I am surprised that Flavio is of the opinion that decoherence (presumably without the necessity of a measurement interaction) leads to quantum collapse because there is no evidence for this. It is purely speculative.
More importantly, I am surprised that you, Matt, think that quantum mechanics is complete.
Both quantum mechanics and Whitehead's organic philosophy represent attempts to describe the physical universe, right? The difference is that Whitehead views feelings and inclinations as factors influencing instances of coming-into-being of form
Quantum mechanics, therefore, appears to be incomplete because if does not recognize the possible importance of feelings when form comes into being and physical trajectories are established..
I should clarify that when I suggested that QM is "complete" I meant only in the context of the debate between Einstein and Bohr, in the sense that it turned out nonlocality is real and so Einstein's reductio ad absurdum about distantly correlated particles was turned on its head.
I made clear that there are still major inconsistencies in physics between QM and relativity, so obviously I don't think it is "complete" in any more general sense, though it may be "more complete" or fundamental than relativity.
We could conceivably have a "complete" physics that still presupposed a metaphysics. For example, I do not expect physics to ever be able to explain why there should be feelings or inclinations in the universe. If we have oriented ourselves metaphysically in the proper way, we would see that physics in fact presupposes prehension as well as aims in nature. Physics can mostly ignore at least conceptual feelings and aims in its morphological descriptions and coordinate divisions of the external world. But since physicists themselves as sentient, deliberately thinking beings exist, when we step back from our physical descriptions of external nature to reflect metaphysically on the conditions of the possibility of science itself, it should become clear that at least the germ of feeling and purpose must be there even in the highly repetitive physical world. But affirming these is a metaphysical and not a physical claim.
There are two notions of collapse in quantum theory that standard presentations run together. These are essentially:
(i) Which actualisation occurred, i.e. which of spin up or down has been selected in a spin measurement.
(ii) That an actualisation has occurred, i.e. that the selection of either spin up or down has completed.
In Whiteheadian terms this would be the difference between the details of an actual occasion, i.e. exactly what eternal objects ingressed and so on, versus the bare fact of an actual occasion, i.e. that the concrescence has completed/reached satisfaction.
Nobody thinks decoherence explains (i), since the theory is probabilistic you cannot say exactly what will happen. However many people think decoherence does model (ii), i.e. it can model that an occasion has occurred.
Roland Omnès's famous book "The Interpretation of Quantum Mechanics" has a long mathematical proof of this in Chapters 5-8 for non-relativistic quantum theory. Relativistic treatments are much more difficult and confined to research papers.
Thank you for responding Darran. I feel this is a key issue in the philosophy of physics, as did Ronald Omnes.
In the abstract of his 2017 paper, "Is Uniqueness of Reality Predicted by the Quantum Laws", Omnes writes "The standard interpretation of q.m. takes for granted an impossibility of deriving wave function collapse from the Schrodinger equation. One raises an opposite possibility, which would make collapse one of the major predictions of this equation..." He goes on to say that his position - essentially that decoherence ("strong incoherence" as he puts it) leads to collapse - is proposed ONLY AS A CONJECTURE which he sees as 'bringing more harmony into this essential part of the philosophy of physics."
Furthermore, in "Quantum Mechanics and the Philosophy of ANW", Michael Epperson contends that facts are produced when the wave function collapses. I asked him whether facts are ever produced through a process of decoherence. He said NO.
One would think that Whiteheadian's, especially, might take the position that without experience of an event, there is no collapse, no actualization, and no facts about the universe are established.
I do not understand how anyone could prove, mathematically or otherwise, that facts are established in the world (spin up or down) while the phenomenon (spin up or spin down) remains unexperienced and therefore 'unmeasured'.
So in his 1994 book Omnès provides a proof of what I have called case (ii). In that 2017 paper he is exploring the possibility that decoherence can actually handle case (i). Decoherence cannot actually achieve this as he mentions in follow on papers. The fact that it concerns case (i) can be seen most easily in his use of "Uniqueness of Reality".
In his 2004 book "Quantum Mechanics and the Philosophy of Alfred North Whitehead" Epperson describes decoherence achieving (ii), but not (i). Omnès and Zurek being the sources quoted for this.
I would agree with Epperson that decoherence cannot produce facts, that would be case (i), i.e. actually tell you that spin up occurred for example. Most physicists and Epperson in his 2004 book only claim it can achieve case (ii), i.e. acknowledge the production of facts.
It's simply that when they say "collapse" some physicists mean (i), some physicists mean (ii) and some mean the combination of (i) and (ii). I personally prefer to say 'objectification' for case (ii). So I would phrase things as:
"Decoherence models objectification, but not collapse"
Being able to model case (ii)/objectification is important as otherwise you wouldn't even know what objects will cause case (i)/collapse.
None of this is incompatible with facts being linked to experience or claiming they happen when unmeasured. I won't overload this comment by going more into this point, but I'll happily say more if you wish. It's related to why myself and others prefer to say 'objectification' for case (ii). A very quick Whiteheadian summary would be that being able to model that a concrescence has reached satisfaction is not a claim that this satisfaction involved no mental pole or subjective aim.
I have continued to consider and look into the distinction you are making though I do not have Omnes book so cannot look at his proof.
Perhaps this example can make the point more concrete:
Lets start with a double slit setup with a low intensity beam of electrons (such that one goes through at a time) creating the familiar interference pattern. Now, if the vacuum is gradually corrupted then electron wave functions would presumably become increasingly decoherent through collisions with gas molecules seeping into the apparatus until the point that the striped interference pattern would eventually disappear altogether.
Given such decoherence (and subsequent lack of interference pattern) it seems apparent that such electrons would be 'objectified' (through decoherence), in your terms, as they passed through the apparatus
So your position, as I understand it, is that the fact is established regarding which slit a given electron has passed through, even though no one in the world knows this fact, which can only become known via measurement.
From my perspective it is far from clear that facts such as this (which slit an electron went through) can exist without anyone knowing about them. Nor does it seem clear that the existence of such facts can be proven mathematically or otherwise.
So I am doubting whether this is what Omnes has proven.
Returning to this level. I've reworded what you called 3(a), hopefully making it clearer.
---According to your view, and presumably Omnes proof, there can be measurements made without measuring devices or any related experiences of measurers. In this light, what is being proven here isn’t all that simple.-----
It's not a claim that measurements can be made without measuring devices or experience of measurers, just that the measurement results become objectified. Like Envisagement in Whitehead.
---Is this purported “reduction of the space of observables to a single one” a random process like reduction of the sphere of potentiality to a single outcome, as in a measurement interaction? ---
It's not the production of an outcome. It's where the space of observables shrinks so that a commutative subalgebra is generated, hence removing complementarity for that particular observable and objectifying the observable's outcomes whatever they may be, but it does not generate those outcomes.
Just returning to this level to prevent the comment boxes becoming very small.
I can see now what you are saying. Let me just ask two questions:
(i) When you say "measurement" I assume you mean it as a primitive, i.e. Not measurement as some kind of physical interaction, but the basic act of recognition by a subject. Is this correct?
(ii) In classical probability do you consider facts to be established independent of the subject using the probability theory? For example when a dice is rolled and modelled with basic high school probability theory, do you consider the dice to be presenting some face prior to the person modelling it seeing the face?
EDIT: I wanted to add something as I feel there may be a mismatch between how I use the word "prove" in mathematical terms and possibly how "prove" is understood otherwise. I only mean "prove in the model", i.e. Omnès proves Quantum Mechanics has the production of facts as a feature via decoherence. That cannot of course "force" facts to exist in the real world. So "one can prove water flows downhill in Navier Stokes solutions" just means the Navier Stokes equation models that feature of water, not that the Navier Stokes equations 'create' that fact or prove its truth in the real world.
Decoherence allows QM to model facts, without it QM would be incompatible with the existence of facts. Something you can prove in a few lines. And thus without decoherence QM would fail quite strongly in modelling the world.
Hi Darran. Thank you for responding. In terms of question (i), yes, by ‘measurement’ I mean recognition of a fact by a subject with a measuring apparatus. Question (ii) is a bit more complicated in my view.
When it comes to histories of physical systems and their unobjectified potentialities and probabilities (present and past) there are correlations and dynamic, often retroactive, causal effects. On pages xii and xiii of his introduction, Epperson introduces an example of a comet that interacts with a passing asteroid, changing its course slightly such that it is now (possibly) aimed to impact Earth in 2 years. This interaction by the comet results in the history of the asteroid being tied to the potentials and histories of many living terrestrial entities.
Now suppose the asteroid, after impact with the comet, was left with a somewhat indefinite, uncertain trajectory such that there was a possibility of hitting the Earth and a possibility of it not hitting. To make it simple, let us suppose there are six potential trajectories of the asteroid after interaction, all with equal probability, one of which results in impact. If, two years later, entities on Earth experience catastrophe then the ‘objective’ and ‘factual’ trajectory of the asteroid two years before would be established retroactively as the one trajectory leading to impact.
Accordingly, the face of the die in a casino will be established as a fact virtually instantaneously, both because of the multiple witnesses who care enough to ask the question and find out the result, but also because of tight correlations between multiple, highly objectified trajectories of local, terrestrial events involving entities with agendas and measuring instruments.
If, on the other hand, the die were dropped inside a relatively lifeless spaceship 10 light years away from Earth there would presumably be no witnesses who cared enough to find out and the resolution of the fact would likely be suspended indefinitely (though its trajectory will be increasingly implicated in local environmental histories)…until someone sees it, or until an experienced event somewhere in the universe correlates with and determines it.
And furthermore, I do think there is often more going on in quantum mechanical wave function collapse than random selection of possibilities according to probabilistic calculation.
Darran, I would like to continue this most interesting conversation especially because it leads directly to a larger, rarely discussed perspective on physics and living organisms. My email, if you wish to respond to me there, is pjtryon@yahoo.com.
I probably will email you, but I'll just need to think a bit. To answer your question, no I am not saying the facts occur without anything experiencing them.
For anybody who might read this in the future, to close off with a summary decoherence can be best understood as objectification. This means that whoever or whatever* first experiences a fact, that fact will remain a fact for all other experiencers. Without decoherence all facts in QM would remain private to the first experiencer. In Whitehead's terms without decoherence QM could not support causal objectification.
*I'm leaving this open as different interpretations of QM differ on what could possibly qualify as an experiencer.
In terms of objectification, collapse of the wave function, experience, and decoherence, it seems to me there is another issue to consider. In q.m., whenever a 'measurement' leads to the production of facts there must be a measurement apparatus which determines what sort of facts are established. In the case of an electron, for example, the facts could denote spin relative to a given axis, or position, or velocity. . . Clearly a given measurement cannot establish all facts relative to a given system because there are always complementary variables that cannot be simultaneously established. So if it is the case that decoherence leads to some 'objective state' without any experience of measurement, then which facts about the system are established?
In decoherence there is no selection or implementation of a measurement apparatus as far as I can see so this becomes a problem, right?
This apparently represents another reason to doubt Omnes proof of actualization type (ii),
Omnes's proof is spread across a few chapters, but the section in Chapter 8 actually concerns the reduction of the space of observables to a single one, hence eliminating the ambiguity of complementarity.
Omnes's proof is calculational, there are other abstract algebraic proofs such as in the classic 1986 paper by Misra and Lockhart.
d'Espagnat's monograph "Veiled Reality" discusses in detail how Omnes's proof does not amount to a denial of the experiencing subject as a presupposition of science, rather it only fully makes sense when framed in terms of an experiencing subject. It's simply a proof that measurements become objectified.
In terms of sentence 1: Is this purported “reduction of the space of observables to a single one” a random process like reduction of the sphere of potentiality to a single outcome, as in a measurement interaction?
If so, then it seems a new function of Nature is being invented or speculated upon: Ongoing, external interactions between physical systems—presumably bumping together or otherwise interacting relatively locally—lead somehow to random selection of a basis for reduction of the wave function. If not, then what serves to determine the basis? Why one variable/observable instead of the complementary one?
Sentence 2: Thank you very much for this reference.
Sentence(s) 3: I cannot make sense of sentence 3(a). You basically say “Omnes proof only (fully) makes sense in a setting in which there is (or is not?) denial of the experiencing subject as a presupposition of science.”. . . I am going to make a stretch here and say that experiencing subjects do exist, so it would make sense that science best recognize and explicitly assert their presence, if not their importance.
Proving objective situational facts exist—are actualized—in the absence of experience and without influential connections that matter, with other events that were/are experienced, still seems speculative to me.
If, as you say in sentence 3(b), “It (Omnes proof) is simply a proof that measurements become objectified” then we have no disagreement, except perhaps, in terms of what actually constitutes a measurement. According to your view, and presumably Omnes proof, there can be measurements made without measuring devices or any related experiences of measurers. In this light, what is being proven here isn’t all that simple.
Apologies for another long comment, but I had a think about how to convey what a quantum field is and its relation to particles in Whiteheadian terms. Here is my attempt. I focus here only on the photon particle and the electromagnetic field.
In quantum field theory we have the following interrelated phenomena:
(i) Photon particles
(ii) Electric and Magnetic fields
(iii) The felt complex of heat, warmth, colour and brightness we call light.
The Classical treatment of these phenomena was characterised by reducing all three to either aspect (i), seen in particulate theories, or aspect (ii) seen in wave theories. The chosen aspect being the only substance, the others being a secondary phenomena.
Quantum Electromagnetic theory puts them all on an even footing, as in Whiteheadian terms they each form an abstractive hierarchy of eternal objects available for actual occasions. So an occasion may manifest a certain number of photons or particular electric and magnetic field strengths or a certain warmth and colour.
These hierarchies are not compatible, i.e. eternal objects from each one cannot be ingressed into the same actual occasion. So when you see a bright red rose it is not valid to say the rose "emitted x number of photons", as 'bright and red' has had unrestricted ingression whereas photon number was not ingressed at all.
However the rules/mathematics of quantum theory allow you to derive the existence of the photon and light abstractive hierarchies from the field hierarchy. It is for this reason we call it a quantum field theory, because the field hierarchy is sufficient to derive the existence and structure of the others. Again though they are all on even footing, the fields are not the true ontological substance. It's more like deriving the presence of the other two legs of a stool from a given one. Dumb analogy but hopefully clear!
Photons are then not really lumps of or waves in the electromagnetic field, but a type of eternal object whose presence is implied by the field eternal objects.
I hope that makes some sense! If it is interesting the Strings in String theory are the same. In other words in string theory everything is not "made of strings", rather string-like eternal objects allow us to derive other eternal objects and their character.
Flavio if you read these, I think quantum field theory makes these points stronger than quantum mechanics does because there an electron really is a type of event. See the last chapter of Haag's "Local Quantum Physics" for more about this.
Also quantum field theory has a way of representing concresence naturally, unlike quantum mechanics which requires "the external classical thing", whether that's mind or something massive enough as you said. Hattich's "Quantum processes: A Whiteheadian interpretation of quantum field theory" really delves into this in depth, but it's a hard book to find these days.
Hello. Good conversation. Thank You.
I am surprised that Flavio is of the opinion that decoherence (presumably without the necessity of a measurement interaction) leads to quantum collapse because there is no evidence for this. It is purely speculative.
More importantly, I am surprised that you, Matt, think that quantum mechanics is complete.
Both quantum mechanics and Whitehead's organic philosophy represent attempts to describe the physical universe, right? The difference is that Whitehead views feelings and inclinations as factors influencing instances of coming-into-being of form
Quantum mechanics, therefore, appears to be incomplete because if does not recognize the possible importance of feelings when form comes into being and physical trajectories are established..
Hi Philip,
I should clarify that when I suggested that QM is "complete" I meant only in the context of the debate between Einstein and Bohr, in the sense that it turned out nonlocality is real and so Einstein's reductio ad absurdum about distantly correlated particles was turned on its head.
I made clear that there are still major inconsistencies in physics between QM and relativity, so obviously I don't think it is "complete" in any more general sense, though it may be "more complete" or fundamental than relativity.
We could conceivably have a "complete" physics that still presupposed a metaphysics. For example, I do not expect physics to ever be able to explain why there should be feelings or inclinations in the universe. If we have oriented ourselves metaphysically in the proper way, we would see that physics in fact presupposes prehension as well as aims in nature. Physics can mostly ignore at least conceptual feelings and aims in its morphological descriptions and coordinate divisions of the external world. But since physicists themselves as sentient, deliberately thinking beings exist, when we step back from our physical descriptions of external nature to reflect metaphysically on the conditions of the possibility of science itself, it should become clear that at least the germ of feeling and purpose must be there even in the highly repetitive physical world. But affirming these is a metaphysical and not a physical claim.
ps- I know I owe you an email!
Philip,
There are two notions of collapse in quantum theory that standard presentations run together. These are essentially:
(i) Which actualisation occurred, i.e. which of spin up or down has been selected in a spin measurement.
(ii) That an actualisation has occurred, i.e. that the selection of either spin up or down has completed.
In Whiteheadian terms this would be the difference between the details of an actual occasion, i.e. exactly what eternal objects ingressed and so on, versus the bare fact of an actual occasion, i.e. that the concrescence has completed/reached satisfaction.
Nobody thinks decoherence explains (i), since the theory is probabilistic you cannot say exactly what will happen. However many people think decoherence does model (ii), i.e. it can model that an occasion has occurred.
Roland Omnès's famous book "The Interpretation of Quantum Mechanics" has a long mathematical proof of this in Chapters 5-8 for non-relativistic quantum theory. Relativistic treatments are much more difficult and confined to research papers.
Thank you for responding Darran. I feel this is a key issue in the philosophy of physics, as did Ronald Omnes.
In the abstract of his 2017 paper, "Is Uniqueness of Reality Predicted by the Quantum Laws", Omnes writes "The standard interpretation of q.m. takes for granted an impossibility of deriving wave function collapse from the Schrodinger equation. One raises an opposite possibility, which would make collapse one of the major predictions of this equation..." He goes on to say that his position - essentially that decoherence ("strong incoherence" as he puts it) leads to collapse - is proposed ONLY AS A CONJECTURE which he sees as 'bringing more harmony into this essential part of the philosophy of physics."
Furthermore, in "Quantum Mechanics and the Philosophy of ANW", Michael Epperson contends that facts are produced when the wave function collapses. I asked him whether facts are ever produced through a process of decoherence. He said NO.
One would think that Whiteheadian's, especially, might take the position that without experience of an event, there is no collapse, no actualization, and no facts about the universe are established.
I do not understand how anyone could prove, mathematically or otherwise, that facts are established in the world (spin up or down) while the phenomenon (spin up or spin down) remains unexperienced and therefore 'unmeasured'.
Philip,
So in his 1994 book Omnès provides a proof of what I have called case (ii). In that 2017 paper he is exploring the possibility that decoherence can actually handle case (i). Decoherence cannot actually achieve this as he mentions in follow on papers. The fact that it concerns case (i) can be seen most easily in his use of "Uniqueness of Reality".
In his 2004 book "Quantum Mechanics and the Philosophy of Alfred North Whitehead" Epperson describes decoherence achieving (ii), but not (i). Omnès and Zurek being the sources quoted for this.
I would agree with Epperson that decoherence cannot produce facts, that would be case (i), i.e. actually tell you that spin up occurred for example. Most physicists and Epperson in his 2004 book only claim it can achieve case (ii), i.e. acknowledge the production of facts.
It's simply that when they say "collapse" some physicists mean (i), some physicists mean (ii) and some mean the combination of (i) and (ii). I personally prefer to say 'objectification' for case (ii). So I would phrase things as:
"Decoherence models objectification, but not collapse"
Being able to model case (ii)/objectification is important as otherwise you wouldn't even know what objects will cause case (i)/collapse.
None of this is incompatible with facts being linked to experience or claiming they happen when unmeasured. I won't overload this comment by going more into this point, but I'll happily say more if you wish. It's related to why myself and others prefer to say 'objectification' for case (ii). A very quick Whiteheadian summary would be that being able to model that a concrescence has reached satisfaction is not a claim that this satisfaction involved no mental pole or subjective aim.
Have a nice day!
Hello Darran,
I have continued to consider and look into the distinction you are making though I do not have Omnes book so cannot look at his proof.
Perhaps this example can make the point more concrete:
Lets start with a double slit setup with a low intensity beam of electrons (such that one goes through at a time) creating the familiar interference pattern. Now, if the vacuum is gradually corrupted then electron wave functions would presumably become increasingly decoherent through collisions with gas molecules seeping into the apparatus until the point that the striped interference pattern would eventually disappear altogether.
Given such decoherence (and subsequent lack of interference pattern) it seems apparent that such electrons would be 'objectified' (through decoherence), in your terms, as they passed through the apparatus
So your position, as I understand it, is that the fact is established regarding which slit a given electron has passed through, even though no one in the world knows this fact, which can only become known via measurement.
From my perspective it is far from clear that facts such as this (which slit an electron went through) can exist without anyone knowing about them. Nor does it seem clear that the existence of such facts can be proven mathematically or otherwise.
So I am doubting whether this is what Omnes has proven.
Returning to this level. I've reworded what you called 3(a), hopefully making it clearer.
---According to your view, and presumably Omnes proof, there can be measurements made without measuring devices or any related experiences of measurers. In this light, what is being proven here isn’t all that simple.-----
It's not a claim that measurements can be made without measuring devices or experience of measurers, just that the measurement results become objectified. Like Envisagement in Whitehead.
---Is this purported “reduction of the space of observables to a single one” a random process like reduction of the sphere of potentiality to a single outcome, as in a measurement interaction? ---
It's not the production of an outcome. It's where the space of observables shrinks so that a commutative subalgebra is generated, hence removing complementarity for that particular observable and objectifying the observable's outcomes whatever they may be, but it does not generate those outcomes.
Hi Philip,
Just returning to this level to prevent the comment boxes becoming very small.
I can see now what you are saying. Let me just ask two questions:
(i) When you say "measurement" I assume you mean it as a primitive, i.e. Not measurement as some kind of physical interaction, but the basic act of recognition by a subject. Is this correct?
(ii) In classical probability do you consider facts to be established independent of the subject using the probability theory? For example when a dice is rolled and modelled with basic high school probability theory, do you consider the dice to be presenting some face prior to the person modelling it seeing the face?
EDIT: I wanted to add something as I feel there may be a mismatch between how I use the word "prove" in mathematical terms and possibly how "prove" is understood otherwise. I only mean "prove in the model", i.e. Omnès proves Quantum Mechanics has the production of facts as a feature via decoherence. That cannot of course "force" facts to exist in the real world. So "one can prove water flows downhill in Navier Stokes solutions" just means the Navier Stokes equation models that feature of water, not that the Navier Stokes equations 'create' that fact or prove its truth in the real world.
Decoherence allows QM to model facts, without it QM would be incompatible with the existence of facts. Something you can prove in a few lines. And thus without decoherence QM would fail quite strongly in modelling the world.
Hi Darran. Thank you for responding. In terms of question (i), yes, by ‘measurement’ I mean recognition of a fact by a subject with a measuring apparatus. Question (ii) is a bit more complicated in my view.
When it comes to histories of physical systems and their unobjectified potentialities and probabilities (present and past) there are correlations and dynamic, often retroactive, causal effects. On pages xii and xiii of his introduction, Epperson introduces an example of a comet that interacts with a passing asteroid, changing its course slightly such that it is now (possibly) aimed to impact Earth in 2 years. This interaction by the comet results in the history of the asteroid being tied to the potentials and histories of many living terrestrial entities.
Now suppose the asteroid, after impact with the comet, was left with a somewhat indefinite, uncertain trajectory such that there was a possibility of hitting the Earth and a possibility of it not hitting. To make it simple, let us suppose there are six potential trajectories of the asteroid after interaction, all with equal probability, one of which results in impact. If, two years later, entities on Earth experience catastrophe then the ‘objective’ and ‘factual’ trajectory of the asteroid two years before would be established retroactively as the one trajectory leading to impact.
Accordingly, the face of the die in a casino will be established as a fact virtually instantaneously, both because of the multiple witnesses who care enough to ask the question and find out the result, but also because of tight correlations between multiple, highly objectified trajectories of local, terrestrial events involving entities with agendas and measuring instruments.
If, on the other hand, the die were dropped inside a relatively lifeless spaceship 10 light years away from Earth there would presumably be no witnesses who cared enough to find out and the resolution of the fact would likely be suspended indefinitely (though its trajectory will be increasingly implicated in local environmental histories)…until someone sees it, or until an experienced event somewhere in the universe correlates with and determines it.
And furthermore, I do think there is often more going on in quantum mechanical wave function collapse than random selection of possibilities according to probabilistic calculation.
Darran, I would like to continue this most interesting conversation especially because it leads directly to a larger, rarely discussed perspective on physics and living organisms. My email, if you wish to respond to me there, is pjtryon@yahoo.com.
Philip,
I probably will email you, but I'll just need to think a bit. To answer your question, no I am not saying the facts occur without anything experiencing them.
For anybody who might read this in the future, to close off with a summary decoherence can be best understood as objectification. This means that whoever or whatever* first experiences a fact, that fact will remain a fact for all other experiencers. Without decoherence all facts in QM would remain private to the first experiencer. In Whitehead's terms without decoherence QM could not support causal objectification.
*I'm leaving this open as different interpretations of QM differ on what could possibly qualify as an experiencer.
Thank you for this, Darran.
In terms of objectification, collapse of the wave function, experience, and decoherence, it seems to me there is another issue to consider. In q.m., whenever a 'measurement' leads to the production of facts there must be a measurement apparatus which determines what sort of facts are established. In the case of an electron, for example, the facts could denote spin relative to a given axis, or position, or velocity. . . Clearly a given measurement cannot establish all facts relative to a given system because there are always complementary variables that cannot be simultaneously established. So if it is the case that decoherence leads to some 'objective state' without any experience of measurement, then which facts about the system are established?
In decoherence there is no selection or implementation of a measurement apparatus as far as I can see so this becomes a problem, right?
This apparently represents another reason to doubt Omnes proof of actualization type (ii),
Philip,
Omnes's proof is spread across a few chapters, but the section in Chapter 8 actually concerns the reduction of the space of observables to a single one, hence eliminating the ambiguity of complementarity.
Omnes's proof is calculational, there are other abstract algebraic proofs such as in the classic 1986 paper by Misra and Lockhart.
d'Espagnat's monograph "Veiled Reality" discusses in detail how Omnes's proof does not amount to a denial of the experiencing subject as a presupposition of science, rather it only fully makes sense when framed in terms of an experiencing subject. It's simply a proof that measurements become objectified.
Hi Darran,
In terms of sentence 1: Is this purported “reduction of the space of observables to a single one” a random process like reduction of the sphere of potentiality to a single outcome, as in a measurement interaction?
If so, then it seems a new function of Nature is being invented or speculated upon: Ongoing, external interactions between physical systems—presumably bumping together or otherwise interacting relatively locally—lead somehow to random selection of a basis for reduction of the wave function. If not, then what serves to determine the basis? Why one variable/observable instead of the complementary one?
Sentence 2: Thank you very much for this reference.
Sentence(s) 3: I cannot make sense of sentence 3(a). You basically say “Omnes proof only (fully) makes sense in a setting in which there is (or is not?) denial of the experiencing subject as a presupposition of science.”. . . I am going to make a stretch here and say that experiencing subjects do exist, so it would make sense that science best recognize and explicitly assert their presence, if not their importance.
Proving objective situational facts exist—are actualized—in the absence of experience and without influential connections that matter, with other events that were/are experienced, still seems speculative to me.
If, as you say in sentence 3(b), “It (Omnes proof) is simply a proof that measurements become objectified” then we have no disagreement, except perhaps, in terms of what actually constitutes a measurement. According to your view, and presumably Omnes proof, there can be measurements made without measuring devices or any related experiences of measurers. In this light, what is being proven here isn’t all that simple.
Apologies for another long comment, but I had a think about how to convey what a quantum field is and its relation to particles in Whiteheadian terms. Here is my attempt. I focus here only on the photon particle and the electromagnetic field.
In quantum field theory we have the following interrelated phenomena:
(i) Photon particles
(ii) Electric and Magnetic fields
(iii) The felt complex of heat, warmth, colour and brightness we call light.
The Classical treatment of these phenomena was characterised by reducing all three to either aspect (i), seen in particulate theories, or aspect (ii) seen in wave theories. The chosen aspect being the only substance, the others being a secondary phenomena.
Quantum Electromagnetic theory puts them all on an even footing, as in Whiteheadian terms they each form an abstractive hierarchy of eternal objects available for actual occasions. So an occasion may manifest a certain number of photons or particular electric and magnetic field strengths or a certain warmth and colour.
These hierarchies are not compatible, i.e. eternal objects from each one cannot be ingressed into the same actual occasion. So when you see a bright red rose it is not valid to say the rose "emitted x number of photons", as 'bright and red' has had unrestricted ingression whereas photon number was not ingressed at all.
However the rules/mathematics of quantum theory allow you to derive the existence of the photon and light abstractive hierarchies from the field hierarchy. It is for this reason we call it a quantum field theory, because the field hierarchy is sufficient to derive the existence and structure of the others. Again though they are all on even footing, the fields are not the true ontological substance. It's more like deriving the presence of the other two legs of a stool from a given one. Dumb analogy but hopefully clear!
Photons are then not really lumps of or waves in the electromagnetic field, but a type of eternal object whose presence is implied by the field eternal objects.
I hope that makes some sense! If it is interesting the Strings in String theory are the same. In other words in string theory everything is not "made of strings", rather string-like eternal objects allow us to derive other eternal objects and their character.
This is very clear and so helpfully articulated.
Wow, really great!
Flavio if you read these, I think quantum field theory makes these points stronger than quantum mechanics does because there an electron really is a type of event. See the last chapter of Haag's "Local Quantum Physics" for more about this.
Also quantum field theory has a way of representing concresence naturally, unlike quantum mechanics which requires "the external classical thing", whether that's mind or something massive enough as you said. Hattich's "Quantum processes: A Whiteheadian interpretation of quantum field theory" really delves into this in depth, but it's a hard book to find these days.
Looking forward to more in this series!