The typical and the exceptional in physics

In summary, the conversation discusses the concept of the superposition principle in quantum mechanics and its implications on macroscopic objects. While there is no limitation on the standard deviation of variables in quantum mechanics, it is argued that successful physics focuses on typical situations rather than exceptional ones. The use of mixed states in statistical mechanics is mentioned as a way to describe macroscopic objects, but it is noted that this already assumes a small standard deviation. The conversation concludes that while it is possible to ignore these problems, it is not a satisfying approach.
  • #106
zonde said:
Pilot wave theory consistently unifies particle and wave descriptions.
That isn't a test of your claim-- your claim was "all valid descriptions of reality can be joined in one consistent system", not "some aspects of a valid description of reality can be joined in one consistent system." Pilot wave theory does not unify quantum mechanics and gravity, and it's not even clear it unifies quantum mechanics with special relativity, so it does not pass your test there.
You haven't provided justification for that assertion. And the ease with which you give up the goal I see as a drawback of your approach.
My justification is the physics has never, in its entire history, presented a fully unified and self-consistent description of reality. There has always been elements missing from the o ntology, so there has always been the need to pick and choose the theory to suit the situation. If physics has always been a certain way, it is odd to imagine that what it actually does is something different from what it has ever actually done! That doesn't mean giving up the goal, it means recognizing that a goal is like a direction, like walking East, not a destination, like arriving at East. There is no more unscientific attitude than the proclamation "we have arrived at the true ontology of the universe," that's what Cardinal Bellamy said. The scientist is always skeptical, always digging deeper, because science doesn't believe in ontology.
 
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  • #107
stevendaryl said:
Then the testable claim "If I prepare a system like this, I will get a measurement like that" follows from our theories.
Yes, it seems to me that if we look at the scientific method, nothing could be more clear than that it is an epistemology. It is a system that goes "model, test, repeat." There is never any step in the scientific method that says "now believe that your model is the reality." Not only is that step absent from science, it is anathema to the basic skepticism that is so essential to scientific progress. Steps like that give you the dark ages, and reliance on authority instead of questioning. So I don't see how anyone can think that science invokes ontology, unless one defines ontology as "picture something that the information is about to breathe meaning into the information", which is not what I mean by ontology-- what we picture in our minds is just more epistemology, and allows us to see all interpretations of QT as pictures. Ontology means arguing over which interpretation is the real one, overlooking that even QT will likely be someday replaced. The attributes of models is all the scientist can ever test, and nothing adjudicates those tests other than more observations-- more information. That's epistemology, and it makes the debate go away-- the Bohmian is someone who says "I like to picture a pilot wave when I apply QT", a Copenhagen follower says "I like to picture a quasi-mystical collapse when I do it." When one strips away the need to be saying something about what actually is, and instead can look at it as a kind of mindset, no problems ensue. We are not trying to figure out reality, which by its nature needs to be unique, we are trying to figure out a good way to think about reality, which by its nature does not need to be unique.
 
  • #108
Ken G said:
I completely agree that science requires semantics, but I don't agree with the association of ontology with semantics.

I never said that.

If you are trying to generate an epistemology, then you are agreeing with me

I was trying to generate an ontology-free epistemology, and explained why it "felt" somewhat unnatural (but then again, block universe has just that same problem so I guess it's not that big of a deal).
 
  • #109
stevendaryl said:
Well, I disagree with you about what science is. But arguing about what science is is philosophy.
This whole thread is not about science but philosophy!
 
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  • #110
Anyway, to get the bundle back together, @Ken G:

1) why is it, then, that the moment we could picture a fully consistent stable backstory of what happens in between preparation and measurement, we would all instantly embrace it? We could just keep with the computational map from preparation and measurement. So there must be something to that idea.
2) by dropping that idea, you are also dropping attempts to make it work, and that eventually may be a limitation. We could end up overlooking something just because we didn't follow our physical intuition, as stevendaryl said: all you say is formally true, but science doesn't always progress by rigid schemes, it has schizophrenic shifting in between conservation and revolution, out-of-the-blue leaps of intuition and so on.

This is along the lines of Feyerabend's critique of Popper, if you're interested, that he tried to put constraints on science that there's no evidence are needed.
 
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  • #111
This came up because it seemed to me that the thermal interpretation was based in the epistemology of the scientific method, where one makes observations on systems and tracks standard deviations and how the standard deviations can be beaten down by making correlations with other information that is available. I'm fine with all that, I think the thermal approach is very solid thinking about how we process information as we do quantum mechanics. I was objecting to the effort to turn it into an ontology, in this case by claiming that what we perceive as a standard deviation between different outcomes in an ensemble of preparations represents measurement error. It seems to make collapse go away by saying it's all a kind of mistake, so needn't be worried about, but it doesn't explain where the mistake comes from. But that doesn't make the thermal interpretation any worse than any other, because they all misstep equally, in my view, when they are regarded as ontologies-- statements of how reality is independently of our preferences of thought. If we just accept that all we test is QT itself, and the interpretations are going to be nonunique ways that different minds will prefer to generate pictures, none of which produces a "reality" because that would be a category error, then all these problems go away. The problems go away if we simply distinguish theories, which the scientist tests, from pictures, which the scientist chooses by preference, from some independent reality, which never appears in the scientific method at all.
 
  • #112
ddd123 said:
1) why is it, then, that the moment we could picture a fully consistent stable backstory of what happens in between preparation and measurement, we would all instantly embrace it?
It depends on what you mean by "embrace." One can embrace a model because it tests out well. One can even embrace a model knowing it doesn't work in all situations, we do that all the time. But one does not need to "embrace" in the sense of an ontology! Here's an example of what I mean. I often invoke the concept of a force of gravity in doing calculations, even though I am personally quite skeptical that there is any such thing as a force of gravity in some independent reality (indeed, I'm skeptical that the concept of an independent reality is a coherent notion in the first place, but that's not my point here). So how can I do that? Why am I not crippled in solving equations that deal with gravity as a force if I don't believe that gravity really is a force? It's because ontology isn't anything important in science, we don't use a belief in what is real-- we invoke pictures, or don't invoke them, like putting on gloves if it's cold outside or not if it isn't.
We could just keep with the computational map from preparation and measurement. So there must be something to that idea.
I am not disputing that part of the scientific epistemology is to invoke pictures, the "backstory" to which you speak. This helps us give meaning to the information, the semantics. But that's still not a claim on what is, it's a claim on how we like to think. The problem is when we get lazy and fail to notice any more that these are modes of thinking, not statements of what is. For example, when I say that a hydrogen atom is composed of a proton with an electron orbiting it, I have invoked a picture, a backstory. I could just solve the equations, but no one ever really "shuts up and calculates", we just don't, we need to have our pictures to organize our thinking. But what we really mean is, "the equations I am solving can be motivated if we picture the hydrogen atom as if it were a proton being orbited by an electron", The hypothetical is what turns ontology into epistemology, and the desire to test the hypothetical is what makes it science. We never need to think we are testing if a hydrogen atom really is a proton orbited by an electron, because we don't get to know that anyway, we are testing the theory that invokes that picture, we are testing that way of thinking. That's all we ever do. That's why I say the goal of science is not to understand reality, the goal of science is to improve our ways of thinking, to get better more accurate and more unified results. That's just our goal-- we don't need any other reason for it, but since our goal is to make sense, we can separate the objective aspects of doing tests from the subjective aspects of choosing pictures we prefer. When it isn't ontology, there just isn't any problem with that separation.
2) by dropping that idea, you are also dropping attempts to make it work, and that eventually may be a limitation. We could end up overlooking something just because we didn't follow our physical intuition, as stevendaryl said: all you say is formally true, but science doesn't always progress by rigid schemes, it has schizophrenic shifting in between conservation and revolution, out-of-the-blue leaps of intuition and so on.
I completely agree with all of that, what I reject is that ontology played any role in any of it. It was all an eloquent description of how scientific epistemology works. We seek a consistent backstory because that's how we think, that is the goal we choose for our efforts, not because we expect the backstory to be the reality. Recall the infamous words of Lord Kelvin in 1900: "There is nothing new to be discovered in physics now. All that remains is more and more precise measurement." The question to ask is not why does the scientist seek a consistent backstory, the question is, having found such a thing, why is it true that any scientist worth their salt should immediately set out to find problems with it?
This is along the lines of Feyerabend's critique of Popper, if you're interested, that he tried to put constraints on science that there's no evidence are needed.
I'd have to see Feyerabend's argument, because I thought Popper did a nice job of showing why those constraints are indeed needed. Science all too easily turns into ontology, at which point it becomes too close to dogma.
 
  • #113
Ken G said:
Pilot wave theory does not unify quantum mechanics and gravity, and it's not even clear it unifies quantum mechanics with special relativity, so it does not pass your test there.

The standard model of particle physics does not unify quantum theory with relativity, because of the Landau pole.
 
  • #114
vanhees71 said:
This is nonsense. In QT nothing, really nothing, depends on whether a human being is looking at something. Nature doesn't care about humans very much.

But if you take the viewpoint that the wave function is epistemic, then quantum theory does depend on epistemic agents (a fancy way generalization of "human beings").
 
  • #115
vanhees71 said:
Yes, read Peres's book. That's the best to prevent one from getting into these esoterics by trying to provide ontology from science. That's the realm of religion/philosophy, not science!

In fact Peres, like Ballentine, does talk about ontology in a misleading way, eg. p426 of the Peres book:

"It is this reduction of our resolving power which allows the emergence of an objective reality, even if only a fuzzy one."

At this point Peres is introducing collapse, but instead of stating his assumptions clearly, he obscures it with a sleight of hand.
 
  • #116
Ken G said:
My justification is the physics has never, in its entire history, presented a fully unified and self-consistent description of reality.
This was not my point. My point was more modest, that when two theories are mutually inconsistent at least one of them is wrong.
 
  • #117
atyy said:
But if you take the viewpoint that the wave function is epistemic, then quantum theory does depend on epistemic agents (a fancy way generalization of "human beings").
Quantum theory, as all of physics, is epistemic. It's about what we can observe in nature and a quantitative description of what we observe.

atyy said:
In fact Peres, like Ballentine, does talk about ontology in a misleading way, eg. p426 of the Peres book:

"It is this reduction of our resolving power which allows the emergence of an objective reality, even if only a fuzzy one."

At this point Peres is introducing collapse, but instead of stating his assumptions clearly, he obscures it with a sleight of hand.
Well, it's your personal opinion that the scientific core of quantum theory, as opposed to possible metaphysical or religious implications, is misleading. That's the freedom of personal belief. The claim that Peres introduces collapse, is however a distortion of his entire book ;-).
 
  • #118
stevendaryl said:
... arguing about what science is is philosophy.

That's right. In fact arguing about what anything "is", is philosophy.

Ken G said:
We are not trying to figure out reality ...

Actually I am trying to figure out reality - but not qua scientist. Indeed the only reason I'm interested in science - these days, since I no longer need a job - is to help me understand what reality "really is". That's the job of philosophy, which uses scientific facts as raw material.

An overall problem with much of this discussion is that philosophy is often considered useless, even bad. The statement "it's philosophy" is taken to mean "it's just philosophy" or "mere philosophy", not worthy of an intelligent person. People are trapped by this incorrect syllogism:

Premises:

1) Only scientific reasoning is valid.
2) But I want to know what reality is.

Conclusion: Therefore the ontological question - what is real - must be scientific, or I can't address it.

Actually both science and philosophy are valid. Ontology is fine, even though it's not science. IMHO.

Simon Phoenix said:
I confess I can't quite get my head around the viewpoint that the wavefunction is merely descriptive of our 'state of knowledge' ...

There's no problem if one also says that science's idea of a rock (for instance) is "merely descriptive of our 'state of knowledge'". Paradox occurs only when you say a rock is ontologically real but a wavefunction (or at least, some aspect of QM) isn't. Something real can't be composed of a bunch of things that aren't real! The paradox is equally avoided if you suppose they're both real, but qua scientist it's best to have no opinion on the issue, which is the province of philosophy.
 
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  • #119
vanhees71 said:
Quantum theory, as all of physics, is epistemic. It's about what we can observe in nature and a quantitative description of what we observe.

But if quantum theory is about "what we can observe", then quantum theory does depend on whether a human being is looking at something or not.

vanhees71 said:
Well, it's your personal opinion that the scientific core of quantum theory, as opposed to possible metaphysical or religious implications, is misleading. That's the freedom of personal belief. The claim that Peres introduces collapse, is however a distortion of his entire book ;-).

Unfortunately you are wrong about the scientific core of quantum theory. Quantum theory is not about ontology, but it is about "what we can observe".
 
  • #120
Now everything gets mixed up. Of course quantum theory is there because humans have discovered it as a description of what's observed but not more, particularly it doesn't provide ontology (neither does classical physics). The observables are defined operationally by real-world measurement processes. Whether even a classical abstraction as the electromagnetic field has an ontic meaning, is completely outside of science. It is a mathematical description that describes successfully what we observe in the corresponding realm of nature, including phenomena from electrostatic and magnetic forces to light (electromagnetic waves). Whether the field is ontic or not, cannot be clarified in any way but is a matter of personal world view. What can be stated scientifically is that it's a mathematical picture which fits to all observations.
 
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  • #121
vanhees71 said:
The observables are defined operationally by real-world measurement processes.

Are there measurement processes without human beings?
 
  • #122
Sure, the data from the LHC, e.g., are taken by detectors and stored on hard disks. No human being could ever take these vast amount of data coming in a very short time.
 
  • #123
vanhees71 said:
Sure, the data from the LHC, e.g., are taken by detectors and stored on hard disks. No human being could ever take these vast amount of data coming in a very short time.

So you claim that if we have a wave function describing the LHC, it will evolve unitarily?
 
  • #124
vanhees71 said:
Whether even a classical abstraction as the electromagnetic field has an ontic meaning, is completely outside of science.
Maybe, but then I would say that it is impossible for a human being to do science without combining it with some elements of meta-science (things outside of science). Meta-science is relevant for science.

Or let me ask you a personal question. Obviously, you are interested in some meta-science and you spend some time for thinking about meta-science and discussing meta-science. Do you think that it makes you a better scientist?
 
  • #125
atyy said:
So you claim that if we have a wave function describing the LHC, it will evolve unitarily?
I think he would say that there is no such thing as a wave function describing the whole LHC.
 
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  • #126
stevendaryl said:
I agree that it is nonsense to believe that physics depends on human observers.
I think the word "physics" is used with two different meanings.

Physics 1 - the laws obeyed by Nature itself

Physics 2 - a science invented by humans to describe their knowledge about nature

Presumably, Physics 1 does not depend on human observers. But Physics 2 certainly does. So one should specify what does one mean by "physics".
 
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  • #127
Physics 1 is not part of physics since it cannot be observed. We can only observe what we can observe. But now, we really start philosophical gibbering (in German we have the very adequate word "Geraune" for it; I don't know whether there is a literate translation to English ;-)) rather than exchanging sound and solid scientific arguments. Indeed, you are right, concerning the "wave function of CERN". I guess, the entire universe wasn't large enough to store the corresponding information.
 
  • #128
vanhees71 said:
Physics 1 is not part of physics since it cannot be observed. We can only observe what we can observe. But now, we really start philosophical gibbering (in German we have the very adequate word "Geraune" for it; I don't know whether there is a literate translation to English ;-)) rather than exchanging sound and solid scientific arguments. Indeed, you are right, concerning the "wave function of CERN". I guess, the entire universe wasn't large enough to store the corresponding information.

But if there is no wave function of CERN, then you are treating CERN as a "classical measuring apparatus", which is the Heisenberg cut.
 
  • #129
secur said:
The paradox is equally avoided if you suppose they're both real, but qua scientist it's best to have no opinion on the issue, which is the province of philosophy.

Here's how Matt Leifer describes the terms in his review paper

"In the present context, an ontic state refers to something that objectively
exists in the world, independently of any observer or agent. In other words, ontic states are the things that
would still exist if all intelligent beings were suddenly wiped out from the universe. On the other hand,
"epistemology" is the branch of philosophy that studies of the nature and scope of knowledge. An epistemic
state is therefore a description of what an observer currently knows about a physical system. It is something
that exists in the mind of the observer rather than in the external physical world."

It would seem, especially for QM, that it is largely a philosophical distinction since one can perform calculations using an ontic or epistemic perspective and get the same answers. However, the PBR theorem purports to rule out a class of epistemic interpretations - in much the same way that Bell's theorem rules out certain hidden variable interpretations.

So I would say that, currently, the matter of ontology vs epistemology with regards to QM (and maybe science) is somewhat philosophical, but I don't think that should dissuade us from attempting to settle the matter scientifically, or to at least put bounds on possible interpretations in the way that PBR claims to do.
 
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  • #130
Simon Phoenix said:
It would seem, especially for QM, that it is largely a philosophical distinction since one can perform calculations using an ontic or epistemic perspective and get the same answers. However, the PBR theorem purports to rule out a class of epistemic interpretations - in much the same way that Bell's theorem rules out certain hidden variable interpretations. So I would say that, currently, the matter of ontology vs epistemology with regards to QM (and maybe science) is somewhat philosophical, but I don't think that should dissuade us from attempting to settle the matter scientifically, or to at least put bounds on possible interpretations in the way that PBR claims to do.

Well, it's in the nature of categorization to draw sharp delineations. Actually things are always fuzzy. For instance math and science are distinct entities but you can't do science without math. And, you can't do science without some sort of philosophy. The only reason to try to draw the boundary is to eliminate - at least reduce - the huge waste of brainpower when the two get confused. For example, Copenhagen and thermal interpretations are, AFAIK, both valid ways to picture what the math describes. Sure, you can prefer one or the other, and debate them - a bit. But at some point realize it just doesn't matter, and let the other guy picture it however he wants.

That's assuming they really are both valid interpretations, or ontologies. It may be possible to prove, rigorously, that what appears valid really isn't. If reality were that way, it couldn't give the experimental results. That's what Bell's inequality (and related experiments) successfully does: rules out a type of at-first-glance plausible model, by clever mathematical and scientific reasoning.

Go ahead and do science using all necessary auxiliaries: philosophy, math, language, logic, classrooms, conferences, grants, salaries, food, water, and many other things which aren't science per se. But whenever you get into one of these endless arguments, it's time to step back a moment. Is it really about science? In that case, argue away, since it's actually decidable. Or, is it really about philosophy? In that case shrug, and agree to disagree. Or, go argue about it (if you must) on a philosophy board, not PF :-)

Matt Leifer said:
In other words, ontic states are the things that would still exist if all intelligent beings were suddenly wiped out from the universe.

A quibble: I see no reason to limit it to intelligent beings, rather any conscious beings with some rudimentary mind. And, BTW, it's possible nothing would still exist if all consciousness were wiped out: that ontology is an artifact of epistemology. That's a key point in this discussion.
 
  • #131
secur said:
That's what Bell's inequality (and related experiments) successfully does: rules out a type of at-first-glance plausible model, by clever mathematical and scientific reasoning.

Yes - and that's really one of the main thrusts of Leifer's article - to examine whether it's possible to rigorously rule out certain ways of looking at things and to lift the debate out of the murky philosophical waters and into the crystal clarity of the light of science o0)

(only slightly tongue-in-cheek there)
 
  • #132
atyy said:
But if there is no wave function of CERN, then you are treating CERN as a "classical measuring apparatus", which is the Heisenberg cut.
There is no problem with the Heisenberg cut, provided that you don't take it too seriously, but merely use it as a practical operational tool. (Perhaps this is not what Bohr would say, but probably something what Peres would agree with.)
 
  • #133
zonde said:
This was not my point. My point was more modest, that when two theories are mutually inconsistent at least one of them is wrong.
But your point is more than that-- you are saying that it would not be true that one of them had to be wrong unless there was a reality that the theories were attempting to model. I see it simply as a logical requirement that both theories cannot be completely correct if they disagree, like saying that if 2+2=4 it cannot also equal 5 unless 4 and 5 are equivalent. We don't need a reality to enforce that mathematical truth, so why do we need it in physics? There is no part of physics that says "this only works if there is a reality", there is only "model, test, repeat, all the while using mathematical logic." We set it up that way because it appears to work, and for no other reason. Certainly not "because there is a reality," no such requirement exists. It's not that there isn't a reality, it's that science doesn't need what it never uses.
 
  • #134
secur said:
Actually I am trying to figure out reality - but not qua scientist. Indeed the only reason I'm interested in science - these days, since I no longer need a job - is to help me understand what reality "really is". That's the job of philosophy, which uses scientific facts as raw material.
Fair enough, I really only mean that the scientist is not trying to do that. As a kind of subroutine invoked by a philosopher, science can be used for that goal, going outside the subroutine. I agree with you that the paradoxes only occur when the "program" being used cannot distinguish the inside from the outside of that subroutine. A computer programmer would instantly notice a problem if there was a specific goto statement within a subroutine that referred to the main program, so why don't physicists notice that same thing when they take scientific ontology seriously in the process of solving physics equations?
Premises:

1) Only scientific reasoning is valid.
2) But I want to know what reality is.

Conclusion: Therefore the ontological question - what is real - must be scientific, or I can't address it.
This is a problem, because the reasoning you just applied is not scientific, it is philosophical. Philosophical reasoning obeys the rules of logic, and uses premises and axioms as you are doing, but it's not scientific reasoning until it looks like "model, test, repeat." So for a set of premises to be part of scientific reasoning ,they can never be taken as axioms of truth, they must always be hypotheses to be tested. It doesn't sound like your goal is to test those premises, it sounds like your goal is to take them as given and go from there. But as soon as you do that, you are not doing scientific reasoning. Thus, this program is incompatible with premises that assert that only scientific reasoning is valid. The program is internally inconsistent, which is the problem with logical positivism, which essentially embodies the subjective philosophy of replacing subjective philosophy with science, which doesn't make sense. It can be fixed either by treating the reliance on scientific reasoning as the hypothesis being tested (which will never close the process because the tests of science never end), or by accepting that other forms of reasoning than science are valid (which opens the problem to what forms of reasoning that includes). Either way, it's a program that does not complete in a finite number of steps, but like science itself, this need not be viewed as a problem if one focuses on the lessons of the journey rather than some final destination.
There's no problem if one also says that science's idea of a rock (for instance) is "merely descriptive of our 'state of knowledge'". Paradox occurs only when you say a rock is ontologically real but a wavefunction (or at least, some aspect of QM) isn't. Something real can't be composed of a bunch of things that aren't real!
Yes, that's right on. In fact, we could view it as rather bizarre that most people regard rocks as ontologically real without doubt, but the wavefunction of an isolated hydrogen atom as an epistemological abstraction, when the wavefunction is much simpler and more precise, and is used in a much more tightly constrained way. I think all that is happening there is that the concept of a "rock" is so much more vague that its epistemological character is more difficult to see. Ironically, this means we only regard wavefunctions as abstractions and rocks as fundamental entities because we understand the former so much better than the latter.
 
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  • #135
Ken G said:
We set it up that way because it appears to work, and for no other reason. Certainly not "because there is a reality," no such requirement exists. It's not that there isn't a reality, it's that science doesn't need what it never uses.

When did science become so defeatist? :wideeyed:

My primary motivation is to understand "why the world is as it is", so to speak. I'll settle for the secondary goal of being able to predict stuff - but ultimately I'm really wanting something a bit more than some set of techniques that 'work' - and when those techniques are said not to be descriptive of some underlying reality but, rather, descriptive of what's going on in my noggin - then I do have to do the occasional sanity check :nb)

Before QM came along I suspect that very few scientists would have held that it is the job of science just to predict stuff, and not to say anything about 'reality'. Of course after QM, when it became awkward (to say the least) to ascribe some 'reality' to the state, I get the impression it was as if there was some collective decision to 'redefine' what science is about.
 
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  • #136
vanhees71 said:
Now everything gets mixed up. Of course quantum theory is there because humans have discovered it as a description of what's observed but not more, particularly it doesn't provide ontology (neither does classical physics). The observables are defined operationally by real-world measurement processes. Whether even a classical abstraction as the electromagnetic field has an ontic meaning, is completely outside of science. It is a mathematical description that describes successfully what we observe in the corresponding realm of nature, including phenomena from electrostatic and magnetic forces to light (electromagnetic waves). Whether the field is ontic or not, cannot be clarified in any way but is a matter of personal world view. What can be stated scientifically is that it's a mathematical picture which fits to all observations.
Surely this must be something no scientist can disagree with, can this not be considered a consensus view? All it does is enforce the distinction between how science is defined, and what people sometimes choose to use it for that goes beyond that definition.
 
  • #137
Simon Phoenix said:
When did science become so defeatist? :wideeyed:
This is a crucial point-- is it really defeatist to notice that science doesn't do ontology because what it actually does is challenge hypotheses? I don't see that as giving up on science, I see it as empowering science. It is the wings that let science fly, that it does not pin itself down to one doomed ontology after another (though that does seem to be how many people seem compelled to use it.) Look at all the doomed ontologies of history, and how effortlessly science abandoned them without a hitch. Is it defeatist to notice science's greatest strength?
My primary motivation is to understand "why the world is as it is", so to speak.
Then let me suggest a minor but crucial reframing of that which is more compatible with science: your primary motivation is to generate a working picture of why the world is as it is. Your working picture should pass a bunch of tests, and offer considerable conceptual unification. And it should contain valuable lessons, not the least of which is that you should expect it to one day be replaced by something almost completely different-- likely after you and I are long gone.
I'll settle for the secondary goal of being able to predict stuff - but ultimately I'm really wanting something a bit more than some set of techniques that 'work' - and when those techniques are said not to be descriptive of some underlying reality but, rather, descriptive of what's going on in my noggin - then I do have to do the occasional sanity check :nb)
We all want more than successful predictions. Nobody ever "shuts up and calculates", we are not adding machines. The pictures we create are wonderful, exquisite, and fascinating, all without the impossible requirement of being some true reality. What's so wrong about freeing the constraints from what science has never been, and let it be what it demonstrably actually is?
Of course after QM, when it became awkward (to say the least) to ascribe some 'reality' to the state, I get the impression it was as if there was some collective decision to 'redefine' what science is about.
I suspect that our modern fascination with the spookiness of quantum mechanics, and the challenges it presents to our concepts of reality, is actually nothing new at all-- it's simply the modern version of what science has constantly encountered. Could going from trajectories to superpositions of wavefunctions be any more shaking to one's world view than going from a stationary Earth at the center of a lofty and exalted heavens, to a random rock at a random location of a vast cosmos of seemingly arbitrary interactions? Every new theory shatters the old ontology, and every generation thinks their own version is the one that is a crisis. I think Feynman's sage words are more the norm than the exception:
"We have always had a great deal of difficulty understanding the world view that quantum mechanics represents. At least I do, because I'm an old enough man that I haven't got to the point that this stuff is obvious to me. Okay, I still get nervous with it... You know how it always is, every new idea, it takes a generation or two until it becomes obvious that there's no real problem. I cannot define the real problem, therefore I suspect there's no real problem, but I'm not sure there's no real problem."
 
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  • #138
Ken G said:
But your point is more than that-- you are saying that it would not be true that one of them had to be wrong unless there was a reality that the theories were attempting to model. I see it simply as a logical requirement that both theories cannot be completely correct if they disagree, like saying that if 2+2=4 it cannot also equal 5 unless 4 and 5 are equivalent. We don't need a reality to enforce that mathematical truth, so why do we need it in physics?
First let me make my statement more general by stating that "when two descriptions are mutually inconsistent at least one of them is wrong" as single theory can implement alternative descriptions.
Now let me give you two examples.
In special relativity you can describe physical situation from different inertial reference frames. These descriptions are mutually consistent.
In orthodox quantum theory it is common to say that say quite large complex object (buckyball) can be in superposition of going through left or right slit. These two descriptions are not mutually consistent because both options are required to predict result.
In second case proposed explanation contradicts realism. Now the question is - can we come up with model that gives correct prediction but does not contradict realism? And pilot wave theory does that.
Ken G said:
There is no part of physics that says "this only works if there is a reality", there is only "model, test, repeat, all the while using mathematical logic." We set it up that way because it appears to work, and for no other reason. Certainly not "because there is a reality," no such requirement exists. It's not that there isn't a reality, it's that science doesn't need what it never uses.
We evaluate models, if they are scientifically acceptable. For example we require that predictions of model are unequivocal.
 
  • #139
Ken G said:
The pictures we create are wonderful, exquisite, and fascinating, all without the impossible requirement of being some true reality. What's so wrong about freeing the constraints from what science has never been, and let it be what it demonstrably actually is?
This is strawman argument. We do not require that our ontologies are true reality. Ontolgies are only good approximations of reality that simplify our current and future models as they are reusable in different models.
 
  • #140
The big problem with ignoring ontology is that people who claim to ignore it actually promote it: eg. Ballentine, Peres and vanhees71.

If they truly did not care about ontology, they would have no problems with collapse.

There are well respected positions that ignore ontology, eg. Bohr, Landau and Lifshitz, Copenhagen as described by Weinberg - but all of these have things which are disavowed by vanhees71, eg. collapse and the Heisenberg cut.
 

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