Relational Quantum Mechanics and Event Centric View

[sayak83]

I several threads now I supported an interactionist or event centric view of Quantum Mechanics. In this view quantum interaction events are ontologically primary and quantum systems (i.e. things) have properties and attributes only in relation to these interaction events. This idea came up with respect to recent experimental demonstration of Wigner's friend paradox, that showed that the objectivity of observable reality is quite shaky

AAAS

Nearly 60 years ago, the Nobel Prize–winning physicist Eugene Wigner captured one of the many oddities of quantum mechanics in a thought experiment. He imagined a friend of his, sealed in a lab, measuring a particle such as an atom while Wigner stood outside. Quantum mechanics famously allows particles to occupy many locations at once—a so-called superposition—but the friend's observation "collapses" the particle to just one spot. Yet for Wigner, the superposition remains: The collapse occurs only when he makes a measurement sometime later. Worse, Wigner also sees the friend in a superposition. Their experiences directly conflict.

Now, researchers in Australia and Taiwan offer perhaps the sharpest demonstration that Wigner's paradox is real. In a study published this week in Nature Physics, they transform the thought experiment into a mathematical theorem that confirms the irreconcilable contradiction at the heart of the scenario. The team also tests the theorem with an experiment, using photons as proxies for the humans. Whereas Wigner believed resolving the paradox requires quantum mechanics to break down for large systems such as human observers, some of the new study's authors believe something just as fundamental is on thin ice: objectivity. It could mean there is no such thing as an absolute fact, one that is as true for me as it is for you.


So some are questioning the tenet that observers can pool their measurements empirically. "It could be that there are facts for one observer, and facts for another; they need not mesh," says study co-author and Griffith physicist Howard Wiseman. It is a radical relativism, still jarring to many. "From a classical perspective, what everyone sees is considered objective, independent of what anyone else sees," says Olimpia Lombardi, a philosopher of physics at the University of Buenos Aires

The interactionist or relational view of QM is an interpretation that proposes precisely this. Physical systems exist and gain properties only at interaction events with other systems and concept of "things with property values" is meaningless when no interaction is happening. Further what these properties are depend on the type of event itself. So we move from "things with properties having interactions via which these properties change" type of ontology to "Interaction events from which things with properties emerge" type of ontology.

The full interpretation is called Relational Quantum Mechanics. A good exposition is in this paper here,

https://royalsocietypublishing.org/doi/full/10.1098/rsta.2017.0312#FN1

The main ideas of QM in this interpretation are:-
a) There is fundamental discreteness in nature, because of which many physical variables can take only certain specific values and not others.
(b) Predictions can be made only probabilistically, in general.
(c) The values that a variables of a physical system takes are such only relative to another physical system. Values taken relatively to distinct physical systems do not need to precisely fit together coherently, in general.
Key points from the paper

The fact that values of variables can be predicted only probabilistically raises the key interpretational question of QM: when and how is a probabilistic prediction resolved into an actual value?

The answer is: when S interacts with another physical system S′. Value actualization happens at interactions because variables represent the ways systems affect one another. Any interaction counts, irrespectively of size, number of degrees of freedom, presence of records, consciousness, degree of classicality of S′, decoherence, or else because none of these pertain to elementary physics.

In the course of the interaction, the system S affects the system S′. If the effect of the interaction on S′ depends on the variable a of S, then the probabilistic spread of a is resolved into an actual value, or, more generally, into an interval I of values in its spectrum.

Now we come to the crucial point. The actualization of the value of a is such only relative to the system S′. The corresponding state ρ′ determined by the actualization is therefore a state relative to S′, in the sense that it predicts only the probability distribution of variables of S in subsequent interactions with S′. It has no bearing on subsequent interactions with other physical systems.

...quantum theory takes this ubiquitous relationalism, to a new level: the actual value of all physical quantities of any system is only meaningful in relation to another system. Value actualization is a relational notion like velocity.

This is the profoundly novel relational aspect of QM.

In my view this interpretation avoids the ontological excessiveness of many-worlds, avoids the need to assume hidden processes like pilot waves that can never be observed, as well as the idealist solipsism of stating that world is real only when a conscious observer is observing it.

Another fact is that this interpretation works well with the background independent formulation needed for Quantum Gravity theories. As the author says:-

My focus on relational QM, indeed, is also motivated by my work in quantum gravity [38,39]. In quantum gravity, where we do not have a background space–time where to locate things, relational QM works very neatly because the quantum relationalism combines in a surprisingly natural manner with the relationalism of general relativity. Locality is what makes this work. Here is how [40]: the quantum mechanical notion of ‘physical system’ is identified with the general relativistic notion of ‘space–time region’. The quantum mechanical notion of ‘interaction’ between systems is identified with the general relativistic notion of ‘adjacency’ between space–time regions. Locality assures that interaction requires (and defines) adjacency. Thus quantum states are associated to three-dimensional surfaces bounding space–time regions and quantum mechanical transition amplitudes are associated to ‘processes’ identified with the space–time regions themselves. In other words, variables actualize at three dimensional boundaries, with respect to (arbitrary) space–time partitions. The theory can then be used locally, without necessarily assuming anything about the global aspects of the universe.

What do you think @Polymath257 @Meow Mix @exchemist @LegionOnomaMoi ?

 

[exchemist]

I several threads now I supported an interactionist or event centric view of Quantum Mechanics. In this view quantum interaction events are ontologically primary and quantum systems (i.e. things) have properties and attributes only in relation to these interaction events. This idea came up with respect to recent experimental demonstration of Wigner's friend paradox, that showed that the objectivity of observable reality is quite shaky

AAAS


The interactionist or relational view of QM is an interpretation that proposes precisely this. Physical systems exist and gain properties only at interaction events with other systems and concept of "things with property values" is meaningless when no interaction is happening. Further what these properties are depend on the type of event itself. So we move from "things with properties having interactions via which these properties change" type of ontology to "Interaction events from which things with properties emerge" type of ontology.

The full interpretation is called Relational Quantum Mechanics. A good exposition is in this paper here,

https://royalsocietypublishing.org/doi/full/10.1098/rsta.2017.0312#FN1

The main ideas of QM in this interpretation are:-
a) There is fundamental discreteness in nature, because of which many physical variables can take only certain specific values and not others.
(b) Predictions can be made only probabilistically, in general.
(c) The values that a variables of a physical system takes are such only relative to another physical system. Values taken relatively to distinct physical systems do not need to precisely fit together coherently, in general.
Key points from the paper

In my view this interpretation avoids the ontological excessiveness of many-worlds, avoids the need to assume hidden processes like pilot waves that can never be observed, as well as the idealist solipsism of stating that world is real only when a conscious observer is observing it.

Another fact is that this interpretation works well with the background independent formulation needed for Quantum Gravity theories. As the author says:-


What do you think @Polymath257 @Meow Mix @exchemist @LegionOnomaMoi ?

This seems to be an elegant summary of the view put forward in Carlo Rovelli's book, which I have been reading. I am not enough of a QM specialist to critique it: the others you have invited to comment will be far better qualified. Personally however, I find it attractive, as it seems indeed to get over a number of the paradoxes about the theory.

Regarding the existence of "things" in between interactions, they do have a sort of existence, it seems to me, in that during that time one can define a wave function that determines what ranges of properties can be manifest in the next interaction. But it is a fuzzy sort of existence. And most importantly, the wave function is not an absolute attribute of the entity, but depends on the situation of the observer. So different wave functions can describe the same entity from different points of view. There is a nice parallel with relativity here.

 

[Polymath257]

I several threads now I supported an interactionist or event centric view of Quantum Mechanics. In this view quantum interaction events are ontologically primary and quantum systems (i.e. things) have properties and attributes only in relation to these interaction events. This idea came up with respect to recent experimental demonstration of Wigner's friend paradox, that showed that the objectivity of observable reality is quite shaky

AAAS


The interactionist or relational view of QM is an interpretation that proposes precisely this. Physical systems exist and gain properties only at interaction events with other systems and concept of "things with property values" is meaningless when no interaction is happening. Further what these properties are depend on the type of event itself. So we move from "things with properties having interactions via which these properties change" type of ontology to "Interaction events from which things with properties emerge" type of ontology.

The full interpretation is called Relational Quantum Mechanics. A good exposition is in this paper here,

https://royalsocietypublishing.org/doi/full/10.1098/rsta.2017.0312#FN1

The main ideas of QM in this interpretation are:-
a) There is fundamental discreteness in nature, because of which many physical variables can take only certain specific values and not others.
(b) Predictions can be made only probabilistically, in general.
(c) The values that a variables of a physical system takes are such only relative to another physical system. Values taken relatively to distinct physical systems do not need to precisely fit together coherently, in general.
Key points from the paper

In my view this interpretation avoids the ontological excessiveness of many-worlds, avoids the need to assume hidden processes like pilot waves that can never be observed, as well as the idealist solipsism of stating that world is real only when a conscious observer is observing it.

Another fact is that this interpretation works well with the background independent formulation needed for Quantum Gravity theories. As the author says:-


What do you think @Polymath257 @Meow Mix @exchemist @LegionOnomaMoi ?

This is very close to my own view.

 

[Altfish]

As Richard Feynman once said ...

"If you think you understand quantum mechanics, you don't understand ... "

 

[Polymath257]

To elaborate further, an electron is *defined* by how it interacts: via the E&M force with a certain strength, via gravity with a certain strength, via the weak nuclear force at a certain strength, etc. Those properties of interactions are what we mean when we say there is an electron being observed.

Similar things hold for all the 'fundamental particles': it is their interaction with other particles that determines what they are.

It is then literally meaningless to say something 'exists' unless it interacts.

 

[exchemist]

To elaborate further, an electron is *defined* by how it interacts: via the E&M force with a certain strength, via gravity with a certain strength, via the weak nuclear force at a certain strength, etc. Those properties of interactions are what we mean when we say there is an electron being observed.

Similar things hold for all the 'fundamental particles': it is their interaction with other particles that determines what they are.

It is then literally meaningless to say something 'exists' unless it interacts.

Does not the wave function preserve information about it between interactions?

 

[Polymath257]

Does not the wave function preserve information about it between interactions?

In a sense. But, more accurately (I think), it describes the probabilities that later interactions will have particular results. Each interaction (potentially) changes the probabilities of later interactions.

So, in the double slit experiment, the beam going through the two slits (one interaction) determines the probabilities of the later interaction at the screen. The double slit means that the next interaction will show an interference pattern.

But, if you go through the slit (one interaction) and then have a position measurement (another interaction), then it may well mean the third interaction (detection at a screen) won't show that interference pattern.

 

[exchemist]

In a sense. But, more accurately (I think), it describes the probabilities that later interactions will have particular results. Each interaction (potentially) changes the probabilities of later interactions.

So, in the double slit experiment, the beam going through the two slits (one interaction) determines the probabilities of the later interaction at the screen. The double slit means that the next interaction will show an interference pattern.

But, if you go through the slit (one interaction) and then have a position measurement (another interaction), then it may well mean the third interaction (detection at a screen) won't show that interference pattern.

Are you saying that the wave function describes the relation between one interaction and the next, rather than information about an entity that continues between interactions?

 

[sayak83]

Are you saying that the wave function describes the relation between one interaction and the next, rather than information about an entity that continues between interactions?

Yes. The proposal is that the wavefunction is a book-keeping device relating the successive interactions and what can be said about the characteristics of the next (potential) interaction given the previous one. There is no entity with coherent formulation of properties that exists in any meaningful way in-between interactions.

 

[RestlessSoul]

"An isolated object, taken in itself, independent of every interaction, has no particular state. At most we can attribute to it a probabilistic disposition to manifest itself one way or another. "
- C Rovelli, Helgoland

 

[exchemist]

"An isolated object, taken in itself, independent of every interaction, has no particular state. At most we can attribute to it a probabilistic disposition to manifest itself one way or another. "
- C Rovelli, Helgoland

Yes, that's what I had taken on board from reading Rovelli. So that suggests there is something, albeit rather indeterminate, that continues.

 

[RestlessSoul]

Yes, that's what I had taken on board from reading Rovelli. So that suggests there is something, albeit rather indeterminate, that continues.

That's how I read it, yes. But that as nothing exists in isolation anyway, the specific qualities of any given phenomena manifest only in relation to other phenomena.

In the context of Rovelli's proposition in The Order of Time, that the universe is constructed not of things but of events, and that objects are really events in a state of temporary equilibrium, then there is no division between one thing and another anyway. It's all one molecular dance. The division between Isaac Newton, say, and the apple that fell on his head, is solely a function of perception. Newton, the apple, gravity, and the physicists epiphany, were all one event, each inseperable from the other. Now had there bern an observer, multiple new angles would then present themselves...

 

[Polymath257]

I several threads now I supported an interactionist or event centric view of Quantum Mechanics. In this view quantum interaction events are ontologically primary and quantum systems (i.e. things) have properties and attributes only in relation to these interaction events. This idea came up with respect to recent experimental demonstration of Wigner's friend paradox, that showed that the objectivity of observable reality is quite shaky

AAAS


The interactionist or relational view of QM is an interpretation that proposes precisely this. Physical systems exist and gain properties only at interaction events with other systems and concept of "things with property values" is meaningless when no interaction is happening. Further what these properties are depend on the type of event itself. So we move from "things with properties having interactions via which these properties change" type of ontology to "Interaction events from which things with properties emerge" type of ontology.

The full interpretation is called Relational Quantum Mechanics. A good exposition is in this paper here,

https://royalsocietypublishing.org/doi/full/10.1098/rsta.2017.0312#FN1

The main ideas of QM in this interpretation are:-
a) There is fundamental discreteness in nature, because of which many physical variables can take only certain specific values and not others.
(b) Predictions can be made only probabilistically, in general.
(c) The values that a variables of a physical system takes are such only relative to another physical system. Values taken relatively to distinct physical systems do not need to precisely fit together coherently, in general.
Key points from the paper

In my view this interpretation avoids the ontological excessiveness of many-worlds, avoids the need to assume hidden processes like pilot waves that can never be observed, as well as the idealist solipsism of stating that world is real only when a conscious observer is observing it.

Another fact is that this interpretation works well with the background independent formulation needed for Quantum Gravity theories. As the author says:-


What do you think @Polymath257 @Meow Mix @exchemist @LegionOnomaMoi ?

I just skimmed the paper and found it quite nice.

I have thought for quite some time that classical metaphysics needs to be modified because of discoveries in physics over the last century or so. This paper seems to get the ball rolling in that direction.

Another aspect of this is that the 'wave function' is NOT given ontological weight. So questions of collapse are simply not relevant. Instead, and in accordance with how Heisenberg originally formulated QM, the interaction becomes dominant and the question is how the spectra of operators related to observables change over time. Also, especially in regard to Wigner's friend, the value of variables depends on what *other* system an interaction is with. Different observational systems will get different results.

I think the main difficulty people will have is the denial of strong realism: variables simply don't have meaning other than in interactions. There is still a weak realism: interactions still happen that are not interactions with conscious entities, thereby giving values to variables even if not observed by a conscious observer. But there is no 'unified viewpoint' that works for all observing systems.

 

[RestlessSoul]

I just skimmed the paper and found it quite nice.

I have thought for quite some time that classical metaphysics needs to be modified because of discoveries in physics over the last century or so. This paper seems to get the ball rolling in that direction.

Another aspect of this is that the 'wave function' is NOT given ontological weight. So questions of collapse are simply not relevant. Instead, and in accordance with how Heisenberg originally formulated QM, the interaction becomes dominant and the question is how the spectra of operators related to observables change over time. Also, especially in regard to Wigner's friend, the value of variables depends on what *other* system an interaction is with. Different observational systems will get different results.

I think the main difficulty people will have is the denial of strong realism: variables simply don't have meaning other than in interactions. There is still a weak realism: interactions still happen that are not interactions with conscious entities, thereby giving values to variables even if not observed by a conscious observer. But there is no 'unified viewpoint' that works for all observing systems.

And there is no objective reality that exists independently of how it is observed. Lots of people won't be comfortable with that, indeed...

 

[sayak83]

And there is no objective reality that exists independently of how it is observed. Lots of people won't be comfortable with that, indeed...

Not observation, interaction. Electron interacting with a photon will still count as an interaction. The observation presupposes a complex observing system. So its better to ditch that term.

 

[RestlessSoul]

Not observation, interaction. Electron interacting with a photon will still count as an interaction. The observation presupposes a complex observing system. So its better to ditch that term.

So in effect, an observation is an interaction? Does this apply only at the sub atomic level, or can we assume that quantum principles apply at the macro level?

 

[sayak83]

So in effect, an observation is an interaction? Does this apply only at the sub atomic level, or can we assume that quantum principles apply at the macro level?

Any interaction. Applies at all scales. At large scales the quantum phenomena called decoherence occurs that makes the system states to the usual classically observed values.

 

[metis]

I several threads now I supported an interactionist or event centric view of Quantum Mechanics. In this view quantum interaction events are ontologically primary and quantum systems (i.e. things) have properties and attributes only in relation to these interaction events. This idea came up with respect to recent experimental demonstration of Wigner's friend paradox, that showed that the objectivity of observable reality is quite shaky

AAAS


The interactionist or relational view of QM is an interpretation that proposes precisely this. Physical systems exist and gain properties only at interaction events with other systems and concept of "things with property values" is meaningless when no interaction is happening. Further what these properties are depend on the type of event itself. So we move from "things with properties having interactions via which these properties change" type of ontology to "Interaction events from which things with properties emerge" type of ontology.

The full interpretation is called Relational Quantum Mechanics. A good exposition is in this paper here,

https://royalsocietypublishing.org/doi/full/10.1098/rsta.2017.0312#FN1

The main ideas of QM in this interpretation are:-
a) There is fundamental discreteness in nature, because of which many physical variables can take only certain specific values and not others.
(b) Predictions can be made only probabilistically, in general.
(c) The values that a variables of a physical system takes are such only relative to another physical system. Values taken relatively to distinct physical systems do not need to precisely fit together coherently, in general.
Key points from the paper

In my view this interpretation avoids the ontological excessiveness of many-worlds, avoids the need to assume hidden processes like pilot waves that can never be observed, as well as the idealist solipsism of stating that world is real only when a conscious observer is observing it.

Another fact is that this interpretation works well with the background independent formulation needed for Quantum Gravity theories. As the author says:-


What do you think @Polymath257 @Meow Mix @exchemist @LegionOnomaMoi ?

Interesting.

BTW, I have a granddaughter who is doing her graduate work at the University of Michigan in quantum chemistry-- she's a helluva lot smarter than her nono (me).

 

[Heyo]

I think the main difficulty people will have is the denial of strong realism: variables simply don't have meaning other than in interactions. There is still a weak realism: interactions still happen that are not interactions with conscious entities, thereby giving values to variables even if not observed by a conscious observer. But there is no 'unified viewpoint' that works for all observing systems.

Yep. That is my problem. QM is more and more becoming an unscientific theory. Aside from my personal, philosophical problem that I'm sure I can overcome, I fear the implication non scientists will draw from it. There are already too many people who deny objective realty. With this interpretation they'll feel even more encouraged.

 

[Heyo]

In a sense. But, more accurately (I think), it describes the probabilities that later interactions will have particular results. Each interaction (potentially) changes the probabilities of later interactions.

So, in the double slit experiment, the beam going through the two slits (one interaction) determines the probabilities of the later interaction at the screen. The double slit means that the next interaction will show an interference pattern.

But, if you go through the slit (one interaction) and then have a position measurement (another interaction), then it may well mean the third interaction (detection at a screen) won't show that interference pattern.

Do you know if anyone had ever tried to make a repeat double slit experiment?
I.e. double slit -> position detector -> double slit -> screen.
The second double slit should lead to an interference pattern if the decoherence from the position measurement is only temporary.