# Ontology and measurement

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• Simple question
LightarrowIn summary, Lightarrow thinks that if we live in a simulation, it is running on some sort of "hardware". He doesn't think that we live in a simulation, and believes that some properties of particles do not exist before being measured. He also thinks that if a property is conserved across huge space and time, it is real. He does not think that the properties are completely defined by equations, but that they are hosted realistically and non-locally in abstract mathematics of quantum mechanics. If you believe that there is something else than the simulation, you are missing part of the equation.f
Nor the same frame will agree with its own previous value just by changing units.
Those "values" are not beable/ontologies in any sense, their usefulness is not to be denied, but they are just labels, not true statements about what is real.
The math actually tell us something important, especially if you think symmetries are real, not artifacts of "frames".
I would name "intrinsic" those properties as mass, charge, spin, which are frame invariant and "not intrinsic" what is not frame invariant, but it's terminology. Don't know the meaning you attribute to the word "ontology" here: momentum is a (very real) physical quantity.
So if I take my navel as a frame, I don't change the momentum of a truck heading straight onto me by jumping out of its way. I know it "for real" because it does not require the same change in momentum.
Because what "counts" here is the momentums difference between your navel and the truck, not their absolute values. Anyway this is a different story from the fact momentum is frame dependent. In this last case momentum is important, and is conserved for an isolated system, providing the frame doesn't change. And if it changes, we simply have to remember to ricalculate all systems momentums. (This is a common mistake among laymen, as you probably know).

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Lightarrow

mattt and PeroK
why does the magnet (u oriented) split the beam in two, equally distributed, different beams and, more important, why does subsequent magnets v oriented again, splits again each beam in other two equally distributed, different beams?
Why not is the question I would ask. And you can only "erase" a component by making it orthogonal. Actually you can use any angle, and then the split will not be equals. All this is pretty straightforward and intuitive, especially for spin.

My intuition (don't know if it can be called "interpretation") is that the (gradient of) B field u oriented destroys the "v+" property of the quantum system (Ag beam) and creates the "u+" property in the first splitted beam and the "u-" property in the other; the field does not affect this if it's oriented along the same axis of which the system has been prepared.
I think I use the same intuition, and that is how I believe measurement device work, the interaction with something existing, (changing it in the process, that's inevitable if you follow strict conservation logic).
That's nudging before is was trendy, and it 's quantum because you get only two outcome.

So in my vision the magnet/field does 3 different things according to the experimental setting and the initial system's state:
I understand why you would want to split "cases", but I prefer a unique (generic) explanation.
BTW your own analyse do depend on the preparation (as it should), so whatever is prepared has to be real before entering the measurement device

2) The system's property is real but the measuring apparatus can: do nothing, destroy, create it, according to the situation. So the property doesn't belong on the system only or on the apparatus only, it depends on both, in general.
Yes, the results depends on the orientation, so it is clear the measurement device do something, it has to.
The property did and will only belong the "particle". There is just a snapshot/collapsed "value" of that property copied/stored in the device. And any identical device put further along will have no choice, but to agree with that "eigenstate". If you change their basis, and only then, there is a clear and progressive change possible in the property.

3) According to Copenhagen interpretation it's the system,
I don't think there are such interpretations. It means more the lack of interpretation.

but in my vision what is called "collapse" is something a bit more complicated and we should refer to the previous points 1), 2) ("fenomenology"?)
It is impossibly complicated if you hang onto locality. I think GRW does it, by taking collapse as a beable, but make different predictions than standard QM (but possibly out of reach of current technical possibility).

5) Don't understand. Momentum is frame dependent so, in a sense, you do create momentum (or energy, or velocity or acceleration, or position, or lenght, ...) by changing frame of reference.
I mean: momentum cannot be changed, it can only be exchanged, whatever the frame.

the measurement apparatus has a very active role in the creating what is "measured".

Then, you put a Higgs Boson (for example) in a detector, and the detector gives it its spin property ?

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Then, you put a Higgs Boson (for example) in a detector, and the detector gives it its spin property ?

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Sorry, don't know how an Higgs boson behave in a Stern-Gerlach apparatus, we were talking of the usual Ag atoms of the standard experiment.
In my vision, if these atoms were prepared in the z+ state, then an apparatus (the magnet made in that way) which is Y oriented (that is, orthogonal to Z; the beam propagates along X) destroyes that z+ property and creates two other property: y+ and y-, in two different, separated, beams.

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Lightarrow

mattt, PeroK and vanhees71
This is an interesting statement, as unpacking it can illuminate the question of measurement and ontology.

Would you say momentum is a property of the system being observed or a property of the "system + observer"? The fact that the "value" varies based on the observer (since different observers may be in different inertial frames) is already a massive hint forcing the issue :
1. If you say it is a property of the system being observed only, then what is observed as different values can't be the same "thing" that is conserved. Then you must have (implicitly or explicitly) in your ontology the idea that there is a conserved "beable" associated with momentum, which manifests itself as different values ("observables") when observed from different inertial frames.
2. But if you say it is a property of the combined "system + observer" only, then, in this case, you do not assume the existence of any underlying "beable" associated with the "observable." This also restricts what you can say about the "system" based on this observed "value." The problem is many who will pick this option (quite reasonably so) go on to discuss and present "value" as though it applied just to the system. This is wrong and leads to more confusion.

Such conceptual clarity is badly needed in the foundations if any significant progress is going to be made.
I would disconnect the concepts "frame of reference" and "observer" because you can "observe" every phenomenon in the frame of reference you choose.
Anyway I don't like the term "observe" or "observer" because they belongs to optics. I prefer "measure/analyze in the X frame".

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Lightarrow

1) Why not is the question I would ask. And you can only "erase" a component by making it orthogonal. Actually you can use any angle, and then the split will not be equals. All this is pretty straightforward and intuitive, especially for spin.

2) I understand why you would want to split "cases", but I prefer a unique (generic) explanation.
BTW your own analyse do depend on the preparation (as it should), so whatever is prepared has to be real before entering the measurement device
1) I can't understand what you mean with "why not is the question I would ask". Yes, if I use other angles the split will not be equal. But, until someone compute the probabilities of detection with this "interpretation" we don't know if it can be correct, at least for this experimental setting.

2) Yes, it would be real, after preparation, but only in relation to the measurement instrument: if it was prepared in z+ state and the instrument is aligned along Z, then it's real. What does it mean? Simply that the magnet destroyes the atom's magnetic moment (m.m.) orientation if it's aligned differently, because it changes the atom's m.m. orientation. Too naive?

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Lightarrow

1) I can't understand what you mean with "why not is the question I would ask".
I emphasis the not because of your post 33 where you declare "the real mystery is" about a totally mundane phenomena that have plethora of classical equivalent.
Bell's elucidate the QM case clearly. There are not that much ways to map ontologies to measurements processes.

So I am going to consider that you think that some property don't exist before measurement (or at least in some arbitrary cases). I've still no clue how you sort out those cases, nor were those property emerge from in those cases.

Yes, if I use other angles the split will not be equal. But, until someone compute the probabilities of detection with this "interpretation" we don't know if it can be correct, at least for this experimental setting.
I mentioned angles because there is a continuum of possible orientation and a continuum of outcome probability. And I don't think that property is "destroyed", when it's probability become 0.5 and only that exact value.

2) Yes, it would be real, after preparation, but only in relation to the measurement instrument: if it was prepared in z+ state and the instrument is aligned along Z, then it's real.
I've added more emphasis. Even without adding entanglement, this does not make a lot of sense to me.
Let's say a bunch of Ag atom are emitted 100 year before and kept nicely in some perfect isolation.
Then we only start building the Stern-Gerlach.
Then we only decide randomly some orientation.
Either all properties are real, or none are.
If the preparation is real, it prepared some real property to be measured.

What does it mean? Simply that the magnet destroyes the atom's magnetic moment (m.m.) orientation if it's aligned differently, because it changes the atom's m.m. orientation. Too naive?
It is not too naive for me, I would say the same, except replacing "destroy" by "changes in response to the initial property value"

lightarrow
I emphasis the not because of your post 33 where you declare "the real mystery is" about a totally mundane phenomena that have plethora of classical equivalent.
Some examples (or even one)?
Bell's elucidate the QM case clearly. There are not that much ways to map ontologies to measurements processes.
I don't know much about it. Can you give me a link to (a free access to) such a document?
So I am going to consider that you think that some property don't exist before measurement (or at least in some arbitrary cases).
Why "arbitrary"? I believed to have shown the functioning.
I've still no clue how you sort out those cases, nor were those property emerge from in those cases.
Don't know how to explain better than that.
I mentioned angles because there is a continuum of possible orientation and a continuum of outcome probability.
Of course.
And I don't think that property is "destroyed", when it's probability become 0.5 and only that exact value.
Ok, yes you are right, I illustrated just the two limiting cases: the property z+ stay the same when the magnet is oriented as Z, the property is totally destroyed when the magnet is orthogonal to Z and ... the system has partially that property in the other cases.
This weird thing doesn't disturb me, at least no longer. I believe we have to make an effort to completely change paradigm, and, in the end, this kind of change I'm trying to propose here seems to me the only solution.
I've added more emphasis. Even without adding entanglement, this does not make a lot of sense to me.
Let's say a bunch of Ag atom are emitted 100 year before and kept nicely in some perfect isolation.
Then we only start building the Stern-Gerlach.
Then we only decide randomly some orientation.
Ok
Either all properties are real, or none are.
According to some definition of the paradigm "real". Maybe we can't call "real" the paradigm I've proposed, but, apart from terminology, I believe, I repeat, that we have to completely change our naive concept of "reality" and we have to find something more refined. My intuition is strong about it.
If the preparation is real, it prepared some real property to be measured.
Only relatively to the instrument.
I agree with Rovelli's relational interpretation, in this.
It is not too naive for me, I would say the same, except replacing "destroy" by "changes in response to the initial property value"
Sorry, have not understood:
"changes in response to the initial property value"

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Lightarrow

Sorry, don't know how an Higgs boson behave in a Stern-Gerlach apparatus, we were talking of the usual Ag atoms of the standard experiment.
In my vision, if these atoms were prepared in the z+ state, then an apparatus (the magnet made in that way) which is Y oriented (that is, orthogonal to Z; the beam propagates along X) destroyes that z+ property and creates two other property: y+ and y-, in two different, separated, beams.

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Lightarrow

Higgs Boson have no Spin.

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Higgs Boson have no Spin.
I looked up now. It has spin 0, not that "has no spin".
"The colour blue" has "no spin", for example.
Even to say "a photon has no mass" is a language misuse; but physicists understand what it means. Laymen instead don't.
For this reason I prefer to say:
"has zero mass"
"has spin 0"
etc.

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Lightarrow

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vanhees71
don't know how an Higgs boson behave in a Stern-Gerlach apparatus
Since the Higgs is spin-0, you would only get one output beam--i.e., the action of the apparatus on a beam of Higgs bosons is a no-op.

lightarrow and vanhees71
Since the Higgs is spin-0, you would only get one output beam--i.e., the action of the apparatus on a beam of Higgs bosons is a no-op.
Yes, after having looked up for the Higgs Boson's properties and found it has spin = 0 it was clear. But I didn't do it before answering physika because I considered his question as provocative.
Thanks, anyway.

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Lightarrow

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Anyway, I'd like to thank you for the interesting discussion, simple question.

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Lightarrow

Some examples (or even one)?
Let's see... "heads" and I'll give you one example .. and "tails" ... also.

I don't know much about it. Can you give me a link to (a free access to) such a document?
Aside from the Spontaneous collapse, I think this document may be what you are looking for.
My point was that there are not an infinite number of those, even if some appear from time to time. Like Arnold Neumaier's thermal interpretation, that I think would fall in the non-collapse realist group.

Why "arbitrary"? I believed to have shown the functioning.
Spin gets attributed only by referring to direction. I don't think you've showed how you can "pick arbitrary" some angle, has being qualitatively different from the other. You've only explained how to do that with respect to initial preparation (which is correct). Thus I don't understand how you can declare that the property measure don't exist at preparation.

This weird thing doesn't disturb me, at least no longer. I believe we have to make an effort to completely change paradigm, and, in the end, this kind of change I'm trying to propose here seems to me the only solution.
Well, I am also in favor of trying paradigms, especially if they addresses some issue. If I understood you well (finally ) you are advocating for some sort of Relational Quantum Theory. Which I think are not realist one.
Still it is an interesting paradigm too. I just have no idea how they addresses non-locality or the Heisenberg cut

Maybe we can't call "real" the paradigm I've proposed, but, apart from terminology, I believe, I repeat, that we have to completely change our naive concept of "reality" and we have to find something more refined. My intuition is strong about it.
OK

Sorry, have not understood: "changes in response to the initial property value"
What is there not to understand, is what bothers me.
-My palm interact with that coin.
-An non-uniform magnetic fields interact with the trajectory of some Ag atom

In both cases the initial values are not decided by the measuring device. That's why you need to place those measuring devices in the path of pre-existing "things".

Anyway, I'd like to thank you for the interesting discussion, simple question.
Same here. Have a great day !