or reality other than what my farm boy common sense insists on believing in.
Several different theories or kinds of reality are proposed:
BM reality: where Local equations of motion solve bell by using the guidance of a guide wave traveling unseen in an extra dimension(s) or space overlapping our own “Local Reality”.
WMI reality: What ever wider reality & dimensions as needed to solve the paradox.
QM reality: With uncertain probabilistic outcomes linked though superposition the original alternate form of reality.
How many are there?

But Bell can only shed light on the (Naive) Local Realism vs. all other forms Realism some with there own version of local (guide wave, extra dimensions, collapse of entanglement, etc.).
But I don’t think Bell can help show or select which of the Non-Naive versions is correct. Leaving it to each version to find another experiment to decide between non-local ideas.

Here is an option - if we look around and find that Einstein Unknown Variable we could kick them all and go with the Naive Realisim instead. Help me out and take a look under your desk anything hidden there?
If not I’ll have to keep looking.

 

[selfAdjoint]

Has anybody seen an experiment to test the premise that I have 100 ghostlike unmaterial eyes which are hanging in China and Japan which unfortunately do not send any signals to my brain (so there is no way to interrogate me to check if I can see beyond my room or not)? SelfAdjoint, honestly, do you not find such kind of reasoning a bit silly ? There have been written plenty of texts by good physicists which explain the necessity of an objective reality as a necessary condition for science to be possible. I still have to wait for the first great physicist to say something positive about solipsism, do not confuse philosophers of physics with physicists. I agree with Norsen concerning the need for realism, I think to have shown on many occasions that it does not exclude a well defined form of local realism. Therefore, I conclude that if his aim is to disprove locality, then well yeh ... on the other hand, it is good that some terminology is settled, although his conclusions about many scientists not knowing what they are talking about when they speak about reality seem to be unfair to say the least.

Careful

And you can cite thousands of experts on the necessity of believing in this or that religion for a coherent life. So what? Nullius in Verba stands at the head of our modern understanding of how to do science. Patrick Vanesch calls relational QM a form of solipsism, yet there are respected physicists who adopt it. It's just opinion.

My statement that external reality is not an operationally defined concept was intended to suggest that it cannot be meaningfully employed in discussing physics, because there is no objective way to decide which of two definitions is preferrable. And that is what I see working in all the hundreds of posts that have been put up here in all the many threads on Bell, locality and interpretation. It isn't science, it isn't even well constructed philosophy!

 

[Careful]

** Patrick Vanesch calls relational QM a form of solipsism, yet there are respected physicists who adopt it. It's just opinion. **

And I agreed with this assesement (actually I made it myself PRIOR to Patrick's intervention), but I also remember from the discussion with f-h that these respected physicists are indeed worried about the lack of synchronisation as they should be. You might want to read what E.T. Jaynes had to say about MWI, he simply said that ``theoretical physics went bezerk''. It is not opinion, an overwhelming majority does not even want to speak about it.

**
My statement that external reality is not an operationally defined concept was intended to suggest that it cannot be meaningfully employed in discussing physics, because there is no objective way to decide which of two definitions is preferrable. **

Rubbish, first of all your operational definition of measurement requires something you cannot capture at all, nobody agrees upon what consciousness is ! In science, you always have to make a definition no matter how you turn or twist the pig. If no such agreement can be made, then you can better close the books and go into politics.

** And that is what I see working in all the hundreds of posts that have been put up here in all the many threads on Bell, locality and interpretation. **

Do you really think that practising scientists care about this ?!
I know of people who think hard about these matters (and that is already not very standard), but none of them would come up with solipsism as it is presented here. 95 percent, in my experience, takes a very pragmatic approach towards this, and with good reason.

** It isn't science, it isn't even well constructed philosophy! **

My god, so you are denying 2000 years of scientific practice ? I am afraid you have been too long amongst ``philosophers'' of science.

By the way if you live by the motto ``on basis of experiments we establish ``truth'' but not on the basis of words of anyone'' well SelfAdjoint, don't forget then that
(a) science is not about the truth, that does not exist. Science is about making a good model of nature in which all factors involved are well defined and fair predictions about the future can be made.
(b) no model should contain any assumption which in principle cannot be falsified by the very instrument of science itself.

Consciouness does not fall under (b), a theory which declares what is real belongs to the material world in principle does.
As I said, you are involved in philsophy of science as we understand it today. The problem with philosophers of science is that they usually do not know the internal dynamics of science where a world view is connected with the boundaries of our understanding. Your philosophy is an unheatlhy extrapolation from the mathematical framework of QM : an extrapolation which shows that any ``believer'' is prepared to acknowledge that he/she did not understand anything about it and is moreover not going to look for anything better ; it is the task of science to take mystery away from things. For example : you are proclaiming the relational point of view (which does contain some serious problems); if you once yourself calculated a solution of Brans Dicke theory or something similar and then imagine the trouble you would have to go through in making such theory a logical theory of relational quantum propositions, to realize in the end that you are stuck with two different notions of time, things like self measuring devices and so on to make your reasoning selfconsistent then I am sure you would pretty quickly pack your bags and try something more realistic to start with.

But again, nothing but philosophical comments, where is the real science ?

Careful

 

[Hurkyl]

This is the last thing I say about this unless you have some objections since all this kind of philosophy is turning my stomach.

Well, the problem is that you haven't answered my question at all. I was trying to translate what you wrote into something more precise, so I could see if what I think you're saying is what you think you're saying.

One could also allow for laws where the value of x now depends on its nearest elements in the future, that would still be a local spacetime theory.

Okay; let's throw in the entire past and future lightcones for simplicity, then discuss particulars when we decide it matters.

 

[Careful]

** Well, the problem is that you haven't answered my question at all. I was trying to translate what you wrote into something more precise, so I could see if what I think you're saying is what you think you're saying. **

:uhh: I *literally* said that your definition of local realism is *fine*, although some alterations could be made (such as taking into account some part of the future), so that makes one wonder why you consider this as no answer at all. Your definition was in no sense more precise (!), you keep on confusing writing clear ideas in a mathematical language as a significant contribution. What I just said, you can all find in Franco Selleri ``The EPR paradox'' chapter 5 : proposed solutions (although he would call holographic solutions ``non local'', better would be apparently non local). In contrast to what some think, rigorous definitions of local realism *have* been made long time ago... Clearly adding some part of the future helps, since then Bob can send a signal to the future of Alice with the result of his measurement and vice versa, but that would be non local, but causal. Some holographic principle is clearly local and solves the issue, it is just that events which are far away on the ``base manifold'' can be arbitrary close together in the extra conal dimension (actually this idea is ``cleaner'' than the wormhole suggestion since you have no problems whatsoever here with defining a global arrow of time), etc... Now, you might want to read this chapter prior to making any further comments on what I said, which is the respectable thing to do. In contrast to some, I am not going to say after you read this, that you might be drawing your conclusions on a paper uttering some simple ideas since at least the physical context is very clear in this book (which should be studied by anyone in that field in my opinion) - Selleri is a first class scientist. EDIT : it needs to be said that the idea of negative probabilities would deserve more attention, a good survey paper on this is ``A review of extended probabilities'' Physical reports, 133, No 6 (1986), pages 337-401.

Careful

 

[RandallB]

(a) science is not about the truth, that does not exist. Science is about making a good model of nature in which all factors involved are well defined and fair predictions about the future can be made.
(b) no model should contain any assumption which in principle cannot be falsified by the very instrument of science itself.

Consciouness does not fall under (b), a theory which declares what is real belongs to the material world in principle does.

I like these; concise and to the point, descriptions.
Do they come from the Selleri (and Afriat) book “The Einstein, Podolsky, and Rosen paradox” you mentioned.
Or do you have another source for them – I ‘d like to read the whole of the ideas around them.

 

[Careful]

I like these; concise and to the point, descriptions.
Do they come from the Selleri (and Afriat) book “The Einstein, Podolsky, and Rosen paradox” you mentioned.
Or do you have another source for them – I ‘d like to read the whole of the ideas around them.

No, they come from me, it is in my blood (and I am dead serious about it) But if you insist, the introduction of the latter book contains some spicy remarks about the sociology of science. However, I all find this a bit sad, you know ... (a) first people say ``you cannot violate the Bell inequalities´´ then (b) when you point out it can be done, it is against their religion. The book of Selleri and Afriat is a true masterpiece of objectivity in science (and very informative as well), he is even slightly critical towards other well known realists. It contains as I seem to remember also a section about *single event* interpretations of the Heisenberg principle and a brief summary of proposed tests to violate it. I would recommend anyone interested in physics to buy it, even if it were just to broaden your horizon and to remain open to the possibility that local realism (or something close to it, like the value of a field in one spacetime point being determined by the field content in some finite part of the future and past lightcones) can return.

However, it does not contain any full solution to the paradox which is satisfactory *in my mind* and which has been shown to reproduce all QM effects (although one can be hopeful). Merely it outlines and explains well the ideas behind the different proposals for the solution of the latter and provides enough useful references.

Careful

 

[Rade]

...What does realism mean to you?...

Reality is that which exists. How humans know it or not is another matter--IMO.

 

[simon009988]

1. What does realism mean to you?
Realisim to me is what your mind percieves.


2. Einstein said: "I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured. I like to think that the moon is there even if I am not looking at it." Is this realism?

This is pure supernatural and cannot be measured in any way, therefore not reality.

 

[Careful]

** 1. What does realism mean to you?
Realisim to me is what your mind percieves. **

So, what is your mind and what is perception ? By what mechanism does your mind operate ?

**
2. Einstein said: "I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured. I like to think that the moon is there even if I am not looking at it." Is this realism? **

This is a form of realism.

** This is pure supernatural and cannot be measured in any way, therefore not reality. **

Sure it can be measured, but not in the way you imagine measurement.
So, your mind measures your mind he and stones, ants and so on have this precious commodity too. Basically, it occurs to me you are denying the practise of physics. How was an electron observed ? By following the presumed track in a bubble chamber one says ``this track was formed by the electron which passed here´´. So, one assumes the electron passed there even if no one had seen it ! We speak about particles, since pictures coming from scattering experiments suggest us such interpretation because we see something *was* there prior to our minds measuring circumstantial evidence for it.

Careful

 

[Hurkyl]

Careful,

You can't communicate very well unless the person speaking and the person listening both think the same thing was said. It happens often that two people will see the exact same words and come away with entirely different opinions about what they said.

I *literally* said that your definition of local realism is *fine*

For example, after reading this, I would have expected there to be, in your original post, a phrase that resembled "your definition of local realism is fine"... or at the very least, expected to see the word "fine".

writing clear ideas

The clarity of an idea is, of course, a subjective notion. And even if the idea is clear, the writing of the idea may not. After all, "yes" is rather clear, yet you managed to write five long sentences in post #5 without managing to convey it to me.

And the converse is true...

you keep on confusing writing clear ideas in a mathematical language as a significant contribution.
...
making any further comments on what I said
...
you might be drawing your conclusions

I was simply trying to figure out what you were saying, while trying very carefully not to "make comments" or to "draw conclusions" -- and making a "significant contribution" was the furthest thing from my mind. But, I did not manage to convey that to you.

I translated into the "mathematical language" because, IMHO, there's less "wiggle room" for conflicting interpretations -- and also because it's a generally more objective language. If we can agree on a mathematical translation, then I would have high confidence that what I think you said matches what you think you said.

But if you would rather be misinterpreted... then you can't complain when it happens.

 

[Careful]

***
I translated into the "mathematical language" because, IMHO, there's less "wiggle room" for conflicting interpretations -- and also because it's a generally more objective language. If we can agree on a mathematical translation, then I would have high confidence that what I think you said matches what you think you said.

But if you would rather be misinterpreted... then you can't complain when it happens. **

Thanks for clearing that out - I will simply add references each time I make an apparently ``strange'' statement. The reason why I gave you a broader answer in my first reply is because local realism (and physics in general) is not something static for me. If I restrict myself to your more or less traditional specification then I am cornered into the four options I mentioned (or you can also declare the measurement loophole to be fundamental); on the other hand, there has always been this interesting possibility of using advanced Green functions ... What I want to tell you is that physics consists of having mechanisms in your mind, imagining yourself how stuff works ; since quantum mechanics makes this difficult for you, the first thing to do is to clear out the latter. I have never been ``pro string theory'' but self Adjoint recently mentioned that he thought to have heard that within ST a non supersymmetric fermi model had been constructed, now that would be interesting physics. We still don't understand yet our first elementary particle (electron models are a recurrent theme in the literature - especially in the 70 ties and 80 ties, some considerable effort was put into that).

Careful

 

[vanesch]

By the way if you live by the motto ``on basis of experiments we establish ``truth'' but not on the basis of words of anyone'' well SelfAdjoint, don't forget then that
(a) science is not about the truth, that does not exist. Science is about making a good model of nature in which all factors involved are well defined and fair predictions about the future can be made.
(b) no model should contain any assumption which in principle cannot be falsified by the very instrument of science itself.

In as much as (a) is a very profound statement, you should apply it entirely logically until the end. I agree with (a), with maybe one small modification: I'm not even sure we can say that "truth doesn't exist", only, that "truth isn't accessible", and we leave in the middle whether truth exists or not. We simply know with certainty that we won't know it with certainty. The realisation of this philosophically elementary fact does - IMO - a lot of good to any of these sometimes heated discussions


And in fact it is entirely the point I'm often making: don't think that what we scientifically "knew" 400 years ago, today, or 400 years from now, has much to do with "truth". It is all about, as stated, making a model of observational data. However, in as much as this model has some logical consistency, it also has its *Platonic*, conceptual existence. As such, I don't agree at all with (b), which I find a totally arbitrary requirement. The only goal of the model is to make a model of observational data. What elements are used to set up such a model is entirely free, I'd say. Of course there can be *preferences* and Occam's rasor is a good guide: two models which are empirically equivalent, but one which has some extra elements which the other doesn't need, might be preferentially rejected in favor of the "simpler" one. But again, this is just a guiding principle, not a strict requirement.

Given that we have no access to "truth", but only to observational data, the best we can ever do is to think up (one or several) models which can explain these observational data. It would be nice too, if these models were logically consistent. But as to what a model should contain, and not, is, IMO, purely a matter of taste. It needs to work, it needs to make correct empirical predictions, it needs to be logically consistent and that's it.

As was pointed out (and as is philosophically also known) is that solipsism is irrefutable (but also not very productive as a starting point). That means that whatever you take as "reality", it is a hypothesis, and nothing more. You can never *prove* any reality, so it is always a hypothesis.
So with the word "reality" always comes a hypothesis.

As to 1.) What does realism mean to me
Looks like Naive would describe me best.

This is correct: the "realism" one is talking about here is what's philosophically called "naive realism" (but without any pejorative meaning to "naive"). It simply means that the hypothesis of reality assumed, is that what constitutes "reality" is nothing else but what is observed.
For a long time, physicists have taken this hypothesis, even without saying so ; it is only since Faraday and his "field lines" that people started talking about "things that might be real but not directly a product of our observation", and hence, a modest departure from naive realism.
It is my understanding that the word "realism" in the context of Bell/EPR/local "realists" etc... is this: a version of naive realism which ultimately makes the hypothesis that observation is what is "real".

Another possible hypothesis of reality (let's not forget that in any case it is a hypothesis), is a version of idealism. That is, we picture reality as a part of the Platonic world of abstract ideas. Observations are then nothing else but specific derivations, through "glasses", from this view. I think personally that this is the most fruitful working frame for a physicist - always keeping in mind that it is entirely hypothetical.
So what should now be taken as this "reality" in this hypothesis ? Well, nothing else but the model which gave us the logically consistent agreements with observation we started with.

Within this frame of thinking, it is of course totally unsound to declare "certain elements of the model agreeing with elements of reality", because we declared, by hypothesis, our model to BE reality. I often called that the "toy world of the theory". It is in this mindset, btw, that I defend MWI as the "correct" interpretation of quantum theory - simply because it assigns reality to the elements of the model (= quantum formalism). Within this frame of thinking, also, MWI is "locally realistic", simply because the dynamical prescriptions have some form of locality to them, for a suitable definition of locality. As an idealism, it is true that MWI is rather remote from any naive realism, which invites all the agressivity towards it by people who assume implicitly naive realism. But this comes about because the initial "hypothesis of reality" was totally different in both cases. So the entire conflict comes about when this idealism is confused with (implicitly assumed) naive realism. It is in this context that the "naive" in naive realism becomes pejorative: its proponents don't realize they already made an implicit hypothesis about what is "real" (while acknowledging also that one can't know this for sure at the same time).

And as we all seem to agree upon the fact that we'll never know what is "true", this discussion can go on for ages without ever finding any resolution.

 

[Careful]

** In as much as (a) is a very profound statement, you should apply it entirely logically until the end. I agree with (a), with maybe one small modification: I'm not even sure we can say that "truth doesn't exist", only, that "truth isn't accessible", and we leave in the middle whether truth exists or not. We simply know with certainty that we won't know it with certainty. The realisation of this philosophically elementary fact does - IMO - a lot of good to any of these sometimes heated discussions **

:rofl: Knitpicker :rofl: I think there exists a reality (we need some form of reality when we make theories), but that indeed we will never know that the ansatz we make about it is true or not. In a pragmatic sense the truth does not exist, since we will never know that we are right even when we are.

**
As such, I don't agree at all with (b), which I find a totally arbitrary requirement. The only goal of the model is to make a model of observational data. What elements are used to set up such a model is entirely free, I'd say. Of course there can be *preferences* and Occam's rasor is a good guide: two models which are empirically equivalent, but one which has some extra elements which the other doesn't need, might be preferentially rejected in favor of the "simpler" one. But again, this is just a guiding principle, not a strict requirement. **

So I guess you have to live with the problem of my hundred eyes in Japan and China as I mentioned in a previous post on this thread. Or you have to anwer my previous objection about how your belief does not contradict the practise of science: I am not speaking about the freedom we have in cooking up the model, but how the model deals with our ability to produce it.

** Within this frame of thinking, it is of course totally unsound to declare "certain elements of the model agreeing with elements of reality", because we declared, by hypothesis, our model to BE reality. ***

So, how would you discover the electron or anything which is NOT in your model ? I mean, you would have to avoid the argument, the electron (positron) was discovered because we observed its track through the nebula.

Careful

 

[vanesch]

So I guess you have to live with the problem of my hundred eyes in Japan and China as I mentioned in a previous post on this thread. Or you have to anwer my previous objection about how your belief does not contradict the practise of science: I am not speaking about the freedom we have in cooking up the model, but how the model deals with our ability to produce it.

I agree with your objection about the eyes in China (and for our Chinese membership: the eyes in New York ), and the fundamental objection I also have with equating *your* observations with reality while denying any "reality out there" by hypothesis. So I go for your second option: the model should indeed be such that within it, an observer should be able to reproduce it (as he obviously was trying to do).
I put that on the slide of "self-consistency" of the model, and "agreement with observation". I think the entire endeavour of MWI people is to try to do exactly that: find A (even if it is totally "bezerk") self-consistent way of deducing how an entity within the model would arrive at those observations and conclusions, as one actually did (in this case, write down the rules of the quantum formalism).

I agree that this is one of the stronger arguments for naive realism: the relationship between observation and reality being by definition (close to) 1-1, this step is evident, while it isn't in an idealist view. Nevertheless, the opposite is, IMO, not *necessary* (even though - I admit - attractive): it is sufficient to have such a self-consistent view (no matter how bezerk), for the idealist, to be satisfied.

So, how would you discover the electron or anything which is NOT in your model ? I mean, you would have to avoid the argument, the electron (positron) was observed because we discovered its track through the nebula.

Elementary, dear Watson :tongue2:

From an idealist view, you cannot "discover" an electron. You can only make observations, and then ponder about it, and come up with a MODEL (as you said yourself), which might then predict said observations.
The model is then "a charged particle which produces tracks in a cloud chamber and which I decide to call 'positron' ".
Once this model gets accepted/integrated/gets other observational successes, in the idealist viewpoint, it then becomes (by convention/hypothesis/majority vote...) an element of reality.

It is the success of the "model of the electron" which turns it into something we call "real".

So, in short, you cannot discover anything. You can only make observations, and think up models of those observations. This successful tandem is then the "discovery" of the entity of your new model, if it turns out to be successful/useful/socially accepted. At least according to the idealist viewpoint.

But of course the closer an observation is to our biological senses, the more intuitive this model becomes ("that's my mom") and from a certain point on, our sense of reality for certain models becomes so overwhelming that questioning this "everyday" reality triggers unfriendly statements about the mental health of the one making those questioning statements . In other words, for everyday observations, we strongly intuitively tend to take on the naive realism viewpoint. The question is whether this intuition is really so fundamental. It is the fundamental objection to an idealist hypothesis.

 

[Careful]

**
Elementary, dear Watson :tongue2: **

Not quite

**
From an idealist view, you cannot "discover" an electron. You can only make observations, and then ponder about it, and come up with a MODEL (as you said yourself), which might then predict said observations. **

Hmmm, I always had the strange idea that from time to time we discover something in our life :rofl:. But when constructing such model, you always use classical reasoning, you assume something was there which did this and that to the nebula which you do observe now. Whether you have acces to this reality or not is some other matter, and what you could measure would probably be some emergent phenomenon and not the ``real'' stuff (even within the theory you construct). Even in quantum mechanics, you can easily uphold the view that at any time the electron is somewhere on the support of its wave function (which would be the track in the nebula), but you simply don't know where.

**But of course the closer an observation is to our biological senses, the more intuitive this model becomes ("that's my mom") and from a certain point on, our sense of reality for certain models becomes so overwhelming that questioning this "everyday" reality triggers unfriendly statements about the mental health of the one making those questioning statements . In other words, for everyday observations, we strongly intuitively tend to take on the naive realism viewpoint. The question is whether this intuition is really so fundamental. It is the fundamental objection to an idealist hypothesis. ***

Ok, so let me ask you this : if quantum theory could be explained in an entirely ``realistic'' way (which it can, by holography (seems very plausibe), the future influencing the present (requires much more work) and so on...) why uphold this ``idealist'' view ? It is not that these two models are in accordance with my intuition, nobody likes to accept a shadowworld beyond ones perceptions, but at least one is able to clearly define it, make the math much easier (a local model in a slightly more complex shadow world is still much more economic that the configuration space methods in QM) and well defined ! I mean, strictly speaking, I cannot close the door for your viewpoint (and basically, I don't care ) but it is a very difficult and unnatural position to maintain as I see it.

Careful

 

[vanesch]

But when constructing such model, you always use classical reasoning, you assume something was there which did this and that to the nebula which you do observe now. Whether you have acces to this reality or not is some other matter, and what you could measure would probably be some emergent phenomenon and not the ``real'' stuff (even within the theory you construct). Even in quantum mechanics, you can easily uphold the view that at any time the electron is somewhere on the support of its wave function (which would be the track in the nebula), but you simply don't know where.

Well, a quantum theory = a "classical" theory + superposition principle, or in other words, what we call "classical" is a basis. If we now have some arguments which make us understand (or make us hope one day we might know) why our *observations* often agree with basis-states (in other words, are classically-looking), then this "classical reasoning" is not so wrong at all. When you do that, you are implicitly reasoning in terms of basis functions, and not in terms of the entire state space, but that doesn't matter. When you say "the electron is somewhere", then this is a shortcut for "I use as a basis, states which I call 'the electron is there', and I will probably observe also states close to 'the electron is here' ", but of course the superposition principle mixes into this which first makes superpositions of the different states, and then also is supposed to explain why my observations are again limited to the one of those states.

So "classical reasoning" is entirely allowed for. It just changed meaning, and became "reasoning in a basis related to observation".

Ok, so let me ask you this : if quantum theory could be explained in an entirely ``realistic'' way (which it can, by holography (seems very plausibe), the future influencing the present (requires much more work) and so on...) why uphold this ``idealist'' view ?

Because it is just another idealist view ! It is not part of naive realism to say that the future determines the present, not any more than parallel worlds are. Simply because our experienced "flow of causality" is just as well part of our observational sense of reality as is anything else, and as such, cannot consider "the future determines the past". I'd say it is just a matter of taste to say what you like more.

Now, in as much as this is technically possible (isn't this the "transactional interpretation of QM" in some way, although I thought it had serious problems for multi-particle correlations - so I'm not well versed in all this), it is just a model amongst others. You should know very well that I'm very favorable of making alternative models.

It is not that these two models are in accordance with my intuition, nobody likes to accept a shadowworld beyond ones perceptions, but at least one is able to clearly define it, make the math much easier (a local model in a slightly more complex shadow world is still much more economic that the configuration space methods in QM) and well defined ! I mean, strictly speaking, I cannot close the door for your viewpoint (and basically, I don't care ) but it is a very difficult and unnatural position to maintain as I see it.

Well, to me they are certainly on the same levels of "bezerkness" and I don't think there's a reason to prefer one over the other, unless one formalism is mathematically much more appealing than another. If some equivalence is established, then it is entirely a matter of taste (and probably of social convention). I think it is then very interesting to look at both models. If equivalence is not established, then this is also a very interesting situation of competing models.

But all this doesn't do away with the fact that the idealist interpretation of the standard quantum formalism still smells more like MWI, and that this other formulation will have its own, different idealist interpretation, given that it will be formally different (though possibly equivalent).

Again, given that this is all matter of hypothesis, I don't see why one should fight over it, or adhere to one over the other. The more different views one is aware of, the more understanding one usually gains of the matter at hand.

This is why I don't fight (intelligent) local realists, nor do I "adhere" to any such vision. It's just interesting to know about, that's all.

 

[Careful]

** Well, a quantum theory = a "classical" theory + superposition principle, or in other words, what we call "classical" is a basis. **

That remains to be seen, as soon as one includes self interactions, it occurs to me that the superposition principle *might* go down the drain if one insists upon the theory to be well defined. Check out one of the latest papers of Thomas Elze on this (if you want to, I will look it up) where you have only a weak form of the superposition principle.

** If we now have some arguments which make us understand (or make us hope one day we might know) why our *observations* often agree with basis-states (in other words, are classically-looking), then this "classical reasoning" is not so wrong at all. When you do that, you are implicitly reasoning in terms of basis functions, and not in terms of the entire state space, but that doesn't matter. When you say "the electron is somewhere", then this is a shortcut for "I use as a basis, states which I call 'the electron is there', and I will probably observe also states close to 'the electron is here' ", but of course the superposition principle mixes into this which first makes superpositions of the different states, and then also is supposed to explain why my observations are again limited to the one of those states. ***

Nonlinearity is the key word I presume, a *dynamical* law of observation should break the superposition principle.

** Because it is just another idealist view ! It is not part of naive realism to say that the future determines the present, not any more than parallel worlds are. **

Well, not quite , first of all observations are still REAL in such world, if Careful sees a dead cat, Vanesch will too, I have no synchronisation difficulties. I have already long time said that if you want to predict the ideal quantum correlations using a local theory, then you will have to redefine what is real. But still, what is real, does not depend upon my perception, on the contrary, the reality will explain perception itself.


**Simply because our experienced "flow of causality" is just as well part of our observational sense of reality as is anything else, and as such, cannot consider "the future determines the past". I'd say it is just a matter of taste to say what you like more. **

Well, I would think the experience of the flow of causality to remain the same for heavy stuff (see my response on the other thread).

** You should know very well that I'm very favorable of making alternative models. **

Of course, this is just a friendly conversation.


**Well, to me they are certainly on the same levels of "bezerkness" and I don't think there's a reason to prefer one over the other, unless one formalism is mathematically much more appealing than another. If some equivalence is established, then it is entirely a matter of taste (and probably of social convention). I think it is then very interesting to look at both models. If equivalence is not established, then this is also a very interesting situation of competing models.**

Well you probably know this paper, but wait ... perhaps not (it contains some important arguments) : ``Simulating physics with computers´´, Richard.P. Feynman, International Journal of Theoretical Physics, Vol 21, Nos 6/7 1982

** Again, given that this is all matter of hypothesis, I don't see why one should fight over it, or adhere to one over the other. The more different views one is aware of, the more understanding one usually gains of the matter at hand. **

Indeed, no fight is necessary !

Careful

 

[setAI]

the problem is that a century later- even smart people have trouble accepting the implications of unitary QM- that is the less that an element of a system is observed- that is causally connected to an observer- the more it is in a superpostional state of ALL possibilities-and this does extend to all scales- it is just too complicated and EXPENSIVE at present to measure those affects with mezzo scale and larger systems- what we call reality is a sum-over-histories of what we are interacting with NOW yet the complexity of our interaction with the environment severly probabilistically limits the possibilites to what appears to be a singular reality and a single past- except at the edges of shadows- as David Deutsch put it

 

[selfAdjoint]

That remains to be seen, as soon as one includes self interactions, it occurs to me that the superposition principle *might* go down the drain if one insists upon the theory to be well defined. Check out one of the latest papers of Thomas Elze on this (if you want to, I will look it up) where you have only a weak form of the superposition principle.

Have you loked into the behavior of solitons? They are a characteristic behavior of nonlinear equations; e.g. it has long been known that the "inverse problem" of identifying a potential in a one-dimensional Schroedinger equation from its scattering behavior leads to Kottweg-DeVries (KdV) nonlinear ODE with soliton solutions.

And they obey a kind of quasi-superposition behavior, so you could have superposition where it counts without assuming it to be some kind of universal ordering principle.

 

[Careful]

** Have you loked into the behavior of solitons? **

Yes

** They are a characteristic behavior of nonlinear equations; e.g. it has long been known that the "inverse problem" of identifying a potential in a one-dimensional Schroedinger equation from its scattering behavior leads to Kottweg-DeVries (KdV) nonlinear ODE with soliton solutions. **

Right


**
And they obey a kind of quasi-superposition behavior, so you could have superposition where it counts without assuming it to be some kind of universal ordering principle. ***


Correct, if you have two bubbles with more or less disjoint support (that is A is very weak where B is very strong), then this automatically leads to that. But the key message here is that the AND automatically becomes an OR, there is almost no interference between the different solitons (so for example a superpostion of two disjoint soliton beams can be seen as just two different beams). In Barut self field for example one can take soliton like solutions for the single events, they behave like particles but still contain the interference information due to the solution of the linear equation - so there is no measurement problem here (actually this only works for fermions). In GRW for example, the unitarity is broken due to the introduction of stochastic noise. When I speak about a non linear extension of the Schrodinger equation, I do not mean to intend that the statistics of the particles (obviously such a psi has no good probability interpretation) is not going to satisfy a unitary evolution law (something which is a very delicate issue, vis a vis black holes), but that the hidden theory which includes single events is necessarily non linear and much more involved (remember, Vanesch and I were talking about the measurement problem) - there can be information loss at the classical level though. The quantization of gauge fields is a very different issue (and might not be necessary at all).

Careful

 

[Careful]

**the problem is that a century later- even smart people have trouble accepting the implications of unitary QM- that is the less that an element of a system is observed- that is causally connected to an observer- the more it is in a superpostional state of ALL possibilities-and this does extend to all scales- it is just too complicated and EXPENSIVE at present to measure those affects with mezzo scale and larger systems- what we call reality is a sum-over-histories of what we are interacting with NOW yet the complexity of our interaction with the environment severly probabilistically limits the possibilites to what appears to be a singular reality and a single past- except at the edges of shadows- as David Deutsch put it ***

Yes and it was for sure problematic that one Einstein could not accept absolute thinking after 250 years of Newtonian bucket dominance. Moroever, I do not have problems accepting the Schrodinger wave at all, I reject the measurement postulate though.

Careful

 

[vanesch]

** Well, a quantum theory = a "classical" theory + superposition principle, or in other words, what we call "classical" is a basis. **

That remains to be seen, as soon as one includes self interactions, it occurs to me that the superposition principle *might* go down the drain if one insists upon the theory to be well defined.

Ok, but then it is not "quantum theory" but another theory. In quantum theory, as far as I know, the strict superposition principle is postulated to hold. If you change that, you have another theory, which may be superior, and we'll then refer to quantum theory as its linear predecessor. If strict linearity leads to inconsistencies, then that only means that quantum theory is inconsistent - but it might be that it is only the quantum field model that might suffer from that, not quantum theory in all generality (for instance with just a finite number of degrees of freedom).

Check out one of the latest papers of Thomas Elze on this (if you want to, I will look it up) where you have only a weak form of the superposition principle.

Pffft... guess I have to say "thank you" for the reference. If I would read all the stuff that is suggested to me, I would spend even less time doing useful stuff

Nonlinearity is the key word I presume, a *dynamical* law of observation should break the superposition principle.

But then it is, strictly speaking, not a standard quantum theory where this superposition is to be strictly valid, no ? But rather a successor.

Well, not quite , first of all observations are still REAL in such world, if Careful sees a dead cat, Vanesch will too, I have no synchronisation difficulties.
I have already long time said that if you want to predict the ideal quantum correlations using a local theory, then you will have to redefine what is real. But still, what is real, does not depend upon my perception, on the contrary, the reality will explain perception itself.

Yes, granted. But so does "a bag of events" (which you sometimes call superdeterminism). We're back to 'correlations happen', and now they come in from the future instead of from some specific initial condition in the past.

What you probably want to say, is that in such a situation, you do not have to delve into the very painful question of exactly what constitutes "an observer", because there are still perfectly well defined events (which do not exist independent of a "branch choice" in an MWI view). Granted. You're relieved from considering this question for the definition of "events". The question is if that's a necessary requirement. Again, it can be advantageous not to have to delve into this. But as, philosophically speaking, sooner or later, you have to confront the question of what exactly is a subjective experience and how it is related to the physical world/model/theory (the famous psycho-physical parallellism von Neumann already realized was the crux in understanding QM), you only bought yourself some time by requiring a physical theory to be clear of these considerations.

So I can understand the desire to uncouple this question from "physics per se", but in my opinion, it is not more than that: something that is to be desired. It's not a hard requirement.

All the ponderings about QM opened this Pandora's box of bringing in conscious/subjective experience into a full physical theory, and once you consider it, it is hard to find a fundamental reason to put it back in the box and reject the idea on some fundamental ground. Sure, things would be cleaner if this messy problem were uncoupled from "physics", but I don't see why we can require this as an absolute requirement, especially because it doesn't fundamentally solve anything about the question of what *is* a subjective experience. It only allows you to ignore the question, not to answer it.

 

[Careful]

**Ok, but then it is not "quantum theory" but another theory. In quantum theory, as far as I know, the strict superposition principle is postulated to hold. If you change that, you have another theory, which may be superior, and we'll then refer to quantum theory as its linear predecessor. If strict linearity leads to inconsistencies, then that only means that quantum theory is inconsistent - but it might be that it is only the quantum field model that might suffer from that, not quantum theory in all generality (for instance with just a finite number of degrees of freedom). **

Three remarks here
(a) no not necessarily: the non linearity works at the level of the single events, not at the level of the statistics per se (I still have superposition there). Quantum theory has no decent account of single events (Schrodinger + collapse ``='' non linear). Something similar goes in BM, the point particles satisfy a non linear ODE in configuration space, but still the statistics is just unitary (the differential equation for the Wigner density is of the Liouville type). Of course I do not believe in point particles, neither in action at a distance ...
(b) Quantum field theory needs an infinite number of degrees of freedom, otherwise no scattering.
(c) Another interpretation would be that at the level of the statistics the Schrodinger equation would be non linear, meaning that you would build in some kind of irreversibility in the dynamics of the latter. I guess you could say that the latter implies some inherent information loss in nature (black holes ?) at the level of the statistics. But I see no need for that ...
My original remark that ``interactions might make QFT non linear'' was intended to mean that a consistent theory of QFT could be written as a ``single particle'' non linear field equation. There is a beautiful book by Karel Kowalski (which I unfortunately could not read yet entirely) ``Methods of Hilbert spaces in the theory of nonlinear dynamical systems´´ which explicitates this. Barut's self field can be seen in a two ways : (a) as a self interacting soliton (one particle), or (b) by solving the equation by iteration, starting from a general solution to the linear one, one can see the higher order correction terms as encoding the multiparticle scattering amplitudes.

**
Pffft... guess I have to say "thank you" for the reference. If I would read all the stuff that is suggested to me, I would spend even less time doing useful stuff **

I give good stuff


***All the ponderings about QM opened this Pandora's box of bringing in conscious/subjective experience into a full physical theory, and once you consider it, it is hard to find a fundamental reason to put it back in the box and reject the idea on some fundamental ground. Sure, things would be cleaner if this messy problem were uncoupled from "physics", but I don't see why we can require this as an absolute requirement, especially because it doesn't fundamentally solve anything about the question of what *is* a subjective experience. It only allows you to ignore the question, not to answer it. ***

I do not agree here, as materialist I would simply say that subjective experience is the result of biophysical processes. What is ``subjective experience´´ anyway ?

 

[Chaos' lil bro Order]

This seems like philosophy and not physics to me but 'realism' or 'reality' are very easy to define in my mind. Reality is independent of observation in the strictest sense, but to humans, we must accept our 'personal' reality as a collection of sensory inputs to which we give meaning to, and draw meaning from. That which is beyond our 5 senses is unknown and cannot be known, period. Barring the emergence of a 6th sense, we are confined to enhancing our 5 senses with the aid of technologically-enabled sensory multipliers such as telescopes, microscopes, voltmeters and microphones, etc. But even these devices that empower our senses with more and more accurate means by which to measure more and more minute amplitudes of physical phenomona, serve only to define reality in a manner that we are hardwired to grasp. Our only possible perspective of the reality of the universe is neccesarily that with which our senses are so kind as to furnish us with. Yet, I still believe that there are fundamental properties of the universe that are consistent in all regions of space.
As a reductionist I find myself thinking that all matter, anti-matter and radiation consists of particles at a sufficiently small scale. In fact, there is no reason to believe that one day we won't split a photon into even smaller fragment consituents, or even split the quantum field and strings into even tinier pieces. Furthermore, we cannot know if there is an upper limit to the size of our universe or if you believe so, our multiverse. Many people picture themselves in the middle of the known magnitudes of scale ruler... we are much bigger than quarks and much smaller than the universe. But for all we know, our observable universe is the limit of 'reality's' size and the quark can be split into pieces 10*trillion times smaller than it is, so really we are giants in the entire schemata of reality, in fact even ants are.
My main point of this idea of what 'true' 'reality' is, is that all conversations wishing to seek truth, should stay within the confines of our senses and the perceptions we create from these curriers of 'reality's' data.

 

[AnssiH]

Sorry for the length, still had to cut things I want to say

Philosophy, sweet :)

1. What does realism mean to you?

I'm a strict materialist, so it means that there is a world out there, which is also the cause of conscious experience. In fuzzy language; Conscious experience is what happens when physical organism starts using such method of prediction that it builds a semantical worldview (=self-supporting, not representing "the truth", but merely "a way to comprehend") out of classifying the patterns it observers into "sensible objects" (with mere "assumptions") until it knows enough about the behaviour of such objects to be able predictions of systems become possible. One arbitrary assumption in such worldview is the assumption that there exists one's "self".

This is literally a hypothesis about the phenomenon of conscious experience existing on the basis of physical things (brains/neurons) expressing by their spatial/temporal form, an artificial model of the "world" around the organism, for the purpose of being able to predict things. We are not conscious of the world around us, but merely of this semantical model.

Consciousness is a side-product of the brain building such a worldview where certain the assumption about "self" has formed, and thus the surrounding world is interpreted in the form "this and that happened to me". The experience of free-will is what only exists in our semantical comprehension of the world, while in fact all our decisions are based directly or indirectly to the outside pressures (things we've learned, and how we interpret the situations according to things we've learned).

Simply put, we make our decisions mechanically based on the cumulated knowledge of our experiences, but we have a conscious experience of our self "searching for" the correct decisions from our worldview (thinking), as if there is a fundamental "self" with free will making choices (well, pretty simple philosophical excercises already show that free-will is a non-sensical thing at a conceptual level already, plus many experiments show that no, we are not aware of having made a decision when the physical state of the brain already reveals the choice has been made. This should not be a surprise to anyone dabbling in materialistic philosophy)

This view also explain why there exists such philosophies as idealism or dualism or anything of that kind. No, it does not prove them wrong, it just explains why there are different ways to see same things, and it explains great many things about our behaviour and about our observations in general.

So we could say that being a materialist is to an extent an arbitrary choice. Why I'm not considering idealism then? Because it tends to lead either a solipsism, or to the idea that some kind of god is "feeding us with our ideas". And also many experiments as judged with a materialistic view say a lot about how our "ideas" exist physically, and with that knowledge it is just too naive to think that "ideas" are fundamental. Simply put, these philosophies make assertions about some very very very complex behaviours being actually fundamental (like the sentient behaviour of god)

And why would anyone believing in solipsism try to convince anyone else that world is solipsistic? HELLO??!

Why I'm not considering dualism, is because it too makes certain assumptions about fundamentals that become apparently naive very quickly.

Why I'm not considering panpsychism; because it's just too damn stupid :) It revolves around unbelievably moronic ideas about what are objects metaphysically. Human brain is not a metaphysical object my friends, nor is your car! This view is completely inconsistent and full of self-contradiction.

So in my view, our understanding of reality is based on making arbitrary assumptions about it until we have a coherent picture for making predictions. Any behaviour is a case of prediction. ANY. Walking, talking, inventing, thinking... Our understanding of anything is literally a case of some pattern being classified into such and such concept that we assume to behaves in such and such ways due to past experiences or assumptions about combinations of concepts, and because of this it is also apparent that no worldview is "correct" or "true" to reality, but merely a method of comprehending it. This is why we can look at any system and understand it in a number of different ways.

This also means that ANY form of realism is to an extent naive realism. Even mine, as it also is based on semantical concepts. We are always forced to make arbitrary assumptions about things that "are fundamentally real", while not even this very classification of reality into sensible objects is in any way "correct" way to see the world, yet it is the ONLY way we can comprehend anything.

One simple thought exercise that reveals a little bit of the problem; look at any shadow around you. Looked? Now look at it again. Ask yourself, is it still the "same" shadow as it was before? No? Yes? What about the shadow of a building in two different days?

No, we should not interpret reality as if shadows have identity. It is just a stable pattern. We should not imply ANYTHING to have identity. The apple in your hand does not have identity as such. To suppose it does, is just a semantical concept, an arbitrary assumption in your worldview. To be more proper to reality, we should just see that there are only stable patterns around us. Stable pattern is something we point a finger at and say "an apple". Not even our "self" has identity. You are at most defined by what has accumulated into your worldview, but to say you are the same person you were yesterday is an arbitrary assumption, and in many ways wrong. We are literally like a wave on the ocean; just a stable shape, not formed of the same "stuff" at every moment, or indeed, at ANY moment. Moment, btw, is also an arbitrary assumption, as is clarified by relativity.

This also means there is no actual TOE out there. At best we can find the simplest way to *describe* reality, but we cannot comprehend how reality really is. For the simple reason that our comprehension is BASED on a worldview that is not rooted to truth, but is merely a self-supporting structure, a circle of beliefs. (If you are wondering, math too is a semantical concept, albeit based on explicit rules)

And to answer your question, reality is out there, causing our comprehension, yet it is beyond true comprehension.

2. Einstein said: "I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured. I like to think that the moon is there even if I am not looking at it." Is this realism?

Like Einstein noted himself; our comprehension of reality is based on certain assumptions about reality. He took out the assumptions about simultaneity to make a consistent model with isotropic speed of light, which is an interesting instance of changing one's worldview from one coherent model into another coherent model. But here he is making certain assumptions about the metaphysical identity of things. A realist doesn't have to assume that an electron has spin, a location and so on before being measured, because we can only measure things with pieces of matter, and thus these properties of electron, indeed the whole electron as we think of it, can be a result of interaction between the measurement device and something else that is not measurable as it is by matter. This whole talk about particles and wave-particle duality and what not is a model based on semantical concepts, and I think it is evident that the difficulties to understand what is going on are because we are simply using wrong concepts to comprehend this. This is evident when we just keep in mind HOW we comprehend things in the first place.

So, while these assertions about electron being such and such regardless of so-called measurement may be wrong, to suppose our comprehension creates the moon is even more wrong.

3. In your opinion, is "realism" an assumption of Bell's Theorem? If so, where does it arise?

It seems to me that localism is a feature of realism only in so far that the ontology of relativity is right. My hopes on that are not particularly high though, so I have no problems at looking at models with non-local action, especially since many instances of non-locality are explainable in local terms if you just change the concepts you are using to comprehend the situation.

For example, ages ago people may have had certain assumptions about the reality of a rainbow. That it is an object that exists in space right where it seems to exist. If you make this assumption about the identity of a rainbow, you would find the rainbow to react to the motion of observer (react to "being measured") in a non-local fashion. It immediately moves when you move. How can that be? Does it know the future and react accordingly? Well no, the concept of rainbow was just royally wrong, what we see was always just an interference pattern on the observer. The rainbow does not exist without an observer. Sounds familiar?

Incidentally, I just started a thread "Quantum mechanics and spacetime" where I'm wondering how it's possible that Einstein was troubled by "spooky action at a distance" when at the same time he believed into static spacetime, and thus no spooky action at a distance makes sense even at a conceptual level (when, metaphysically, does the spooky action happen, Einstein? :), and also the spooky action is easily explainable as a deterministic phenomenon if you just change your concept of what light is more towards what it appears to be in terms of spacetime (a static connection that just exists in some static shape in spacetime).

Just a few related thoughts that popped into my mind while writing this.

1. The apparent paradoxes associated with time travel are a simple instance of us using wrong concepts to comprehend reality. Even with the idea of time travel over static spacetime there is no sense of "when" the time travel happened. It had always happened, or it had never happened. Simply put, some of our concepts of reality are wrong here.

2. The mainstream model about the big bang has equally mysterious conflict in its concepts. It is asserted that in the beginning there was an event where "spacetime" was first created, and for that reason it does not make sense to ask what was "before" big bang. Well, if the spacetime was created, this means the whole thing, the past and the future, was created. As such it makes no sense to assert that within the spacetime there is a moment "in the beginning" where "it was created". The box cannot contain itself. The concept of "event" does not fit into the idea of big bang. There can be no moment inside the spacetime that defines "when" it was formed! (All in all, the question of origins refers back to the question of "why is there reality?")

3. The method of science IS philosophy, but a form of philosophy that is in my opinion sorely lacking in "philosophic thinking". To scientists I say, either "just shut up and calculate", or be more careful with your assertions about reality, and understand that any assertions you make are more or less based on ARBITRARY way to understand the system we call reality. All the assertions above, even this one, is done based on my view. I hope others can find some meaningful thoughts in it.

 

[vanesch]

This seems like philosophy and not physics to me but 'realism' or 'reality' are very easy to define in my mind.

Of course it is philosophy ! Talking about what is "realism" is metaphysical (and hence philosophical), because the essential discussion between "local/non-local realists" and "quantum physicists" is about the fundamental requirements of "reality" that has to be satisfied for something to be called "a physical theory". The "realists" tell the quantum physicists that they are in deep trouble because their theory (quantum theory) doesn't satisfy the metaphysical requirements a physical theory should satisfy, according to them. Nevertheless, this discussion is about physics: namely about what are the requirements for a theory to be a physical theory. But the discussion is not physics itself, given that we are defining what is/is not "acceptable physics".

When asked, most physicists would say that physics is building mathematical models which explain observations (theory), and doing experiments to verify mathematical models (experimentalists).
Realists put an extra requirement into this: they want 1) the mathematical models to be fair representations of "reality" and 2) they want observations to correspond to an observer-independent "reality" in a straightforward 1-1 way.

This sounds extremely reasonable, but QM fails the test at first sight.

Once we are at this point, we should examine more closely all the things that lie on the table, and the main discussion is here about the concept of "reality". Now, the specialists on that issue are philosophers, who have thought about this for quite some more time than physicists used to do (them usually being more occupied with the mathematics of their theories).

And it turns out that the concept of "reality" is not so evident, after all.

Reality is independent of observation in the strictest sense, but to humans, we must accept our 'personal' reality as a collection of sensory inputs to which we give meaning to, and draw meaning from. That which is beyond our 5 senses is unknown and cannot be known, period.

And what tells you with certainty that what your 5 senses tell you is any more "knowable" than what comes from "extensions" ? This is the kind of question philosophers have given a lot of thought to.

Now, as I said previously, it is of course desirable not to have to delve into these issues to do physics. It would be nice to be able to uncouple these issues from physics, and be able to postulate a physical reality which has a 1-1 correspondence with sensory experiences. As such, we could postulate a physical, objective reality totally independent of subjective observation, which, in one way or another, corresponds 1-1 to our subjective observation. This would be nice, and in fact, classical physics did that perfectly. However, I don't see why this "requirement of simplicity" should hold fundamentally. It is not because it would simplify our conception of nature (a clear picture of "physical reality" and a separate, rather fuzzy idea about where subjective experience comes from, but happily independent of the former) that things HAVE to be this way.
This vision of the world is what philosophers call "naive realism".

Even Plato didn't think the world was simple like this. So, nice as it would be, I think one cannot *require* it. If this requirement makes us put into the dustbin a highly successful theory such as quantum theory, then this is food for thought. What has to go ? Our "naive realism" requirement, or quantum theory ?

My main point of this idea of what 'true' 'reality' is, is that all conversations wishing to seek truth, should stay within the confines of our senses and the perceptions we create from these curriers of 'reality's' data.

I think that all conversations seeking "truth" are starting off badly.

 

[vanesch]

Philosophy, sweet :)

1. What does realism mean to you?

I'm a strict materialist, so it means that there is a world out there, which is also the cause of conscious experience.

As a dualist, I'm going to challenge a few of the statements you make here. I know that it is not fashionable amongst scientists to fight materialism, but I take the challenge.

My main challenge to materialists is: tell me, from a strictly materialist viewpoint, under what conditions a physical system devellops conscious experience. Now, I know that I can get "answers" to that, but they are totally arbitrary (and depend strongly on the field of activity: from neurologists, computer scientists, zoologists... you get widely different answers which just redefine the word "consciousness" into one or other arbitrary physical property, often strongly antropologically centered). For instance, if you take a neurologist's viewpoint (memory, sensory perception and associative circuitry that has access to both, constructing a self-perception), then a PC with a web cam looking at its motherboard and running something like Photoshop is a conscious being...

In fuzzy language; Conscious experience is what happens when physical organism starts using such method of prediction that it builds a semantical worldview (=self-supporting, not representing "the truth", but merely "a way to comprehend") out of classifying the patterns it observers into "sensible objects" (with mere "assumptions") until it knows enough about the behaviour of such objects to be able predictions of systems become possible. One arbitrary assumption in such worldview is the assumption that there exists one's "self".

Let me say something totally crazy at first sight to illustrate my problem with it:
The question of course being what physical processes are being "methods". Is a crystal moving defects around building any worldview of which we might not have understood the significance under its sensory experience of sounds and vibrations ? Are the velocity fields in a turbulent flow of sufficient complexity in fact some form of "thinking" ?
To us, these seem like totally random events, but maybe to a thinking water flow, the electrochemical processes in a human brain seem totally arbitary.

How is a materialist going to define strictly what physical processes give rise to some subjective experience, and what not ?

So my point is that this problem of emergence of subjective experience is not solved by defining it away, and that it plays a potentially fundamental role in the way we define what is "an observation", which, in turn, is a fundamental concept in any scientific endaveour, given that theories are tested against observations (and hence subjective experiences).
It might be (see my previous postings) that both have nothing to do with one another, but this is, to me, not a strict requirement.

This is literally a hypothesis about the phenomenon of conscious experience existing on the basis of physical things (brains/neurons) expressing by their spatial/temporal form, an artificial model of the "world" around the organism, for the purpose of being able to predict things. We are not conscious of the world around us, but merely of this semantical model.

Well, recently I got into a discussion with someone who had to write a manager degree thesis in the medical sector. He's in the sector of the highly mentally handicapped, and the his subject is, how to motivate the low level staff by explaining them that these patients are really conscious human beings which can suffer as well as them. Indeed there's sometimes a serious problem of demotivation, often leading to mis treatment of the patients (not serious mistreatment, but daily rough handling and lack of care). To give you an idea: the average mental age of the patients is between 6 months and 1 year (although they are 30 - 50 year olds).

According to your definition, it is hard to say whether these are really "conscious beings": they almost make no predictions ! At best, they roll themselves in their excrements in as far as they have any controlled motricity.

His answer was in fact rather smart: Pascal's bet. We don't know if they are conscious beings or not. But let us imagine they are, after all, not. If we take care of them, then we're simply wasting our time and money. Now imagine they are, and we don't take care of them, and mistreat them. Then we are monsters.
It's worse to be monsters than to waste our time. So in doubt, let's be nice to them.

Consciousness is a side-product of the brain building such a worldview where certain the assumption about "self" has formed, and thus the surrounding world is interpreted in the form "this and that happened to me". The experience of free-will is what only exists in our semantical comprehension of the world, while in fact all our decisions are based directly or indirectly to the outside pressures (things we've learned, and how we interpret the situations according to things we've learned).

Simply put, we make our decisions mechanically based on the cumulated knowledge of our experiences, but we have a conscious experience of our self "searching for" the correct decisions from our worldview (thinking), as if there is a fundamental "self" with free will making choices (well, pretty simple philosophical excercises already show that free-will is a non-sensical thing at a conceptual level already, plus many experiments show that no, we are not aware of having made a decision when the physical state of the brain already reveals the choice has been made. This should not be a surprise to anyone dabbling in materialistic philosophy)

Yes, I agree with the free will thing. But that's not the discussion. The discussion is about the emergence of a subjective experience.
So the point is: when is there, and when is there not, within a physical structure, an 'awareness' ?
When does a physical process lead to an awareness, and when not ? Imagine you think up a definition which places your body outside of it. So according to your definition, you are not conscious, after all. Does that make sense ? So in what way are you then allowed to think up criteria which make up your definition of "consciousness" ?
In fact, you intuitively "know" that people are conscious, and you try to think up a set of conditions so that they all fall in the category of "conscious beings" while keeping out obvious counter examples, like PC's, robots, and ants. In other words, you try to fit humans "after the fact".
I'm sure that in the 16th century, a thing playing a strong chess game would be considered as a conscious thing. Simply because at that time, one could not think it possible for something else but a human to do so.

So we could say that being a materialist is to an extent an arbitrary choice. Why I'm not considering idealism then? Because it tends to lead either a solipsism, or to the idea that some kind of god is "feeding us with our ideas".

I don't think this is the only issue possible (I'm not religious for instance). I think materialists try to deny an aspect of the world, which is the existence of subjective experience. That doesn't mean one has to deny the link between this subjective experience and the material world, but it means that one cannot *derive* it from the reductionist description of the material world, and that you need some *extra input* to say when, and when not, subjective experiences can emerge from a physical structure.
(this is in fact as close to materialism that a dualist can come: yes, subjective experience finds its origin in the material world, but "it didn't have to happen"). The problem is that most if not all materialist arguments are strictly behavioural, and hence miss the point, because the *behaviour* of a physical structure being governed by physical laws, it doesn't NEED any emergence of subjective experience for it to behave that way. Hence behaviour can never be a proof for the existence "inside" of any subjective experience. Which excludes any inquiry into subjective experience from any experimental inquiry, *except for one's own*.

And also many experiments as judged with a materialistic view say a lot about how our "ideas" exist physically, and with that knowledge it is just too naive to think that "ideas" are fundamental. Simply put, these philosophies make assertions about some very very very complex behaviours being actually fundamental (like the sentient behaviour of god)

The "Platonic world of ideas" is of course not the world of *human* ideas, but the abstract concept of mathematical structures.

And why would anyone believing in solipsism try to convince anyone else that world is solipsistic? HELLO??!

Because it's fun to talk to one's own chimera ? :tongue:

Why I'm not considering dualism, is because it too makes certain assumptions about fundamentals that become apparently naive very quickly.

I think you're thinking of only specific forms of dualism here. As I said, dualism essentially says that reductionist physical laws are not sufficient to explain the emergence of subjective experiences, simply because those physical laws would do fine all by themselves without such emergence. As such it becomes fundamentally impossible to *derive* from those physical laws, when subjective experiences emerge, and when not, and it is not because you arbitrarily decree that something of the kind happens for certain systems, that this is so. There are dualist visions with souls, deities and all the panoply you like, but this is, IMO, not the essence. The essence for me is that there is no a priori way to *derive* exactly when subjective experience emerges, and when not, from reductionist laws.

Now, after this highly philosophical debate, what does this have to do with quantum theory ?

Well, MWI proponents such as myself claim that we've been all wrong about *exactly which elements of physical reality* are to be suffering subjective experience. In classical physics, this corresponds to sets of physical degrees of freedom in certain configurations (say, living brains), while in MWI, this corresponds to certain *slices of state space* spanned over these degrees of freedom.

But in order to even be able to say this, we need some freedom in postulating freely what is, and what is not, potentially corresponding to a subjective experience independently of "physical reality" (and hence we need a minimum of "dualism"). If we can for instance *postulate* that certain quantum states of a restricted set of degrees of freedom (such as the material degrees of freedom of a brain) correspond to subjective experiences, and others don't, and we now find that the "state of the universe" simply contains a superposition of said states, then we could decree that these are "parallel" and slightly different subjective experiences, each corresponding to the SAME degrees of freedom (the brain). That's different than the view that there are ghosts in the brain or anything. But it is not a strictly materialist viewpoint, because what is, and what is not, a material state corresponding to an experience and not, is not derivable from the physical laws themselves, and needs to be postulated separately.

So in my view, our understanding of reality is based on making arbitrary assumptions about it until we have a coherent picture for making predictions. Any behaviour is a case of prediction. ANY. Walking, talking, inventing, thinking... Our understanding of anything is literally a case of some pattern being classified into such and such concept that we assume to behaves in such and such ways due to past experiences or assumptions about combinations of concepts, and because of this it is also apparent that no worldview is "correct" or "true" to reality, but merely a method of comprehending it. This is why we can look at any system and understand it in a number of different ways.

I agree here. As I said: reality is a working hypothesis that allows one to "comprehend" the world, which is, for a being, essentially reduced to its subjective experiences. It's a way of classifying subjective experiences.

This also means that ANY form of realism is to an extent naive realism. Even mine, as it also is based on semantical concepts. We are always forced to make arbitrary assumptions about things that "are fundamentally real", while not even this very classification of reality into sensible objects is in any way "correct" way to see the world, yet it is the ONLY way we can comprehend anything.

I don't see, for instance, how an MWI view (which, I think, satisfies all of the above criteria), can be called a form of naive realism...

No, we should not interpret reality as if shadows have identity. It is just a stable pattern. We should not imply ANYTHING to have identity. The apple in your hand does not have identity as such. To suppose it does, is just a semantical concept, an arbitrary assumption in your worldview. To be more proper to reality, we should just see that there are only stable patterns around us. Stable pattern is something we point a finger at and say "an apple". Not even our "self" has identity. You are at most defined by what has accumulated into your worldview, but to say you are the same person you were yesterday is an arbitrary assumption, and in many ways wrong. We are literally like a wave on the ocean; just a stable shape, not formed of the same "stuff" at every moment, or indeed, at ANY moment. Moment, btw, is also an arbitrary assumption, as is clarified by relativity.

... or a state in statespace ?

This also means there is no actual TOE out there.

I don't see how this can be decided, one way or another. To me, a TOE is a logically consistent model which can describe all our observations.
That doesn't mean that it may not turn out to be false one day, or that several of them can be found (or none ?), but I think the question of the existence of such a model, at any time, is an entirely undecided question.

3. The method of science IS philosophy, but a form of philosophy that is in my opinion sorely lacking in "philosophic thinking". To scientists I say, either "just shut up and calculate", or be more careful with your assertions about reality, and understand that any assertions you make are more or less based on ARBITRARY way to understand the system we call reality. All the assertions above, even this one, is done based on my view. I hope others can find some meaningful thoughts in it.

I couldn't agree more