Is there life after death according to MWI theory?

[Maaneli]

But that's sort of tangential to my point -- proponents of MWI have to clear a huge hurdle before they can even begin to have a serious discussion about the pros and cons of their interpretation as compared to other ones, and once they do, they are still at a disadvantage due to the high degree of skepticism that many others would start such discussions with. So, I don't find it that surprising that the proponents of MWI tend to be more passionate about it than proponents of other interpretations.


I have one brief comment on your comments:

I don't think you can ensure that in any interpretation -- probabilities are fickle like that.

Historically, the serious specialists that I mentioned who have opposed MWI have been able to come up with arguments independent of their personal disbelief in the ontology of MWI.

Actually, you can ensure in other formulations of QM that probabilities are *most likely* to be conserved. Read about the typicality and subquantum H-theorem arugments for pilot wave theory and stochastic mechanics. GRW theories also have a completely well-defined probability evolution given by a stochastic collapse law. These approaches also suggest new predictions. MWI on the other hand heavily relies on decision theoretic arguments to show that an observer in any world will *always* see the Born rule, and these arguments are subject to dispute in a way that the arguments for the other formulations aren't.

 

[Hurkyl]

Does anyone know whether we know for *certain* whether Schrodinger's cat is in fact entangled with the wave function of the decaying atom? Has anyone ever tested this experiment or one like it?

Thermodynamics would make it effectively impossible to test it with an actual cat. What do you mean by 'like' here? There are lots of experiments that demonstrate entanglement.

 

[Hurkyl]

however until there is any good evidence in MWI's favour or other parallel universe hypothesis people

There is good evidence for parallel universes: that's what you get from unitary evolution. A 'world' is a component of a quantum state; most (all?) quantum interpretations have them. Even the Copenhagen interpretation has them between measurement events.

You're not thinking of 'parallel universes' in the way science fiction does, are you? That has nothing to do with the topic at hand.

 

[peter0302]

Yep. In fact, a single universe requires more assumptions than many-worlds, i.e., wavefunction collapse. MWI is little more than eliminating the collapse postulate.

But I agree there's no *evidence* right now that anyone interpretation is more likely to be right, and that includes MWI. I prefer it - slightly - merely because it requires fewer postulates and because I rather enjoy the idea of every possibility - even remote ones - actually occurring. :) (Of course, the bad possibilities are equally likely as the good, so maybe that's not so good after all...)

You're not thinking of 'parallel universes' in the way science fiction does, are you? That has nothing to do with the topic at hand.

"Parallel universes" are, however, a consequence of taking the interpretation to its logical conclusion, are they not?

 

[QMecca]

WOAH, you seriously said "single universe requires MORE assumptions than infinite SPLITTING(noone has ever ever ever ever ever ever seen this magical splitting taking place) universes?"

That's crazy.

Solipsism requires less assumptions than objective reality, your just god, simple.
Seriously man... you going to get shaving sores with the way you use that razor

 

[spidey]

It's a logical fallacy, but however, it doesn't have that wide acceptance among physicists.
Your logic is a bit faulty, true, just because we can't detect them in ANYWAY it doesn't mean they don't exist, just like God, ghosts, pink unicorn, valhalla etc.
Hence: it's nothing but an idea.
Given our evidence, occam razor says: single world.
Occam Razor is no "God method" that is omniscient, however until there is any good evidence in MWI's favour or other parallel universe hypothesis people should refrain from advocating them as "true" as a mental-masturbation-exericse, sure, as factual science, NO!
.

MWI is no strange than wavefunction collapse...MWI gives every possible outcome in different worlds...it also solves paradoxes related to time travel...

 

[spidey]

Spidey,

"The two widely accepted interpretations among the scientific community are copenhagen and MWI ... the greats who believe in MWI are Richard feynman,hawking,wheeler and many others...do u think that they believed MWI for no valid reason? MWI solves all paradoxes unlike other interpretations... "

The problem with that is scientists are human like everyone else which means they can have biased opinions like the rest of us. By the way Wheeler, if his theories are anything to go by, suspected the observer defined reality version of qm.

I rememeber seeing a science documentary during the early 80s with Hawking and a few other tier1 phycists. The program was about whether there were other planets around stars as in the case of our solar system. Hawking is on record saying more or less "probably not - we are a fluke event, including the planets". He was very very very wrong. Not just a little.

The other reason why i doubt the opinion of many phycists on MWI is because there is a loathing in scientific circles to accept the real paradox at the heart of the measurement problem - the observer. Hundreds of not thousands of experiments have been devised in order to rule out the "observer" as a causal factor in wave collpase. All have failed so far.

My advice is treat scientific opinion as you would treat any other.

Yes,I agree that opinions of scientists can also be wrong but they don't give their opinions just like that and without knowing that...there would be valid reasons for their opinions...
one thing why i like MWI is that it solves time travel paradoxes...and i believe MWI is no strange than wavefunction collapse...

 

[Coldcall]

spidey,

"Yes,I agree that opinions of scientists can also be wrong but they don't give their opinions just like that and without knowing that...there would be valid reasons for their opinions..."

The problem is scientists err on the side of caution; as in the example i gave you from Stephen Hawking where he claimed only 25 years ago that our solar system with planets were probably a fluke. Did he really think that or did he just think he would follow the pragamatic line of thinking at the time?

I like to take Kuhn's thinking on how science progresses which is that the majority of "consensus" scientists are not doing anything too exciting and instead adding little bits of knowledge to standard theories such as qm, SR, Chaos etc...The scientists who have changed paradigms are usually revolutionary types who at first were scoffed at by their peers such as Einstein and even Newton.

In relation to qm interpretations one has to take into consideration why we need all these various different philosophical models for what is essentially the same thing - qm.

 

[peter0302]

WOAH, you seriously said "single universe requires MORE assumptions than infinite SPLITTING(noone has ever ever ever ever ever ever seen this magical splitting taking place) universes?"

And yet someone has seen the "pilot wave" or the wavefunction collapse? Hm...

That's crazy.

Well that's a scientific observation if I've ever seen one.

Seriously man... you going to get shaving sores with the way you use that razor

Hehe, now that is funny.

 

[Hurkyl]

WOAH, you seriously said "single universe requires MORE assumptions than infinite SPLITTING ... universes?"

Well, yeah. Unitary evolution (the mechanism by which worlds split) is extremely well-tested, and a central component of every interpretation of quantum mechanics^*. In order to get a single world, you need to postulate the existence of an additional form of dynamics.

*: At least, all that I know of

(noone has ever ever ever ever ever ever seen this magical splitting taking place)

How do you figure? We see the effects of splitting all the time on microscopic scales -- Bell tests, quantum erasure experiments, quantum computers, ...

 

[Hurkyl]

Okay, I don't think I risk sidetracking serious discussion by asking more about this...

Actually, you can ensure in other formulations of QM that probabilities are *most likely* to be conserved. Read about the typicality and subquantum H-theorem arugments for pilot wave theory and stochastic mechanics.

But the point was that it couldn't be ensured -- it's not really fair to complain that MWI doesn't give a guarantee when other theories cannot.

MWI on the other hand heavily relies on decision theoretic arguments to show that an observer in any world will *always* see the Born rule, and these arguments are subject to dispute in a way that the arguments for the other formulations aren't.

Specific references on this would be nice. The cursory reading I've done lately seem to suggest the case is much more solid than you indicate, and I've worked out my own exercise to convince myself that the frequentist probabilities come out correctly, at least in a simple case...

You say above that these other interpretations are 'most likely' to work out; however, there's a subtle problem with such a criterion: either you have introduced a circular dependence on the very probabilities you're trying to justify, or you have a bootstrap issue about where these first likelihoods come from. I will assume the arguments you describe have an adequate alternate notion of 'likelihood'. But as far as I can tell, MWI does too.

GRW theories also have a completely well-defined probability evolution given by a stochastic collapse law.

Upon a very cursory first glance, it would seem that GRW would be incompatable with macroscopic quantum effects, such as superpositions of currents or Bose-Einstein condensates. How is this reconsiled?

 

[Maaneli]

Okay, I don't think I risk sidetracking serious discussion by asking more about this...


But the point was that it couldn't be ensured -- it's not really fair to complain that MWI doesn't give a guarantee when other theories cannot.


Specific references on this would be nice. The cursory reading I've done lately seem to suggest the case is much more solid than you indicate, and I've worked out my own exercise to convince myself that the frequentist probabilities come out correctly, at least in a simple case...

You say above that these other interpretations are 'most likely' to work out; however, there's a subtle problem with such a criterion: either you have introduced a circular dependence on the very probabilities you're trying to justify, or you have a bootstrap issue about where these first likelihoods come from. I will assume the arguments you describe have an adequate alternate notion of 'likelihood'. But as far as I can tell, MWI does too.



Upon a very cursory first glance, it would seem that GRW would be incompatable with macroscopic quantum effects, such as superpositions of currents or Bose-Einstein condensates. How is this reconsiled?

Hurkyl,

I am referencing this article by Vaidman on MWI, which discusses the problems with the interpretation of probability under sections 4, 5, 6.

http://plato.stanford.edu/entries/qm-manyworlds/#4

Also this conference on Everett MWI (which used to have transcripts of the discussions). In particular, see the abstracts of Albert, Maudlin, and Valentini.

http://users.ox.ac.uk/~everett/abstracts.htm#bub

Also, pilot wave theories do a better job at deriving the Born rule because one can always show by Valentini's H-theorem that if a configuration of particles starts out of quantum equilibrium, it will be guaranteed to relax to rho = |psi(x,t)|^2 in the future. The typicality arguments of DGZ show that if rho = |psi(x,t)|^2 for the universal wavefunction, then conditional wavefunctions describing subsystems of particles in the universe will also be guaranteed to be rho = |psi(x,t)|^2 distributed for all times (this is called equivariance). This is what I mean by "ensures". MWI on the other hand has trouble with preserving the Born rule even if an observer starts out seeing the Born rule probability distribution initially. Would you like me to reference the papers on derivations of the Born rule in pilot wave theories?

 

[Maaneli]

Upon a very cursory first glance, it would seem that GRW would be incompatable with macroscopic quantum effects, such as superpositions of currents or Bose-Einstein condensates. How is this reconsiled?

They aren't inconsistent. A BEC for example is still a relatively microscopic (micron-size), low density configuration of particles. And even then, they don't last beyond the order of a few seconds, depending on a number of parameters. Decoherence always eventually happens. That is what GRW would essentially predict with its stochastic collapse law.

 

[peter0302]

Hey Hurkyl, do you know anything about Deutsch's claims that he proved the Born rule using nothing more than Everett's assumptions? Has that claim held up?

If so I'd say that by Occam's standards MWI is definitely in the lead.

 

[Hurkyl]

Hey Hurkyl, do you know anything about Deutsch's claims that he proved the Born rule using nothing more than Everett's assumptions?

I'm sure I've heard of that claim before, but I don't know the specifics. I view Deutsch with skepticism, though: as I vaguely recall, he tends to claim far more than I believe appropriate.

If so I'd say that by Occam's standards MWI is definitely in the lead.

You can do better still. All observations you ever make will be conditioned upon, for example, the fact you submitted a PF post at 20:35 EDT on 7-19-2008. There are a wide variety of quantum states that become completely indistinguishable when conditioned upon that fact. This suggests we should seek to further tweak the theory to eliminate this redundancy: allow for many different quantum states are perfectly accurate representations of the same physical state.

(Compare to allowing many different kets to refer to the same quantum state, or many different coordinate charts to represent the same space-time)

IMHO, this greatly simplifies a variety of conceptual 'issues' and allows a sort of unification of a lot of the ways of thinking about quantum mechanics. I believe this to be the essense of the relational interpretation, although it's presented from a different perspective.

 

[muppet]

In response to the OP... it's interesting to note that Everett believed in quantum immortality- that somewhere, in one of the infinitely many branches of the universal wavefunction, you just carried on going for ever. His daughter killed herself, and left a suicide note sying that she would join her father in a parallel universe- which goes to show he should have explained it to her properly

The thing I don't like about Everett's interpretation is that particles don't really exist within it (at least not in his original proposal, which is the variant I know most about, and the only one I've heard which really makes sense). To me there doesn't seem to be anything that unites the eigenfunctions of the various operators- such diverse functions as complex exponentials and dirac delta functions- as single 'state' without some localised(ish ) particle, the various different properties of which they are merely descriptions.

 

[peter0302]

His daughter killed herself, and left a suicide note sying that she would join her father in a parallel universe- which goes to show he should have explained it to her properly

Good heavens, is that true?

That just goes to show you how quantum interpretation can have just as profound an impact - and just as potentially dangerous - as a religious belief. I still say that there is a fine line between scientific interpretation and religion.

 

[peter0302]

ROFLMAO. That last post was my 666th. That's spooky!

 

[QMecca]

Well, this is one of my very very deep concerns about people like Deutsch going mass-public saying he got some PROOF of MWI, which everyone who knows the first thing about QM knows he doesn't.
However nonscience interested people doesn't, they appeal to authority.

David Deutsch is just too crazy for me..
He just believes in it more than Kent Hovind believe in christianity, which makes him borderline obsessed, which gets in way of the science.
Presenting the idea of immortality like "well no known physical laws goes against it", uhm well, uh, death do.
It's crazy... which is why I believe whenever quantum mechanics is presented in the news or whatever it should be stricktly said: THIS IS A PERSONAL OPINION, not science, not facts, this is this persons VIEW/FAITH.

I mean even if some form of MWI turned out to be true, quantum immortality isn't implied by it. I even believe Deutsch has that view.


The fact there's no 50000000000 year olds in this universe pretty much debunks quantum immortality for me.

 

[Coldcall]

Hurkyl,

"How do you figure? We see the effects of splitting all the time on microscopic scales -- Bell tests, quantum erasure experiments, quantum computers, ... "

No; we see decoherence or wave function collapse occur we see no evidence of "splitting of universes".

MWI proponents do themselves no favours by using such semantics. The "decoherence" mob did the same thing by claiming that it resolved the measurement problem when in fact it did nothing of the sort.

 

[peter0302]

You're missing mine and Hurkyl's point. Wavefunction collapse is an assumption on top of splitting, not in lieu of. You need an extra step to get rid of the extra worlds, and that is where there is no evidence.

Also, interpreatively, it's pretty difficult to explain DCQE without at least resorting to many-worlds for part of the experiment (i.e. in between the time the first photon hits and the second photon hits, the worlds have split, and then come together if the second photon hits the eraser). If you believe in one-world, retrocausality is pretty much the only explanation you have left.

 

[muppet]

Peter: that was taken from the Wikipedia entry on Hugh Everett III; it looks like the references are to online material if you want to check it up. I should probably have also mentioned that she was a schizophrenic .

 

[QMecca]

You're missing mine and Hurkyl's point. Wavefunction collapse is an assumption on top of splitting, not in lieu of. You need an extra step to get rid of the extra worlds, and that is where there is no evidence.

THIS is pure ******** Peter, I'm a little rush so I can't go into details, but the first noncollapse interpretation proposed was put forth before the Solvay conference: PILOT WAVE THEORY.
I say no more, it accounts for wave/particle duality better than ANYONE, nothing is rejected. No problem with probability.

I agree proposing a collapse of wavefunction caused by observation = ********.
The appearance of wavefunction collapse is due to the fact particles exist AND waves.
It doesn't reject either.
Neither does it propose any other universes or "splitting".
So yeah, deBB add least of all, it just takes into account all that exist and don't speculate too much.
Seculation is good, but until experiments, it's worth nothing and is nothing.

 

[Maaneli]

THIS is pure ******** Peter, I'm a little rush so I can't go into details, but the first noncollapse interpretation proposed was put forth before the Solvay conference: PILOT WAVE THEORY.
I say no more, it accounts for wave/particle duality better than ANYONE, nothing is rejected. No problem with probability.

I agree proposing a collapse of wavefunction caused by observation = ********.
The appearance of wavefunction collapse is due to the fact particles exist AND waves.
It doesn't reject either.
Neither does it propose any other universes or "splitting".
So yeah, deBB add least of all, it just takes into account all that exist and don't speculate too much.
Seculation is good, but until experiments, it's worth nothing and is nothing.

QMecca is right. Also, the pilot wave theory is actually mathematically simpler than MWI because the guiding equation is deduced directly from the Schroedinger continuity equation. It is just the ratio of the quantum probability current J and the quantum probability density rho so that

dQ/dt = J/rho.

That's all. No measurement postulates of any kind, and no convoluted decision theoretic arguments to justify quantum probabilities.

 

[Hurkyl]

THIS is pure ******** Peter, I'm a little rush so I can't go into details, but the first noncollapse interpretation proposed was put forth before the Solvay conference: PILOT WAVE THEORY.

As I understand it, the pilot wave is mathematically the same as the wavefunction, evolving according to ordinary unitary evolution -- and therefore splits into worlds.

 

[Hurkyl]

So yeah, deBB add least of all, it just takes into account all that exist and don't speculate too much.
Seculation is good, but until experiments, it's worth nothing and is nothing.

It's not always about speculating about reality. I don't really care one whit about the question about what is 'really' real, and view that whole line of discussion is mainly an excuse for people to trumpet their personal biases. However, there is also pedagogy to be considered -- how to organize and understand the information contained in the theory. In that respect, MWI is the most important interpretation, since its aim is to understand unitary evolution, a mechanic present in most (all?) approaches to quantum mechanics.

 

[peter0302]

I don't really care one whit about the question about what is 'really' real, and view that whole line of discussion is mainly an excuse for people to trumpet their personal biases.

Agreed!

Peter, I'm a little rush so I can't go into details, but the first noncollapse interpretation proposed was put forth before the Solvay conference: PILOT WAVE THEORY.

I never said MWI was the first. Lord knows, being first rarely means being best.

I say no more, it accounts for wave/particle duality better than ANYONE, nothing is rejected. No problem with probability

Better than ANYONE, eh? Incidentally, where did this sudden influx of Bohm Zealots come from?

Anyway, pilot wave theory is still a hidden variable theory. It still requires more assumptions than MWI, namely that there is a real particle whose position is well defined which is being guided by the potential wave which is a real force.

It does, like MWI, get rid of the collapse postulate. But it replaces the collapse postulate with the "hidden" particle, and so the appearance of collapse is a consequence of the fact that there _is_ a hidden particle which is influenced by different branches of the wave depending on when/where it's located.

However, MWI still needs fewer assumptions, and this is the reason: get rid of the guiding potential and the hidden particle, and you've got MWI - which, alone, can account for all experimental results. This is true essence of the oft-misunderstood Occam's razor (despite the risk of nicking my face with it). This, plus the fact that you have no problems with nonlocality, retrocausality, or mandatory agnosticism, which all plague one or more of the various other interpretations. And, it's the only interpretation which, to my knowledge, has a snowball's chance of ever being disproven (depending on what ever comes of quantum gravity theory) and has led to useful new research (i.e. decoherence, which is becoming central to quantum computing). And it's the first time in history science has provided a candidate for the answer to the age-old question "why are we here?" (MWI's answer: every one and every thing is every where).

All in all I'd say Everett has made quite a contribution to physics and philosophy and the way his work has been bastardized, misinterpreted, and ridiculed by some is quite a shame.

Rather than you saying to me "show me the evidence of the extra worlds," I should be saying to you "show me evidence of this pilot wave and this hidden particle, and moreover explain to me where the energy comes from to make this mystical wave." Similarly, to Copenhagenists I would say "give me a logically self-consistent and objective physical definition of wavefunction collapse and show me the evidence for it." Since we all agree that unitary evolution and decoherence is occurring, the burden of proof is on those of you who believe something more is going on. Otherwise, MWI wins by default.

Oh, darn that's me arguing like a lawyer again.

 

[QMecca]

Asking where the energy for the wave comes from is rather retarded for someone defending a hypothesis who claim it makes infinite universes out of nothing all the time...

 

[peter0302]

You really have a mastery for labels don't you? Retarded, crazy, *****, and so forth. Shame you can't actually say anything substantive about the topic, because this statement:

claim it makes infinite universes out of nothing all the time...

Demonstrates you don't know what you're talking about.

But if you're interested in expanding your horizons beyond your personal notions of what is and is not "retarded" I suggest you read this:

http://www.hedweb.com/manworld.htm

 

[QMecca]

I was responding your own arrogance in the same manner.

"Where does the energy for the wave come from".

Think about it for a second...

 

[peter0302]

Read the FAQ, and you'll see why your point is wrong.

I'll give you a hint:

Slice a piece of paper in half. You now have two pieces of paper. Did you need more wood to make that extra piece?

 

[QMecca]

still requires infinite energy.
from your anology, everytime you split you should lose energy and become nothing eventually, pretty quick actually. lol
I know the anology doesn't fit what your believing in, I'm just saying:

debb says there's only one universe, the universe = particles.
finite, deterministic, objective.

simpler than infinite unobserved universes...



Also: if you truly believe in MWI, why bother even talking / discussing these matters, everyone you interact with are gone in 00000000000000,1nano seconds.

 

[Maaneli]

As I understand it, the pilot wave is mathematically the same as the wavefunction, evolving according to ordinary unitary evolution -- and therefore splits into worlds.

Hurkyl,

Yes, the pilot wave is mathematically the same as the wavefunction. But you can't say it splits into "worlds" because that is an MWI concept, and deBB theory is a different theory than MWI. You can however say the pilot wave in deBB branches (after a measurement interaction) from an initial superposition state, and the point particle continues into only one of those branched eigenstates and gets piloted by it for all subsequent times, according to the Schroedinger and guiding equations. The other empty wavefunctions propagated away and still evolve according to the Schroedinger equation. In the experiment (measurement), we only see the point particle, and the wavefunction is never directly observed as you probably know. This is another argument that deBB proponents would make for why deBB theory has a clearer ontology than MWI - it more directly explains what we fundamentally see in experiments: particles. Personally, I have never been able to understand what a "world" in MWI is exactly. Could you explain it?

By the way, decoherence theory already also implies that the most fundamental observable basis for the wavefunctions in a measurement interaction is in fact the position basis, which is what the pilot wave also says. In other words, all measurement interactions (the pointers in a measuring device) can ultimately reduced to position measurements. That is another big difference between MWI and deBB theory.

By the way, there is yet another big difference between MWI and deBB theory. The evolution of quantum probabilities. As I have also referenced elsewhere in this forum, while MWI cannot predict anything beyond the Born rule (quantum equilibrium in the pilot wave language) probability time evolution of the psi field, the deBB theory predicts the possibility of nonequilibrium dynamics. For example please, read here Valentini's abstract from a recent conference on Everett's MWI:


Pilot-wave theory: Everett in denial? - Antony Valentini

We reply to claims (by Tipler, Deutsch, Zeh, Brown and Wallace) that the pilot-wave theory of de Broglie and Bohm is really a many-worlds theory with a superfluous configuration appended to one of the worlds. Assuming that pilot-wave theory does contain an ontological pilot wave (a complex-valued field in configuration space), we show that such claims arise essentially from not interpreting pilot-wave theory on its own terms. Pilot-wave dynamics is intrinsically nonclassical, with its own (`subquantum') theory of measurement, and it is in general a `nonequilibrium' theory that violates the quantum Born rule. From the point of view of pilot-wave theory itself, an apparent multiplicity of worlds at the microscopic level (envisaged by some many-worlds theorists) stems from the generally mistaken assumption of `eigenvalue realism' (the assumption that eigenvalues have an ontological status), which in turn ultimately derives from the generally mistaken assumption that `quantum measurements' are true and proper measurements. At the macroscopic level, it might be argued that in the presence of quantum experiments the universal (and ontological) pilot wave can develop non-overlapping and localised branches that evolve just like parallel classical (decoherent) worlds, each containing atoms, people, planets, etc. If this occurred, each localised branch would constitute a piece of real `ontological Ψ-stuff' that is executing a classical evolution for a world, and so, it might be argued, our world may as well be regarded as just one of these among many others. This argument fails on two counts: (a) subquantum measurements (allowed in nonequilibrium pilot-wave theory) could track the actual de Broglie-Bohm trajectory without affecting the branching structure of the pilot wave, so that in principle one could distinguish the branch containing the configuration from the empty ones, where the latter would be regarded merely as concentrations of a complex-valued configuration-space field, and (b) such localised configuration-space branches are in any case unrealistic (especially in a world containing chaos). In realistic models of decoherence, the pilot wave is delocalised, and the identification of a set of parallel (approximately) classical worlds does not arise in terms of localised pieces of actual `Ψ-stuff' executing approximately classical motions; instead, such identification amounts to a reification of mathematical trajectories associated with the velocity field of the approximately Hamiltonian flow of the (approximately non-negative) Wigner function --- a move that is fair enough from a many-worlds perspective, but which is unnecessary and unjustified from a pilot-wave perspective because according to pilot-wave theory there is nothing actually moving along any of these trajectories except one (just as in classical mechanics or in the theory of test particles in external fields or a background spacetime geometry). In addition to being unmotivated, such reification begs the question of why the mathematical trajectories should not also be reified outside the classical limit for general wave functions, resulting in a theory of `many de Broglie-Bohm worlds'. Finally, because pilot-wave theory can accommodate violations of the Born rule and many-worlds theory (apparently) cannot, any attempt to argue that the former theory is really the latter theory (`in denial') must in any case fail. At best, such arguments can only show that, if approximately classical experimenters are confined to the quantum equilibrium state, they will encounter a phenomenological appearance of many worlds (just as they will encounter a phenomenological appearance of locality, uncertainty, and of quantum physics generally). From the perspective of pilot-wave theory itself, many worlds are an illusion.
http://users.ox.ac.uk/~everett/abstracts.htm#valentini

And see this:

Generalizations of Quantum Mechanics
Philip Pearle and Antony Valentini
Published in: Encyclopaedia of Mathematical Physics, eds. J.-P. Francoise, G. Naber and T. S. Tsun (Elsevier, 2006).
http://eprintweb.org/S/authors/All/va/Valentini/8


So these are all the reasons why it is not possible to say that pilot wave theory simply reduces to MWI. Hope this helps.

 

[Hurkyl]

So these are all the reasons why it is not possible to say that pilot wave theory simply reduces to MWI. Hope this helps.

That is not what I was saying. I am claiming:

MWI employs particular methods to study the evolution of a state evolving unitarily.
The evolution of a pilot wave, is mathematically equivalent to a state evolving unitarily.
Therefore, the methods employed by MWI may be used to study the evolution of a pilot wave.



However, I admit that do I expect a formal equivalence here, and furthermore one that equates the "unitary evolution of universal wavefunction" part of MWI with the "unitary evolution of pilot-wave" part of BM. In addition to the observation above, this would merely require:
(1) A demonstration that every universal wavefunction permitted by MWI is capable of appearing as a pilot wave in some instance of BM.
(2) The identification of a structure definable in the MWI formalism (but not necessarily physically definable or even observable) to which the particle component of BM can be mapped.
Mathematics is surprisingly robust in regard to its ability to achieve feats like this. But I do not intend to assert in this thread that such an equivalence exists.

 

[Maaneli]

That is not what I was saying. I am claiming:

MWI employs particular methods to study the evolution of a state evolving unitarily.
The evolution of a pilot wave, is mathematically equivalent to a state evolving unitarily.
Therefore, the methods employed by MWI may be used to study the evolution of a pilot wave.

Sorry for the misunderstanding. I was addressing both you and the other guy on your side.

I disagree with your thesis. The only methods MWI employs on the evolution of a psi field is an interpretation of the psi field as a physically real world with a classical evolution. It also requires a way of justifying that rho = |psi|^2 for the observers in these psi fields, and it cannot do this without additional decision theoretic assumptions (BTW, this is why it is not the simplest interpretation of QM even though it is claimed to be). Valentini explains in that abstract I posted why a thesis like yours cannot work.