The strategy of your argument here is an excellent example of inappropriate reductionism; you seek to explain frame dependence of motion and observer dependence of quantum state/properties as being mere instances of conceptual relations between thought and object. — fdrake
‘Thought and object’. It is just that instinctive division which is called. Into question by ‘the observer probllem’. Anyway - thanks for your considered criticism, I appreciate the time you have taken. — Wayfarer
Yeah, that's a nice way IMO to avoid issues with relativity.
And BTW, as I said to NoAxioms a similar problem arises in Relativity, if one wants to avoid the 'block universe idea' as suggested by Rietdijk-Putnam argument(here's the link to the Wikipedia article). There is a very nice 'insight article' on Physics Forums that gives a counter-argument (which is reminiscent of the reasoning on which, for instance, RQM is based): https://www.physicsforums.com/insights/block-universe-refuting-common-argument/. — boundless
One of the two propositions in such instances must be true and the other false, but we cannot say determinately that this or that is false, but must leave the alternative undecided. One may indeed be more likely to be true than the other, but it cannot be either actually true or actually false. It is therefore plain that it is not necessary that of an affirmation and a denial, one should be true and the other false. For in the case of that which exists potentially, but not actually, the rule which applies to that which exists actually does not hold good. — Aristotle, On Interpretation, §9
It seems not contradictory at all for Bob to find the state of the photon still in superposition, despite the conflict wording in the article. — noAxioms
Had also John Horgan misattributed such a view to Wheeler? — boundless
Not defining something undetectable (in SR) is fine, and I suppose the standard presentation of SR is that there isn't one. But GR, to the embarrassment of Einstein, had to admit to an apparent preferred foliation (which is not an inertial frame), so SR would actually be sort of wrong if it asserted that no preferred local frame can exist, and SR has never been shown to be wrong. — noAxioms
A preferred foliation is one thing. A preferred moment (presentism) is more of an offense to relativity — noAxioms
If presentism is true, what is the rate of advancement of objective time? Equivalently, by how much is say a clock that tracks GMT dilated? It isn't moving very fast, but it's the depth of the gravity well I'm interested in. I thought of this when I tried to look it up. The absolutists sort of group together like the flood geologists and put out all this propaganda against Einstein, but none of those denial sites quote this absolute dilation factor, which you think would be one of their flagship points like the absolute frame. But they evade the topic. Why is that? Must be embarrasing... — noAxioms
The one from GR is not enough? — noAxioms
Yes, I know about the superdeterminism loophole. I also dismiss it enough to state that Bell eliminated locality and counterfactual definiteness from both being true. I see none of the listed interpretations hold both to be true, utilizing the superdeterminism loophole, so it seems the world agrees with that assessment. — noAxioms
Nice find with the PF article and I fully agree with it. I was going to mention the Andromeda paradox and the idea of potentiality in relation to it in my previous post. So we seem to thinking along similar lines here. — Andrew M
It also reminds me of Aristotle's future sea battle example where he contrasts potential and actual: — Andrew M
Yes, I agree - it's just what quantum mechanics predicts will happen and so it's not contradictory (or unexpected) at all. But it does challenge objective collapse theories since they modify the standard formulation. — Andrew M
Since none of this is new (it is demanded by QM right from the early days), how do any of the objective collapse interpretations get around this? Does this experiment change something? Did they expect a different result? I don't think so.Yes, I agree - it's just what quantum mechanics predicts will happen and so it's not contradictory (or unexpected) at all. But it does challenge objective collapse theories since they modify the standard formulation. — Andrew M
The expansion of space is uniform only under one foliation. It isn't absolutely uniform since it seems resistant to local mass, but only under one foliation does the expansion switch to accelerating everywhere at once. Essentially, only the the frame that corresponds locally to that foliation has the property of isotropy both in what is and in appearance.Do you mean that some geometries in GR require such a foliation (rather than simply allow)? — boundless
It apparently goes against the spirit of SR, and it pained Einstein to not keep that in GR. Physics is different in other frames since non-local observations are allowed in GR.AFAIK, there are attempts to reconcile dBB and SR that use a preferred foliation (which is not prohibited by Lorentz symmetry) but I think that this does not satisfy many people because it goes against the 'spirit' of Relativity.
Of course. One objectively orders any pair of events, and other may or may not attach an ontological status to each event (has or has not yet happened). A preferred foliation has no such ontological status. There is still spacetime with all events having equal ontology. Presentism has no spacetime, only space, with only current events existing (happening) and not any of the others. That sounds like a huge difference of reality to me.A preferred foliation is one thing. A preferred moment (presentism) is more of an offense to relativity
— noAxioms
But is there a real difference between the two?
I don't understand this comment. Under presentism, there is no spacetime. Only objectively current events are present, and the other events don't exist, so can't be present.I mean, If the structure of space-time requires such a foliation, IMO I can define a frame where all these events are present. For such a frame, there is an absolute simultaneity, which is precisely the reason why AFAIK Lorentz aether theory is criticized.
No, there would still be an absolute simultaneity. I can still sync remote clocks. I just find it difficult to build a clock that is designed to run in a location of known dilation and have it compensate for that in order to record the passage of absoute time. If it were possible to do that, the objective age of the universe could be known, but we only know the figure (13.8 BY) in dilated Earth time, which is obviously running slow. The universe is older than that, but by how much is the question.If presentism is true, what is the rate of advancement of objective time? Equivalently, by how much is say a clock that tracks GMT dilated? It isn't moving very fast, but it's the depth of the gravity well I'm interested in. I thought of this when I tried to look it up. The absolutists sort of group together like the flood geologists and put out all this propaganda against Einstein, but none of those denial sites quote this absolute dilation factor, which you think would be one of their flagship points like the absolute frame. But they evade the topic. Why is that? Must be embarrasing...
— noAxioms
I'd agree with the objection you are making. But IMO what you are saying is also a clue that one cannot make an absolute simultaneity (or rather, it is possible but would be 'hidden'...).
You might be interested in the following article that addresses this issue:
But it didn't take physicists long to realise that while the Wheeler-DeWitt equation solved one significant problem, it introduced another. The new problem was that time played no role in this equation. In effect, it says that nothing ever happens in the universe, a prediction that is clearly at odds with the observational evidence.
— Quantum Experiment Shows How Time ‘Emerges’ from Entanglement — Andrew M
Since none of this is new (it is demanded by QM right from the early days), how do any of the objective collapse interpretations get around this? Does this experiment change something? Did they expect a different result? I don't think so. — noAxioms
The expansion of space is uniform only under one foliation. It isn't absolutely uniform since it seems resistant to local mass, but only under one foliation does the expansion switch to accelerating everywhere at once. Essentially, only the the frame that corresponds locally to that foliation has the property of isotropy both in what is and in appearance. — noAxioms
AFAIK, there are attempts to reconcile dBB and SR that use a preferred foliation (which is not prohibited by Lorentz symmetry) but I think that this does not satisfy many people because it goes against the 'spirit' of Relativity. — boundless
It apparently goes against the spirit of SR, and it pained Einstein to not keep that in GR. Physics is different in other frames since non-local observations are allowed in GR. — noAxioms
Of course. One objectively orders any pair of events, and other may or may not attach an ontological status to each event (has or has not yet happened). A preferred foliation has no such ontological status. There is still spacetime with all events having equal ontology. Presentism has no spacetime, only space, with only current events existing (happening) and not any of the others. That sounds like a huge difference of reality to me. — noAxioms
I'd agree with the objection you are making. But IMO what you are saying is also a clue that one cannot make an absolute simultaneity (or rather, it is possible but would be 'hidden'...). — boundless
No, there would still be an absolute simultaneity... — noAxioms
Great. Interestingly, I discovered that the same point is made by Carlo Rovelli to defend his 'relational' view, see: https://www.youtube.com/watch?v=vbYeAaCloiM . At 4:55, Valentini makes the same question that he made in the other video (namely that different observers might disagree about what happens) and at 53:52 Rovelli answers by citing the Andromeda Paradox - so we are in good company :wink: . It is a very good discussion, BTW (other than Rovelli and Valentini, also Saunders and Wallace (and others) participate in the discussion). This might also be of interest to noAxioms. — boundless
[4:55] Valentini sets up the scenario as Rovelli deciding to speak at the conference (or not) based on measuring a particle spin as spin up (or spin down). Rovelli measured spin up and so here they are talking at the conference. However a super-intelligent being in the future measures interference.
[53:52] Rovelli: Antony asks, "Carlo, some super-intelligent is believing that you are not here because in his wave function you're superimposing, there's no fact of the matter. Does this bother you?"
I think it doesn't because it's exactly the kind of thing that happens in theoretical physics all the time. I think it's very similar to what happens in special relativity. If I take Einstein's simultaneity convention, right now in Andromeda there is something which has already happened with respect to the - not the past cone but the simultaneity convention - with respect to which I haven't happened yet with respect to this.
This makes no sense whatsoever but that's the structure of the world. The relation between when things happen for who are complicated. I think with this guy in the future, I could talk if I could survive until then, I could talk to him and we would agree and the fact that now, for him, in the future before I interact with him there is a discrepancy in what we see doesn't really bother me.
Valentini: For him, there wouldn't be a fact of the matter about the past?
Rovelli: That's right.
(3) All events in the past light cone of a given event are real (i.e., fixed and certain) for an observer at that event.
The reason this accounts for all of our observations is that information can’t travel faster than light, so anything we observe at a given event can only give information about the past light cone of that event.
So we can see Rovelli's reasoning in the above exchange. For Alice on Andromeda, Carlo on Earth only potentially exists until a local interaction (say, a telescopic observation at light speed) brings him into her present (and then past). Similarly, for Bob the superintelligent being in the future, Carlo is only potentially at the conference until a local interaction decoheres the superposition (say, Bob talks to Carlo). — Andrew M
A further thought here is that I think this allows a representational interpretation of the wave function for RQM in terms of what is actual and potential for any given observer. What is locally entangled with an observer is actual (the past and present, measurements and interactions), what is not is potential (the future, spacelike separated regions, superpositions). — Andrew M
There may indeed be “peaceful coexistence” between Quantum nonlocality and Relativistic locality, but it may have less to do with signaling than with the ontology of the quantum state. Heisenberg's view of the mode of reality of the quantum state was briefly mentioned in Section 2 — that it is potentiality as contrasted with actuality. This distinction is successful in making a number of features of quantum mechanics intuitively plausible — indefiniteness of properties, complementarity, indeterminacy of measurement outcomes, and objective probability. But now something can be added, at least as a conjecture: that the domain governed by Relativistic locality is the domain of actuality, while potentialities have careers in space-time (if that word is appropriate) which modify and even violate the restrictions that space-time structure imposes upon actual events. The peculiar kind of causality exhibited when measurements at stations with space-like separation are correlated is a symptom of the slipperiness of the space-time behavior of potentialities. This is the point of view tentatively espoused by the present writer, but admittedly without full understanding. What is crucially missing is a rational account of the relation between potentialities and actualities — just how the wave function probabilistically controls the occurrence of outcomes. In other words, a real understanding of the position tentatively espoused depends upon a solution to another great problem in the foundations of quantum mechanics − the problem of reduction of the wave packet.
That is one thin explanation. If what Alice did wasn't complex enough to objectively collapse the wave function, she should be able to measure the subsequent superposition herself and not leave it to Bob. Of course, QM theory won't allow that, so the 'thin' explanation see to go against QM itself.Since none of this is new (it is demanded by QM right from the early days), how do any of the objective collapse interpretations get around this? Does this experiment change something? Did they expect a different result? I don't think so.
— noAxioms
They would predict that Wigner would not see interference for sufficiently complex friend systems. So the options are to either accept the experiment's result as falsifying their theory or else show that the experiment isn't scaled up enough to trigger a physical collapse by their criterion. — Andrew M
It seems not to be. It would probably violate SR if it was.Maybe the point is that the foliation is not directly observable. — boundless
Yes. What is: Space is expanding everywhere equally(ish) at all simultaneous points. I say 'ish' because it expands more in empty places than crowded places, but not more in any particular direction. This isn't true in other frames.As you say, we can observe only a "frame that corresponds locally to that foliation has the property of isotropy both in what is and in appearance". Just a guess. As I said, I am quite at loss.
All of relativity seems to depend on locality, while QM interpretations might have other ideas. It is why I resist interpretations that discard locality in favor of counterfactual definiteness. I just don't see how relativity can make sense without locality. One can blatantly change the past, not just events outside one's future light cone.I see...but if this does mean that non-locality is compatible with GR (as it is usually understood) why people consider non-locality problematic?
Don't get your Dutch names wrong... I've got one myself.Well, yeah, you are right.
But IMO this leads either to the 'Andromeda Paradox'/Riedtjik-Putnam argument scenario or some form of retro-causality.
Way to kill an afternoon, eh? Thank you for the link. Not sure how much I'm interested in sinking an interpretation that I've already listed as low probability. I'd rather see them sink RQM. Always best to have ones own cage rattled once in a while.Anyway, Antony Valentini proposed that cosmological observations might help to solve interpretational problems in QM. The de Broglie-Bohm interpretation actually makes the same predictions of QM only if the 'quantum equilibrium hypothesis' is satisfied, i.e. if the modulus square of the wave-function corresponds to the actual probability distribution (this assures that dBB satisfies the Born Rule). However, in general, this might be not true. Hence his proposal: maybe at the earliest stages of the evolution of the Universe, that hypothesis was not satisfied and - as a consequence - we should see empirical evidence against the Born Rule.
Here is the link to his talk (at the same conference): https://www.youtube.com/watch?v=XYZV9crCZM8.
Here the link to the Q&A session: https://www.youtube.com/watch?v=8qnuNLB61RA.
It seems not to be. It would probably violate SR if it was. — noAxioms
Doing these sorts of measurements is how they determined the acceleration of expansion in the first place. You can't measure what is now, but you can measure how it appears now. — noAxioms
All of relativity seems to depend on locality, while QM interpretations might have other ideas. It is why I resist interpretations that discard locality in favor of counterfactual definiteness. I just don't see how relativity can make sense without locality. One can blatantly change the past, not just events outside one's future light cone.
That and the fact that counterfactual definiteness has all sorts of seemingly paradoxical philosophical baggage that goes away if you don't accept the principle. — noAxioms
Don't get your Dutch names wrong... I've got one myself. — noAxioms
The Andromeda thing and the Rietdijk-Putnam thing are pretty much the same, and are only paradoxical if you try to combine assumptions from both interpretations of time. All that proves is that they are not both correct. — noAxioms
Presentism demands an objective ordering of events (although no particular one), but a preferred folation does not demand a preferred moment in time. — noAxioms
Way to kill an afternoon, eh? — noAxioms
Thank you for the link. — noAxioms
Not sure how much I'm interested in sinking an interpretation that I've already listed as low probability. I'd rather see them sink RQM. Always best to have ones own cage rattled once in a while. — noAxioms
That is one thin explanation. If what Alice did wasn't complex enough to objectively collapse the wave function, she should be able to measure the subsequent superposition herself and not leave it to Bob. Of course, QM theory won't allow that, so the 'thin' explanation see to go against QM itself.
Of course maybe I just don't understand this explanation. I have not read your link and am not sure that I would find the answer there satisfactory. — noAxioms
In my eyes, outcomes 1 and 2 would indicate fundamentally new physics. I will not consider these cases further and regard quantum theory to be a universal physical theory. This leaves us with situation 3 as the only possible outcome of Deutsch's thought experiment. The outcome is compatible with the Everett interpretation: each copy of the observer observes a definite but different outcome in different branches of the (multi)universe. The outcome is compatible with the Copenhagen interpretation too, but it is rarely discussed what the implications of this claim are for our understanding of physical reality within the interpretation. The rest of the current manuscript is devoted to this problem. — On the quantum measurement problem - Caslav Brukner
I'd rather see them sink RQM. Always best to have ones own cage rattled once in a while. — noAxioms
There are different takes. For IMHO a very interesting Neo-Kantian non-representionalist reading (among the 'Copenaghists'), check this article of Michel Bitbol (I already quoted it in this thread - I quote it again here for convenience): http://www.bourbaphy.fr/bitbol.pdf (according to him, Bohr's epistemology was close to Kant's views...). Or, if one prefers the video of the talk: https://www.youtube.com/watch?v=pYRLapWBqJY.
Another instance of interpretation of the wave-function in terms of potentiality-actuality can be found in this paper by Kastner et al: https://arxiv.org/abs/1709.03595. — boundless
Actually, this interpretation of the wave-function is also held by some Copenaghists. For instance, Abner Shminoy wrote in the older version of the SEP on Bell's Theorem:
There may indeed be “peaceful coexistence” between Quantum nonlocality and Relativistic locality, but it may have less to do with signaling than with the ontology of the quantum state. Heisenberg's view of the mode of reality of the quantum state was briefly mentioned in Section 2 — that it is potentiality as contrasted with actuality. This distinction is successful in making a number of features of quantum mechanics intuitively plausible — indefiniteness of properties, complementarity, indeterminacy of measurement outcomes, and objective probability. But now something can be added, at least as a conjecture: that the domain governed by Relativistic locality is the domain of actuality, while potentialities have careers in space-time (if that word is appropriate) which modify and even violate the restrictions that space-time structure imposes upon actual events. The peculiar kind of causality exhibited when measurements at stations with space-like separation are correlated is a symptom of the slipperiness of the space-time behavior of potentialities. This is the point of view tentatively espoused by the present writer, but admittedly without full understanding. What is crucially missing is a rational account of the relation between potentialities and actualities — just how the wave function probabilistically controls the occurrence of outcomes. In other words, a real understanding of the position tentatively espoused depends upon a solution to another great problem in the foundations of quantum mechanics − the problem of reduction of the wave packet.
The link is to the section 'Philosophical Comments' of the article - Shimony lists other possible positions. — boundless
the domain governed by Relativistic locality is the domain of actuality, while potentialities have careers in space-time (if that word is appropriate) which modify and even violate the restrictions that space-time structure imposes upon actual events. — Shiminoy
In particular, “real” should not be restricted to “actual” objects or events in spacetime. Reality ought also be assigned to certain possibilities, or “potential” realities, that have not yet become “actual.” These potential realities do not exist in spacetime, but nevertheless are “ontological” — that is, real components of existence.
The quantum concept of a “probability wave,” describing the likelihood of different possible outcomes of a measurement, was a quantitative version of Aristotle’s potential, Heisenberg wrote in his well-known 1958 book Physics and Philosophy. “It introduced something standing in the middle between the idea of an event and the actual event, a strange kind of physical reality just in the middle between possibility and reality.”
The dependence of what is observed upon the choice of the experimental arrangement made Einstein unhappy. It conflicts with the view that the universe exists "out there" independent of all acts of observation. In contrast, Bohr stressed that we confront here an inescapable new feature of nature, to be welcomed because of the understanding it gives us. In struggling to make clear to Einstein the central point as he saw it, Bohr found himself forced to introduce the word "phenomenon". In today's words, Bohr's point - and the central point of quantum theory - can be put into a simple sentence: "No elementary phenomenon is a phenomenon until it is a registered (observed) phenomenon".
...It is wrong to think of that past [i.e. of a photon that has travelled billions of light years] as "already existing" in all detail. The "past" is theory. The past has no existence except as it is recorded in the present.
....useful as it it is under everyday circumstances [i.e. pragmatically] to say that the world exists "out there" independent of us, that view can no longer be upheld. There is a strange sense in which this is a "participatory universe".
Bad news for the 'arche-fossil'! — Wayfarer
(my italics)A phenomenon is not yet a phenomenon until it has been brought to a close by an irreversible act of amplification; such as the blackening of a grain of silver bromide emulsion or the triggering of a photodetector
Anything macroscopic which happened in the past makes, we know, a rich fallout of consequences in the present. But whether we deal with the fall of the tree or the evidence for the dab of paint on the canvas or the motion of the moon through the sky, the number of quanta that come into play is so enormous that the unseen quantum individuality of the act of observation can hardly be said to influence the event observed
This is the sense in which, in a loose way of speaking, we decide what the photon shall have done after it has already done it. In actuality it is wrong to talk of the "route" of the photon. For a proper way of speaking we recall once more that it makes no sense to talk of a phenomenon until it has been brought to a close by an irreversible act of amplification; 'No elementary phenomenon is a phenomenon until it is a registered (observed) phenomenon'
He then reiterates his previous clarification between an anthropomorphic sense of 'observation' and his preferred description of it:We cannot speak in these terms without a caution and a question. The caution: "consciousness" has nothing whatsoever to do with the quantum process.
We are dealing with an event that makes itself known by an irreversible act of amplification, an indelible record, an act of registration. Does that record subsequently enter into the consciousness of some person, some animal or some computer?
Is that the first step in translating the measurement into meaning?
.Hoe does quantum mechanics today differ from what Bishop Goerge Berkeley told us two centuries ago, 'esse est percipi', to be is to be perceived'? Does the tree not exist in the forest unless someone is there to see it? Do Bohr's conclusions about the role of the observer differ from those of Berkeley? Yes, and in an important way, Bohr deals with the individual quantum process. Berkeley, like all of us under everyday circumstances, deals with multiple quantum processes
An old legend describes a dialog between Abraham and Jehovah. Jehovah chides Abraham: 'You would not even exist if it were not for me!', "Yes Lord, that I know", Abraham replies, "but also You would not be known if it were not for me"
In our time the participants in the dialog have changed. They are the universe and man. The universe, in the words of some who would aspire to speak for it, says 'I am a giant machine. I supply the space and time for your existence. There was no before before I came into being, and there will be no after after I cease to exist. You are an unimportant bit of matter located in an unimportant galaxy."
How shall we reply? Shall we say "Yes, oh universe, without you I would not have been able to come into being. Yes you, great system, are made of phenomena, and every phenomenon rests on an act of observation. You could never even exist without elementary acts of registration such as mine"?
Are elementary quantum phenomena (note not consciousness dependent - me), those untouchable, indivisible acts of creation, indeed the building material of all that is? Beyond particles, beyond fields of force, beyond geometry, beyond space and time themselves, is the ultimate constituent, the still more ethereal act of observer-participancy? For Dr. Samuel Johnson, the stone was real enough when he kicked it. The subsequent discovery that the matter in that rock is made of positive and negative electric charges and more than 99.99 per cent of empty space does not diminish the pain that it inflicts on one's toe. If that stone is someday revealed to be altogether emptiness, "reality" will be none the worse for the finding.
Are billions upon billions of acts of observer-participancy the foundation of everything? We are about as far as we can be today from knowing enough about the deeper machinery of the universe to answer that question
He clearly ascribes the role of 'irreversible acts of amplification' to the lab equipment, rather than human consciousness. — fdrake
In 1958, Schrödinger, inspired by Schopenhauer... published his lectures Mind and Matter. Here he argued that there is a difference between measuring instruments and human observation: a thermometer’s registration cannot be considered an act of observation, as it contains no meaning in itself. Thus, consciousness is needed to make physical reality meaningful. As Schrödinger concluded, "Some of you, I am sure, will call this mysticism. So with all due acknowledgement to the fact that physical theory is at all times relative, in that it depends on certain basic assumptions, we may, or so I believe, assert that physical theory in its present stage strongly suggests the indestructibility of Mind by Time." 1
Are elementary quantum phenomena those untouchable, indivisible acts of creation, indeed the building material of all that is? Beyond particles, beyond fields of force, beyond geometry, beyond space and time themselves, is the ultimate constituent, the still more ethereal act of observer-participancy?
All you've demonstrated is that you didn't read Wheeler's paper closely, and that you didn't actually understand the arche-fossil argument (which is my fault). Perhaps I should make a thread on it. — fdrake
Wheeler thinks macroscopic phenomena are largely 'untouched' by quantum effects; ancestral statements can easily be produced. They can even be produced about the photon whose past was determined by observation; how long did it take to get here? Longer than the lifetime of human history. — fdrake
You've quoted two passages, one from Bohr, one from Wheeler, both of which call into question the objectivity of scientific observation, as if they support the objectivity of scientific observation. So - who is not reading what? :-) — Wayfarer
What I am arguing is that, you take 'the world out there' as independently real, always existing, regardless of any observation by us. — Wayfarer
Claiming observer=human again. Bohr and Wheeler have gone to pains to say that this isn't so. — fdrake
We can still use the objectifying language of classical physics to make statements about observable facts. For instance, we can say that a photographic plate has been blackened, or that cloud droplets have formed. But we can say nothing about the atoms themselves. And what predictions we base on such findings depend on the way we pose our experimental question, and here the observer has freedom of choice. Naturally, it still makes no difference whether the observer is a man, an animal, or a piece of apparatus, but it is no longer possible to make predictions without reference to the observer or the means of observation. To that extent, every physical process may be said to have objective and subjective features. The objective world of nineteenth-century science was, as we know today, an ideal, limiting case, but not the whole reality.
The dependence of what is observed upon the choice of the experimental arrangement made Einstein unhappy. It conflicts with the view that the universe exists "out there" independent of all acts of observation.
It from bit. Otherwise put, every "it" — every particle, every field of force, even the space-time continuum itself — derives its function, its meaning, its very existence entirely — even if in some contexts indirectly — from the apparatus-elicited answers to yes-or-no questions, binary choices, bits. It from bit symbolizes the idea that every item of the physical world has at bottom — a very deep bottom, in most instances — an immaterial source and explanation; that which we call "reality" arises in the last analysis from the posing of yes-no questions and the registering of equipment-evoked responses; in short, that all things physical are information-theoretic in origin and that this is a participatory universe.
(Source: https://arxiv.org/pdf/quant-ph/9609002.pdf ; emphasis mine)In order to prevent the reader from channeling his/her thoughts in the wrong direction, let me anticipate a few terminological remarks. By using the word “observer” I do not make any reference to conscious, animate, or computing, or in any other manner special, system. I use the word “observer” in the sense in which it is con- ventionally used in Galilean relativity when we say that an object has a velocity “with respect to a certain ob- server”. The observer can be any physical object having a definite state of motion. For instance, I say that my hand moves at a velocity v with respect to the lamp on my table. Velocity is a relational notion (in Galilean as well as in special relativistic physics), and thus it is al- ways (explicitly or implicitly) referred to something; it is traditional to denote this something as the observer, but it is important in the following discussion to keep in mind that the observer can be a table lamp. Also, I use information theory in its information-theory mean- ing (Shannon): information is a measure of the number of states in which a system can be –or in which several systems whose states are physically constrained (corre- lated) can be. Thus, a pen on my table has information because it points in this or that direction. We do not need a human being, a cat, or a computer, to make use of this notion of information.
Thanks for the links! I had a quick skim. I find Rovelli's approach more natural than either of those. Bitbol's approach seems overly metaphysical and Kastner's approach is non-local. — Andrew M
As one of us (SK) has observed (Kauffman 2016, Chapter 7), we might plan to meet tomorrow for coffee at the Downtown Coffee Shop. But suppose that, unbeknownst to us, while we are making these plans, the coffee shop (actually) closes. Instantaneously and acausally, it is no longer possible for us (or for anyone no matter where they happen to live) to have coffee at the Downtown Coffee Shop tomorrow. What is possible has been globally and acausally altered by a new actual (token of res extensa).6 In order for this to occur, no relativity-violating signal had to be sent; no physical law had to be violated. We simply allow that actual events can instantaneously and acausally affect what is next possible (given certain logical presuppositions, to be discussed presently) which, in turn, influences what can next become actual, and so on. In this way, there is an acausal ‘gap’ between res extensa and res potentia in their mutual interplay, that corresponds to a form of global nonlocality.
[Footnote 6]: While ‘acausal’ in the classical sense of efficient causality (wherein one actual state causally influences another actual state), in the quantum mechanical sense of causality wherein potentia are treated as ontologically significant, the actualized state is understood to ‘causally’ alter the probability distribution by which the next ‘possible’ state is defined. For further discussion of this distinction between classical efficient causality and quantum mechanical causality, see Epperson (2004, 92-93; 2013, 105-6). On the other hand, under certain circumstances and at the relativistic level, where decay probabilities are taken into account, the relation between an actualized state and the next QP state may itself be indeterministic (see, e.g. Kastner 2012, Section 3.4 and Chapter6).
First, as with Rovelli, I think that quantum mechanics is local. Second, as with Aristotle, potentialities don't "do" anything, only actual systems do. — Andrew M
Instead, the term "potential" provides a natural way for Wigner and his friend to describe the scenario from their own perspective and also to describe the scenario from the other's perspective.
So when the friend (Alice) measures spin up, that actualizes (i.e., realizes) the particle's spin potential for her. But she also knows that both the spin and her subsequent measurement of the spin are only potentials for Wigner until Wigner measures the friend's system in that basis.
The actual/potential terminology combined with RQM's relationalism provides an ordinary language abstraction over the underlying mechanics. That abstraction preserves locality, factual definiteness, freedom of choice and, crucially, a referent within the universe that provides a view from somewhere (i.e., the system's reference frame). — Andrew M
Get involved in philosophical discussions about knowledge, truth, language, consciousness, science, politics, religion, logic and mathematics, art, history, and lots more. No ads, no clutter, and very little agreement — just fascinating conversations.