Problems with Many Worlds Interpretation

[nazarbaz]

Then I'll give you some examples:
1) Aristotelian vs. Newtonian vs. Einsteinian gravity. The represents a clear sequence in converging accuracy-- Aristotelian is not quantitative at all, Newtonian is magnificently accurate for celestial motion. In most applications, Einstenian gravity adds little in the way of increased accuracy, yet holds that gravity is not a force but a bending of spacetime-- two more different ontologies would be hard to find. Einstein's theory essentially widens the domain of high accuracy outcomes, so is clearly moving toward some kind of convergence in accuracy, but the ontology borrows nothing at all from Newton other than some dependence on mass.

2) Classical vs. Quantum mechanics-- again we have two theories that agree essentially completely on some scales of phenomena, but QM extends the domain of high-accuracy outcomes to smaller systems. So there is clearly a convergence of accuracy happening when you pass from CM to QM, but the ontology is completely different once again-- we go from motion being described by position as a function of time to motion being ruled by inobservable mathematical entities that only pass into the real domain when they are in some sense forced to choose a definite outcome by their environment.

3) Thermodynamics vs. Statistical Mechanics-- here we have general laws about how heat and temperature behave, accurate for large systems in thermodynamic equilibrium, transitioning into statistical rules that apply to systems of particles. The latter extends the accuracy of the predictions to systems with fewer particles and different kinds of interparticle forces. The ontology is again completely different-- thermodynamics is a continuous description, statistical mechanics is an atomic description.

And the list goes on. In each case, we find advances that extend the domain of accuracy from one theory to the next, exhibiting a clear convergence of predictive reliability, so show a clear "arrow of progress" in regard to predictive power. Yet, these advances are accomplished via radical shifts in the basic ontology, exhibiting no tendency at all for the ontologies to "converge" other than the most basic consistency requirement. And today, we have research into "string theory", another complete change in ontology, targeted at achieving accuracy improvements that are so tiny they as yet cannot even be probed by our technology.
All well and good to say, but what does this really mean? When gravity was a force, was that "actual knowledge" of some aspect of nature, even when it became a curvature of spacetime? Or when it is something that strings are doing? All we ever get to know is the accuracy of our predictions.

1. What is problmatic with your view is the fact that you treat the aristotelian, Newtonian and einsteinian physics as equivalents, almost like there is no progress over time and no widening of our perception of the universe.
2. There is a certain trivialization of science findings in your approach and I suspect that you are confusing science facts and scientific hypotheses. If you are right : does it mean that the electron is an "interpretation" of something unreachable to our brains and that light bending next to huge masses is a "metaphor" ? If yes, justify it.
3. My main argument is the fact that our actual science is well grounded relating definite objects with consistent propositions, not general ontological claims with profound global theories. What is matter and energy ? How the universe was born ? That's exactly our wide margin of progress.
4. As I told you, your approach could be useful with highly hypothetical claims but cannot stand as foundation to an epistemology. Somehow you're urging science to give an explanation to almost everything in order to give it the right to make ontological claims, which is not reasonable.
5. The radical distinction between "calculation" and "ontology" seems like a fallacy. In physics, there's no other way to study our objects of interest than mathematics. To find or decide which mathematical model could give us an insight on the object is the main goal of science. The process is obviously contingent, not all of our physical theories are equally right or close to the true nature of objects. Remember : the relation between the subject and the object is the essence of the scientific experience.
6. Science is a work in progress with both nicks and continuities. So nuance.

 

[eqblaauw2]

1 So you think science has progress (a view In my opinion also adequately defended by Popper, so I agree with you)
2 but you agree with me that newer theories aren't in itself better then older ones (a statement that cannot be derived from point (1). (if that's what you said, my english isn't perfect)
I also agree with you (again if that's what you're trying to say) that if we talk about mwi it would be better if we all would talk about mwi with parallel universes and copies of ourselves, because that would help a lot of confusion out of the way. (that's also the 'version(s)' of mwi (s) that I at least tried to get clear in my poll))
That being said the drastically ontological claims, just like a theory being newer isn't an argument for it's quality, aren't itself an argument for it's quality. Most physics find 'that' mwi a bridge to far, and they have their reasons.
I don't want to make a discussion about mwi impossible, I just want to make the discussion fair and square.

 

[BruceW]

I also agree with you (again if that's what you're trying to say) that if we talk about mwi it would be better if we all would talk about mwi with parallel universes and copies of ourselves, because that would help a lot of confusion out of the way. (that's also the 'version(s)' of mwi (s) that I at least tried to get clear in my poll))
That being said the drastically ontological claims, just like a theory being newer isn't an argument for it's quality, aren't itself an argument for it's quality. Most physics find 'that' mwi a bridge to far, and they have their reasons.
I don't want to make a discussion about mwi impossible, I just want to make the discussion fair and square.

About earlier, I understand that you put energy into making a poll, which is good, and I didn't mean to say that it was useless. I just meant to say that it helps to define exactly what you mean when you say 'MWI' or 'CI'.

You've said here that your poll was on the MWI of 'literal' parallel universes. This is very different to the MWI of 'no non-unitary collapse'. Did you explain to the people you were polling that you wanted to know their opinion on 'literal' parallel universes? Because its important that all the people you polled were answering the same question.

For example, for me, I think 'no non-unitary collapse' is a useful interpretation. And I think allowing non-unitary collapse is also a fine interpretation (as long as the non-unitary collapse happens only for the 'end-user' of the calculation). But I think any interpretation that uses the existence of parallel, non-interacting universes to be totally ridiculous.

Although, if that interpretation can be used to predict physical phenomena, and if it agrees with all experimental results, then it is still not really 'wrong'. Its just that it makes unnecessary postulates, in my opinion.

 

[eqblaauw2]

About earlier, I understand that you put energy into making a poll, which is good, and I didn't mean to say that it was useless. I just meant to say that it helps to define exactly what you mean when you say 'MWI' or 'CI'.

You've said here that your poll was on the MWI of 'literal' parallel universes. This is very different to the MWI of 'no non-unitary collapse'. Did you explain to the people you were polling that you wanted to know their opinion on 'literal' parallel universes? Because its important that all the people you polled were answering the same question.

For example, for me, I think 'no non-unitary collapse' is a useful interpretation, and so is allowing non-unitary collapse as an interpretation. But I think any interpretation that uses the existence of parallel, non-interacting universes to be totally ridiculous.

Although, if that interpretation can be used to predict physical phenomena, and if it agrees with all experimental results, then it is still not really 'wrong'. Its just that it makes unnecessary postulates, in my opinion.

yes I did, I said in the introduction as clear as I could that the poll was only relevant for the mwi that stated that there where parallel universes and copies, that actually existed. I don't know if I used the word literally, but I think there was no reason what so ever why you could think this wasn't meant to be taken literally. I think how I said it thus maid it clear that I was interested in the opinion of the literally existence of those universes and persons.
That being said 6 persons of the 28, and the 18 that voted c said (without being asked) informed me that they disliked any version of mwi whatsoever (that they where aware of).
(you can read the poll on the site, but I didn't mention the introduction I think)

 

[Ken G]

1. What is problmatic with your view is the fact that you treat the aristotelian, Newtonian and einsteinian physics as equivalents, almost like there is no progress over time and no widening of our perception of the universe.

Why would anyone treat those as equivalents?

2. There is a certain trivialization of science findings in your approach and I suspect that you are confusing science facts and scientific hypotheses.

Well I see no trivialization, I just see the unembellished facts of the situation. If we stick to what there is actual evidence of, then it is what I said.

If you are right : does it mean that the electron is an "interpretation" of something unreachable to our brains and that light bending next to huge masses is a "metaphor" ?

Yes, I would say those things are pretty obviously interpretations and metaphors, that's what scientific ontology always is.

If yes, justify it.

What requires justification is anything else. It is clearly the null hypothesis that these things are interpretations and metaphors. What do you think they are, and how can you make a logical argument they are that?

3. My main argument is the fact that our actual science is well grounded relating definite objects with consistent propositions, not general ontological claims with profound global theories. What is matter and energy ? How the universe was born ? That's exactly our wide margin of progress.

Hmm, you know what matter and energy are? You know how the universe was born? The rest of us are all ears.

4. As I told you, your approach could be useful with highly hypothetical claims but cannot stand as foundation to an epistemology.

And where did I say I was laying out a foundation for an epistemology? That's the scientific method, we already have that.

Somehow you're urging science to give an explanation to almost everything in order to give it the right to make ontological claims, which is not reasonable.

I am? Almost everything? I'd settle for just one thing, actually, one explanation that "gives us the right" to make ontological claims. And what happens when that explanation gets replaced by a totally different one with a completely different ontology?

5. The radical distinction between "calculation" and "ontology" seems like a fallacy. In physics, there's no other way to study our objects of interest than mathematics.

So calculations are ontology? That is the claim you are making? Have you really thought that through?

To find or decide which mathematical model could give us an insight on the object is the main goal of science.

Yes, here you are making sense. Insight, not ontology.

Remember : the relation between the subject and the object is the essence of the scientific experience.

Agreed, this is a demonstrable crux of the scientific method.

6. Science is a work in progress with both nicks and continuities.

Yes, it is a work in progress. So that is an argument that ontologies do converge?

 

[Ken G]

1 So you think science has progress (a view In my opinion also adequately defended by Popper, so I agree with you)

Yes, science demonstrably makes progress.

2 but you agree with me that newer theories aren't in itself better then older ones (a statement that cannot be derived from point (1). (if that's what you said, my english isn't perfect)

Which theory is "better" is highly context dependent, yes. Which theory has a "truer ontology" is highly questionable. Ontologies behind theories are fascinating glimpses into the meaning of a theory. Reality is another matter.

I also agree with you (again if that's what you're trying to say) that if we talk about mwi it would be better if we all would talk about mwi with parallel universes and copies of ourselves, because that would help a lot of confusion out of the way.

I wouldn't presume to tell people who use MWI how they should use it, except to say that they should use it for what interpretations should always be used for-- a way to motivate a sense of understanding of a theory in a way that resonates with some set of philosophical priorities. They should not confuse themselves that they are talking about some reality that is independent of those priorities.

Most physics find 'that' mwi a bridge to far, and they have their reasons.
I don't want to make a discussion about mwi impossible, I just want to make the discussion fair and square.

I agree that in my experience, most physicists are not as drastically rationalistic as is required to see MWI as a "truth" about reality.

 

[juanrga]

Hello,

While the majority of physicists embrace the Many Worlds interpretation of quantum decoherence, I am holding out hope for the Copenhagen interpretation or better yet, a undiscovered interpretation.

Please allow me to pose three problems I have with the MW interpretation.

1) There is a nonzero prob of me spontaneously becoming a miniature sun. Let me elaborate. Since I am made of atoms, there is a nonzero prob that all of the subatomic particles comprising each of the nuclei of my atoms are all one kilometer away except for a single proton and single electron in each atom. I.e. I am now spontaneously comprised of only hydrogen atoms. Now let's say that since even the exact position of these hydrogen atoms is uncertain they are close enough that gravity overpowers all and nuclear fusion takes place. I.e. I have become a miniature sun.

The probability of this happening is obviously miniscule, but nonzero. With the CI interpretation this will never happen because the probability is so small that the universe is not old enough for such a low probability to have been realized. However with MWi since the probability is nonzero, it has happened. Moreover it has been happening every second of every day since the minute I was born in some parallel universe.

2) My second problem with MW intepretation is how can an interference pattern result in a double slit experiment if the particle is actually traveling through a different slit in separate universes. Shouldn't the interference only occur if the particle is traveling through both slits simultaneously in the same universe?

3) My third problem with MW is that it really does away with the concept of probability although many quantum experiments have shown that the concept does exist. For example, take a weighted coin which is 99% more likely to flip heads, than tails. CI predicts that a 100 flips would yield 99 heads and 1 tail. With a single flip, one is much more likely to get a head than a tail. However with MW, one flip will result in head in one universe, tail in another so therefore 50-50 probability.

Can someone help me to understand these issues any better? Thanks!

The standard interpretation is the Copenhagen one. Many worlds (MW) is a collection of nonsense as has been repeatedly showed in the literature. It is still maintained alive from people who do not understand QM.

Maybe you would take a look to Streater list of lost causes in physics, the section about MW: http://www.mth.kcl.ac.uk/~streater/lostcauses.html#XII

 

[eqblaauw2]

The standard interpretation is the Copenhagen one. Many worlds (MW) is a collection of nonsense as has been repeatedly showed in the literature. It is still maintained alive from people who do not understand QM.

Maybe you would take a look to Streater list of lost causes in physics, the section about MW: http://www.mth.kcl.ac.uk/~streater/lostcauses.html#XII

well that's a little bit strong (although I think I agree with you, it's a possibility that this statement causes a strong reaction of people who feel misjudged).
Maybe, to be a little arrogant, my poll is a better way to make a similar (tough a little less strong) point. Do I think it wouldn't be bad to read the website you mention.

 

[nazarbaz]

Why would anyone treat those as equivalents?
Well I see no trivialization, I just see the unembellished facts of the situation. If we stick to what there is actual evidence of, then it is what I said.
Yes, I would say those things are pretty obviously interpretations and metaphors, that's what scientific ontology always is.
What requires justification is anything else. It is clearly the null hypothesis that these things are interpretations and metaphors. What do you think they are, and how can you make a logical argument they are that?
Hmm, you know what matter and energy are? You know how the universe was born? The rest of us are all ears.
And where did I say I was laying out a foundation for an epistemology? That's the scientific method, we already have that.
I am? Almost everything? I'd settle for just one thing, actually, one explanation that "gives us the right" to make ontological claims. And what happens when that explanation gets replaced by a totally different one with a completely different ontology?
So calculations are ontology? That is the claim you are making? Have you really thought that through?
Yes, here you are making sense. Insight, not ontology.
Agreed, this is a demonstrable crux of the scientific method.Yes, it is a work in progress. So that is an argument that ontologies do converge?

Your approach is not scientific, it is philosophical. The progress means the ability to meet and understand, even partially, the objects, not to make calculations about them. I am of course aware that we are far away from being able to make sense of the physical world but I manage to make a room for it in the near or the far future. Because that's the true mission of science.
I was right, you are a postmodernist who lives in "interpretations", "narrativities" and "metaphors". What kind of effectivity could have a technology if we don't have the shadow of a clue of what things are... ? Magic, maybe ?

 

[eqblaauw2]

Your approach is not scientific, it is philosophical. The progress means the ability to meet and understand, even partially, the objects, not to make calculations about them. I am of course aware that we are far away from being able to make sense of the physical world but I manage to make a room for it in the near or the far future. Because that's the true mission of science.
I was right, you are a postmodernist who lives in "interpretations", "narrativities" and "metaphors". What kind of effectivity could have a technology if we don't have the shadow of a clue of what things are... ? Magic, maybe ?

Well I have serious doubts that people who are working and thinking about that technology and don't subscribe to mwi don't have a serious clue.
Of which we have a good indication they are in the majority don't have the slightest clue. I believe according to Tegmark even in quantum computing they are in the majority, if you want to take the polls tegmark conduct, or cites *I don't know who conducts those polls he cites*, seriously, but let's just do for the sake of good faith. (David Raub is another case, because I think I refuted that poll successfully. Although you're entitled to have your own opinion about that).

The poll (talk about a vague poll):

An informal poll taken at a conference on quantum computation at the Isaac Newton Institute in Cambridge in July 1999 gave the following results:

Do you believe that new physics violating the Schro ̈dinger equation will make large quantum com- puters impossible? 1 yes, 71 no, 24 undecided
Do you believe that all isolated systems obey the Schro ̈dinger equation (evolve unitarily)? 59 yes, 6 no, 31 undecided
Which interpretation of quantum mechanics is clos- est to your own?
(a) Copenhagen or consistent histories (including postulate of explicit collapse): 4
(b) Modified dynamics (Schro ̈dinger equation modified to give explicit collapse): 4
(c) Many worlds/consistent histories (no col- lapse): 30
(d) Bohm (an ontological interpretation where an auxiliary “pilot wave” allows particles to have well-defined positions and velocities): 2
(e) None of the above/undecided: 50

But even if you do think that. It's still isn't an absurd conclusion that we have technology that we don't have the slightest clue how it works.
that doesn't have to involve magic. People have worked with technology that involved gravity for ages, while they hadn't (and some might say still don't) have the slightest clue how it works.
Also the 'technology' you seem to refer to is very controversial (there isn't a quantum computer that I know of yet, if you might want to imply that, but I don't know if you do since you don't really seem to make it clear what you mean).
sorry

 

[juanrga]

well that's a little bit strong (although I think I agree with you, it's a possibility that this statement causes a strong reaction of people who feel misjudged).
Maybe, to be a little arrogant, my poll is a better way to make a similar (tough a little less strong) point. Do I think it wouldn't be bad to read the website you mention.

Well in your poll in this same forum you add some of the responses that you received.

X1:

I think the many worlds interpretation is nonsense.

X3:

The many-worlds theory is a silly mistake

X5:

The theory is false because it is inconsistent.

I do not find too many difference with what I said:

Many worlds (MW) is a collection of nonsense as has been repeatedly showed in the literature.

But thanks by your post.

 

[eqblaauw2]

Well in your poll in this same forum you add some of the responses that you received.

X1:

X3:

X5:

I do not find too many difference with what I said:

But thanks by your post.

You make a good point.
And no thanks.

 

[juanrga]

Hi jtbell,

from: http://www.anthropic-principle.com/preprints/manyworlds.html

"Political scientist" L David Raub reports a poll of 72 of the "leading
cosmologists and other quantum field theorists" about the "Many-Worlds
Interpretation" and gives the following response breakdown [T].

1) "Yes, I think MWI is true" 58%
2) "No, I don't accept MWI" 18%
3) "Maybe it's true but I'm not yet convinced" 13%
4) "I have no opinion one way or the other" 11%

Amongst the "Yes, I think MWI is true" crowd listed are Stephen Hawking
and Nobel Laureates Murray Gell-Mann and Richard Feynman. Gell-Mann and
Hawking recorded reservations with the name "many-worlds", but not with
the theory's content. Nobel Laureate Steven Weinberg is also mentioned
as a many-worlder, although the suggestion is not when the poll was
conducted, presumably before 1988 (when Feynman died). The only "No,
I don't accept MWI" named is Penrose.

This is the 'highly unscientific' (Max Tegmark own words) poll taken at a 1997 quantum mechanics workshop, where Gell-Mann is listed as a believer in the interpretation, although he explicitly rejected the view, for instance.

 

[Ken G]

Your approach is not scientific, it is philosophical.

Not at all, what I am doing is separating the science from the philosophy. Often people get them all mixed up together.

The progress means the ability to meet and understand, even partially, the objects, not to make calculations about them.

What objects are you understanding?

I am of course aware that we are far away from being able to make sense of the physical world but I manage to make a room for it in the near or the far future. Because that's the true mission of science.

This is exactly the kind of "mixing up" philosophy and physics that I'm pointing out. We have no kind of basis to scientifically support these beliefs of yours, all we have any evidence of whatsoever is that we will continue to push new theories into domains where our predictions are currently suspect. That's it, that's what we can say. How do you know when you have made sense of the physical world? You expect a sign that reads "you have it correct-- you have reached your destination"? Every single scientific culture since Aristotle thought they were making room to make sense of the physical world in the near future! These are just the facts of the matter, as scientists, we should at least deal in facts.

I was right, you are a postmodernist who lives in "interpretations", "narrativities" and "metaphors".

Nah, I just know the difference between a scientifically demonstrable claim that is not liable to change in the future, and an interpretation that is.

What kind of effectivity could have a technology if we don't have the shadow of a clue of what things are... ? Magic, maybe ?

Let's examine your logic here. Your syllogism is apparently "we have effective technology, any effective technology must be based on understanding "what things are", ergo, we understand what things are." Does that really sound like a logically bulletproof argument to you? You can't think of any examples of technologies that worked fine being used by people who had no idea of why? Do we have any idea why two slits make a diffraction pattern, just because we can write an equation that predicts it? Why do you think we can build and fly airplanes without knowing any string theory?

 

[BruceW]

The standard interpretation is the Copenhagen one. Many worlds (MW) is a collection of nonsense as has been repeatedly showed in the literature. It is still maintained alive from people who do not understand QM.

Maybe you would take a look to Streater list of lost causes in physics, the section about MW: http://www.mth.kcl.ac.uk/~streater/lostcauses.html#XII

That website doesn't specifically rule out MWI, it just seems to say that MWI isn't useful. Also (sorry if I'm boring everyone with this point again), the 'no non-unitary collapse' version of MWI and the 'non-unitary collapse only happens for the end-user of the calculations' version of CI seem to be exactly the same thing (except the philosophical slant is different, but I don't really care about that either way).

 

[Ken G]

All interpretations of QM are the same except for the philosophical slant, so if you don't care about that, then what differences do you see in any of them? It's all the same theory, you realize!

 

[eqblaauw2]

This is the 'highly unscientific' (Max Tegmark own words) poll taken at a 1997 quantum mechanics workshop, where Gell-Mann is listed as a believer in the interpretation, although he explicitly rejected the view, for instance.

you seem to mix up two polls, the one cited by tegmark (which really says nothing very pro to mwi (in my opinion), and is in tegmark's own opinion highly unscientific, with people voting more then once, with 8 people voting for mwi, and in which copenhagen is still number one, if you don't count the instrumental version). And david raub's one, you're right when you say that 'Gell-Mann is listed as a believer in the interpretation, although he explicitly rejected the view, for instance' (unless you think consistent histories, that doesn't contain parallel universes and copies of everything on earth, is a version of mwi, which I think is kind of strange thing to argue for, since the many-worlds of the many-worlds interpretation aren't there in consistent histories).
just trying to get the fact straight, no real relevant criticism intended.

 

[juanrga]

That website doesn't specifically rule out MWI, it just seems to say that MWI isn't useful. Also (sorry if I'm boring everyone with this point again), the 'no non-unitary collapse' version of MWI and the 'non-unitary collapse only happens for the end-user of the calculations' version of CI seem to be exactly the same thing (except the philosophical slant is different, but I don't really care about that either way).

It says rather more than that. It says that the subject arose from a «misguided» point of view, remarks that «the idea of the wave-function of the universe is meaningless», that «there is nothing to the many-worlds theory», that is based in hopes «by its advocates», that they do not understand what they are trying («if this were possible, then we just arrive at quantum mechanics»)...

In short, it is a «lost cause» as the website title emphasizes.

 

[juanrga]

you seem to mix up two polls, the one conducted of david raub (which really says nothing very pro to mwi (in my opinion), and is in tegmark's opinion highly unscientific, with people voting more then once, with 8 people voting for mwi, and in which copenhagen is still number one, if you don't count the instrumental version). And david raub's one, where you're right when you say that Gell-Mann is listed as a believer in the interpretation, although he explicitly rejected the view, for instance.
just trying to get the fact straight, no real relevant criticism intended.

You are welcome

 

[eqblaauw2]

You are welcome

haha thanks I edited it (if that's what you tried to make me aware of)
greetings Edo

 

[BruceW]

All interpretations of QM are the same except for the philosophical slant, so if you don't care about that, then what differences do you see in any of them? It's all the same theory, you realize!

I see. I was thinking of objective collapse theory as one of the interpretations of QM. But I guess it is a separate theory to QM. (Since it makes different predictions compared to the other interpretations of QM).

So 'interpretation', by definition, means that there is no way to experimentally distinguish between different interpretations?

 

[Ken G]

So 'interpretation', by definition, means that there is no way to experimentally distinguish between different interpretations?

Yes, I would say that is true. If it makes different predictions, it's a different theory, not a different interpretation of a theory. However, different interpretations might stimulate different new theories, so they are not moot.

 

[BruceW]

Yes, I would say that is true. If it makes different predictions, it's a different theory, not a different interpretation of a theory. However, different interpretations might stimulate different new theories, so they are not moot.

I get you. That makes sense.

 

[Fra]

However, different interpretations might stimulate different new theories, so they are not moot.

I agree. Thus one can say that the "constructive" sense of "interpretations" is different ways to ask or construct the OPEN questions.

In QM for example, there are a certain domains where there is hard experimental confirmation. But there are other domains where it's not confirmed at all.

Unification is a good example. It's simply ambigous exactly HOW to "extrapolate" current measurement theory from the well tested domain of subsystems (except a full GUT is still lacking) to the not at all tested domain of cosmological systems (or open systems).

These are the areas where I find the discussion intersting. It's exactly what you take to be the CORE of quantum mechanics, that determines the most plausible extrapolation it to new territory.

/Fredrik

 

[BruceW]

It says rather more than that. It says that the subject arose from a «misguided» point of view, remarks that «the idea of the wave-function of the universe is meaningless», that «there is nothing to the many-worlds theory», that is based in hopes «by its advocates», that they do not understand what they are trying («if this were possible, then we just arrive at quantum mechanics»)...

In short, it is a «lost cause» as the website title emphasizes.

If we're talking about the interpretations of QM as being equivalent in their predictions, then how is MWI a 'lost cause'? We could equally well choose to use MWI instead of CI. (Or use any of the other interpretations). I think Ken G puts it well when he wrote that 'different interpretations might stimulate different new theories'. So maybe the website is saying that MWI is unlikely to lead to any new predictions/theories?

 

[eqblaauw2]

If we're talking about the interpretations of QM as being equivalent in their predictions, then how is MWI a 'lost cause'? We could equally well choose to use MWI instead of CI. (Or use any of the other interpretations). I think Ken G puts it well when he wrote that 'different interpretations might stimulate different theories'. So maybe the website is saying that MWI is unlikely to lead to any new predictions/theories?

I think that's why david deutsch call's mwi a theory (not that is an argument in it's favor by any means), because it does make predictions: predictions of (now) unobservable universes, that's a prediction (he thinks that one day there will be observational evidence for this, but even if there will be not, it predicts a lot of unobservable universes).

that being said, I have stopped taking david deutsch serious. In an email he said this to me:Unfortunately, even that is not as simple as it sounds.

The rejection of Everett's theory is in my opinion mainly a sociological phenomenon, unlike any other in physics. I suspect that it is rooted in the intellectual intimidation of physics students, and in a complex niche that yearns for quantum mysticism in the general public. As a result, many physicists are reluctant to discuss the issue at all, and they couch their opinions in platitudes or equivocation. Further relevant issues are discussed in Chapter 12 of *The Beginning of Infinity*.

IRONY ALERT
yes and the aliens have caused 9/11 in a complex niche between the cia and al qaida.
ENDING OF IRONY ALERT

p.s.
his book 'the beginning of an infinity' is a theory of everything that combines the qm interpretation of Hugh Everett (that's to say it lightly a bit controversial, but ok you're free to believe in it), with the interpretation of the evolution theory by Dawkins (that's also controversial), with the theory of Popper (in my humble opinion completely misinterpreted by david deutsch), and that all together mixed by david deutsch.
To say that is a lot of names and interpretations (and no 'generaly excepted' interpretations/theories by 'the' scientific community) (except popper, but he messes that, again in my humble opinion, completely up, and the evolution theory, but not with the interpretation of dawkins), seems an understatement.

 

[Ken G]

If we're talking about the interpretations of QM as being equivalent in their predictions, then how is MWI a 'lost cause'?

Yeah, in my view that section of the article translates to "here's why the many-worlds interpretation does not fit into my own personal philosophical priorities about what science is", but it is not actually framed that way. The article would do much better to simply analyze what those philosophical priorities are, and then it follows rather immediately whether MWI fits into them. This would put the focus on its proper place.

 

[eqblaauw2]

Yeah, in my view that section of the article translates to "here's why the many-worlds interpretation does not fit into my own personal philosophical priorities about what science is", but it is not actually framed that way. The article would do much better to simply analyze what those philosophical priorities are, and then it follows rather immediately whether MWI fits into them. This would put the focus on its proper place.

well I think d.d. en others' theory is scientific without the positive connotation,
if you think bad science isn't science, then I think it isn't (see my previous post).
if you think speculations that aren't necessary at all is philosophy, then I think it's philosophy

 

[Ken G]

In mathematics, one does not argue the axioms, one simply identifies the axioms and tracks their ramifications. Physicists have something to learn from that model.

 

[BruceW]

I think that's why david deutsch call's mwi a theory (not that is an argument in it's favor by any means), because it does make predictions: predictions of (now) unobservable universes, that's a prediction (he thinks that one day there will be observational evidence for this, but even if there will be not, it predicts a lot of unobservable universes).

Again, it depends what you mean by MWI. Not all versions of MWI require many universes. The MWI with many literal, separate universes is one particular way of explaining the probabilities of outcomes.

But even the version of MWI with many universes doesn't make different predictions to CI. It does make different predictions to objective collapse theory, but that's because objective collapse theory is not standard QM.

Edit: To explain further, in the MWI with many universes, these universes are supposed to be completely noninteracting, so there is no way (even in principle) to be able to do an experiment to show their existence. This is one of the reasons why I don't like this version of MWI.

 

[eqblaauw2]

Again, it depends what you mean by MWI. Not all versions of MWI require many universes. The MWI with many literal, separate universes is one particular way of explaining the probabilities of outcomes.

But even the version of MWI with many universes doesn't make different predictions to CI. It does make different predictions to objective collapse theory, but that's because objective collapse theory is not standard QM.

Edit: To explain further, in the MWI with many universes, these universes are supposed to be completely noninteracting, so there is no way (even in principle) to be able to do an experiment to show their existence. This is one of the reasons why I don't like this version of MWI.

that's why I said david deutsch and others', not everyone's mwi,
p.s. It would be helpfull if there would be one definition of mwi, in physics there's seems to be a bit of a problem with definitions, so everyone can make the most strange claims about what's been generally accepted or not. I suggest we call mwi, the one with mw that extually exist in a strong sense (because the weak sense can mean anything).
greetings Edo

 

[BruceW]

Good idea.
I don't know much about the MWI of many literal universes, could you help me on an explanation?

Its often said on the web that these different universes are non-interacting. So are they simply a statistical justification of the probability in QM?

Or are they meant to represent each component of the state vector in some basis? For example, if we had ldead cat> + lAlive cat> then does one universe have ldead cat> and the other have lAlive cat> and the two universes would in fact interact (but only slightly, since decoherence has happened)?

 

[eqblaauw2]

well I could direct you to david deutsch and tegmark and you can google david bryce, but then again I think I would direct you to a lot of bull

 

[Ken G]

For example, if we had ldead cat> + lAlive cat> then does one universe have ldead cat> and the other have lAlive cat> and the two universes would in fact interact (but only slightly, since decoherence has happened)?

I think that is very much the idea. The point of MWI is not just to give a statistical basis to the interpretation of a probability (as being N events out of M possibilities, because the ensemble interpretation allows that just fine), it is to have a mathematical description of any closed system that maintains both unitarity and completeness. So that's why the "alive cat" and the "dead cat" must both be equally real in MWI, regardless of what we see when we open the box, because nothing else would allow us to interpret unitarity as giving a complete description of the reality of closed systems (including closed systems that involve observers).

 

[juanrga]

If we're talking about the interpretations of QM as being equivalent in their predictions, then how is MWI a 'lost cause'? We could equally well choose to use MWI instead of CI. (Or use any of the other interpretations). I think Ken G puts it well when he wrote that 'different interpretations might stimulate different new theories'. So maybe the website is saying that MWI is unlikely to lead to any new predictions/theories?

Because, as explained before in this thread, many-worlds is not an interpretation of QM but a collection of nonsense arising from misunderstandings of QM [*]. Re-read the quote that you are citing, and the associated website, paying special attention to clever words as «belief», «misguided», «meaningless»...

[*] The confusion in the many-worlds literature is evident on that some advocates claim that this is another interpretation of QM, whereas others claims this is a different theory leading to (never tested) new 'predictions'.

 

[juanrga]

I have stopped taking david deutsch serious. In an email he said this to me:Unfortunately, even that is not as simple as it sounds.

The rejection of Everett's theory is in my opinion mainly a sociological phenomenon, unlike any other in physics. I suspect that it is rooted in the intellectual intimidation of physics students, and in a complex niche that yearns for quantum mysticism in the general public. As a result, many physicists are reluctant to discuss the issue at all, and they couch their opinions in platitudes or equivocation. Further relevant issues are discussed in Chapter 12 of *The Beginning of Infinity*.

Many physicists are reluctant to discuss the issue, because it has been discussed in detail up to extenuation and simply they have better things to devote their limited time than to correct mistakes already corrected, not one, but several times in the literature.

 

[eqblaauw2]

Many physicists are reluctant to discuss the issue, because it has been discussed in detail up to extenuation and simply they have better things to devote their limited time than to correct mistakes already corrected, not one, but several times in the literature.

I'm sorry in my post that is partly about the mail d.d. send me I was a little bit sloppy. This can lead to a minor misunderstanding (not a misunderstanding by you specifically juanrga). The 'unfurtionally this is also not as simple as it sounds' is from d.d. not from me.
The rest of the (in my opinion very vague and slightly ridiculous) conspiracy theory is also from d.d.

greetings Edo,

p.s. Does anyone know how I can fully unsubscribe my account?, I think I've said what I wanted to say about this subject, and I do not intend to say anything at other threads at this moment.

 

[juanrga]

So that's why the "alive cat" and the "dead cat" must both be equally real in MWI, regardless of what we see when we open the box,...

This reflects the main MWI position very-well and explains why MWI has been labeled as unscientific, for very good reasons, by some.

 

[juanrga]

I'm sorry in my post that is partly about the mail d.d. send me I was a little bit sloppy. This can lead to a minor misunderstanding (not a misunderstanding by you specifically juanrga). The 'unfurtionally this is also not as simple as it sounds' is from d.d. not from me.
The rest of the (in my opinion very vague and slightly ridiculous) conspiracy theory is also from d.d.

greetings Edo,

p.s. Does anyone know how I can fully unsubscribe my account?, I think I've said what I wanted to say about this subject, and I do not intend to say anything at other threads at this moment.

I interpreted the last paragraph as d.d. and (curiously) added the first line for avoiding anyone to attribute the paragraph to you instead of to d.d.

About your question I have no idea. Why do not you ask the Staff?
Regards

 

[Ken G]

This reflects the main MWI position very-well and explains why MWI has been labeled as unscientific, for very good reasons, by some.

I feel it should really be labeled as "unempiricist" rather than "unscientific." Most people feel that science is deeply rooted in empiricism, that's true, but quite a few scientists, probably most notably some of the great theoretical physicists, see it as more deeply rooted in rationalism (i.e., the mathematical models are the reality, the observations are just how we check those models). If you adopt the latter view, you say that observations can falsify models, but observations do not falsify that the cat is both alive and dead because the observations are coming from within the system, and may not have access to complete information about the system. But the empiricist view is that observations must have access to complete information because they define complete information. Rationalists say that complete information is whatever we think it is, not whatever we observe it to be. Consider the question in the book by the celebrated astrophysicist Mario Livio, "is God a mathematician?" (http://plus.maths.org/content/god-mathematician) So it's not exactly "unscientific" to be rationalistic-- the relative fortunes of empiricism and rationalism have demonstrably ebbed and flowed many times in the fledgling history of our physics.

 

[juanrga]

I feel it should really be labeled as "unempiricist" rather than "unscientific." Most people feel that science is deeply rooted in empiricism, that's true, but quite a few scientists, probably most notably some of the great theoretical physicists, see it as more deeply rooted in rationalism (i.e., the mathematical models are the reality, the observations are just how we check those models). If you adopt the latter view, you say that observations can falsify models, but observations do not falsify that the cat is both alive and dead because the observations are coming from within the system, and may not have access to complete information about the system. But the empiricist view is that observations must have access to complete information because they define complete information. Rationalists say that complete information is whatever we think it is, not whatever we observe it to be. Consider the question in the book by the celebrated astrophysicist Mario Livio, "is God a mathematician?" (http://plus.maths.org/content/god-mathematician) So it's not exactly "unscientific" to be rationalistic-- the relative fortunes of empiricism and rationalism have demonstrably ebbed and flowed many times in the fledgling history of our physics.

Empirical method is not a synonymous for experimental method. And this latter is only a part of the scientific method.

Using your «may not have access to complete information about the system» as basis for your «So that's why the "alive cat" and the "dead cat" must both be equally real in MWI, regardless of what we see when we open the box» is another instance of why MWI has been labeled as «unscientific» by most scientists. Other reasons are the internal inconsistencies. See quotes and polls given before. References analyzing MWI and its flaws are multiple. See also the website «lost causes» given before.

No physicists would confound physical reality with the mathematical models used to represent part of that reality. It is curious that Mario Livio discusses Euclidean geometry in his book, because Feynman in his course in physics (with Leighton and Sands) precisely explains the differences between physics and maths using a light ray and Euclidean geometry. Feynman emphasizes how the mathematical (geometric) model is only an approximation to physical reality (the physical object) and how answering what is the range of validity of that approximation is a subject of experimentation and not of reasoning only.

Finally, I want to add that the history is full of rationalist who believed that they could explain the world by reasoning only. I can now recall the father of «rational thermodynamics», a mathematician very polemic with the work of physicists and chemists working in thermodynamics (He used the term «Onsagerists» in pejorative ways, although Onsager won a Nobel for his remarkable work in thermodynamics). He and his coworkers used the term «rational» to emphasize that the thermodynamics developed by others was 'irrational' (of course, using their own criteria and definitions). The funny part was when his 'rational' formulations were confronted with experimental data and miserably failed in a number of tests; whereas the 'irrational' theories of physicists and chemists worked and continue to be taught at universities of all the world.

 

[Ken G]

References analyzing MWI and its flaws are multiple. See also the website «lost causes» given before.

Nothing in that "lost causes" website was at all convincing tht MWI has flaws, that website was merely categorizing the philosophical priorities of its author. Given those priorities, it is obvious that MWI would not be looked on favorably. That's the point-- one can only judge interpretations subject to a set of philosophical priorities. We don't argue axioms, we merely identify them, and track their ramifications.

No physicists would confound physical reality with the mathematical models used to represent part of that reality.

But that isn't true. A strongly rationalistic physicist, like say Max Tegmark or Steven Weinberg, will do exactly that. They may well recognize that any given model has shortcomings, but they view the "actual truth" as simply a deeper model that is very much along the same lines as the existing one but with some improved features. Above all, they view the truth about the reality as being described by a mathematical model, because to them, that's just exactly what truth is. There's just no point in arguing axioms like that, only in identifying them, and tracking their ramifications.

It is curious that Mario Livio discusses Euclidean geometry in his book, because Feynman in his course in physics (with Leighton and Sands) precisely explains the differences between physics and maths using a light ray and Euclidean geometry. Feynman emphasizes how the mathematical (geometric) model is only an approximation to physical reality (the physical object) and how answering what is the range of validity of that approximation is a subject of experimentation and not of reasoning only.

Feynman always tended toward empiricism, which is one reason I like his approach. But a rationalist could easily counter that Euclidean geometry is only one brand of geometry, and no one ever said reality had to be Euclidean. They would still hold that reality is fundamentally geometric, whether Euclidean or some other.

Finally, I want to add that the history is full of rationalist who believed that they could explain the world by reasoning only.

Indeed, they always tend to "go overboard" in interpreting the ramifications of each new theory, I agree. All the same, every theorist dons a "rationalist hat" pretty much every time they sit down to try and conjure a new theory. So there is no question that rationalism is a useful angle from which to view reality, even if one does not have to take it quite as seriously as the "God is a mathematician" camp does.

I can now recall the father of «rational thermodynamics», a mathematician very polemic with the work of physicists and chemists working in thermodynamics (He used the term «Onsagerists» in pejorative ways, although Onsager won a Nobel for his remarkable work in thermodynamics).

And there's the rub right there-- he won a Nobel. So there is a demonstrable value to being able to think rationalistically. But I agree that rationalism is probably not a good way to build a world view that transcends what science can demonstrate-- it's just too unlikely to be right.

He and his coworkers used the term «rational» to emphasize that the thermodynamics developed by others was 'irrational' (of course, using their own criteria and definitions). The funny part was when his 'rational' formulations were confronted with experimental data and miserably failed in a number of tests; whereas the 'irrational' theories of physicists and chemists worked and continue to be taught at universities of all the world.

The way I put that earlier in the thread is, the problem with rationalism is that the theories keep changing but the observations don't. Still, the rationalist counters that a good theory is always a good theory-- for whatever it is good at. To me, the bottom line is, "don't take the theory too seriously." Or how this is often said, "the map is not the territory."

 

[BruceW]

Nothing in that "lost causes" website was at all convincing tht MWI has flaws, that website was merely categorizing the philosophical priorities of its author. Given those priorities, it is obvious that MWI would not be looked on favorably. That's the point-- one can only judge interpretations subject to a set of philosophical priorities. We don't argue axioms, we merely identify them, and track their ramifications.

That's true. I feel that MWI doesn't match my philosophical preference, but I can see that it is a viable interpretation.

One more question: What if we said that non-unitary collapse doesn't happen, and we also said there is only one 'world'? I guess from there we could say that the wavefunction only tells us about a large statistical ensemble of similarly-prepared systems (ensemble interpretation). Or we could say the wavefunction is real, and then we need some way to make sense of the probabilities of individual outcomes.

MWI makes sense of it by saying that each component of the (pure) state vector in the measurement basis represents a different 'world'. Are there any other ways to make sense of measurement without resorting to the subjective non-unitary collapse which CI advocates?

 

[Ken G]

What if we said that non-unitary collapse doesn't happen, and we also said there is only one 'world'? I guess from there we could say that the wavefunction only tells us about a large statistical ensemble of similarly-prepared systems (ensemble interpretation).

Yes, that's the "ensemble interpretation", it simply holds that QM is not a complete description for individual systems.

Or we could say the wavefunction is real, and then we need some way to make sense of the probabilities of individual outcomes.

Yes, there is quite a tension between definiteness and indefiniteness in quantum mechanics. The two seem to be halves of the same coin.

Are there any other ways to make sense of measurement without resorting to the subjective non-unitary collapse which CI advocates?

The deBroglie-Bohm approach holds that the initial state is already collapsed, we just don't know it. It places a level of mathematics beneath the wave function, interpreting the wave function like we interpret the density of a gas-- an emergent equilibrium property of a more complicated underlying system. The emergent equilibrium is treated statistically, but the underlying system is deterministic and inaccessible in practice. It is the closest to classical, but still has an "angels on a pin" feeling because it equilibrates so readily that we never encounter anything else.

 

[juanrga]

Nothing in that "lost causes" website was at all convincing tht MWI has flaws, that website was merely categorizing the philosophical priorities of its author. Given those priorities, it is obvious that MWI would not be looked on favorably. That's the point-- one can only judge interpretations subject to a set of philosophical priorities. We don't argue axioms, we merely identify them, and track their ramifications.
But that isn't true. A strongly rationalistic physicist, like say Max Tegmark or Steven Weinberg, will do exactly that. They may well recognize that any given model has shortcomings, but they view the "actual truth" as simply a deeper model that is very much along the same lines as the existing one but with some improved features. Above all, they view the truth about the reality as being described by a mathematical model, because to them, that's just exactly what truth is. There's just no point in arguing axioms like that, only in identifying them, and tracking their ramifications.
Feynman always tended toward empiricism, which is one reason I like his approach. But a rationalist could easily counter that Euclidean geometry is only one brand of geometry, and no one ever said reality had to be Euclidean. They would still hold that reality is fundamentally geometric, whether Euclidean or some other.
Indeed, they always tend to "go overboard" in interpreting the ramifications of each new theory, I agree. All the same, every theorist dons a "rationalist hat" pretty much every time they sit down to try and conjure a new theory. So there is no question that rationalism is a useful angle from which to view reality, even if one does not have to take it quite as seriously as the "God is a mathematician" camp does.
And there's the rub right there-- he won a Nobel. So there is a demonstrable value to being able to think rationalistically. But I agree that rationalism is probably not a good way to build a world view that transcends what science can demonstrate-- it's just too unlikely to be right.The way I put that earlier in the thread is, the problem with rationalism is that the theories keep changing but the observations don't. Still, the rationalist counters that a good theory is always a good theory-- for whatever it is good at. To me, the bottom line is, "don't take the theory too seriously." Or how this is often said, "the map is not the territory."

The lost causes in physics website gives technical arguments against MWI.

Evidently, the criticism of MWI, which I have pointed out before is purely technical and has been published in journal of physics (e.g., Int. J. Mod. Phys. A 5 1745-1762 1990), not in philosophical magazines, as you seem to believe.

It is very ironic that you write about the role of axioms, because precisely one of the main criticism of the MWI literature is that its main advocates either lack to give a complete set of axioms, from which one could explain the physical world (reason for which the theory has been labeled «unscientific») or them give us a set of self-contradictory axioms (reason for the which «The theory is false because it is inconsistent»; quote X5 in this same thread).

Max Tegmark confounds physics with philosophy in his post-modern Radical Platonism: MUH.

Steven Weinberg is also aware of the differences between physics and maths. Precisely in his textbook gravitation and cosmology, Weinberg explains why he follows what he calls a non-geometrical presentation of the subject, and remarks in the preface how the electromagnetic interaction cannot be understood in geometrical terms.

You have completely misinterpreted Feynman's point of view. He was not talking about the limitations of Euclidean geometry in regard to more general geometries. He was talking about the limits of mathematics and the differences with physics. He chose Euclidean geometry as an simple illustrative example adequate to his audience (people taking an introductory physics course).

 

[Ken G]

The lost causes in physics website gives technical arguments against MWI.

If you will make that claim, please cite them. I didn't see any.

Evidently, the criticism of MWI, which I have pointed out before is purely technical and has been published in journal of physics (e.g., Int. J. Mod. Phys. A 5 1745-1762 1990), not in philosophical magazines, as you seem to believe.

And you think MWI proponents have no answer to that article?

It is very ironic that you write about the role of axioms, because precisely one of the main criticism of the MWI literature is that its main advocates either lack to give a complete set of axioms, from which one could explain the physical world (reason for which the theory has been labeled «unscientific») or them give us a set of self-contradictory axioms (reason for the which «The theory is false because it is inconsistent»; quote X5 in this same thread).

The MWI camp generally holds that their axioms are the smallest set of anyone's. I think that's true, I just don't think that suffices as a reason to make it one's world view. Their axioms are indeed quite simple-- closed systems evolve according to the Schroedinger equation, and quantum mechanics describes what is really happening. That's it, those are the axioms of MWI. The irony is, a lot of people think those things are true, but simply don't realize that means they are adopting MWI.

Max Tegmark confounds physics with philosophy in his post-modern Radical Platonism: MUH.

Tegmark does not appear to view MUH as physics, he understands that it is philosophy. It is more the people like the Nobel laureate Weinberg who blur that distinction, when they invoke the anthropic principle in scientific arguments.

Steven Weinberg is also aware of the differences between physics and maths. Precisely in his textbook gravitation and cosmology, Weinberg explains why he follows what he calls a non-geometrical presentation of the subject, and remarks in the preface how the electromagnetic interaction cannot be understood in geometrical terms.

I don't see how your logic follows from that example. All he is saying is that geometric maths doesn't cut it-- he is a believer in complete unification. But he certainly feels that physics is converging on a true (mathematical) description of reality, he regards the anthropic principle as a scientific principle useful in making predictions, and he holds that a "landscape' of multiple universes is a valid scientific theory. All this while claiming that he sees no role for philosophy in physics. Like many, his own philosophy doesn't seem to count.

You have completely misinterpreted Feynman's point of view. He was not talking about the limitations of Euclidean geometry in regard to more general geometries. He was talking about the limits of mathematics and the differences with physics. He chose Euclidean geometry as an simple illustrative example adequate to his audience (people taking an introductory physics course).

What I said is that Feynman tends toward empiricism. That's quite true, yet identifying Feynman's philosophical preferences certainly does not support your position that philosophical preferences are irrelevant.

 

[BruceW]

juanrga, that's an interesting paper you mentioned. I found the preprint here: http://xxx.lanl.gov/PS_cache/gr-qc/pdf/9703/9703089v1.pdf
Just to make it clear at the start: In this paper, the guy is using the word 'axioms' to mean mathematical axioms (i.e. not to do with the philosophical meaning of the theory, but the actual physical core of it).

I think these 2 quotes summarise the paper pretty well:
Even in modern formulations MWI still seem seriously inadequate. Thus the aim of this paper is to argue that the literature neither contains nor suggests a plausible set of axioms for an MWI that describes known physics.
This means that the argument in the paper assumes that MWI must have different axioms to standard QM. So the guy who wrote this paper is talking about MWI as a separate theory to QM (not just a particular interpretation of QM).

The useful criticisms of MWI do not stem from an inability to accept the picture of multiple branching universes, nor do serious critics merely say that they do not see how to reduce macroscopic physics to an MWI. They assert either that particular physical facts are demonstrably not logically deducible from the axioms of MWI, or else they criticize the axioms proposed (usually on grounds of complexity or arbitrariness)
At the end of this quote, he seems to imply that it is possible to make MWI a different theory to QM and to make it agree with known physics, but then this makes the axioms complex/arbitrary. So this is a philosophical argument against MWI. (To paraphrase: 'yeah, it works, but I don't like the axioms.')

For most of the paper, he provides a few possible axiomatisations of MWI (as a separate theory to QM) and then shows that they each fail as a theory. So he's not providing a technical argument against MWI as an interpretation. He's providing technical argument against MWI as a different theory.

 

[juanrga]

If you will make that claim, please cite them. I didn't see any.
And you think MWI proponents have no answer to that article?

That was not the point.

The MWI camp generally holds that their axioms are the smallest set of anyone's. I think that's true, I just don't think that suffices as a reason to make it one's world view. Their axioms are indeed quite simple-- closed systems evolve according to the Schroedinger equation, and quantum mechanics describes what is really happening. That's it, those are the axioms of MWI. The irony is, a lot of people think those things are true, but simply don't realize that means they are adopting MWI.

The 'simple' Schrödinger postulate is already in QM. MWI advocates copied it but misinterpreted and misapplied (as correctly stated in the lost causes site).

What is more, there is not a single and consistent set of MWI axioms, with each MWI advocate proposing his owns. The irony is the pretension of the existence of one MWI formulation when there exist one per author.

Tegmark does not appear to view MUH as physics, he understands that it is philosophy.

He writes «physics» and has been precisely criticized by that.

It is more the people like the Nobel laureate Weinberg who blur that distinction, when they invoke the anthropic principle in scientific arguments.

Weinberg has been criticized by his use of such unscientific principle. But that was not the point.

I don't see how your logic follows from that example. All he is saying is that geometric maths doesn't cut it-- he is a believer in complete unification. But he certainly feels that physics is converging on a true (mathematical) description of reality, he regards the anthropic principle as a scientific principle useful in making predictions, and he holds that a "landscape' of multiple universes is a valid scientific theory. All this while claiming that he sees no role for philosophy in physics. Like many, his own philosophy doesn't seem to count.
What I said is that Feynman tends toward empiricism. That's quite true, yet identifying Feynman's philosophical preferences certainly does not support your position that philosophical preferences are irrelevant.

You misinterpret both Feynman and me again. He is not talking about philosophy but about the difference between physics and maths. If you read what he wrote, you will discover, with irony, that he starts his lecture with a critic of philosophers and of how the point of view of physics is superior when dealing with physical objects.

 

[juanrga]

juanrga, that's an interesting paper you mentioned. I found the preprint here: http://xxx.lanl.gov/PS_cache/gr-qc/pdf/9703/9703089v1.pdf
Just to make it clear at the start: In this paper, the guy is using the word 'axioms' to mean mathematical axioms (i.e. not to do with the philosophical meaning of the theory, but the actual physical core of it).

I think these 2 quotes summarise the paper pretty well:
Even in modern formulations MWI still seem seriously inadequate. Thus the aim of this paper is to argue that the literature neither contains nor suggests a plausible set of axioms for an MWI that describes known physics.
This means that the argument in the paper assumes that MWI must have different axioms to standard QM. So the guy who wrote this paper is talking about MWI as a separate theory to QM (not just a particular interpretation of QM).

The useful criticisms of MWI do not stem from an inability to accept the picture of multiple branching universes, nor do serious critics merely say that they do not see how to reduce macroscopic physics to an MWI. They assert either that particular physical facts are demonstrably not logically deducible from the axioms of MWI, or else they criticize the axioms proposed (usually on grounds of complexity or arbitrariness)
At the end of this quote, he seems to imply that it is possible to make MWI a different theory to QM and to make it agree with known physics, but then this makes the axioms complex/arbitrary. So this is a philosophical argument against MWI. (To paraphrase: 'yeah, it works, but I don't like the axioms.')

For most of the paper, he provides a few possible axiomatisations of MWI (as a separate theory to QM) and then shows that they each fail as a theory. So he's not providing a technical argument against MWI as an interpretation. He's providing technical argument against MWI as a different theory.

I think that all of this was answered before:

The preprint correctly states that none of the different MWI formulations found in the literature contains an internally consistent and complete set of axioms that reproduces the known physics. Either the axioms are contradictory or the predictions do not agree with what we observe in labs or both.

You already asked me about if MWI is an interpretation of QM or another theory, and you received at least two answers, one from mine.

 

[Ken G]

That was not the point.

In any event, I disagree with your "point". All I notice is you chose not to provide any of the support I requested that you provide.

You misinterpret both Feynman and me again. He is not talking about philosophy but about the difference between physics and maths. If you read what he wrote, you will discover, with irony, that he starts his lecture with a critic of philosophers and of how the point of view of physics is superior when dealing with physical objects.

Feynman was a terrific physicist, but his knowledge of, and appreciation for, anything else was not so legendary. In particular, he had nothing but disdain for both psychology and philosophy, but was never considered a master of either, indeed he was positively ignorant of both. I think we'll just have to give him a pass for his closedmindedness on both those counts. All I can say is, among those who don't know much about philosophy, there is a very clear tendency to adopt the attitude that philosophy is counted as anything that other people think.