Problems with Many Worlds Interpretation

juanrga

Contrary to your misconception, there is not need to demonstrate limits of the current postulates of QM today, because the limitations of the postulates are well-known since that QM born. Everyone who has studied QM knows that the projection postulate is not a dynamical postulate. In fact, there is not even variable time in that postulate.

The extension or improvement of QM was not the point. The point I was making was about your incorrect claim that Penrose supports/likes/accepts MWI, when he does not clearly.

I am not «arguing that MWI is inconsistent with those current postulates because it also doesn't provide» a dynamical description of R. What I said is totally different. I said that MWI is both internally inconsistent and incompatible with QM by other reasons. I said, for instance, that MWI cannot give R, because R is irreducible to U.

I think this is rather easy to understand. If you start with a theory like MWI that uses only U, you cannot obtain R.

If you look to the figure above you can see that really serious people (i.e., people who understand QM) uses both R and U. People who do not understand QM (fortunately a tiny minority), believes that MWI is another interpretation of QM, but, as has been shown in this thread, MWI is a misinterpretation of QM.

Your following misconceptions and rewrites of Penrose were already corrected before.

The rest of your post is a new collection of misconceptions and systematic rewrites of what I and others said. I will be brief,

Nowhere I said that Gell-Mann does not understand QM. You said it.

Nowhere I said that GR is needed to prove the postulates of QM. You said it.

Nowhere I said that Penrose can prove how reality will work based on estimations of the breaking of spacetime superpositions. You said it.

And so on.

In fact, apart from not saying anything of that, I have said the contrary, which makes still more funny your tactic. For instance, regarding Penrose's work in spacetime superpositions I wrote:

Which is a way to say that those exotic effects are not needed for understanding R.

There are many more misconceptions and very serious mistakes in the rest of your post...

Ken G

Tell me, just where do you imagine that I said there is a need to "demonstrate" the limits of the postulates today? Nowhere. What I actually said is that some people are working to fix these limitations, hoping to create a new set of postulates that are not necessarily the ones that MWI is consistent with (my whole point here), such as Penrose, while others, such as Hawking, are not bothered by the limits of those postulates because the experiments can be predicted either way. That is just what Hawking meant when he said that Penrose is a Platonist (someone who would be bothered by limits in the postulates because he believes the postulates are trying to be the reality) whereas he is a positivist (someone who believes that all we can ever say about reality is the outcome of our experiments, so if we predict those, that's the best we can ever hope to do.) You are not hearing what I'm saying, you seem to need to keep replacing it with something else so you can refute what I never said.
Yes of course, anyone who has studied the current postulates of QM, like you, like me, like Hawking, etc., does indeed know that, because it is perfectly obvious. It also has nothing to do with anything I've said in this whole thread. The question is, why do you think it does? Because you're not hearing anything I'm saying? Please quote me where you imagine I said that Penrose likes or accepts MWI! I never said (or thought) any such thing, and indeed I clarified several times that I never said that. One more time: what I said, and continue to maintain, is that the reason Penrose rejects MWI is the same as the reason he feels the postulates of QM are unsatisfactory, to wit, the theory is not directly connected to what we perceive without ad hoc nondynamical treatments of wave function collapse. What's more, the sole thing that distinguishes the various interpretations of QM is how they handle the ad hoc character of this collapse that is in the current postulates of QM. This is also why they are all perfectly consistent with QM, they simply do what is ad hoc (their funambulisms) in different ways. Someone like Hawking, who only cares that it works, isn't too bothered by that; someone like Penrose, who wants the postulates to be a description of the reality itself, is bothered by that. What this all means is that Penrose would object to all the interpretations of QM, because he objects to QM itself-- until its postulates can be "fixed", and hopefully include gravity.
And I have said that this theorem requires essentially philosophical assumptions that any MWI enthusiast would reject. That's what I meant when I said you are simply overlooking your own philosophical biases. I asked you where in the proof of the theorem you quote is there an observer, where is there an observer's mind, and where is there the epistemology that observer chooses to use to decide what it means for a theory to be valid. Until you put those things in your proof, you have not gone beyond your own philosophical assumptions. So we return to my original remark: physics is not mathematics. We can now append this remark: mathematical physics is impossible to connect with the rest of the body of physics without philosphical assumptions, and much of the debate that has people like Penrose saying Deutsch is "not serious" while Deutsch says Penrose is doing "aesthetics not physics", is all around their different philosophical assumptions and objectives for physics.
If this were as categorically true as you imagine, then no one would have thought MWI is a reasonable interpretation of QM. So you now have an argument on the table that says "it is easy to understand that MWI could never be an interpretation of QM." Can you see the logical flaw in your position? I can. It holds that any proponent of MWI is an idiot. I think you actually believe that, but your logic is faulty because you have not tracked your own assumptions.

The actual truth is that if you start with only U, you cannot obtain R without altering your philosophical preconceptions about what physics should be trying to do, or how we should regard the connection between physics and reality, especially in regard to the importance of empiricism. It you want it 'more "technically", just look at the proof of any theorem that says you can't get R from U, and look where the philosophical assumptions come in. You might need to see outside your box a bit more.

Um, I think you should have a look at your own figure again. Penrose puts the "only U" camp under "serious about psi". Perhaps your own definition of "serious" is a little different from Penrose's? As near as I can tell, you define it as "agrees with me". (But you are right that I misplaced Gell-Mann.)
I did? News to me. How does one "prove a postulate"? I might imagine proving the consistency of two different postulates, but of course no one thinks the postulates of GR are consistent with the current postulates of QM.Yet Penrose thinks those exotic effects are needed for understanding R. So like I said, the experts do not agree at the frontier-- so simply citing their opinions does not prove anything. But even more to the point, Penrose does not think that the current postulates of QM allow us to understand R! That is all I need to establish my argument-- if Penrose really thought that MWI is not consistent with the current postulates of QM (and there is no evidence he does, and evidence to the contrary like what Hawking said about Penrose's position), then whey would he bother to criticize MWI on the grounds that you can't use it to get R from U dynamically without going to new postulates? The answer is, all he cares about is the latter issue, it is of no concern to him if MWI is consistent with the current postulates, and indeed I believe he thinks it is.Correction, there are many more mistakes in your furtive imagination applied to my posts. You first must demonstrate that you can actually hear the words I am using before you can critique them effectively. Communication is the hardest thing.

What Penrose thinks is that the current postulates of QM need modifying, in ways that, once they accomplish what Penrose's philosophical preferences convinces him they should, will leave no room for MWI. That is not a claim that MWI is inconsistent with the current postulates of QM, and it not a claim that Penrose's program will work. I can't say it any clearer than that.

juanrga

And Penrose correctly points that the central issue «has very little to see with Platonism/positivism». Moreover, Penrose does not consider himself a Platonist...

This is all untrue. You also continue using the term «funambulisms» in a different way to how I introduced the term here.

Hawking believes that MWI works, but he, of course, has never proved such thing. However, the contrary thing, --i.e., that that MWI does not work-- has been proven.

Penrose is bothered because MWI does not work (bold face from mine):

I wonder why you think that the mathematical proof that R and U are irreducible needs of such inputs as an «observer mind». I know that most of philosophical literature is rather confused about QM and still believe that collapse of wavefunctions is caused by the mind of an observer, but this all is the usual philosophical nonsense that lead to the well-known physicists reply: «Shut up and Calculate».

There are many instances of correct statements that, however, are denied by some minority of persons with philosophical prejudices.

For instance, «Earth is not flat» is a correct statement. Still some people today think that their Flat Earth 'theory' is a reasonable interpretation of the properties of our planet, and they even join in a Society

http://en.wikipedia.org/wiki/Flat_Earth_Society

My point here is that it does not matter how many times MWI is proven wrong, useless or nonsensical; you probably will always find someone who supports MWI.

Evidently the mathematical proof that U and R are irreducible has nothing to see with «philosophical preconceptions» neither with «philosophical assumptions».

Not only I am right on that you misplaced Gell-Mann, but you continue misreading and confusing everything.

If you were to read what I wrote, then you would see that I wrote «really serious». Although you think that is my definition, it is not mine. Penrose explains, in his book, who in that diagram is really serious (Penrose own words) about QM and who is not.

For instance, Penrose correctly claims that Hawking is not «really serious» about QM.

It seems evident that you confound «serious about psi» with my «serious about QM». The «serious about psi» label is different. Penrose uses this label to differentiate those who believe that Psi is something about our mind of those who understand that Psi gives the physical state of the quantum system.

Ken G

Often you have claimed that MWI is inconsistent with the current postulates of QM, and you've claimed this has been proven (I already told you that any such proofs will express philosophical priorities that need not be accepted), and now you actually bold-face a sentence by Penrose as if it supported this stance, yet it clearly says nothing of the sort! That's your evidence? What Penrose said is that MWI doesn't solve the problem with QM. That is just precisely what I told you that Penrose felt about MWI. Yet you see no importance in what Penrose did not say: that MWI is inconsistent with the current postulates of QM! You are an intelligent person, probably extremely so, so why can you not see that if Penrose thought MWI was inconsistent with the postulates of QM he would have said so?

I think it is pretty clear what Penrose is actually saying-- he is saying that MWI doesn't solve the problems that the the current postulates of QM have. That means, he doesn't think MWI goes beyond those postulates, in the way his own intepretation attempts to do.
Simple. The proof will make assumptions about what it is talking about. Anyone who simply rejects those assumptions, say on the grounds that it does not make any account of the observer's mind (which is obviously part of any complete accounting of physical phenomenon), and thus reject the "proof." That is the nature of proofs: they are only as good as their assumptions.

Apparently you are unaware that "shut up and calculate" is also a philosophical stance. Most people do realize that. More to the point, shutting up and calculating means use QM to make predictions, which we already know how to do and nothing that Penrose is doing has anything to do with that (he hopes his approach can be empirically demonstrated, but that is certainly not why he is doing it, and frankly there is fairly little likelihood that it will be empirically demonstrated any time soon).

Well, you might think that comparing Hawking and DeWitt to Flat Earth society members is a cool rhetorical device, but I think it is meaningless hooey.
That is where you are quite wrong, as I explained above. Maybe we would make better progress if you would cite such a proof, and then I will show you the philosophical assumptions involved.
See? Your philosophical preferences are showing already, yet you seem blind to them. Your position is evidently that it is an objective fact that Psi gives "the physical state of a quantum system." What is a physical state? What is a quantum system? Please prove to me what these things are. Use pure mathematics please, no "funambulism". Oh, and no philosophy either, obviously.

juanrga

I have bold-faced a sentence by Penrose by another reason, evidently.

The proofs that MWI is internally inconsistent and disagree with QM predictions were given many messages ago and repeated often...

This is untrue.

Philosophers are very confused about this topic.

It is not needed to appeal to observer's mind to understand quantum measurement, just as it is not needed to appeal to observer's mind to explain how a thermometer works.

The idea that quantum measurement has something to see with a human mind is pure nonsense.

You seems unaware that the slogan was invented to avoid the rambling endlessly about the philosophical implications of QM, and is appropriate to use when there is an imbalance between the amount of philosophy and the amount of calculation.

The mathematical proofs were given to you several times before, and you systematically ignored. Although you continue disputing them using philosophical pseudo-arguments.

Once again the «philosophical preferences» are only in your mind.

If you open a textbook in QM (I cited some), you can learn why Psi gives the physical state of a quantum system. Examples of quantum systems and their properties are given as well in textbooks.

Of course, the concept of physical state is more general. For instance, any textbook on thermodynamics will explain you what is the physical state of a thermodynamic system at equilibrium.

Such books are to be found in the Physics section (not in the philosophy section) of your favorite library.

Ken G

And evidently, I'm missing the bold-faced sentence where Penrose actually says what you keep claiming he is saying: that MWI is inconsistent with any theory that can make the same tested predictions as the current postulates of QM that can be found in standard textbooks. Your argument lacks evidential support in a very blatant and obvious way, yet in all your posts, you cannot correct this gaping flaw.
And I repeated many times that to be what you claim, such proofs must stick entirely to the postulates of QM, with no philosophical assumptions at all. As such, they must use the postulates of QM to present a complete accounting of everything that is involved in a "QM prediction", including how such predictions are confronted with observations (to give the concept of "prediction" meaning in the first place). As such, they must account for the observer involved in verifying the prediction. They don't. Now, you might think that's a technicality, but obviously it isn't, as this is precisely the crux of many of the distinctions in the interpretations of QM. But I'm repeating myself.
So you claim, but you are wrong. To see this, all we need to do is what I suggested we do: present me with such a "proof", and I will show you where the philosophical assumptions appear, and how an MWI proponent could reject those assumptions. It's really quite simple-- you can't get R from U, but the MWI proponent doesn't think you ever get R. You only get R when you adopt certain philosophical assumptions about what a prediction is, and how physics should work. Go ahead, show me your favorite proof, this won't take long.
When it comes to issues like this, everyone is a philosopher. You are just another one of those who defines "philosophy" as "everything I don't agree with", and "scientific fact" as "everything I do." But that's not actually what philosophy is. I'm sure Penrose understands the role of philosophy, as Hawking clearly does as well. Penrose merely adopts the label "very serious about QM" for people who share his philosophical objectives. Many others, like Mermin, do not-- they don't think QM is anything but a system for making predictions, and there is no dispute among anyone about how to use QM to do that, at least in regard to everything that has already been observed that is used to support QM.
Interesting philosophical opinions. I would say they are quite naive, as is typical of people who don't know when they are using philosophy.
More philosophical opinionating. But I would say it is perfectly demonstrable that all of physics, not just quantum measurement, as "something to do with the human mind." Indeed, I would say that is quite obvious, but what is obvious to me and what is obvious to you can be very different things, and since we are both intelligent, this must trace back to our different philosophical priorities and assumptions. The main difference between us is that I realize this and you do not.
I know perfectly well why the slogan was invented. I also know the words of Aristotle: "If you will philosophize, then you will philosophize. If you will not philosophize, then you will philosophize." Or those of Blaise Pascal: "To ridicule philosophy is really to philosophize." Either ponder on those, or dismiss the intelligences of Aristotle and Pascal. The truth is that "shut up and calculate" is not a means for avoiding philosophy, it is a philosophy, it is a very deep statement about the limitations of science that most scientists like yourself given your claim that those who understand QM know that a wave function is truly a "physical state", while dodging the request to even define that term) are loathe to believe, yet think they are "serious" in their disbelief.
Pick your favorite one, any one will suffice, and cite the assumptions that it uses. I may have to uncover the implicit ones, though.
I realize you believe this, simply repeating your beliefs is rather pointless. Or is that what you call a logical argument?
Now your argument is just plain silly. Of course I know all about QM textbooks, as do all the other people who don't think that psi is a "physical state" (they begin by attempting to define the term, which of course is the whole point-- by not even trying to do that, you expose the frailty of your position). The fact is, textbooks are not interested in establishing their philosophical assumptions, they are all implicit. This is simply because textbooks are not trying to probe the philosophical foundations of QM that would let you actually prove the things you claim that QM can prove. Instead, textbooks are interested in laying out the theory well enough that it can be used to make calculations, but it always dodges the issue of collapse. This is the entire reason that we have so many different interpretations of QM in the first place! You appear to think we can sector those interpretations into two camps: those that agree with your implicit philosophical assumptions, which you call the "serious" ones, and those that do not, which you dismiss. That is actually quite typical behavior of people who don't understand philosophy, I see it on all sides of the interpretation debates. That's why I pointed out that Deutsch claims Penrose is "doing aesthetics not physics", while Penrose says Deutsch is "not serious." Obviously, these people cannot agree, and the clear reason is they have not recognized how their philosophical opinions have colored their judgements. What gives Penrose the right to judge what is serious? What gives Deutsch the right to judge what is physics? These are issues that physicists do not agree on, it's just that simple-- deal with it!
And in the process, will make idealizations and philosophical assumptions. The point is, I can very easily recast thermodynamics, or any physics theory, into something that looks completely different, yet makes all the same predictions that can actually be tested, yet proves very different things about what that theory can and cannot do, by simply adopting a very different philosophical stance. This is precisely what you do not realize.

juanrga

Therefore your argument has moved from Penrose-agrees-with-me to show me a sentence where Penrose-agrees-with-you.

Sorry, but I do not need to find a sentence from Penrose supporting my claim that MWI is nonsense. I already supported my claim.

Maybe you missed this point again, but the reason which I cited Penrose was because you pretended him to support your philosophy, when he just agrees with me that MWI is both inelegant and not-working. Read the quotes again.

This very much summarizes the point.

Effectively, as I repeated and repeated R cannot be derived from U (because is irreducible). That is the reason which QM includes both R and U.

Although for decades the MWI community has done claims that they have an alternative interpretation of QM using only U, their theory is internally inconsistent and disagrees with QM predictions.

Now you finally agree that the R that cannot be obtained from U can be 'obtained' from U when, your own words, «you adopt certain philosophical assumptions»

I am really satisfied and this point.

Thank you.

Ken G

Actually, I already presented the evidence that Penrose agrees with me-- the problem is that you have presented none that he agrees with you. As this is the crux of your entire position here, I think that is a serious flaw in your stance.

As I expected, you still cannot provide evidence that the Wiki article was wrong when it claimed that Penrose thinks MWI is consistent with current QM, but that current QM is missing something important, and so by implication MWI is missing something important. I agree with the Wiki, it completely checks with all the evidence presented in this thread, nor have you refuted it with a shred of evidence.Yet again you are imagining something that never had anything to do with this thread. It is clear you have no idea what I'm saying every time you attempt to summarize it. You would actually do much better sticking with my words.
That has never been the source of the disagreement. Read my words again. The source of the disagreement is whether or not we can take it as a scientific fact that we do get "R". I have told you that this "fact" actually requires certain philosophical assumptions and priorities that are not required to adopt, and indeed MWI proponents generally do not, which is pretty much the entire point. There is no experiment that requires that R be part of the reality that QM postulates are trying to describe, there is just the observer perception, which as I said is not part of your theory, or any theory, of QM. Until that problem is fixed, if it can be fixed, the issue will always reduce to philosophical priorities-- largely around the role of rationalism and empiricism in asserting what a physics theory is trying to do.
That is also not the least bit relevant to this thread. The issue was not whether MWI could derive R from U according to some set of laws (we should know that is impossible), it was simply whether or not MWI is a consistent interpretation with the fact that we perceive R. That is entirely different-- for example, CI never makes any effort whatsoever to "derive R" from some deeper principles, yet obviously CI is consistent with R because it simply includes it as an ad hoc postulate (something Penrose sees as a big problem, and Hawking does not, both for philosophical reasons). Similarly, MWI includes the ad hoc postulate that R is perceived because of the action of the perceiver, and the fact that it has not succeeded in connecting that to any deeper principles seems to me like a perfectly obvious extension of the problem of having no theory of perceivers. Nor do you, nor does Penrose.

So given the absence of a theory of quantum gravity that can do what Penrose would like it to do, and given the absence of a theory of perceivers that can do what I am saying would be necessary to do, what these "proofs" actually accomplish is simply tracking the logical ramifications of the various philosophical priorities in concert with what has been experimentally established about quantum systems. That is what I have been trying to tell you all along.

That is also irrelevant to the thread. Nowhere did I claim that MWI gives a mathematically closed accounting of the predictions of QM, I said it is an interpretation that is consistent with those predictions. The predictions require nothing beyond the mathematics of how to do them, which there is no disagreement about. What there is disagreement about is how to find a set of postulates that put those predictions on a sound and rigorous mathematical footing, which simply does not exist at present (because of the problem of no dynamical accounting of the perception of collapse). That's why Penrose, and others, are trying to create one! Why on Earth would they need to do that if one already existed?
Unfortunately you still have understood nothing I said. Pity, your inability to understand these nuances will continue.

fellupahill

Finally. I found someone who agrees.

I think along the same logic.

What is the chance that we live in the one universe were NONE of the crazy but possible outcomes happen. We seem to be made of what is predicted will happen.

notnews32

My question for many-worlds proponents would be how the laws of quantum mechanics are reconciled in these outliar universes. How can intelligent life observe these fundamental laws of nature for which we have accounted for 100% of possible outcomes given that they do not observe the same distribution of outcomes that we do? Would you suggest that there is no universe in which every event is unprobable, and that these unprobable events scatter themselves through an infinite number of universes?

kith

If you agree with the MWI you also have to acknowledge that the laws of physics appear different in a very small fraction of the multiverse. I don't think this is a problem for a person who accepts the existence many worlds in the first place.

You can also expand this idea. What forbids that the laws of physics can actually be different in other universes? Maybe your universe is a very unlikely one and you only perceive it to be normal, because you need very special conditions for the emergence of the ability to perceive? (->anthropic principle)

Such verbal ramblings can be done endlessly with a MWI background. This is probably why it is so popular in pop science.

Ken G

Is it essential to accept a multiverse if you accept MWI? In my view, those two ideas are quite different, and you could have either one without the other (though holding one certainly makes it easier to hold the other!). The multiverse is used to "explain" why the parameters (and maybe even laws) of our universe are what they are, within the "landscape" of other possibilities. The "many worlds" are not the multiverse, they would be aspects of a single universe with a single set of parameters and laws, but many islands of mutually incoherent processing agents trying to figure out those laws. All of the "many worlds" would have the same cosmological parameters, for example, because I don't think those parameters are thought of as dynamically evolving in statistically distributed ways, but rather as being stochastically distributed over the multiverse right from the start, independently of any subsequent evolution. That's my understanding anyway, it all seems a bit far-fetched to me and I'm not sure if I could even count anthropic reasoning as an "explanation" of how things are, but merely as an observation that must be true. Explanations shouldn't have to be true.
Right, and that's what makes it so hard to use anthropic reasoning for anything constructive-- can we really say what the distribution is we are selecting from? Are universes that obey laws likely or unlikely? If life that thinks in ways that leads to anthropic principles requires a universe that obeys laws, how could we ever tell if we are in a majority or minority universe just because ours appears to respect laws? And does ours really respect laws, or is it natural that intelligence finds something that it can interpret that way?

bohm2

This is another paper that just came out today discussing some of the arguably less well-known criticisms against MWI:
Nothing happens in the Universe of the Everett Interpretation
http://lanl.arxiv.org/pdf/1210.8447.pdf

Hurkyl

Based on your quote, the abstract, and skimming the introduction, there is a very straightforward response to the paper: it forgot about dynamics.

Demystifier

Dynamics is nothing but a unitary transformation from one point in the Hilbert space to another. As long as all points in the Hilbert space look the same (which is one of central claims in the paper), such dynamics does not bring anything interesting.

Quantumental

Forgot about dynamics? He mentions dynamics specifically 11 times.

Quantumental

What are your take on the paper?
Seems to be a very interesting one, but seeing as how many papers have been written about MWI I struggle to believe he has found a new "fatal" flaw