I don't have time for a long reply, so a quick one:Ken G said:
Fredrik said:
I am probably what would classify as a "solipsist extremist" in your view, but definitely think your statement that this view doesn't contribute to anything seems wrong IMHO.Hurkyl said:
is the idea that the two interacting systems, react back to their environment in a way that depends only upon the information they have about each other. This is a deep form of locality, which means that the local action depends only on local information, and that this is something that needs to be understood, when you try to DESCRIBE the action of a complex system, from an external perspective, this insight has deep implications for exactly HOW the "theory" scales as you change the observer, from one of the inside subsystems, to an external system (say from a proton to a lab scale observer)But the issue is, is the connection between our "unlimited" math, and the physical world, what is limited? And what does it mean to understand something, if not simply having successful predictions encased in an aesthetically pleasing structure? If that's all it is, then how does "I understand" get equated with "what the universe is doing"? I see it as simply faulty logic that makes that connection.Dmitry67 said:
A lot of people misunderstand the role of solipsism in science. Solipsism, at its heart, is simple skepticism, which is a core value of all science. It does not say "you cannot know, so why bother", that is a kind of "solipsism gone mad" approach that many people then equate with any effort to watch exactly how we come to our conclusions. Thus it has become synonymous with "unconstructive." But nothing could be farther from the truth about the role of skepticism in science. All skepticism really does is say "don't pretend you know what you do not know, because if you do, it may close off the very door you need to go through to get to the next level of understanding." It's exactly what Einstein did when he said, in effect, do you really know there is an aether, because the observations say the aether covers its tracks, so maybe the real lesson is that something that covers its tracks so well isn't real in the first place. Kind of like those many worlds-- maybe the next theory that replaces quantum mechanics will benefit from a postulate along the lines of why the many worlds do not exist, a way to think of things where that which covers its tracks so well may be viewed as superfluous.Hurkyl said:
Pretending we know what we does contribute to closedmindedness. That's why there is nothing wrong with liking to adopt the picture of MWI as a personal choice that has no authority to tell reality what it is doing. Don't tell reality, for example, that quantum suicide is true-- the consequences might be more drastic than missing out on relativity.
I think that is an interesting insight. You are essentially encoding solipsism into the theory itself-- saying that how we interact with a system, and what we are capable of understanding about a system, are actually parts of the system itself. That means that the subject/object separation, so valuable for so many eons of physics, has become fundamentally a block to obtaining a more powerful theory. I have felt that way too-- I believe that the next great theory of physics will involve a theory of the mind in a way that is holistic with the environment. I may be wrong, of course, but if I'm right, it certainly casts a different light on the usual objections to solipsism.Fra said:IMHO, solipsism "at it's finest"
Ken G said:
Yes, but that only argues that the MUH perspective is self-consistent, not that it is true. Newton's laws are self-consistent, and Newton might have even thought they were true-- but they were later found to have limitations that did not appear within the laws themselves. I would argue that is typical, it is exactly what we should expect.Dmitry67 said:
It is a matter of opinion what constitutes "eliminating" a problem. For example, many people eliminate those problems, and many others, by saying "it's God's will." Most scientists don't accept that as a valid way to eliminate the problem because it is just a mindset that achieves cognitive resonance in its proponents, without accomplishing any demonstrable or evidential support among its critics. Sound familiar? It's not that there is anything wrong with choosing to hold to MUH-- science does not say you are wrong. What is wrong is to argue that science demonstrates the truth of MUH, because that is just exactly what it does not do.
Ken G said:
I agree, but I never expect any theory to prove anything other than the logical connections to its own axioms. That's all part of what a theory is, but we want to know whether it is true or not.Dmitry67 said:
MUH isn't a theory at all, it is a means of achieving an aesthetic sense of cognitive resonance. Things like that were separated from science thousands of years ago, so I'm not sure now is the time to bring them back in.
Yes exactly. But with emphasis on that it's now just how we humans interact with the system, it's how any parts of the universe interact by other parts. This insight, provides us with deeper way to understand the origin of any interaction, and thus to address unification since as you scale the complexity of the interacting parts down, it becomes impossible for them to execute complicate interactions. It just looks complicate from the point of view of an external observer due to that fact that the simple theory scales into a - not so simple theory. Without this insight, we end up with spaces of parameters which we don't konw why they are tuned as they are.Ken G said:
Ken G said:
Pure philosophy makes falsifiable predictions too-- "philosophy will someday let us understand everything there is to know." But of course, that prediction doesn't really mean anything, because it is not currently testable, nor does it give us guidance on where to start looking to test it. What you're saying about MUH is not much better-- it might provide some guidance to those looking for the next great theory of physics (calling that a TOE is kind of silly, if you ask me), but it might just as easily provide false guidance as good guidance. Perhaps that means it is just as well that some people accept a MUH perspective, and some don't-- that latter group is more or less the purpose of solipsism when it is used constructively.Dmitry67 said:
It's definitely more than this, because what you're saying sounds more like a statistical interpretation than like a MWI. At the very least, a MWI supporter has to believe that QM describes reality. (See my posts earlier in the thread if you're thinking about asking what that means).BruceW said:
No I don't have a citation. I think you're right. Everett didn't insist that the Born rule should be recovered from branch counting. Or maybe he did, I don't know. What I'm trying to say is that I have no memory of reading anything that suggests that he is personally to blame for that idea. But Everett did remove the Born rule from QM. (I don't remember where I read that. If you doubt it, I guess I can start looking for original articles). This removed the theory's ability to make predictions, and therefore made it something less than a theory. He must have thought that there would be some way to recover it.Hurkyl said:
While I appreciate that you want to give your speech, you're responding to a straw-man. As far as I'm concerned, solipsism is fine -- it's a well-known irrefutable position. The problem is that you invoke it as if it changes anything in the discussion; I don't care if you think there's a world out there or if it's all in your head, because as far as I can tell, all of the important questions remain essentially the same.Ken G said:
It's funny that you mention this, because it's one of my central points. Time and time again, we see that we should be listening to our physical theories rather than imposing our prior views of how reality behaves.
Maybe it will. And maybe the next theory of cosmology will benefit from a postulate of absolute time. However:
Wikipedia skimming:Fredrik said:
I am very skeptical of physicists' "derivations" of the Born rule. The ones I've come across haven't exactly looked convincing. I think Gleason's theorem is the only way to justify the Born rule, but it seems to me that it can't be thought of as a derivation of the Born rule from the rest of QM. The rest of QM doesn't even suggest that probabilities are involved, let alone that they should be assigned by probability measures on the lattice of closed linear subspaces. But Gleason's theorem tells us that every probability measure on that lattice is of the form [itex]M\mapsto\operatorname{Tr(\rho P_M)}[/itex], where [itex]\rho[/itex] is a positive, self-adjoint operator with trace 1, and [itex]P_M[/itex] is the projection operator associated with the closed linear subspace M. Note that it doesn't just tell us how to calculate probabilities given a state. It also tells us what mathematical objects to think of as states.Hurkyl said:
Your words demonstrate that I was not responding to a straw man at all-- I was trying to explain solipsism to someone who misconstrues its purpose in exactly the way I expected. Your statement that it is an "irrefutable position" exposes exactly the misconception I attempted to dispell, as did Fredrik.Hurkyl said:
Yes, indeed you have not understood my objectives at all, nor Fredrik's it would seem. There is actually a very constructive purpose in the challenge "if you would maintain that MWI is true, you must give me more than cognitive resonance, because I can get that using many different things other than mathematical logic that stems from an undecidable rationalist assumption" (like the one you correctly identified above). As I said, MWI is just one thing-- the ultimate rationalist dream about what physics is. The problem is, physics has never been that before, though the rationalists thought it was, time and time again. You seem to feel these past rationalist failures are harmless-- it "doesn't change the questions." The harm isn't in changing the questions, not at all-- it is in pretending that the questions are answered, when they are not. That's the whole point of solipsism-- to keep track of when the questions aren't really answered, so we don't close a door that might have the next answer sitting right behind it. You see that as a pointless mission, strangely. I counter that what is pointless is to mistake an interpretation of a theory as something true-- that is wrong on two counts:
Why do you imagine I think that? Every objection I've given is to adopting MWI as truth about reality, rather than what it actually is-- an allowed interpretation of the QM theory. Why would we imagine MWI is anything other than what it is?
Time and time again, the postulates of our theories prove to not be quite the truth. That is innocent if we are only using them to predict outcomes, but it is awful if we think they are true and cease doing what science should always do-- maintain skepticism about our postulates and seek why they are wrong, not adopt faith-based world views that rely on them.
You are confusing the choosing of the postulates of a theory with forming an interpretation of those postulates. How did MWI help us choose the postulates of QM? You can ignore the rest of my "speech" if you have any decent answer to that.
What I suggested above as "solipsism at it's finest" is actually a interpretation, that understands QM as a limiting case, thus the "solipsist extremist" like myself, is convinced that QM as it stands needs to be generalized. Not in order to explain what it already can do well, but in order to solve open issues with unification and gravity.Hurkyl said:
If you truly are not singling MWI out as being different, then most of what you've said is completely irrelevant. If your objection applies to all of physics, then it doesn't have any bearing on the discussion.Ken G said:
but I can't see anything MWI is doing differently from anything else.
One interesting point, though, is that perspectives aren't disjoint. MWI, for example, already includes all of the CI viewpoint, except for the specific point that collapse is the 'truth about reality' -- that outcomes are definite from the bird's eye view.
Right -- "not quite the truth". That's very different from "diametrically opposed to the truth".
Every variant of the Copenhagen interpretation I have ever seen gives a positive answer to the first* -- I don't know how an interpretation could justifiably be labelled "CI" if it does not.Ken G said:
What I am singling out about MWI is the fervor with which people hold to it. That's why I mentioned quantum suicide a few times. I think it's perfectly clear that the MW is more than an I to those who hold to it, it is a faith-based world view (faith in postulates, not religious faith). That is also why I mentioned rationalism so many times-- rationalism is a means of attributing truth, it is much more than a non-unique equivalent interpretation of a physics theory.Hurkyl said:
Two simple questions I would put to you to clarify the claims you are making on the MWI:
MWI does a whole lot more than challenge viewpoints about definite outcomes! Just look at the language people use around it. MWI makes assertions about indefinite outcomes. Simply challenging beliefs about definite outcomes is the approach of solipsism. Ironic that you would now claim to hold the solipsistic high ground!
Sure, that's because CI is a more minimal ontology than MWI. That's a strength of CI, not a weakness as you are painting it here.
That could change in a heartbeat if the next great theory invokes an aether. You are not stating any kind of physical principle here, it's an expression of prejudice only. Actually, the pendulum tends to swing.
I was referring to the postulates, not the interpretations. Interpretations have no relationship with truth, they have relationships with postulates, and their ontological stance is merely informal, like a picture. That's the problem with how people talk about MWI, right there-- they think it is something more than a picture, but they cannot justify treating it such without simply marrying the philosophy of rationalism.
OK, then we have a point of interest here: we have different interpretations of what CI is. The question you brought up before was:Hurkyl said:
I think you misunderstand the CI. You are referring to the issue:
I'm not interested in this topic of sociology.Ken G said:
For question 1: yes. I add two caveats:
But those aren't new assertions -- they are assertions that are consequences of the basic setup of quantum mechanics: quantum states and unitary evolution.
There's some sort of converse fallacy in there, but that aside, aren't you being inconsistent? I sure got the impression you had previously been defending the definite outcomes of CI a while ago.
Eh? In the most basic CI, they have identical ontologies: wave-functions correspond to what's "real".
Eh? It's the most central tenet of empiricism -- that we derive knowledge from the results of observation and experiment!
Interpretations, more or less by definition are means by which we give meaning to the elements of our physical theory.
If you don't think interpretations are more than pictures, then stop thinking about MWI as being more than a picture then. :tongue:
I'm not aware of MWI lacking a description for this. For any two distinct mutually exclusive outcomes X and Y, "I perceive X and I perceive Y" is fairly clearly an outcome no observer could ever perceive.Ken G said:
No, it asserts more strongly that the outcome is definite.
This is the collapse, and specifically what MWI does not do. It's enough to claim that we perceive one outcome -- we don't have to take the extra step and tell reality that it has chosen a definite outcome.
What you have said above post amounts to a "yes" answer to the intent of my question. What I hadn't noticed until now is that you were picking at my phrasing to justify a negative response -- e.g. claiming collapse as something incomprehensible, and thus cannot be part of how we "understand" the behavior of the system.
Hurkyl said:
Decoherence doesn't say anything the least bit different in an MWI approach as in a CI approach. You don't even need an interpretation yet, decoherence simply limits the types of wavefunctions that either approach is going to need to interpret. The fundamental rift between MWI and CI happens later-- it happens when we notice that decoherence has destroyed correlations between what we do observe, and what we do not observe. Thus, decoherence is not a reason to favor MWI, it is the way to see that MWI and CI are physically equivalent-- we either don't see those "other worlds" because we don't cohere with them, or we don't see them because they do not exist. No physical difference at all. But MWI is a world view, a claim on reality, whereas CI is an honest admission of lack of knowledge about that reality. MWI is faith-based (faith that the postulates are true), so is closed, CI is solipsistic in the constructive sense, so is open to admitting what it simply does not know.
That claim is not supportable. You are essentially claiming that because rationalists believe in their postulates, this is somehow going to be needed for the next theory. String theory requires MWI? No. String theory is completely compatible with CI, for all the same reasons that quantum mechanics was. The history of physics is rife with the rationalist dream of a "TOE", and every generation thought they essentially had it, just a few minor tweaks is all they would need. Until, that is, they discovered that the new theory had postulates that were dramatically different in their ontological suggestions. But that won't happen this time, you say...
None of the theories "embrace" collapse any more than they embrace MWI. All the theories we have now are completely ambivalent to these questions, and the next theory could just as easily be inspired by CI empiricism as by MWI rationalism. We just don't know, because right now we don't even have a theory that is any different in the two veins, so even imagining a theory that would care about that difference is difficult. Remember, the unitary postulate is not required as a claim against reality in any of these theories, it is merely a claim on how the mathematics works. As long as their is a Born rule, we cannot physically distinguish MWI and CI.
But this line of reasoning is not relevant to the issue of distinguishing MWI and CI, because as I said, CI is completely consistent with decoherence. In fact, CI needs decoherence just as badly as MWI does-- all decoherence does is bring us to the place where we then need to make a choice in how we will interpret the meaning of the Born rule. What is clear enough is that the phenomenon of decoherence makes it impossible to physically distinguish CI from MWI. Do you disagree?
No, that's exactly the point-- MWI is not a consequence of the postulates about unitary evolution, it is a consequence of an additional claim about what is actually evolving unitarily. CI has all the same unitary evolution in the wave function as MWI! The sole difference is that CI does not interpret the thing that is evolving unitarily as the reality itself, it interprets the thing that is evolving unitarily is the machinery for making predictions. In short, CI calls a postulate of a theory a postulate of a theory, and MWI calls it a claim on reality. Which is more honest about what we know?
I'm not sure what you are saying here, in my view there is nothing subtle or ambiguous about the concept of definiteness. From the empirical standpoint, what is definite is what is observed, period-- it's completely straightforward. That's the whole point of the CI, in fact. I was saying that the MWI takes the rationalist tack of putting stock in the indefinite outcomes of observations-- the outcomes in the "other worlds" which are indefinite in the sense that we have no empirical evidence to say those outcomes ever do actually occur anywhere.
Absolutely not. This may be our core disconnect-- I maintain that you maintain a kind of caricature of the CI. The core tenet of the CI, as it seems to me it is described by Bohr and Heisenberg, is that quantum mechanics is an information theory. It is a theory about how we must update our knowledge of a system as one of two things happen: closed systems evolve in time (including decoherence), or a measurement is registered (which is a "manual" type of information updating). As such, no wave function is ever regarded as real in CI, it is always regarded as a mathematical device that enters into statistical predictions via the Born rule. The fundamental reality there is not the wave function, and indeed is regarded as inscrutable. Why would Born say "there is no such thing as the quantum world" if he thought a wave function was real?
We agree there-- CI has two fundamental types of information updating, whereas MWI doesn't view it as information at all, it views it as the reality. The unification of these two aspects of CI is the main advantage of MWI, but it comes at a pretty significant cost-- it forces us to drop empiricism as the way of demonstrating scientific truth, in favor of the rationalistic desire to say "what unifies is what is real." It's the rationalistic dream that our access to truth is via our concepts, rather than by our experiences. But this is no surprise to anyone who understands rationalism.
Not quite, because everything that matters in that sentence is all locked up in the word "meaning." Empiricism and rationalism use two completely different approaches to that "meaning"-- to a rationalist, the meaning of a theory is the reality itself, and to an empiricist, the meaning of a theory is a kind of mental game, like chess, whose outcome is found to be successful at predicting what is the actual reality-- the outcome of experiment. So when the CI "gives meaning" to the postulates of QM, it does so without making ontological claims on any reality other than the outcome of the observation, because there is no reality other than the outcome of the observation. That simple statement rules out many worlds a priori.
Exactly-- you are a rationalist. I already know that. There's nothing wrong with being a rationalist as long as you understand that you are one.
But I have no problem at all with MWI as a picture. In fact, I have no problem at all with MWI as a natural world view for a rationalist. All I'm saying is, people who adopt MWI don't think of it as a picture, they think of it as a world view, which means they are rationalists. That in turn means that they have bought off on a suite of perspectives that have been well studied throughout the history of both physics and philosophy, and its pitfalls and successes have been well documented. I happen to be pointing to the pitfalls, but I do not deny that theoretical physicists tend toward rationalism, and they have certainly had their successes. But if you look at someone like Einstein and his relativity, what you see is a careful balance between the aesthetic power of unifying principles like the need for the laws to be the same for all observers, and the rock-solid grounding that essentially says "build your postulates from that which all observers can agree on." Can all observers agree on the different outcomes of the observations that appear in the many worlds? There's a more violent departure from empiricism there than rationalists have previously been willing to make, so it ushers those pitfalls right to the fore.
I already had a long post, so I won't go on here, but I wanted to address this issue. I just don't see how you can claim that MWI has any way to account for the particular outcome of an observation. In MWI, all outcomes occur in the "actual reality", so there simply is no accounting for us in "our branch" of the reality-- our placement in this branch is undescribed by MWI, so it has already lost what it claimed was its raison d'etre-- unity and completeness in the description. What answer can be given, that is fundamentally dictated by MWI, to the question, why did I perceive the result I did? Is there some attribute of me that requires I get "spin up" rather than "spin down", or are we to imagine that there is some additional process that decides what I'll get versus what someone else in another world will get? There's no avoiding the need for a "model of me" to enter the story. That's exactly what CI avoids-- by accepting, a priori, the outcome I get as the actual reality, there is immediately no need to account for why I got what I got-- I got it because that's what happened. Why that happened, and not one of the other possibilities, is regarded as fundamentally mysterious in CI. The question goes away because we have not set out to answer it, whereas MWI claims to leave nothing as fundamentally mysterious, it purports to be a complete description of what is actually happening-- but it doesn't deliver without a model of me.Hurkyl said:
Ken G said: