Sure, but in a mind-independent view, you bringing it to mind has zero effect on the thing itself. — noAxioms

What thing would that be?

Incidentally a nice Australian Broadcasting Corp feature on the 100 year anniversary of Heisenberg's famous paper https://www.abc.net.au/news/science/2025-07-29/quantum-mechanics-100-years-physics-heisenberg-schroedinger/105425950

From a purely speculative metaphysical perspective, bottom line is, one’s decision on his relation to himself follows necessarily from whether or not the volitions of his will justify his worthiness of being happy. Clear conscience on steroids, so to speak. — Mww

I prefer thinking about these things in a virtue ethics framework, but I think we aren't say different things here. I would say that 'clear conscience on steroids' fulfills our nature...

You'd have to show where QM says anything like that. QM does not contradict empirical experience. — noAxioms

Yeah, I should have phrased it better. I meant something like 'QM without the reduction postulate'. If you do not accept collapse, you still have superposition and interference. So, you need to explain why we do percieve everything in a definite state. Many claim that the 'appearance of collapse' given by decoherence is enough. Others disagree.

Right. There's no cat experiencing superposition or being both dead and alive. There's (from the lab PoV) a superposition of the cat experiencing living, and of experiencing dying by poison. A superposition of those two experiences is very different than the cat experiencing both outcomes. Each experience is utterly unaware of the other. — noAxioms

I know. But I was questioning if decoherence is enough for the appearance of collapse. Interference terms remain, they become however very, very small. Is that truly enough to explain our 'definite' experience (same goes for the cat's experience)?

'Definite states' sounds awfully classical to me. MWI is not a counterfactual interpretation, so is seems wrong to talk about such things. — noAxioms

Definite means something like this. Consider a spin 1/2 particle. When we measure the spin (say) in the z-axis we obtain either '+1/2' or '-1/2'. So, '+1/2' and '-1/2' are 'definite states'. The general quantum state of that particle can be written as a linear combination of these 'definite states'. Let's call this basis 'basis 1'.
But again the same is true for the states '(1/sqrt(2))*('+1/2' +'-1/2')' and '(1/sqrt(2))*('+1/2' -'-1/2')'. These two states are an orthogonal basis but they do not correspond to anything in our experience. Still, a genral quantum state of the same spin 1/2 particle can be written as a linear combination of these two vectors. Let's call this basis 'basis 2'.

Here things go tricky, however. Why, when we make a measurement, does the quantum state collapse or appear to collapse in one state of the 'basis 1' instead of 'basis 2'? Certainly 'basis 1' describes the states that correspond to our experience. But if MWI-supporters do not want to make any reference to experience to explain how we have the quantum-classical transition, then why systems evolve as if they have to appear to collapse in a state of the 'basis 1', which happens to correspond to our experience?

This is a part of, as I understand it, the 'preferred basis problem'. MMI posits that 'basis 1' is selected by the mind. But 'pure MWI' claims to be 'QM without the collapse postulate' and no other additional axiom like the collapse/reduction.

I don't think that this objection is fatal, though. But to me it suggests that there is more in the story than just states in the Hilbert space and their evolution as MWI would claim.

Hard to read, lacking the background required, but it seems to say that there are no 'worlds' from any objective description of say the universal wave function. It has no 'system states', something with which I agree. There are no discreet worlds, which again, sounds like a counterfactual. I think the paper is arguing against not so much the original Everett paper, but against the DeWitt interpretation that dubbed the term 'worlds' and MWI and such. I could be wrong. — noAxioms

Yeah, the paper is a bit technical and also beyond my paygrade. Basically, however, it tries to reject MWI by adducing that if a MWI supporter doesn't add some postulate to 'pure QM without the collapse postulate' you can't explain how the universe decompose in subsystems, how the preferred basis is selected etc. So, I would say that it does apply to any Everettian interpretation with the universal wavefunction. RQM seems unaffected by the criticism.

I meant something like 'QM without the reduction postulate'. — boundless

QM doesn't have a reduction postulate, but some of the interpretations do. Each seems to spin the role of measurement a different way.

If you do not accept collapse, you still have superposition and interference.

Yes, the latter two are, but the meaning of especially superposition is still interpretation dependent. Superposition itself is baked into the mathematics.

So, you need to explain why we do percieve everything in a definite state.

I suppose that explanation is interpretation dependent as well.

But I was questioning if decoherence is enough for the appearance of collapse.

It seems to be enough given an interpretation (MWI say) that explains it that way.

Interference terms remain, they become however very, very small. Is that truly enough to explain our 'definite' experience (same goes for the cat's experience)?

Interference is a statistical effect, so with no particle can interference be measured, let alone measured by the particle in question. But it can be concluded given hundreds of thousands of objects all being treated identically. So I suppose a really huge crowd of people (far more than billions) could collectively notice some kind of interference if they all did something identical. I cannot fathom what that experiment would look like or how any of those people could survive it.

Basically, in MWI the branching is explained by saying that there is a superposition of definite states.

Definite means something like this. Consider a spin 1/2 particle. When we measure the spin (say) in the z-axis we obtain either '+1/2' or '-1/2'. So, '+1/2' and '-1/2' are 'definite states'. — boundless

OK. They're post-measurement, so they are definite, sure, but post-measurement, they're not in superposition anymore, so it's only in superposition of definite state relative to a system that has not yet measured the lab doing the spin measurement.

This is very well illustrated by the cat, where death when -1/2 is measured. From inside the box, there is one definite state and the cat is alive or dead depending on that. From outside the box, they know the measurement has been performed, but don't know the result of it. So the cat is in superposition of the interior definite state of being dead and alive, but the cat is not in a exterior definite state, meaning it is still in superposition relative to the lab. And yes, they can measure interference in principle.
In practice, there's no way to keep the cat alive and in superposition since there's no way to prevent information from leaking out of the box.

Here things go tricky, however. Why, when we make a measurement, does the quantum state collapse or appear to collapse in one state of the 'basis 1' instead of 'basis 2'?

Interpretation dependent obviously. Some interpretations have no concept of 'our' experience since there's no 'you' that satisfies the laws of identity and non-contradiction. Keep that in mind.


But if MWI-supporters do not want to make any reference to experience to explain how we have the quantum-classical transition, then why systems evolve as if they have to appear to collapse in a state of the 'basis 1', which happens to correspond to our experience?[/quote]MWI does not collapse in a state of the basis 1 which happens to correspond to our experience. It denies the bold parts at least. Basis 2 is also experienced, and as much by the pre-measurement 'you' as is the post-measurement 'you' that's in state 1, which is to say, not by the same person as the one before.

This is a part of, as I understand it, the 'preferred basis problem'. MMI posits that 'basis 1' is selected by the mind.

What is 'the mind' per MMI? It is some dualistic mind thing, sort of a moving spotlight which gets to pick which path it follows, with the other paths left as zombies? That sounds like uni-mind, so no, probably not that. You can tell I don't know much about MMI, especially the part about how they define 'mind'. Do trees similarly select their bases? Where do they draw the line between what has a 'mind' and what doesn't?

Yeah, the paper is a bit technical and also beyond my paygrade. Basically, however, it tries to reject MWI by adducing that if a MWI supporter doesn't add some postulate to 'pure QM without the collapse postulate' you can't explain how the universe decompose in subsystems, how the preferred basis is selected etc.

There's no preferred basis in MWI. That much I know. Can't speak for MMI.

What thing would that be? — Wayfarer

We were discussing 'worlds', which is loosely referenced by the word 'thing' in my statement, despite not being an object. A world is unaffected by something elsewhere imagining one.

Incidentally a nice Australian Broadcasting Corp feature on the 100 year anniversary of Heisenberg's famous paper

Cool article, compressing 100 years of quantum history into a few pages. It harps a lot on how Einstein really wanted a locally real universe, and perhaps never knew it was hopeless. His critique was critical to the development of quantum theory.

A world is unaffected by something elsewhere imagining one. — noAxioms

Which world?

As soon as you name a ‘world’ or a ‘thing’ or ‘an unknown object’ which you claim is unaffected by or separate from your thought of it, you are already bringing it within the ambit of thought. The realist always has something in mind when he or she speaks of ‘something unaffected by thought’. It’s a Chinese finger trap - you can’t even say it without undercutting the point.

His [Einstein’s] critique was critical to the development of quantum theory. — noAxioms

Yes, but the article acknowledges that. It quotes Alain Aspect:

"When people say, 'Oh, you showed Einstein wrong', I say, 'Come on, I showed Einstein was great,'" he said in response to the award.

I’ve listened to a couple of interviews with Sir Roger Penrose of late, and he’s adamant that quantum theory is wrong - and you’d think he would know! But when you drill down, his objection is philosophical, not scientific.

Discover Magazine: In quantum mechanics an object can exist in many states at once, which sounds crazy. The quantum description of the world seems completely contrary to the world as we experience it.

Sir Roger Penrose: It doesn’t make any sense, and there is a simple reason. You see, the mathematics of quantum mechanics has two parts to it. One is the evolution of a quantum system, which is described extremely precisely and accurately by the Schrödinger equation. That equation tells you this: If you know what the state of the system is now, you can calculate what it will be doing 10 minutes from now. However, there is the second part of quantum mechanics — the thing that happens when you want to make a measurement. Instead of getting a single answer, you use the equation to work out the probabilities of certain outcomes. The results don’t say, “This is what the world is doing.” Instead, they just describe the probability of its doing any one thing. The equation should describe the world in a completely deterministic way, but it doesn’t.

Notice the ‘should’! Penrose’s gripe is the same as Einstein - the belief that the world is a certain way, and it’s science’s job to discern that, to discover ‘the way it is’. But what if physical reality is actually indeterminate on a fundamental level? What if it really is probabilistic and in some basic sense incomplete? That is the idea that drives scientific realism around the bend. Whereas there are philosophies, ways of seeing the world, in which that openness is understood. This is one of the points of convergence between quantum physics and the Buddhist philosophy of emptiness (śūnyatā).

(This has been explored by credible academic sources, moving beyond popular mysticism, to examine genuine philosophical parallels. Theoretical physicist Carlo Rovelli, founder of loop quantum gravity, has written seriously about how Nagarjuna’s philosophy of emptiness—the idea that phenomena lack intrinsic existence—resonates with quantum mechanics’ relational ontology, where particles and properties exist only through measurement relationships rather than independently. Academic journals have published rigorous analyses, such as SpringerLink’s examination of “Two Aspects of Śūnyatā in Quantum Physics,” which argues that both quantum mechanics and (Middle-Way) Buddhism suggest there are no intrinsically existing particles with inherent properties, but rather that all phenomena arise through dependent relationships. This philosophical convergence centers on the idea that reality is fundamentally relational rather than consisting of purportedly mind-independent objects, challenging the classical scientific assumption that the objective domain has fixed, determinate properties independent of observation. It dovetails well with aspects of the Copenhagen and QBist interpretation, not so much with classical realism.)

QM doesn't have a reduction postulate, but some of the interpretations do. Each seems to spin the role of measurement a different way. — noAxioms

Yes. In order to get definite outcomes without interference you need that axiom (or some modifications of the mathematical apparatus of QM as in dBB)

It seems to be enough given an interpretation (MWI say) that explains it that way. — noAxioms

MWI was developed before decoherence. MWI supporters like decoherence because it seems to explain the branching. It doesn't IIRC remove interference however. I believe that it is legit to ask if it is 'enough' to explain our experience.

Interference is a statistical effect, so with no particle can interference be measured, let alone measured by the particle in question. But it can be concluded given hundreds of thousands of objects all being treated identically. So I suppose a really huge crowd of people (far more than billions) could collectively notice some kind of interference if they all did something identical. I cannot fathom what that experiment would look like or how any of those people could survive it. — noAxioms

Ok. But this still doesn't refute my point. It is conceivable to observe interference it it exists. So, perhaps, some versions of MWI are falsifiable?

So the cat is in superposition of the interior definite state of being dead and alive, but the cat is not in a exterior definite state, meaning it is still in superposition relative to the lab. And yes, they can measure interference in principle. — noAxioms

But in this relationalist view, the basis is selected via the experimental apparatus. In MWI one should IMO expect to derive everything from the universal wavefunction. I don't think that your view is affected by that argument.

There's no preferred basis in MWI. That much I know. Can't speak for MMI. — noAxioms

Yes, but there is a preferred basis in our experience. How does MWI account for that? Here what Schwindt concludes:

I have shown that it is always possible to factorize the global Hilbert space into subsystems
in such a way, that the story told by this factorization is that of a world in which nothing
happens. A factorization into interacting and entangling subsystems is also possible, in
infinitely many arbitrary ways. But such a more complicated factorization is meaningful
only if it is justified through interactions with an external observer who does not arise as
a part of the state vector.
The Many World Interpretation is therefore rather a No World Interpretation (according to the simple factorization), or a Many Many Worlds Interpretation (because each of
the arbitrary more complicated factorizations tells a different story about Many Worlds
[7]).

So, perhaps, there are 'Many-Many Worlds'...

(This has been explored by credible academic sources, moving beyond popular mysticism, to examine genuine philosophical parallels. Theoretical physicist Carlo Rovelli, founder of loop quantum gravity, has written seriously about how Nagarjuna’s philosophy of emptiness—the idea that phenomena lack intrinsic existence—resonates with quantum mechanics’ relational ontology, where particles and properties exist only through measurement relationships rather than independently. Academic journals have published rigorous analyses, such as SpringerLink’s examination of “Two Aspects of Śūnyatā in Quantum Physics,” which argues that both quantum mechanics and (Middle-Way) Buddhism suggest there are no intrinsically existing particles with inherent properties, but rather that all phenomena arise through dependent relationships. This philosophical convergence centers on the idea that reality is fundamentally relational rather than consisting of purportedly mind-independent objects, challenging the classical scientific assumption that the objective domain has fixed, determinate properties independent of observation. It dovetails well with aspects of the Copenhagen and QBist interpretation, not so much with classical realism.) — Wayfarer

Notice that Rovelli IMO overstates the similarities. Yes, his interpretation has a lot in common with Madhyamaka. But Madhyamaka has an (epistemic) 'idealistic' bent to it that Rovelli doesn't capture. Ultimately, all apperances are illusion-like or equivalent to illusions. I doubt that Rovelli would agree with that. QBism perhaps is closer to Madhyamaka but perhaps QBism risks to reify 'agents' in a way that Nagarjuna would not have approved.

Still, I am happy that physicists find inspiration in those views. It might mean something... not sure what but I don't think that it doesn't mean anything.

Notice that Rovelli IMO overstates the similarities. — boundless

Perhaps. It's been said he has a nihilist view of Nāgārjuna, and this kind of mistaken interpretation is not infrequent even amongst expert readers.

Have you encountered the charming and ebullient Michel Bitbol? I learned of him on this forum and have read some of his articles. He is a French philosopher of science who has published books on Schrodinger, among other subjects. Also has an expert grasp of Buddhist philosophy. See for example It is never Known but Is the Knower (.pdf)

There are convergences between Buddhism and physics, but they're nothing like what you would assume at first glance. It has to do with the ontology of Buddhism, which is not based on there being Aristotelian substances or essences, and also on the way that Buddhism understands the inter-relationship of 'self-and-world'. It has a relational, not substantial, ontology. Husserl sang high praises of it.

Perhaps. It's been said he has a nihilist view of Nāgārjuna, and this kind of mistaken interpretation is not infrequent even amongst expert readers. — Wayfarer

Ironically, in a sense the problem is the opposite, i.e. he still 'reifies' too much things and leans toward a physicalism that is not very compatible with the views of Nagarjuna. Ultimate truth is beyond concepts and it is also presented as saying that, ultimately, things 'do not arise'. Appearances aren't negated but they are seen as mere apperances, neither true nor false, like 'moon in the water' as Nagarjuna compared conditioned things in his Sixty Stanzas of reasoning.
I do believe that Rovelli's views are similar to the 'conventional truth' espoused in Buddhist traditions. Interdependence is central also in RQM but in Buddhism one goes beyond that.

Have you encountered the charming and ebullient Michel Bitbol? I learned of him on this forum and have read some of his articles. He is a French philosopher of science who has published books on Schrodinger, among other subjects. Also has an expert grasp of Buddhist philosophy. See for example It is never Known but Is the Knower (.pdf) — Wayfarer

Yes! Bitbol is an excellent source. Notice that he is also closer to QBism than Rovelli's RQM. I also believe that they are good friends.

There are convergences between Buddhism and physics, but they're nothing like what you would assume at first glance. It has to do with the ontology of Buddhism, which is not based on there being Aristotelian substances or essences, and also on the way that Buddhism understands the inter-relationship of 'self-and-world'. It has a relational, not substantial, ontology. Husserl sang high praises of it. — Wayfarer

Agreed!

As soon as you name a ‘world’ or a ‘thing’ or ‘an unknown object’ which you claim is unaffected by or separate from your thought of it, you are already bringing it within the ambit of thought. The realist always has something in mind when he or she speaks of ‘something unaffected by thought’. It’s a Chinese finger trap - you can’t even say it without undercutting the point. — Wayfarer

A tempting argument. But you beg the question, which is whether speaking of something affects it. An obvious question is, "In what way is it affected".
I maintain that naming something (most things) is a Cambridge change, that is, a change that does not affect the object itself. It will not surprise you that there is a good deal of debate about this. You might like to look at SEP - Change See especially sections 2 and 5. There is also a Wikipedia entry - Cambridge change
I can guarantee you that mentioning these entries will not change a syllable that is in them.

Question: how do you arrive at….

But you beg the question, which is whether speaking of something affects it. — Ludwig V

….from….

As soon as you name a ‘world’ or a ‘thing’ or ‘an unknown object’ which you claim is unaffected by or separate from your thought of it, you are already bringing it within the ambit of thought. — Wayfarer

First of all, why isn’t it “effects” rather than “affects”?
But most of all, the second doesn’t say anything about speaking of something, which makes the question-begging claim irrelevant. Doesn’t it?

To name is to first think, that is, to conceive, that which is subsequently cognized in a judgement. To name a ‘thing’ is to already have conceived that which is represented in a cognition as a particular thing. It follows that to name a ‘thing’ is not the same as a thing named.

You said nothing is changed by speaking of it, which is true, but your comment referenced something which wasn’t claiming anything was spoken. I got confused, is all.

Just wonderin’…..
—————-

On Cambridge change:

“….Among the trivial subjects of discussion in the old schools of dialectics was this question: “If a ball cannot pass through a hole, shall we say that the ball is too large or the hole too small?” In this case it is indifferent what expression we employ; for we do not know which exists for the sake of the other. On the other hand, we cannot say: “The man is too long for his coat”; but: “The coat is too short for the man.”

We are thus led to the well-founded suspicion that (…) all the conflicting sophistical assertions (…), are based upon a false and fictitious conception of the mode in which the object of these ideas is presented to us; and this suspicion will probably direct us how to expose the illusion that has so long led us astray from the truth….”
(A490/B518)

I bring this up only to show, once again, what seems new, mostly isn’t.

Yes! The origin of the word is a relation, and yet over time it gets thought of as a property. Elephants existing to me slowly becomes elephants existing period. — noAxioms

It may well be special because it is observed. But observing something doesn’t normally cause it to exist. So even if it is special because it is observed, it may exist for some other reason. You need to demonstrate that there is no other reason.

Yes! The origin of the word is a relation, and yet over time it gets thought of as a property. Elephants existing to me slowly becomes elephants existing period. That which stands out to an observer seems observer dependent. So I'm looking for a definition where yea, it stands out, but not necessarily to anything observing or caring about it. Still a relation though. — noAxioms

If it doesn’t stand out to anything observing or caring about it, it’s not a relation. It’s like claiming to be a parent when you don’t have a child.

That sounds pretty objective. A thing either is or it isn't, a property that is true or false. But then how does an existing elephant differ from the nonexisting elephant, in any way that matters to it? That's a hard question since most dismiss the question before thinking about it. — noAxioms

I’m glad we agree on something. However, to establish the difference (or similarity) between A and B, you have to identify A and B. Suppose that A is the existing elephant. Your problem is that you have no non-existing elephant to take the place of B. You might find a partial solution in Meinong’s work, but you might not find his arguments persuasive.
I need convincing that existence is binary, but I guess that’s a side-issue.

Well, it stands out to us, so it exists as a relation. There doesn't seem to be a test for the existence as a property. That's the problem with the word slowly changing meaning from its original definition. — noAxioms

I can see why you would see it like that. I maintain that the sense of a word now trumps the sense of a word 1,000 years ago.
However, Kant argued that “exists” is not a predicate, which means that existence is not a property. Many philosophers agree with him about that, even if they disagree with much else that he argued for.

Again, this topic is about ontology, not a completely different definition of the word that means genuine vs, counterfeit. — noAxioms

I’m afraid I have been lazy in not giving you the variety of examples that was really needed and left you with the impression that “real” is equivalent to “genuine” as opposed to “counterfeit”. It is true that “real” can be equivalent to “existing” as opposed to “non-existing” as in “imaginary” or “proposed” or “rumoured” or “mythical”. But consider “real property” which means land and similar property as opposed to, for example, intellectual property, stocks and bonds, good will, &c. or “real earnings” as opposed to earnings before allowing for inflation, real cars as opposed to toy cars, real ghosts as opposed to pretend ghosts, real anger as opposed to simulated anger, a real murderer as opposed to an actor of a murdere, a real flower as opposed to an artificial flower. I could go on.
In none of these examples is “real” opposed to “non-existing”. “Unreal”, by the way, is a whole other problem, and you will see from those examples that it is by no means always the opposite of “real”. “Real” is a protean word, capable of being applied to a wide variety of objects, and taking on various different meanings in these contexts, If you are still not convinced, you can find many other examples in dictionaries, which, remember, are compiled on the basis of actual uses and not on the basis of what anyone thinks they should mean.

Agree. I said that to show that it seems to be a valid mind-independent definition of existence, and an objective one this time, one that provides a test to pass or not. — noAxioms

Some reservations. Your formulation has the consequence of limiting existence to things that have causal relationships with each other – that is, physical things. Materialists or physicalists would, no doubt be happy with that. But no-one else will. Plato clearly takes it in that sense, (which justifies the formulation you have) but then rejects it precisely because it denies existence to anything that is not physical – he cites the virtues and the soul. (See Sophist 246 – 7.) It could be made to work in other contexts, I think. Still, it’s a step forward for me. But then, I’m not even looking for a single definition of “exists”. I think that, like “real”, it has different meanings in different contexts. The existence of numbers is not the same as the existence of trees, and the existence of sensations is different again.
The meaning of a word is given in the context of its use in the local structure (a.k.a. language game) in which it is used.

You said nothing is changed by speaking of it, which is true, but your comment referenced something which wasn’t claiming anything was spoken. I got confused, is all. — Mww

I think that one cannot name something by merely thinking, because the name has to be shared to be meaningful. Hence I focused on the speaking rather than any preparatory thought..

I bring this up only to show, once again, what seems new, mostly isn’t. — Mww

Too true. Though I think some people would argue that Geach's version of the point was rather different from Kant's.

S’all good.

But you beg the question, which is whether speaking of something affects it. An obvious question is, "In what way is it affected". — Ludwig V

@Mww replied for me.

Remember this thread started in part with

The Principle of Counterfactual Definiteness (PCD) asserts "the ability to assume the existence of objects, and properties of objects, even when they have not been measured". Efforts have been made to demonstrate say the existence of a photon 'in flight', only to come up empty. Photons only exist in the past of the event at which they are measured.

One of many such apparent paradoxes in quantum physics - which is, after all, supposed to be the science of fundamental particles.

As soon as you name a ‘world’ or a ‘thing’ or ‘an unknown object’ which you claim is unaffected by or separate from your thought of it, you are already bringing it within the ambit of thought. — Wayfarer

So much wrong with that sentence. Nit: I didn't name any particular world. I didn't have a particular one in mind, especially since it's quite difficult to do so. Secondly, I didn't claim anything, but I am defending the stance of those that claim a mind-independent reality. In such a stance, there is no 'ambit of thought'. That term presumes a very different stance. Under the mind-independent view, somebody thinking about X (X not being something in his causal reach) has zero effect on X, and in particular, has zero contribution to whatever the ontological state of X is.

The realist always has something in mind when he or she speaks of ‘something unaffected by thought’.

Arguably so, but being thought of doesn't change it to be affected by thought.
We've switched to 'realist' now. I suppose most of those claiming mind independent existence of say some rock consider said rock to be real. Being real and existing are often synonyms, or treated as such, but there are pages keeping the two terms distinct.

It’s a Chinese finger trap - you can’t even say it without undercutting the point.

I haven't seen the point undercut, despite your implication of 'ambit'.

[Einstein’s] critique was critical to the development of quantum theory. — noAxioms
Yes, but the article acknowledges that. — Wayfarer

I know. I was relaying a couple snippets from the article since Einstein's realist leanings have been noted multiple times in this topic.

Discover Magazine: In quantum mechanics an object can exist in many states at once, which sounds crazy. — Wayfarer

Only in some interpretations, and not crazy, just unintuitive.

The equation should describe the world in a completely deterministic way, but it doesn’t.

Schrödinger equation is deterministic actually. Penrose also seems to be a realist, which doesn't contradict QM, it just contradicts locality. Does he also disagree with say Bohmian mechanics?

But what if physical reality is actually indeterminate on a fundamental level?

There are those interpretations as well, such as objective collapse.

Theoretical physicist Carlo Rovelli, founder of loop quantum gravity, has written seriously about how Nagarjuna’s philosophy of emptiness—the idea that phenomena lack intrinsic existence—resonates with quantum mechanics’ relational ontology, where particles and properties exist only through measurement relationships rather than independently.

Preaching to choir

MWI was developed before decoherence. MWI supporters like decoherence because it seems to explain the branching. It doesn't IIRC remove interference however. — boundless

Why would you want interference removed? It is seen. Even a realist interpretation like DBB has the photon going through one slit and not the other, yet interference patterns result. We experience that. Perhaps we're talking past each other.

Yes, but there is a preferred basis in our experience.

You don't know that, there being no evidence of it. Under MWI, there's no 'our', so every basis is experienced by whatever is entangled with that basis, with none preferred.

It may well be special because it is observed. But observing something doesn’t normally cause it to exist. So even if it is special because it is observed, it may exist for some other reason. You need to demonstrate that there is no other reason. — Ludwig V

A realist might want to justify the existence of whatever he asserts to exist, but I don't count myself among them. I actually think its a big problem. I mean sure, the elephant exists because its parents got busy one day, but that's not a fundamental cause.

If it doesn’t stand out to anything observing or caring about it, it’s not a relation.

Nonsense. Two pebbles are (at a particular moment in time) a meter apart. That's a relation ('is a meter from') even without them ever being observed or known.

I’m glad we agree on something. However, to establish the difference (or similarity) between A and B, you have to identify A and B. Suppose that A is the existing elephant. Your problem is that you have no non-existing elephant to take the place of B. — Ludwig V

Maybe I'm in the presence of elephant B and I've no relation to the existing A one. That would imply that I don't exist since such relations (in the presence of) tend to be between things with similar ontology.
Given that statement, you may want to retract the 'agree on something', but if existence is a property, there's no way to know if you have it. It's usually assumed, but doing so renders the property meaningless.
I did say I wasn't a realist. I usually define 'exists' as the original 'stands out to' relation, in which case yea, B exists to me and A does not. It's objective existence (a property) that is a realist stance, and it makes little sense to me.

You might find a partial solution in Meinong’s work — Ludwig V

My prior topic was on exactly that. I am more open to Meinong than most. My focus was on his rejection of existence being prior to predication (EPP). Given that rejection, I can be in the presence (a predicate) of elephant B without either of us existing.

However, Kant argued that “exists” is not a predicate, which means that existence is not a property.

I don't know Kant all that well, but doesn't his 'exist' boil down to 'I know about'? That is a predicate. Kant isn't exactly a ball of mind-independent opinions.
To reject objective existence as a predicate is to embrace EPP.

Some reservations. Your formulation has the consequence of limiting existence to things that have causal relationships with each other – that is, physical things.

There's plenty of causal structures that are not typically classified as physical. Conway's Game of Life (GoL) is one example. A medium spaceship is an object in that structure. It moves (at 0.5c), can be created and have causal effects. It exists by this EP definition. But it lacks mass, energy, etc, words that are meaningful to our particular physics.

Yes, Plato certainly used a different definition than EP. Plato cites the soul as something lacking in causal interaction? That seems contrary to how souls are often defined.

One of many such apparent paradoxes in quantum physics — Wayfarer

PCD is not paradoxical, it just isn't classical.

Why would you want interference removed? It is seen. Even a realist interpretation like DBB has the photon going through one slit and not the other, yet interference patterns result. We experience that. Perhaps we're talking past each other. — noAxioms

Yes, I think so. Probably it is because also I am muddlying the waters lol.

Anyway, my contention is that if the interference terms are too significant, in the Schrodinger's cat experiment, the version of the observers that sees the 'alive' cat should perceive in some ways the other 'world'. I get that decoherence explains that, due to the decoherence between the observer and the system you get definite outcomes but IMO one also needs that the interference terms become negligible to get the appearance of classicality (i.e. 'definitiness').

Hope I clarified a bit.

You don't know that, there being no evidence of it. Under MWI, there's no 'our', so every basis is experienced by whatever is entangled with that basis, with none preferred. — noAxioms

I disagree. In my example of spins, for instance, we observe either '+1/2' or '-1/2', but we never observe the state 1/sqrt(2)('+1/2'+'-1/2'). In other words, I am not sure how, in MWI, from 'first principles', without the assuming from the start that MWI must be consistent with our experience, we can derive the classical features that we observe.

Anyway, this is not an important point. I mean, perhaps it is asking too much.

Anyway, my contention is that if the interference terms are too significant, in the Schrodinger's cat experiment, the version of the observers that sees the 'alive' cat should perceive in some ways the other 'world'. — boundless

They are nowhere near sufficiently significant. I cannot think of a scenario, however trivial, where you'd see this. It would be the equivalent of measuring which slit the photon passed through, and still getting an interference patter. Interference comes from not knowing the state of the cat, ever.

In my example of spins, for instance, we observe either '+1/2' or '-1/2', but we never observe the state 1/sqrt(2)('+1/2'+'-1/2').

Sure we do. You observe that by not measuring the spin, same as not measuring which slit.

They are nowhere near sufficiently significant. I cannot think of a scenario, however trivial, where you'd see this. It would be the equivalent of measuring which slit the photon passed through, and still getting an interference patter. Interference comes from not knowing the state of the cat, ever. — noAxioms

Yeah, I was just wondering if their magnitude is small 'enough' after measurement/interaction. Some years ago, I read that there was some debate on this point.

Sure we do. You observe that by not measuring the spin, same as not measuring which slit. — noAxioms

I meant that the 'normal' basis is selected, after the measurement, due to the fact that our experimental apparatuses are structured in some ways. In other words, the reason why we observe things in the 'right' basis is that the the experimental apparatus has those properties it has. However, in principle, you could have that after the measurement the state vector 'collapses' to one of the vector in the 'wrong' basis.

But, again, it is perhaps an useless observation. No theory in physics, after all, explains why the world is structured in the way it is. So, MWI is perhaps also immune by this 'criticism'.

A realist might want to justify the existence of whatever he asserts to exist, but I don't count myself among them. I actually think its a big problem. I mean sure, the elephant exists because its parents got busy one day, but that's not a fundamental cause. — noAxioms

So what is more fundamental than that?

Nonsense. Two pebbles are (at a particular moment in time) a meter apart. That's a relation ('is a meter from') even without them ever being observed or known. — noAxioms

Oh, I see. The criterion you are applying is simply "being in a relation with something that exists".

I am more open to Meinong than most. My focus was on his rejection of existence being prior to predication (EPP). Given that rejection, I can be in the presence (a predicate) of elephant B without either of us existing. — noAxioms

I can make some sort of sense to your acceptance of Meinong's rejection of EPP. I need to pay more attention to him, (thanks for that) but so far I can't make any sense at all of your being in the presence of elephant B.

I don't know Kant all that well, but doesn't his 'exist' boil down to 'I know about'? — noAxioms

Not really. Phenomena are dependent on minds for their existence (and properties). But noumena are not.

To reject objective existence as a predicate is to embrace EPP. — noAxioms

That's not at all obvious to me. I'm lost.

There's plenty of causal structures that are not typically classified as physical. — noAxioms

I won't quibble about that. It's a side-issue.

Yes, Plato certainly used a different definition than EP. Plato cites the soul as something lacking in causal interaction? That seems contrary to how souls are often defined. — noAxioms

Well, he lived in different times and thought with different concepts.

I mean sure, the elephant exists because its parents got busy one day, but that's not a fundamental cause. — noAxioms
So what is more fundamental than that? — Ludwig V

The cause of its parents of course.
I list what is probably classified by Aristotle as an efficient cause of the elephant. More fundamental would be a root cause, something realists need to face.

Two pebbles are (at a particular moment in time) a meter apart. That's a relation ('is a meter from') even without them ever being observed or known. — noAxioms
Oh, I see. The criterion you are applying is simply "being in a relation with something that exists".

That would be a different relation than the one I listed. I mean, that's like 'being in a relation with something that's green', which begs the question 'what if it's a meter from something that's not green?'. It seems your relation asserts something in addition to the relation. Mine did not. That relation is a predicate, and if EPP is not accepted, only the relation 'is a meter from' is sufficient. Existence of neither object is required. With EPP, yea, they need to exist before they can be a meter apart.

I can make some sort of sense to your acceptance of Meinong's rejection of EPP. I need to pay more attention to him, (thanks for that) but so far I can't make any sense at all of your being in the presence of elephant B.

No different than the two things a meter apart. Existence of either thing is not required if EPP is rejected, so I can be in the presence of a nonexistent elephant. Since related things often (not always) seem to share ontology, I probably wouldn't exist either. My suggestion is that since elephant A & B are identical except for A existing, nether A nor B has any empirical test to see which is which. For this reason, I find existence defined as an objective property to be useless. Hence my not being a realist. All the problems of realism are solved.

doesn't [Kant's] 'exist' boil down to 'I know about'? — noAxioms

Not really. Phenomena are dependent on minds for their existence (and properties). But noumena are not.

I really don't know Kant then. Those are not idealist ideas.

I meant that the 'normal' basis is selected, after the measurement, due to the fact that our experimental apparatuses are structured in some ways. In other words, the reason why we observe things in the 'right' basis is that the the experimental apparatus has those properties it has. However, in principle, you could have that after the measurement the state vector 'collapses' to one of the vector in the 'wrong' basis. — boundless

I don't understand any of that. There is no right/wrong basis under MWI. They all share the same ontology, but some are more probable than others, whatever that means.

Arguably so, but being thought of doesn't change it to be affected by thought. — noAxioms

I’m not saying that an object is ‘affected by thought’. I’m thinking of the Statue of Liberty right now which will make no difference to it whatever. The question of mind independence that is of interest to me, is the sense in which the world exists independently of the mind.

I don't understand any of that. There is no right/wrong basis under MWI. They all share the same ontology, but some are more probable than others, whatever that means. — noAxioms

No worries, as I myself said it is a quite secondary issue. Even if there is a counter-intuitive increase of number of 'bases' it is not a problem, I guess, for MWI-supporters as they already accept that there many more 'worlds' out there.

Thanks for the patience!

That relation is a predicate, and if EPP is not accepted, only the relation 'is a meter from' is sufficient. Existence of neither object is required. With EPP, yea, they need to exist before they can be a meter apart. — noAxioms

Yes, there's a real problem about EPP. The root of the problem is the idea that something can exist before any predicates apply to it, or that something can have a predicate applied to it before it exists. Neither works. Hence "prior" cannot mean "temporally prior" so it needs to be reinterpreted or abandoned. It could mean something like "more fundamental", but I can't make any sense of that either. The only position that makes any sense to me is "co-arising" or interdependence.

My suggestion is that since elephant A & B are identical except for A existing, nether A nor B has any empirical test to see which is which. For this reason, I find existence defined as an objective property to be useless. Hence my not being a realist. All the problems of realism are solved. — noAxioms

Well, you're still left with the problems of idealism. For me, your suggestion demonstrates that predication without existence makes no sense. I already knew that existence without predication makes no sense. So I'm left with interdependence.

There's a real problem about EPP. The root of the problem is the idea that something can exist before any predicates apply to it, or that something can have a predicate applied to it before it exists. Neither works. Hence "prior" cannot mean "temporally prior" so it needs to be reinterpreted or abandoned. — Ludwig V

First of all, 'prior' is their language, and it isn't a temporal reference. EPP says (without using that contentious word) that 'only existing things can have predicates', which is arguably self contradictory since a nonexistent thing would have no predicates, which is in itself a predicate. Meinong rejects that, so existence is not a requirement for predication.

Part of the issue is that EPP isn't very specific about what definition of 'exists' is being referenced in its statement. Under def 1 (idealism), and 4 (deliberate assignment), predication seems prior to existence.
Definition 3 (relational) also doesn't seem to require EPP. So that leaves 2 (part of the universe) and 5 (objective), the only ones that arguably need it, but if EPP is not assumed, I don't see any contradiction that follows from predication without existence.

OK, def 2 as worded arguably of needs it because the universe needs to stand out from other universes, else it's just a universe. But since two objects can be a meter apart in one of the other universes, EPP isn't necessary for the predication, only for it being (unexplainably) preferred.

So EPP fails at every step. You seem to find that problematic, but without begging EPP, you need to point out what contradiction results from it, being very specific about how you're defining your terms.

Well, you're still left with the problems of idealism.

As I said, under idealism, the elephant's existence is due to its being observed, being a phenomenon. That phenomenal relation results in the existence of the elephant, hence predication is prior to existence under idealism. You disagree I take it.

I already knew that existence without predication makes no sense.

If you define existence as 'standing out', yea, it can't stand out without predicates. Under idealism, that would mean existence despite not being perceived, which isn't really idealism then. 2-4 seem to require predication, yes. 5 (objective)? That one seems contradictory only because existence under def 5 is a property (not a relation), and a property is a predicate, as is the lack of the property.

Thanks for your input Ludwig. Forcing me to work stuff out, which is good.

My reply to you here belongs in my EPP topic.

The question of mind independence that is of interest to me, is the sense in which the world exists independently of the mind. — Wayfarer

Just calling it 'the world' seems to be an assumption that this world is preferred, presumably because it is perceived. This sounds like a very mind dependent stance to me.

Even if there is a counter-intuitive increase of number of 'bases' — boundless

Everett's thesis had to dumb-down the number of bases due to the finite but inexpressibly large actuality of the actual figure. For instance, you (a physical object with extension, at a moment in time) is undergoing trillions of splits such that there is no one measured state except relative to some measuring event well after said moment in time. Hence Rovelli saying that a thing cannot measure itself, it can only measure something sufficiently in the past to have collapsed into a coherent state. Not sure if it's Rovelli's term, but an extended system (a person say) at an extended moment in time, is a sort of extended spacetime event called a 'beable'.

Everett's thesis had to dumb-down the number of bases due to the finite but inexpressibly large actuality of the actual figure. — noAxioms

IMO not just for that reason, but also because he had to explain how 'classicality' arises.

Hence Rovelli saying that a thing cannot measure itself, it can only measure something sufficiently in the past to have collapsed into a coherent state. — noAxioms

Ok. I thought that he said that a thing can't measure itself becuase a thing can't interact with itself. Interesting.

'beable'. — noAxioms

The term 'beable' was introduced by John Bell as opposed to 'observable'. Basically, 'beable' were objects or properties that are definite (i.e. that can be represented mathematically with definite quantities) even if there is no measurement. Local realists, like Einstein, hoped to explain everything in terms of 'local beables' (like, say, point particles, local values of fields and so on) which interact with local interactions (i.e. interactions that aren't faster than light). Of course, what Bell proved is that you have either to assume that, ultimately, there are no 'beables' in the sense expressed above or that, ultimately, there are 'nonlocal beables' or at least beables that interact with faster than light interactions.

You can see a pdf file of John Bell's article about 'local beables' here: https://cds.cern.ch/record/980036/files/197508125.pdf