You have a commitment to the reality of the domain of sense-experience, but you don’t see the way in which the mind itself imbues that domain with reality. — Wayfarer
the distinction between concepts and what is conceptualised is not merely conceptual, it is real — fdrake
Does this mean you disagree with the claim 'The existence of X is different from our ability to conceptualise X'? — fdrake
to hypostatise those constraints as imbuing nature with reality is to forget the distinction between the concept and what it conceptualises. — fdrake
Nature only becomes understood through our attunement to it, by relearning how to see when it shouts 'no!'. — fdrake
We need to get rid of the notion of:
- absolute (observer-independent) state of a system
- absolute (observer-independent) value of a physical quantity
- absolute (observer-independent) fact
(Paul Davies, The Goldilocks Enigma: Why is the Universe Just Right for Life, p 271)The problem of including the observer in our description of physical reality arises most insistently when it comes to the subject of quantum cosmology - the application of quantum mechanics to the universe as a whole - because, by definition, 'the universe' must include any observers. Andrei Linde has given a deep reason for why observers enter into quantum cosmology in a fundamental way. It has to do with the nature of time. The passage of time is not absolute; it always involves a change of one physical system relative to another, for example, how many times the hands of the clock go around relative to the rotation of the Earth. When it comes to the Universe as a whole, time loses its meaning, for there is nothing else relative to which the universe may be said to change. This 'vanishing' of time for the entire universe becomes very explicit in quantum cosmology, where the time variable simply drops out of the quantum description. It may readily be restored by considering the Universe to be separated into two subsystems: an observer with a clock, and the rest of the Universe. So the observer plays an absolutely crucial role in this respect. Linde expresses it graphically: 'thus we see that without introducing an observer, we have a dead universe, which does not evolve in time', and, 'we are together, the Universe and us. The moment you say the Universe exists without any observers, I cannot make any sense out of that. I cannot imagine a consistent theory of everything that ignores consciousness...in the absence of observers, our universe is dead'.
Does this mean humans are necessary to the existence of the universe? While conscious observers certainly partake in the creation of the participatory universe envisioned by Wheeler, they are not the only, or even primary, way by which quantum potentials become real. Ordinary matter and radiation play the dominant roles. Wheeler likes to use the example of a high-energy particle released by a radioactive element like radium in Earth's crust. The particle, as with the photons in the two-slit experiment, exists in many possible states at once, traveling in every possible direction, not quite real and solid until it interacts with something, say a piece of mica in Earth's crust. When that happens, one of those many different probable outcomes becomes real. In this case the mica, not a conscious being, is the object that transforms what might happen into what does happen. The trail of disrupted atoms left in the mica by the high-energy particle becomes part of the real world.
At every moment, in Wheeler's view, the entire universe is filled with such events, where the possible outcomes of countless interactions become real, where the infinite variety inherent in quantum mechanics manifests as a physical cosmos. And we see only a tiny portion of that cosmos. Wheeler suspects that most of the universe consists of huge clouds of uncertainty that have not yet interacted either with a conscious observer or even with some lump of inanimate matter. He sees the universe as a vast arena containing realms where the past is not yet fixed.
You claim that nothing existed prior to the advent of observers — Janus
Science has a huge blind spot in the midst of it, and, like every blind spot, it is ignored by the blinded subject. This blind spot is something obvious but that remains virtually unseen: our situation, our experience, ourselves in the most intimate acceptation of this pronoun. Usually, the blind spot of science is concealed by scientists in the future of their discipline. They believe that in the future, something that is still inconceivable today will allow objective knowledge to account for subjectivity. But this belief is unwarranted, and it triggers virtually all the so-called “foundational problems” of objective science. — Bitbol
We have this picture of the empty universe, but this picture still implies an observer who provides that sense of scale and relationship within which all judgements about 'what exists' become meaningful. — Wayfarer
Don't know what you mean by 'reverse polarity' — noAxioms
If Alice discards the result like that, then it wasn't done. Memory of having done it doesn't change that. A mirror doesn't reflect a photon. It measures it and sends a new photon out at the new angle and same polarity, and is afterwards unaffected by having done that. It doesn't count as a measurement since the photon is still in superposition. — noAxioms
I believe that Rovelli himself treats the wave-function as not descriptive. So, he would not say that there are 'many physical branches'. — boundless
The reason is that in MWI you regard the entire universe as the single 'real system' and you need to add an 'additional structure' in order to decompose the universe into subsystems. In RQM, the subsystems are the 'primary' because they are given by experience (in MWI, instead you try to derive experience from the universal wavefunction). — boundless
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
Well, yeah I honestly do not know how you can explain that if you assume that the wave-function is not 'real'. So, I unfortunately cannot give you a response. — boundless
If the wave-function is taken as 'real', then the situation is still different from MWI IMO (as I explained above, hoping that it made some sense LOL...). Mauro Dorato apparently tried to explain RQM in terms of dispositions, check: https://arxiv.org/pdf/1309.0132.pdf — boundless
Speaking Wheeler, it's always fun to remember his unequivocal stance for all those who like to misinterpret him on this point, that: "Consciousness' has nothing whatsoever to do with the quantum process" (Wheeler, “Law Without Law”). — StreetlightX
We live in a "participatory universe," Wheeler suggested, which emerges from the interplay of consciousness and physical reality, the subjective and objective realms.
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The idea that mind is as fundamental as matter—which Wheeler's "participatory universe" notion implies--also flies in the face of everyday experience. Matter can clearly exist without mind, but where do we see mind existing without matter? Shoot a man through the heart, and his mind vanishes while his matter persists. As far as we know, information—embodied in things like poetry, hiphop music and cell-phone images from Libya--only exists here on Earth and nowhere else in the universe. Did the big bang bang if there was no one there to hear it? Well, here we are, so I guess it did (and saying that God was listening is cheating).
Part of me would love to believe that consciousness is not an accidental by-product of the physical realm but is in some sense the primary purpose of reality. Without us to ponder it, the universe makes no sense; worse, it's boring. But the hard-headed part of me sees ideas like the "it from bit" as the kind of fuzzy-headed, narcissistic mysticism that science is supposed to help us overcome.
Wheeler was one of the first prominent physicists to propose that reality might not be wholly physical; in some sense, our cosmos must be a “participatory” phenomenon requiring the act of observation--and thus consciousness itself. Wheeler also drew attention to intriguing links between physics and information theory, which was invented in 1948 by mathematician Claude Shannon. Just as physics builds on an elementary entity, the quantum, defined by the act of observation, so does information theory. Its “quantum” is the binary unit, or bit, which is a message representing one of two choices: heads or tails, yes or no, zero or one.
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But Wheeler himself has suggested that there is nothing but smoke. “I do take 100 percent seriously the idea that the world is a figment of the imagination,” he remarked to physicist/science writer Jeremy Bernstein in 1985. Wheeler must know that this view defies common sense: Where was mind when the universe was born? And what sustained the universe for the billions of years before we came to be
Thanks - that would be my reading as well. — Andrew M
As I see it, the decompositions that are of interest are those that are robust to interactions with the environment. So the ordinary objects of our experience, by virtue of being persistent and observable, are robust. That physical structure has emerged through an evolutionary process (as underpinned by decoherence), it's not a priori.
In other words, as you say above and Rovelli mentions in his talk, we start from the structure that we observe in our experience and work from there. It's not a Platonic endeavor. Now RQM is not solipsistic. It generalizes from individuals, to humans, to things, and ultimately to all systems and composites of systems that can interact. I think that MWI just takes that one step further and sees the universe itself as a system with a reference frame and a quantum state that can be described. So you don't need an excursion through arbitrary decompositions to take that final step. — Andrew M
But on the idea that nothing happens in the Everettian universe, I think that is true in one sense. If one person is pulling on a rope from one end and someone else is pulling with equal force from the other end then there is a high-level abstract sense in which nothing is happening. But there's obviously a lot going on at lower levels. If the universe is itself in superposition then, similarly, in that frame of reference, nothing is happening - there's no time, no dynamics, etc. But it doesn't follow that under the hood, in the reference frames of subsystems, that nothing is happening. — Andrew M
Maybe a related idea here is to regard values in non-interacting systems in terms of potential. So, for Wigner, interference indicates that the friend has made an actual measurement in their reference frame but the measurement only has a potential value for Wigner until an interaction actualizes it for him (in accordance with the principle of locality).
That is distinct from a hidden variable theory that supposes that the friend has made an actual measurement that is merely unknown to Wigner, with the Bell inequality issues that that would entail. — Andrew M
Don't know what simultaneity has to do with it. Relativity seems to work fine with a defined preferred present, even if there is no way to determine it in SR. I suppose that with spooky action at a distance, a preferred foliation would unambiguously label one event as the cause and the other as an effect, but as the experiment that Wayfarer linked shows, there is no spooky action. The distant person (Alice) can make the measurement and Bob (local) know it because it was a scheduled thing. And yet Bod can measure his half of the pair and verify it is still in superposition. QM demands this, so it is not an interpretation.thing . The OP sort of disproves and spooky action at a distance. Alice knows that Bob will take a measurement in one second, and knows the result she will learn tomorrow when Bob reports it, and yet Bob verifies continued superposition, and then an hour later he actually measures the polarity. The superposition doesn't go away due to Alice's action. Therefore there is no spooky action at a distance. No? — noAxioms
The table says it denies locality. OK, I see the note [15] which seems to claim a sort of loophole in Bell inequality. I do suppose that relativity has an implication of locality since without it, events with cause/effect relationship are ambiguously ordered. Not sure if relativity theory forbids that explicitly. A nice unified theory would be nice. The sort of 'weak' non-locality required by dBB interpretation claims to be Lorentz invariant, so that means causes and effects are unambiguously ordered, no? Not an expert, but if Alice and Bob both measure their entangled polarities fairly 'simultaneously', it seems the order of events is hardly Lorentz invariant. So maybe I just don't understand that note. — noAxioms
A 'strong correlationist' might say that it appears that ionic bonding would exist before the advent of sentient beings. I believe that Schopenhauer is a 'stronger correlationist' than Kant, because he says explicitly that you cannot even think about the universe where no sentient being exist and the previous story of the universe is actually related to the opening of the 'first eye' (i.e. the appearance of the first conscious being) and he also believed that the 'thing in itself' was singular. — boundless
Physicists have long suspected that quantum mechanics allows two observers to observe different, conflicting realities. Now they’ve performed the first experiment that proves it by experimental realisation of what was previously a thought-experiment called ‘Wigner’s Friend’. — Wayfarer
This is the nub of the issue.
I think you’re arguing from the general perspective of representative realism: that concepts represent (or fail to represent) some principle or phenomena. So in this picture of representative realism, there is the thinking subject and then there's the domain of objects, energies and forces which we confront, analyse, and attempt to understand. — Wayfarer
The problem that brought us to this point in the discussion, however, can't be conceptualised this way, or rather, it eludes being captured within this kind of framework. It has forced scientists to say things like:
We need to get rid of the notion of:
- absolute (observer-independent) state of a system
- absolute (observer-independent) value of a physical quantity
- absolute (observer-independent) fact
It is the 'absolute fact' that I'm taking issue with. Whereas, I *think* your positing a 'transcendent real' that we're always working on getting a more and more adequate conceptualisation of, as a kind of domain of (at least potentially) absolute fact. — Wayfarer
I compared what Alice did to what the mirror did since neither seems to collapse the wave function. There is still but one mirror and Alice, and somewhere down a pipe there is a state in superposition still. Sounds like no measurement was done, even if both the mirror and Alice have a green light over their heads indicating that yes, the event was noticed and measured, but no state from that measurement was retained.If Alice discards the result like that, then it wasn't done. Memory of having done it doesn't change that. A mirror doesn't reflect a photon. It measures it and sends a new photon out at the new angle and same polarity, and is afterwards unaffected by having done that. It doesn't count as a measurement since the photon is still in superposition.
— noAxioms
It seems to me that a measurement was nonetheless done, even when the original state of the mirror is restored. Of course, the experimenter may not care about that since it didn't entangle them with the photon and because the information has been erased. I think we agree on the mechanics. Or do you see more to it than that? — Andrew M
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.Well, I agree that a preferred frame is not actually incompatible with the predictions of Relativity. So, in this sense we can say that SR is not incompatible with such an idea. But, I was referring to the 'standard presentation' of SR, so to speak, where you do not define a 'preferred frame'. — boundless
GR shows that the variable isn't hidden, but only because real spacetime doesn't conform to SR's nice flat uniform gravity special case.Anyway, I'd agree with what you say here. But IMO problems with locality arise if you introduce hidden variables.
The one from GR is not enough?Well, AFAIK in dBB you need to somehow define a way to define an 'absolute simultaneity'.
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.But in any case, non-locality is inevitable in dBB IMO. To avoid it, you either need 'retrocausality' or 'superdeterminism' but I find both ideas untenable.
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