Problems with Many Worlds Interpretation

[Hurkyl]

I suppose I should reply to this too.

So let's concentrate on eigenstates and superposition states, it seems we can get to the heart of the nonunitarity of our experiences perfectly well in that language.

The connection between unitary evolution and experience proposed in MWI and other similar interpretations quite explicitly depends on the fact that our experiences are described by mixed states; I suspect whatever plan you wish to propose won't have anything useful to say on the subject.

But I'll play along some to see if it goes in a useful direction.

Aside: in thought experiments like what I'm imagining, I like to treat qubits as toy experimenters and CNOT gates as toy measuring devices. I don't suppose you'd go for that?

The second one is most key, that one is equivalent to the statement "experience is nonunitary."

I don't see how, unless you presume the ontological position that, in the bird's eye view, "I saw tails" is either bird's eye true or bird's eye false.

 

[Hurkyl]

I am not following the significance you attach to this statement. If no experience can distinguish between definite and indefinite outcomes, then the empiricist says there is no difference, and labels all experiences as definite outcomes.

Why does your empiricist care? Why does he bother making any assertions at all? What criteria does he use?

My scientist might invoke pedagogy.

 

[Eqblaauw]

Eqblaauw. That post merely describes skepticism. Something science accepts and allows. But skepticism doesn't mean you should go around not believing the most likely solution just because it might "just look like it's right".

Not that I am taking stance here either way, since it seems to me that we have peanuts in the way of data to making such grandious hypotheses about the universe.

Also, offtopic but, Freud was taken seriously because his arguments were compelling and the majority of people (psychologists included) are not incredibly self aware and cannot, themselves, readily examine their own psyches. It's not because his theories so accurately described psychological phenomena that one would have to have been crazy to not accept them.

I agree with the last sentence completely (so your not arguing against me here).
I've read quite a lot of Freud, and his arguments aren't that compelling either.
And what I say is basically what Karl Popper says (I've just found this):

I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appear to be able to explain practically everything that happened within the fields to which they referred. The study of any of them seemed to have the effect of an intellectual conversion or revelation, open your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirmed instances everywhere: the world was full of verifications of the theory. Whatever happened always confirmed it. Thus its truth appeared manifest; and unbelievers were clearly people who did not want to see the manifest truth; who refuse to see it, either because it was against their class interest, or because of their repressions which were still "un-analyzed" and crying aloud for treatment.

http://www.stephenjaygould.org/ctrl/popper_falsification.html

I try to believe the most likely solution, but a test that can falsify it surely has to be done before I can make up my mind about what it is.
And, as you also choose, 'we don't know yet' is certainly an answer too.

 

[Fredrik]

So are you finally adopting the long-standing tradition of formulating physics from the bird's eye perspective because it's much easier to understand and compute with, and deriving the frog's eye view from it?

This sounds pretty strange to me. In the case of QM, we don't even know how to derive the frog's view from the bird's view. Even in classical SR and pre-relativistic classical mechanics, I wouldn't say that we have a tradition of deriving the frog's view from the bird's. Instead we do a lot of talking about inertial frames. Isn't that a frog's view concept? (The coordinate independent statements of GR would be an example of a bird's view in classical physics).

 

[Ken G]

Why does your empiricist care? Why does he bother making any assertions at all? What criteria does he use?

Simple-- the empiricist wishes to use science to describe his/her experiences. Not the experiences he/she imagines he/she could have under different circumstances, like your qubit experimenter, but rather the ones we actually have. This is just the point. I'm afraid that everything you say about what a scientist is sounds to me like someone who is pretending to be experiencing something other than what they are actually experiencing, and focusing on explaining the pretend experiences rather than the real ones. You want the god's eye view, but never experience it, and you just say "no bother, I'll pretend I'm experiencing it, because that pretense fits in better with my rationalistic objectives." Yes, I get that, it's all you are really saying to me-- you have rationalistic objectives and simply see no point in empiricism.

Now, as more of an empiricist, I see yours as a kind of fantasy world to make for onesself, but it is not a fantasy world that involves any wrong predictions, it's just one where you imagine your experiences are something other than what they are. Since you encounter no inconsistencies doing that, I cannot say there is anything unscientific or wrong about it, but it is quite clearly un-empiricist. About all I can try to do here is get you to see that you have indeed made a choice to follow a radically rationalistic path, and not continue your pretense that you are "just being a scientist."

About the only "high ground" available to empiricism is the one I've already mentioned-- by making my bedrock what is actually experienced, that will not change in the future. By making yours a world view anchored to the rationalistic concept of unitarity, yours could fall down tomorrow. Given the history of science, you should actually expect it to take a little more time than that, and you might not even live to see it, so again you have nothing to worry about.

 

[Hurkyl]

Instead we do a lot of talking about inertial frames. Isn't that a frog's view concept?

As I understand the term "frog's view", not at all. For simplicity, consider the familiar example of the twin paradox. The frog's view is that Terrance experiences the (relativistic) Doppler effect -- through his telescope he watches Stella celebrate 8 birthdays over 16 years, and then 8 more birthdays over the next 4 years. He doesn't "see" the constant time dilation factor described by his inertial reference frame -- he has to do the calculations to plot his observations relative to that frame.

EDIT: centrifugal force is a good classical example. It's something that people talk about a lot in their frog's eye experiences -- but how do we understand it? I learned to first understand mechanics in inertial frames, and use that to derive how things behave in rotating frames. I'm under the impression that's how most learn it.

 

[Hurkyl]

Simple-- the empiricist wishes to use science to describe his/her experiences.

Okay. We have seen both definite outcomes and indefinite outcomes describe his/her experiences.

You said he uses science to decide -- how? What is his criteria? In what way does science tell you to decide to choose the definite outcome description?

All I'm hearing from you is the dogmatic assertion that our experiences are definite. You never tell me why you make that choice between two indistinguishable alternatives -- you just assert that it's the right choice, and proceed to tell me all of the consequences of it being right choice, and ridicule me for not accepting your dogma.Just for fun, let's talk to my buddy Chrono.

Me: Hey Chrono, you still using classical mechanics?
Chrono: Nope, I've upgraded to Lorentz Ether Theory?
Me: LET? Why not Special Relativitiy
Chrono: Because it doesn't describe my experiences
Me: What do you mean?
Chrono: It can't tell me what "now" is. It pretends there is no such thing.
Me: But now is relative.
Chrono: No it's not. Now is now. Are't you experiencing now right now?
Me: Er, sure, but what constitutes now depends on my reference frame.
Chrono: Our experience with time is absolute. Sure, you can get the right predictions with inertial reference frames, but it doesn't describe what we actually experience.
Me: Oh? How can you tell the difference between absolute time and relative time.
Chrono: You can't.
Me: See? So why don't you switch to special relativity?
Chrono: Because my experiences are of absolutely time.
Me: But you just said you can't distinguish between the two! How can you tell the difference?
Chrono: I can't. So I choose absolute time, because that describes my experiences.
...​

 

[Ken G]

EDIT: centrifugal force is a good classical example. It's something that people talk about a lot in their frog's eye experiences -- but how do we understand it? I learned to first understand mechanics in inertial frames, and use that to derive how things behave in rotating frames. I'm under the impression that's how most learn it.

These are good examples, and it shows us we have an interesting issue here-- just what is the frog seeing anyway, and are some frogs getting a "preferred view"? It is indeed traditional to tell new students "don't worry about centrifugal forces, noninertial frames will only confuse you." But is that the core principle of relativity, that noninertial frames should be avoided? No it isn't-- that's the "old way of thinking." The new recognition is that sometimes frogs accelerate, yet they should be just as reliable a witness to what is "really happening" as those who are not. Hence, we need theories of physics that explain the experiences of inertial frogs, and noninertial frogs, and they need to be the same laws. That's what Einstein didn't like about the "special" in SR, and I suspect that was as much his motivation for a general theory of relativity as the desire to treat gravity.

So the crux of relativity, to me, is that the connection between experience, and the laws of physics, is entirely local, and that is because experience is also entirely local. The "eigenvalues" of relativity are local. You say a twin sees the other twin doing something, but that's not actually true-- the one twin sees some photons entering his eye that came from the other twin. That's not at all the same thing-- the photons are in the twin's eye, it is a local experience. The laws must account for the local experience, not the nonlocal bridging using bogus concepts like "simultaneity". Relativity tells us not to build our theories out of global "god's eye" views like simultaneity-- or unitarity.

 

[Ken G]

Okay. We have seen both definite outcomes and indefinite outcomes describe his/her experiences.

I still have no real idea what you even mean by an "indefinite outcome", it sounds like an oxymoron to me. Let me ask you this: do you actually believe that when you, personally, flip a coin, and look at it, the outcome you perceive is a mixed state of heads and tails? And do you call that a definite or an indefinite outcome?

You said he uses science to decide -- how? What is his criteria? In what way does science tell you to decide to choose the definite outcome description?

Science doesn't tell you, language does. We experience outcomes. We define that word "definite" to go with that. That's it, there's not even a role for science yet. Science comes in when it is time to understand and predict the outcome.

All I'm hearing from you is the dogmatic assertion that our experiences are definite.

Again, that is neither dogma, nor assertion. It's just language. Definite means we know it. That's it, that's what it means. So my "dogmatic assertion" is that we know our experiences. I suppose I could see that as "empiricist dogma", but it's certainly a pretty tame variety. Nowhere near as radical as "when I flip a coin I perceive both outcomes I just don't know that I do", which is more or less what you seem to be saying.

You never tell me why you make that choice between two indistinguishable alternatives -- you just assert that it's the right choice, and proceed to tell me all of the consequences of it being right choice, and ridicule me for not accepting your dogma.

First of all, I have never once ridiculed you, you are quite mistaken there. My efforts have been simply to get you to see that you are so radical a rationalist that you cannot seem to even conceive of empiricism. That's not ridicule, I really don't think there's anything wrong with your position. I just want you to see it is radical.

Chrono: I can't. So I choose absolute time, because that describes my experiences.

Way off. The whole point of "proper time" is that it is just precisely time that is locally experienced. Absolute time was always the rationalistic notion, proper time was always the empirical version. That's what I mean that rationalistic theories like Galilean relativity disappear overnight, but observations, like proper time, do not.

 

[Hurkyl]

But is that the core principle of relativity, that noninertial frames should be avoided?

I have no idea where you got this idea.

From the enclosing paragraph, it almost sounds like you are asserting we should always try to work in generalized coordinates^* chosen to be as closely related to your own perception as possible, without paying any regard for issues of calculation or learning or understanding.

*: SR and GR are a red herring! This idea is already present in classical mechanics and geometry.

 

[Ken G]

I have no idea where you got this idea.

What idea are you referring to? I was saying that the lesson of relativity is that all observers are in some sense "equally positioned", whether inertial or not, to bear true witness on what is happening, and what's more, they should all be able to apply the same laws to explain what they see. That seems like a fairly natural interpretation of relativity to me, do you differ?

From the enclosing paragraph, it almost sounds like you are asserting we should always try to work in generalized coordinates^* chosen to be as closely related to your own perception as possible, without paying any regard for issues of calculation or learning or understanding.

Not quite, I'm saying that our observations are closely related to our own perceptions. Understanding them is then something different. The role of empiricism is to say what reality is, the role of rationalism is to understand what empiricism has already told us is the reality. That would be how I sort the two. Your perspective seems to exactly reverse that.

 

[Fra]

About the issue of the metaphors bird/frog/god views and how they are related, and how relativity and QM can be seen as examples of this idea, I think herein indeed lies a core of logic that at least I would use to classifys different pictures. (post#284)

I didn't follow the entire Ken/hurky discussion and I am not sure about their exact definitions of frog/bird/god, but here is my attempt at classification.

This is how I understand the metaphors:

frog ~ an inside observer (an observer beeing in principle a "subsystem of the universe", nothing to do with humans)

This means the "the universe" is loosely understood as a big collection of interacting frogs.

frog's view ~ the VIEW of the big picture that the frog itself can INFER from interactions with other frogs. This is necessarily always incomplete and generally always changing.

birds ~ an observer that can see a larger "collection" of frogs from perspective; this means that if you think of the bird as seeing "everything" and having all info, then that's te "gods' view", anything "more realistic" simply means that the bird is nothing but a BIG FROG.

For a realist, I think the god's view is more compelling as it's the most complete (the only problem is that no one actually has this picture, but the scientist themselves is a BIG FROG too).

(I wonder what Ken means by rationalist? do you by any chance mean the same as realist?)

For the empirist the god's view is a mental construction that is useless. Instead the birds view is nothing but a frogs view scaled up to a big frog. (This is equivalent to Smolins argument about "small susystems" in this paper http://pirsa.org/08100049). He never from what I recall use the words frog and bird, but the essence of saying that "timeless laws" make senes only for small subsystems, is the essence of the statement that "an EFFECTIVE god's view only exists when the BIG FROG (the bird) is BIG ENOUGH.

This is why the framework of the LIMIT (BIG FROG -> ifinity) disconnects from the proper inside view (small frog). This is why this connection is lost and it takes some new perspectives to see it's still there.

This "limit framework" is IMHO what dominates mainstream models, and this causes problem for example with QG and unification because the "proper" frog view is lost; all we have is an equivalence class of frog view, but the small frog does not see this, only a sufficiently BIG frog AND onlt if the limit is taken right.

The next arguments would be to connect bird and frog in interactions and then note where this places relativity and QM, and what the missing pieces (still open issue) are... but I'll drop that if this staring point makes not sense to anyione

/Fredrik

 

[Fra]

Relativity tells us not to build our theories out of global "god's eye" views like simultaneity-- or unitarity.

I've learned that the subtle differences that exists exactly are seen different but different people. It seems possible to argue that both views can agree that the other view is confused.

The problem becomes more complicated also conceptually when you go from "classical theory" (meaning realist theory) to QM (observational). Rovelli's RQM paper is a good example of what I see as broken reasoning. It contains both great points and overlooking of others (IHMO at least).

To give this argument an edge; you can even argue that there are two constructing principles behind relativity, that are almost clashing, and there are two ways to realize the merging.

1) On one hand relativity denies the realism of absolute "spacetime" and acknowledges that each observer infers a "different spacetime". Relativit however ONLY speaks about spacetime. There are OTHER things that also are infered, which when accounted for would generalize this reasoning.

2) The other principle is that the laws of physics, must be the same to all observers. MUST here is what follows from Einsteins structural realism (I do not agree with this though). Thus the only way to realize this, is to find the covariance of hte laws, that explain how different observers relate.

IF you see the observer-observer transformations (which then encode the invariants) as elements of realism, there is no clash. I think it's fair to say that this is the by far most common view. The realist thinks that only such deterministic transformations are worth beeing called "laws", thus the position isn't negotiable.

IF you however, insist that these transformations arne't "given" and that they are a result of an inference or abduction from experiments (from empirical perspecive), then the two constructing principles actually contradict each other, because the conclusion is something like: the only "proper observables" (read observer invariants) are actually not observable by any observer - it takes a god to observer them (or limiting constructions for EFFECTIVE observations). This is the problem. Empirist extermist says that laws of the realist simpyl doen't exists. All there EVER is are "effective laws" and the idea is to find optimal inferences - given the acknowledged incompelteness; and the conjecture is that this is more constructive that realist stances.

Realists typically thinks of the latter as circular reasoning since it failes to be capturs in a single timeless, fixed mathematical formalism. Empirist would simply call it evolutionary learning (science), and explicitly acknowledges the de facto limitations, instead of pretending to lean on a god-view backbone that isn't inferrable.

/Fredrik

 

[Ken G]

frog ~ an inside observer (an observer beeing in principle a "subsystem of the universe", nothing to do with humans)

This means the "the universe" is loosely understood as a big collection of interacting frogs.

I would modify this slightly, to clarify some important distinctions. To be an observer requires more than just being "part of the collection", there is some requirement that the observer must "process information like we do" to count in a way that is useful to our use of the term. So you're right that a tree can in some sense observe itself when it falls down, but for it to count in our term, it must "observe itself the way we would." We have no idea how a tree is really observing itself, if the phrase even means anything-- instead, we must "put ourselves in the place of the tree" before we can claim the tree is acting like what we mean by an observer. I'm not placing arbitrary constraints on the language, I honestly don't see how term "observer" could possibly mean anything else, and still hold any kind of empirical meaning to us.

So this means that what the universe "is a collection of" is something a bit more general than "observers." The distinction is going to matter, because what we call "quantum systems", or "macro systems acting like quantum systems", might well be exactly the systems that lack the processing power to be called "observers" (or at least, they don't process in a way we recognize).

frog's view ~ the VIEW of the big picture that the frog itself can INFER from interactions with other frogs. This is necessarily always incomplete and generally always changing.

I would actually start the "frog" lower in the hierarchy-- no communication with other frogs, just interactions with the non-observers. The "raw experience" of a single frog.

birds ~ an observer that can see a larger "collection" of frogs from perspective; this means that if you think of the bird as seeing "everything" and having all info, then that's te "gods' view", anything "more realistic" simply means that the bird is nothing but a BIG FROG.

Here I would agree the bird's view assembles frog's views, including the views we consider hypothetically (like "if a frog were there, what would it see"). But note this is a very specific type of information, so even if we assemble it all, it's not all the information (unless we define this to be information, that's a subtle issue I won't take a position on). The key point is that the god's eye view is something quite different, because it does not ask "what would a frog see", it just asks "what is." The god's eye view is the view of the rationalist, it is a conceptual framework for talking about truth (rather than an empirical one). The "many worlds" are, to me, a quintessentially example of a "god's eye view", and so is the whole Tegmark hierarchy of multiverses. Tegmark is in effect placing himself in the position of god, that his rationalist perspective can "see" what empirical interactions cannot. I'm not saying he has a god complex, I don't really mean any religious overtones-- I'm saying he is a dyed-in-the-wool rationalist.

For a realist, I think the god's view is more compelling as it's the most complete (the only problem is that no one actually has this picture, but the scientist themselves is a BIG FROG too).

Realism is actually something quite a bit different. It is defined as people who "take their perceptions at face value", such that what is real is what we have access to. The key tenet of realism is that our limitations do not actually limit us, because they are fundamental to us, so we basically shouldn't care about any reality that is outside our limitations. So there's a subset of realists who are empiricists, who say that what is real is exactly what we perceive (I would call that Einstein's brand), and there is a subset who are rationalists, who say that what is real is the god's eye view accessible to our reason (I would call that Tegmark's brand). None of these are "naive realists" (http://en.wikipedia.org/wiki/Naïve_realism), who say that reality is exactly what we perceive it to be, there's no need for us to reinterpret reality based on either other observer's points of view, or over-arching conceptual principles. It's the "show me" brand of realism taken to its logical conclusion, and I don't think anyone in this discussion espoused that brand.

For the empirist the god's view is a mental construction that is useless. Instead the birds view is nothing but a frogs view scaled up to a big frog.

Exactly. That's why I feel an empiricist would need to bring in a new concept, the "god's eye view", to treat what rationalists are talking about.

This "limit framework" is IMHO what dominates mainstream models, and this causes problem for example with QG and unification because the "proper" frog view is lost; all we have is an equivalence class of frog view, but the small frog does not see this, only a sufficiently BIG frog AND onlt if the limit is taken right.

Here I disagree with what I believe you are saying. In relativity, it is actually codified right in the laws (rationalistic laws at that) that what the laws must be built from are frog's eye views, fed into a rationalist machine called "compute the invariants." That's why relativity can still be interpreted (by an empiricist) as completely empirical-- it is a theory that acts only on what are demonstrably frog's eye views (it takes as input only things frogs could not only perceive, but also communicate about-- the invariants are functions of only things that are local and communicable to frogs). That's where spacetime comes from-- locality + communication.

IF you see the observer-observer transformations (which then encode the invariants) as elements of realism, there is no clash. I think it's fair to say that this is the by far most common view. The realist thinks that only such deterministic transformations are worth beeing called "laws", thus the position isn't negotiable.

Yes, I agree that is conventional for both empiricists and rationalists, and is the approach I take too.

IF you however, insist that these transformations arne't "given" and that they are a result of an inference or abduction from experiments (from empirical perspecive), then the two constructing principles actually contradict each other, because the conclusion is something like: the only "proper observables" (read observer invariants) are actually not observable by any observer - it takes a god to observer them (or limiting constructions for EFFECTIVE observations). This is the problem. Empirist extermist says that laws of the realist simpyl doen't exists.

Yes, I see what you mean. But here I would substitute "rationalist" where you have "realist." The empiricist is still being a realist when they admit that laws must be built from invariants even though no one sees the invariants, because the empiricist rejects the rationalist idea that there "really are laws" in the first place. Instead, the empiricists says that there "really are observations", but that we must try to build laws or we can't use the observations effectively. The laws are from us, not nature (though of course they are constrained by nature or they won't work). The advantage of this approach is that the laws can change, as they do, and the empiricist never has to say "OK, we were wrong before, but we have it right this time." That stance just gets kind of embarrassing after too many centuries! (But the rationalist has many successes to point to, mysteriously many, so I don't claim this means empiricists are "right" and rationalists are "wrong", my goal is only to elucidate the consistency packages involved.)

All there EVER is are "effective laws" and the idea is to find optimal inferences - given the acknowledged incompelteness; and the conjecture is that this is more constructive that realist stances.

I agree that is the empiricist stance, but I wouldn't call it non-realist, only non-naive-realist. The empiricist is a realist whenever they say "there is a reality that is accessible through observation", or "if there is any reality that is not accessible to observation, it is angels on the head of a pin to us." They can admit that this reality is quite subtle and surprising, and needs to be kind of cobbled together in an intelligent way that looks for things like invariants and unitary principles. However, these principles are never the reality-- they are always our efforts to make sense of the reality.

Realists typically thinks of the latter as circular reasoning since it failes to be capturs in a single timeless, fixed mathematical formalism.

That's what I would call rationalism.

 

[Fra]

I think you almost got my points, but I think I am more radical that you, we disagree on some points... som quick ocmments.

I would modify this slightly, to clarify some important distinctions. To be an observer requires more than just being "part of the collection", there is some requirement that the observer must "process information like we do" to count in a way that is useful to our use of the term. So you're right that a tree can in some sense observe itself when it falls down, but for it to count in our term, it must "observe itself the way we would." We have no idea how a tree is really observing itself, if the phrase even means anything
...
So this means that what the universe "is a collection of" is something a bit more general than "observers." The distinction is going to matter, because what we call "quantum systems", or "macro systems acting like quantum systems", might well be exactly the systems that lack the processing power to be called "observers" (or at least, they don't process in a way we recognize).

The way I used "observer" I already had in mind the generalization you refer to. However in my view, even a quantum system is a perfectly good observer. However, to understand how this process information, is identical to the problem of understanding it's action; just like we in current theory have an action for the standard model. This action exactly encodes how "matter processes information about other matter and fields" - or at least so goes my conjecture.

But the point is that this isn't such a wild conjecture as one may think. It follows from a coherent reasoning in empirist spirit. I just take it to it's extreme. In particular I object to the structural realism that exists even in the empirist take on relativity. To see why, all you need to do is to consider exactly how observer transformations are inferrd from experiments. There is no a priori reason to think that they have to be observer independent (*)

IF you see the observer-observer transformations (which then encode the invariants) as elements of realism, there is no clash. I think it's fair to say that this is the by far most common view. The realist thinks that only such deterministic transformations are worth beeing called "laws", thus the position isn't negotiable.

Yes, I agree that is conventional for both empiricists and rationalists, and is the approach I take too.

To avoid misunderstanding: I described tis picture, but I do not share it. See above (*)

More later

/Fredrik

 

[Fra]

IF you however, insist that these transformations arne't "given" and that they are a result of an inference or abduction from experiments (from empirical perspecive), then the two constructing principles actually contradict each other, because the conclusion is something like: the only "proper observables" (read observer invariants) are actually not observable by any observer - it takes a god to observer them (or limiting constructions for EFFECTIVE observations). This is the problem. Empirist extermist says that laws of the realist simpyl doen't exists.

Yes, I see what you mean. But here I would substitute "rationalist" where you have "realist."

The empiricist is still being a realist when they admit that laws must be built from invariants even though no one sees the invariants, because the empiricist rejects the rationalist idea that there "really are laws" in the first place. Instead, the empiricists says that there "really are observations", but that we must try to build laws or we can't use the observations effectively.

Given your premise, you'r right. If the empirist assumes what you describe, then they are also a realist. This is what I'd call "structural realism" (you give it some other labels). This was part of my point, we agree so far. Often people don't see this "realism".

This was relevant in the MWI, CI discussion since both views contains realism, just applied to different things.

But my follow up point was that this postion is not necessary. You can be a more radical and reject even this form of realism. Unlike your last claim, I don't see it as "nessary" to make observations useful.

This is exactly what I reject. I call this irrational. I wrote MUST myself in a previous post, but it was just to emphasis the "common view". By I do not personally share it. I used to think like that however, so I certainly see why you can think it's a MUST.

This is actually a different view. It expresses an ambition, not a CONSTRAINT. My take on this is that laws are evolving, and what realist empirist calls the invariant, are in my view only defined by letting the observers interact, and this is a physical process and the invariants are only manifested in equilibrium points. There just is no a priori logical reason why all observers MUST infer the same laws. It's however true that if they don't, their interaction would be chaotic. Instead my point is that while there is no a priori MUST, when these observes (read parts othe universe = matter systems) there will be a selective pressure for them to reach an agreement and concensus, or destructive feedback will destroy disagreements. The emergent consensus is the result of a negotiation and this consensus is the invariants (encoded as the establised communication). In this picture, thus the "MUST be invariants" are instead EXPECTED equilibrium poitns in the negotiation process.

ie. The MUST is equivalent to the assumption that we have equilibrium. and while I think we are at equilibrium at the moment, to undertand unification and origina of forces, I think we need to think beyond this equilibrium. I think the breaking of some supersuppoery at big band is better understood as emergence of interactions from chaos. It's mainly a different view of thinking rather than something else.

But to realize that, we need to undersand how the "generalized observers" count and encode infotmation. How the inferred law from say an atom, cna be communicated to a large frog (say a human) is what we do when we probe matter and try to see how matter "behaves" at high energy.

Noone has done this of course, but it seems like a plausible possition if you take the empirist and inference view to it's extreme.

My main point is then this: The "pure interpretations" somehow, makes no difference. Both suggest no path forward. The above view, which I personally see as originating in the CI view but purified and taken to it's extreme, do suggest ways forward. This is why I prefer this interpretation. The arguments often used by CI, that the collapse is nothing but information update etc... become less "convincing" unless you are coherent about the reasoning and also at least reject the reality implicit in the classical background. And if you DO take it seriously, you find yourself formulating a totally different and much deeper question than what you started with. This is why these interpretational discussions are always difficult.

/Fredrik

 

[Ken G]

But my follow up point was that this postion is not necessary. You can be a more radical and reject even this form of realism. Unlike your last claim, I don't see it as "nessary" to make observations useful.

I agree you don't need realism to make observations useful, it is objectivity that you need, by which I mean borrowing cautiously from the rationalistic construct of "laws" that are observer independent. To have empirical objectivity, we first need to accept all observer's testimonies as valid descriptions of reality, and then we need to find functions of those observations that strip off the observer dependence, like 4-vector norms. The latter is need to have laws that are observer independent. Note how empiricist this program is-- the laws are not the reality here, because reality is observer dependent, and the laws are not. This is just the goal the empiricist sets out for laws-- how well it works is another matter, and is accepted as mystery by empiricists. Of course, rationalists don't see it as mysterious that laws work, because they think the laws are the reality. But they have their own problems, not the least of which is the fact that laws change but observations don't.

There just is no a priori logical reason why all observers MUST infer the same laws. It's however true that if they don't, their interaction would be chaotic.

Actually we agree here-- I didn't mean "must build laws from invariants" to mean "nature decrees they must do this", I mean they "must" if they want to achieve the goal of laws that do not reference observers. My point is that observations "must" by their nature refer to observers, but it is our desire as scientists to build laws that do not refer to observers, so we "must" do that to be successful. It's a different kind of "must", I agree.

The insight here might be that the fundamental rule of objectivity is not "all observers must see the same thing", that went out with relativity. But more than that, if objectivity requires "observers must be able to agree that they both hold valid versions of the reality," then useful objectivity requires "observers must be able to understand the other's story using an observer independent rule for doing that." That last is what invariants imply, and without it, science becomes a kind of negotiation, as you say, but it needs to be more-- it needs to be a negotiation with observer-independent rules, unlike negotiations over car prices and so forth.

The emergent consensus is the result of a negotiation and this consensus is the invariants (encoded as the establised communication). In this picture, thus the "MUST be invariants" are instead EXPECTED equilibrium poitns in the negotiation process.

Yes, I can buy that, if we further stipulate that the goal is to establish observer-independent rules for reaching those expected equilibria. Here's where the rationalist says that the observer-independent rules of engagement are the reality itself, but the empiricist says they are only the reality of our desires as scientists to make sense of what is happening.

But to realize that, we need to undersand how the "generalized observers" count and encode infotmation. How the inferred law from say an atom, cna be communicated to a large frog (say a human) is what we do when we probe matter and try to see how matter "behaves" at high energy.

Here we have a key juncture-- we can go CI and say that there is no quantum world, meaning that there is no negotiation for atoms because atoms don't negotiate-- the laws we seek express the goals of our own intelligence, so that is the only kind of negotiation we can refer to when making those laws. That would be my approach. You seem to have a more rationalist/empiricist mixture in mind, where the fundamental talking points of the negotiation are empirical, but you can contemplate how an atom might involve itself in such a negotiation, that can be given some meaning for you. I don't say that can't work, I just hold more of the Wittgenstein view (if a lion could talk, we wouldn't understand it anyway).

My main point is then this: The "pure interpretations" somehow, makes no difference. Both suggest no path forward.

I agree that the highest purpose of an interpretation is not to understand reality better, because it is the theory that is the attempt to understand reality, whereas the interpretation is just how we understand the theory (and the interpretation can turn into a kind of pretense of knowing what we do not know, that's my sole beef with MWI). The highest purpose is to guide the way forward to the next theory, that actually will understand reality better (and make us feel foolish for adopting essentially mystical interpretations like MWI or the way some people talk about CI).

The arguments often used by CI, that the collapse is nothing but information update etc... become less "convincing" unless you are coherent about the reasoning and also at least reject the reality implicit in the classical background.

I agree that people who talk about CI-esque "collapse" as if it was a real transition of some kind don't understand what (I believe) Bohr was saying. It's not very satisfactory to say "the wave function is real, and its collapse is real", that's why many people reject CI but that's not really what CI says at all. CI says the wave function was never real, so it can't "really collapse", and MWI says it was always real, so it can't collapse either. They actually agree that collapse is a disconnect, they just align with different ends of the disconnect. But CI might say that we cannot reject the implicit reality of the classical background, because that is just how we think, and if we imagine we are thinking any other way (even abstractly as in MWI), we are really just engaging in classical modes of thought in more beguiling disguises. That is how I would personally characterize Hurkyl's descriptions of experiences of mixed states.

 

[Dmitry67]

That is just exactly what empiricism demands, yes-- the cosmological principle is a rationalist principle when taken as an ontology (it is an empiricist principle when you say "as far as we have seen so far, the universe behaves like this, and we have no reason to expect otherwise at the moment"). Note empiricism also does not assert that what is beyond the horizon is "unreal", it merely asserts agnosticism around what is beyond that horizon. Empiricism is being awake to the things that might change, i.e., what has not been observed yet that might be different from what has. It's true what Hurkyl mentioned-- this already requires some form of rationalism to be mixed in there, empiricism does require logic. But it tries to stay honest about what we know, and what we don't.
True, as long as you bear in mind the distinction between "not real" and "unreal." In other words, empiricism does not say there is nothing inside an event horizon, or that the material we see crossing it disappears into a pandimensional void, or even that GR can't make predictions about what is in there. It simply says we don't know what is in there, because the universe has put up a "no trespassing" sign. There are other competing theories to GR, by the way, about what is going on inside event horizons, so this is the point of empiricism: we resist pretending we know what we have not empirically established. That is one of the clear lessons of the history of physics.
Why would I, these are quite clear tenets of empiricism. To be clear, I do not wish to claim that empiricism has it all right and rationalism has it all wrong-- rationalism has had its successes too. My actual point is we need to be aware when we are adopting one perspective or the other, because I've found that rationalists often think they are "just doing physics", and seem to have completely missed the two-headed nature of this discipline.

Then I just don't share your religion :)
Many people study the interior solutions of the Black Holes - and you just proclaim it waste of time...
Sorry.

 

[Dmitry67]

I already dispelled that syllogism by pointing out where you assumed that it was only possible to perceive "heads" or "tails", which is the entire reason that the outcomes are nonunitary. So you embedded the assumption that the only possible outcomes were non-unitary, and then used that to prove a theorem that was in fact part of your assumptions. See if your theorem works if the possible experiences of the state are "heads", or "tails", or "a superposition of heads or tails." Where is the proof now?

We can see only definite outcomes.
It is a result of Quantum Decoherence - purely mathematical, liek 2+2, not even physical.

 

[Eqblaauw]

your quote under your posts says it all

 

[Ken G]

Then I just don't share your religion :)
Many people study the interior solutions of the Black Holes - and you just proclaim it waste of time...
Sorry.

You are not looking very closely at what I said. Empiricism does not demand there is no point in looking across EHs, it asserts that we note there is something important about the fact that we have no empirical knowledge of what is in there. As always, we cannot look under every rock, so all physicists have to make their best guess about what constitutes an observation that has basically already been done, and one that has not already been done. We don't have much reason to think observations on one side of an EH will be different from the other side, though we have every reason to believe observations near the singularity might be something we haven't seen. No religion involved, the key is simply keeping track of what we are actually doing, and the difference between what we know and what we don't know-- with perhaps a tiny bit of attention to the history of science.

 

[Ken G]

We can see only definite outcomes.
It is a result of Quantum Decoherence - purely mathematical, liek 2+2, not even physical.

You are talking about decoherence, that has nothing to do with the difference between MWI and CI. I find myself having to repeat this often, it seems. Both MWI and CI need decoherence, it explains why we need an interpretation of collapse in the first place. But it does not give us any interpretation of collapse. The difference between MWI and CI is how you treat the difference between flipping a coin and not looking (decoherence, pure QM, no interpretation needed), and flipping a coin and looking (now you need an interpretation to explain your experience of seeing the result). To put it succinctly-- MWI and CI differ not about the presence of mixed states, but about the meaning of mixed states. MWI says all outcomes in the mixed state actually occur, even in an individual outcome, and CI says all outcomes only occur for an ensemble, each individual trial yields only one. They have the same problem: they must account for why our perceptions don't match the mathematics of QM. The difference between MWI and CI is fairly simple-- MWI takes the mathematics as the reality and tries to modify how we think about perception, and CI takes the perception as the reality and tries to modify how we think about the mathematics. Either is valid, but perceptions don't change and mathematical treatments do.

 

[Hurkyl]

Let me ask you this: do you actually believe that when you, personally, flip a coin, and look at it, the outcome you perceive is a mixed state of heads and tails? And do you call that a definite or an indefinite outcome?

No -- my perception itself is in a mixed state of perceiving heads and perceiving tails. This is indefinite outcomes, because reality did not pick one of heads or tails, nor did it pick one of "I saw heads" or "I saw tails".

Do I "believe" it? In so much as I "believe" anything science. It's suggested both by statistical mechanics and by unitary evolution.

If it were just statistical mechanics, I might apply Occam's razor to justify not thinking about it since the mixtures don't play a part in time evolution -- not even to unobservable parts. (but then again, I might not -- the typical interpretation of random variables is IMO quite lacking when compared to the mathematical theory)

Nowhere near as radical as "when I flip a coin I perceive both outcomes I just don't know that I do", which is more or less what you seem to be saying.

But then, rejecting absolute time was also once a rather radical notion. There are people today who still refuse to make that paradigm shift.

Science doesn't tell you, language does. We experience outcomes. We define that word "definite" to go with that.

Then what I've been calling "indefinite outcomes" are actually definite by this definition. The question is (at least in the classical case) if we consider whether a physical proposition holds in "reality", does the "truth" of the proposition take values in the two-valued Boolean logic {true, false}, or does it take values in some other Boolean algebra?

Way off. The whole point of "proper time" is that it is just precisely time that is locally experienced. Absolute time was always the rationalistic notion, proper time was always the empirical version. That's what I mean that rationalistic theories like Galilean relativity disappear overnight, but observations, like proper time, do not.

Imagine how you would feal saying that to Chrono, and having him deny you at every turn, repeatedly stating that our experience is with an absolute notion of time, no matter how SR wants to deal with the topic.

That's how I've felt throughout this discussion.

 

[Hurkyl]

Here I would agree the bird's view assembles frog's views, including the views we consider hypothetically (like "if a frog were there, what would it see"). But note this is a very specific type of information, so even if we assemble it all, it's not all the information (unless we define this to be information, that's a subtle issue I won't take a position on). The key point is that the god's eye view is something quite different, because it does not ask "what would a frog see", it just asks "what is."

So, what would you call a view that has all of the information, but does care about what frogs can see? Because that is how I've been using the phrase "bird's eye view".

And I'm pretty sure labeling MWI as an interpretation that doesn't care about what frogs can see to be completely misguided -- except for the most basic stuff, nearly everything I've seen on the topic is ultimately concerned with the issue of trying to make sense of the question "what does a frog see?" in a unitary description of the universe, and also to check if the answer has the potential to match our experiences with reality.

 

[Ken G]

No -- my perception itself is in a mixed state of perceiving heads and perceiving tails.

So "your perception" is something different from "what you perceive," where by the latter statement, I just mean what you perceive. You are in effect saying that your perceptions are informed by your knowledge of quantum mechanics, but that is not the normal meaning to the term "your perception." So this is the basis of my claim that your stance is highly un-empiricist, perhaps even radically un-empiricist. You are reinterpreting your own perceptions using a rationalist filter-- that is more or less the definition of rationalism, of the most radical form I can imagine. Not that there's anything logically inconsistent with such a stance-- it was always my goal only to make you see you are not "just being a good scientist" here, you are quite purposefully adopting a highly rationalistic perspective on reality, just so that your highly rationalistic perspective could be interpreted as a valid description of reality. Fully self consistent, but you should recognize that this is simply not the standard meaning of "perception", and certainly not what any empiricist means by the word.

This is indefinite outcomes, because reality did not pick one of heads or tails, nor did it pick one of "I saw heads" or "I saw tails".

I didn't ask you what reality picked, I asked you what you perceive when you look at a coin. See the difference? It has to do with the definition of the word perceive, which you seem to feel you can alter at your own whim.

 

[Hurkyl]

So "your perception" is something different from "what you perceive," where by the latter statement, I just mean what you perceive.

How are they different? You gave a complete^* description of the coin -- a mixture of heads and tails. I replied with a complete description of my perception -- a mixture of seeing heads and seeing tails. We could go further and completely describe them jointly -- a mixture of 'heads and me seeing heads' and 'tails and me seeing tails'.

*: with respect to anything relevant to the discussion. (e.g. you didn't say whether it was a nickel or a penny)


From the setup you gave, there are no absolutes about particular outcomes -- neither "I saw heads" nor "I saw tails" hold. However, the absolute "I saw heads or I saw tails" does hold. More importantly, the relative statements "If the coin is heads, I saw heads" and "If the coin is tails, I saw tails" both hold^*, as do the more trivial claims "If I saw heads, I saw heads", "If I saw tails, I saw tails", and "If I saw heads, I did not see tails".

*: if my perceptions are valid, of course.

You are in effect saying that your perceptions are informed by your knowledge of quantum mechanics, but that is not the normal meaning to the term "your perception."

Is a perception a "raw experience" or is it one that has been processed by instinct, intuition, and reason?

I don't have a "raw experience" of seeing heads. Nobody does. The perception of heads only appears after things like passing through the image processing part of our brain, being pattern matched against familiar notions, being categorized into abstract notions like "coin" and "heads on a coin", and so forth.

My understanding of these abstract notions, like "here", "now", and "outcome" are informed by relativity and MWI.

And the details of all of the above are influenced by my a huge variety of factors -- education being one of them.

I didn't ask you what reality picked, I asked you what you perceive when you look at a coin. See the difference?

I see heads or I see tails.

If nobody talked about "what 'reality' picked", the question is completely vacuous. Alas, the split between CI and MWI is precisely about something equivalent^* to the question of "what 'reality' picked".

*: for purposes of this discussion

 

[Ken G]

You gave a complete^* description of the coin -- a mixture of heads and tails. I replied with a complete description of my perception -- a mixture of seeing heads and seeing tails.

It's clear that you do not distinguish the way you think about your perceptions from your perceptions themselves. You claim your perception of seeing a coin toss has changed since learning quantum mechanics, but I'm skeptical you really perceive anything different at all-- rather than just think differently about the experience. It's a pretty radical rationalist that can see no distinction between having an experience, and having a process of analysis about how to make sense of the experience.

Is a perception a "raw experience" or is it one that has been processed by instinct, intuition, and reason?

This returns us to the fact that mindless rocks do not perceive anything. There is no doubt that perception requires some kind of intelligent processing, but only the die-hard rationalist thinks that perceptions of coin flips change after you learn quantum mechanics. If I ask you what ice cream you prefer, you can certainly imagine that you are saying "<chocolate, vanilla>", but that just isn't going to be the sound that your ears hear come out of your mouth. Frankly it's fascinating to hear from such a completely radical rationalist, the complete invalidation of the most basic sensory experiences, based on the postulates of a theory that is only known to be highly accurate in certain situations, is quite a new discovery for me. I am quite serious that I see nothing logically wrong in your approach, but I also see it as nothing less than devoutness.

If nobody talked about "what 'reality' picked", the question is completely vacuous. Alas, the split between CI and MWI is precisely about something equivalent^* to the question of "what 'reality' picked".

Well, it normally starts with the basic recognition of what a perception feels like, and then moves on to what reality is. I'm afraid we got stuck at what a perception feels like.

 

[Ken G]

So, what would you call a view that has all of the information, but does care about what frogs can see? Because that is how I've been using the phrase "bird's eye view".

If it cares about what frogs can see, then it is not a wave function, it is comprised only of eigenvalues. It could be a mixture of eigenvalues, but not a superposition state. That's the god's eye view. The problem with what you're saying here is that to have what you call a bird's eye view, you must completely buy off on the god's eye view. So there really is no bird's eye view the way you describe it. If there is no god's eye view, then there is simply no justification to imagine that reality itself involves mixed states other than in the ensemble sense. The bird's eye view I talked about involves the union of frogs that could communicate in principle. Any other non-causally connected frogs cannot be seen by birds, but only by gods.

And I'm pretty sure labeling MWI as an interpretation that doesn't care about what frogs can see to be completely misguided -- except for the most basic stuff, nearly everything I've seen on the topic is ultimately concerned with the issue of trying to make sense of the question "what does a frog see?" in a unitary description of the universe, and also to check if the answer has the potential to match our experiences with reality.

Frogs see eigenvalues. That's what we experience. You have to enter into pretense to imagine something different, there's a ghost in that machine.

 

[Dmitry67]

You are not looking very closely at what I said. Empiricism does not demand there is no point in looking across EHs, it asserts that we note there is something important about the fact that we have no empirical knowledge of what is in there. As always, we cannot look under every rock, so all physicists have to make their best guess about what constitutes an observation that has basically already been done, and one that has not already been done. We don't have much reason to think observations on one side of an EH will be different from the other side, though we have every reason to believe observations near the singularity might be something we haven't seen. No religion involved, the key is simply keeping track of what we are actually doing, and the difference between what we know and what we don't know-- with perhaps a tiny bit of attention to the history of science.

Then General Relativity creates a problem for your Empiricism, because you have to define the 'shape' of your knowledge in the spacetime.

For example, ANYONE can jump into the BH to get an experience and to learn what is inside directly from the experiment. However, that knowledge won't be able to escape from the BH, so the poor experimenter won't be able to share it with the rest of the humankind (and as I remember in your definition it was important). So we can't learn what is inside the BH, right? Well, that conclusion is too atrophic. We prefer some area of spacetime just because it is more habitable.

So let me ask you, what is a “knowledge” – is it eternal mathematical truth, which can’t be located in spacetime (like the fact that the number 17 is prime) or is it an information (and in such case it can be located in spacetime)

 

[Dmitry67]

You are talking about decoherence, that has nothing to do with the difference between MWI and CI. I find myself having to repeat this often, it seems. Both MWI and CI need decoherence, it explains why we need an interpretation of collapse in the first place. But it does not give us any interpretation of collapse. The difference between MWI and CI is how you treat the difference between flipping a coin and not looking (decoherence, pure QM, no interpretation needed), and flipping a coin and looking (now you need an interpretation to explain your experience of seeing the result). To put it succinctly-- MWI and CI differ not about the presence of mixed states, but about the meaning of mixed states. MWI says all outcomes in the mixed state actually occur, even in an individual outcome, and CI says all outcomes only occur for an ensemble, each individual trial yields only one. They have the same problem: they must account for why our perceptions don't match the mathematics of QM. The difference between MWI and CI is fairly simple-- MWI takes the mathematics as the reality and tries to modify how we think about perception, and CI takes the perception as the reality and tries to modify how we think about the mathematics. Either is valid, but perceptions don't change and mathematical treatments do.

At first, what version of CI are you talking about? Bohr or Neumann flavor, or something else? CI is very old, was developed when Decoherence was not discovered yet, so the whole point of CI was to invent an artificial 'collapse' to explain why do we see definite outcomes. As an artificial creation, CI is not self-consistent and complete, it fails to give any predictions until you call (or not) any group of atoms a 'measurement device' or not.

 

[Fra]

invent an artificial 'collapse' to explain why do we see definite outcomes.

The collapse does not "explain" anything, it is just an honest acknowledgment of what happens when you ask a question: Given the experimenters of observers prior conception, she formulates and fire a question into your environment (make a measurement), and typically you will receive a backreation from your environment (or subsystem of it) and this is the answer. Typically this revises your prior conceptions. That's the whole point of making a measurement, you want to get new information, or "updated information", so your expectations are updated.

In what way can you possibly call this artificial? It's rather a very honest description of the situation.

To try to deny the concept of information updates seems to miss the original question, which is that the observer needs to make a decision and act, in order to maintain it's integrity and survive. This can be undertsood both in terms of a human scientists but also in terms of material observers, that can be destabilized by the environment unless it's in agreement with it.

I'd say that the concept of god's view and similar stuff, now that's artificial

/Fredrik

 

[kith]

I'm not very familiar with MWI, but is it correct, that it postulates the density operator ϱ to be the fundamental state which describes reality?

This suggests that MWI is nothing quantum mechanical, but also present in classical mechanics (points in phase space vs. probability distributions). As far as I can see, this removes all information-theoretic content from statistical mechanics, which seems very odd to me.

Any thoughts on this?

 

[Hurkyl]

If it cares about what frogs can see, then it is not a wave function, it is comprised only of eigenvalues.

This is just silly. It's like telling me that anyone who reads a real analysis textbook doesn't care about computing derivatives, that anyone reading The Lord of the Rings can't be interested in the geography of Middle Earth, or that anyone who makes use of a coordinate chart in classical mechanics cannot possibly care about what people see.

Caring about the frogs see means caring what the frogs see, not bending over backwards to try and encode what frogs see into eigenvalues, and not crippling ourselves by trying to avoid using anything else in our theories. Using a coordinate chart when working with classical mechanics isn't an act of radical rationalism, is it?

It could be a mixture of eigenvalues, but not a superposition state.

This is where the importance of relative state comes into play. Even if a whole system is in a pure^* state, its subsystems can be in mixed states -- in fact, they can transition from pure to mixed and back again. Overlooking that fact is the fatal flaw in the old argument that unitary evolution by itself is incapable of matching our experiences.

This observation was the origin of the MWI.

*: The term "superposition state" has no inherent meaning -- the notion of superposition only makes sense when viewing states as kets, and even then only after having chosen a basis.

Frankly it's fascinating to hear from such a completely radical rationalist, the complete invalidation of the most basic sensory experiences, based on the postulates of a theory that is only known to be highly accurate in certain situations, is quite a new discovery for me.

I find your view of my arguments completely baffling. As of yet, I have failed to discern any rhyme or reason to them, except by considering the hypothesis that you are either attacking a straw-man or have fallen victim to what you say I am doing -- that you have equated the very idea of experience with a particular philosophy and can't entertain the thought that they aren't literally as they are described classically.

 

[Ken G]

For example, ANYONE can jump into the BH to get an experience and to learn what is inside directly from the experiment. However, that knowledge won't be able to escape from the BH, so the poor experimenter won't be able to share it with the rest of the humankind (and as I remember in your definition it was important). So we can't learn what is inside the BH, right?

Observers can be outside each others' light cones without event horizons. They are just bearing witness to real events that cannot be shared, so each will form an incomplete picture of the whole. That is how empiricism works, we all get an incomplete picture, but we get the perceptions we get, and we build a reality from it. Some of us will never build a reality that has black hole singularities in it, that's empricism-- there's no problem there, it's just a pill we must swallow. Empiricism starts with the expectation that the reason we invoked physics in the first place was to predict the things that affect us, and use that to inform decisions about things that we can affect. The rest is angels on the pin.

So let me ask you, what is a “knowledge” – is it eternal mathematical truth, which can’t be located in spacetime (like the fact that the number 17 is prime) or is it an information (and in such case it can be located in spacetime)

The question here is what is the knowledge that physics gives us, not mathematics (mathematics knowledge is always purely tautological to the axioms, so it is an exercise in "knowing thy axioms." Physics for the empiricist is knowing , and gaining power over, thy experiences.). What is the purpose of quantum mechanics? I gave the answer that I think would be pretty standard for empiricism, what would you say is the purpose of quantum mechanics?

 

[Ken G]

In what way can you possibly call this artificial? It's rather a very honest description of the situation. To try to deny the concept of information updates seems to miss the original question, which is that the observer needs to make a decision and act, in order to maintain it's integrity and survive. This can be undertsood both in terms of a human scientists but also in terms of material observers, that can be destabilized by the environment unless it's in agreement with it.

I'd say that the concept of god's view and similar stuff, now that's artificial

I agree completely, well put.