Is there life after death according to MWI theory?

[spidey]

Uhm, after what I've read Hawking and Weinberg believe MWI is true in a "abstract sense" like 5 is a abstract number, while 5 cows are real.

As for Feynman and Wheeler, I thought they were inspiration for J G Cramer to come up with Transactional Interpretation, where did they defend MWI?

Hawking was made famous and the "new Einstein" for his work on black holes which turned out wrong, I'm not saying he is not smart as hell, but I wouldn't then place him on a pedastol and say everything he agrees with is right.

Also "MWI solves all paradoxes unlike other interpretations" wrong, debroglie-bohm does that too, simpler and less occam razor sores.
Plus, if your going to appeal to authority, I'd say Louis de-Broglie, David Bohm, John S. Bell are 3 just as "the greats", don't you?
Not to mention Einstein who made it his mission to convince David Bohm to not abounded realism.

Please read
http://en.wikipedia.org/wiki/Many-worlds_interpretation#Acceptance_among_physicists

MWI is getting good support from scientific community and is increasing...Just because we couldn't see or feel or prove other worlds,it doesn't mean that there are no worlds other than ours..

 

[Coldcall]

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.

 

[Hurkyl]

Actually, the criticisms of MWI are more severe than the others (spare CI which is just too vague to begin with).

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:

Some people criticize MWI by saying ... there seems no clear way to ensure that "observers" in a "world" will always see the Born rule probability distribution.

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

 

[QMecca]

Please read
http://en.wikipedia.org/wiki/Many-worlds_interpretation#Acceptance_among_physicists

MWI is getting good support from scientific community and is increasing...Just because we couldn't see or feel or prove other worlds,it doesn't mean that there are no worlds other than ours..

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 considered by some to be unfalsifiable and hence unscientific because the multiple parallel universes are non-communicating, in the sense that no information can be passed between them. Others[34] claim MWI is directly testable. Everett regarded MWI as falsifiable since any test that falsifies conventional quantum theory would also falsify MWI.[35]

According to Martin Gardner MWI has two different interpretations: real or unreal, and claims that Stephen Hawking and Steve Weinberg favour the unreal interpretation.[36] Gardner also claims that the interpretation favoured by the majority of physicists is that the other worlds are not real in the same way as our world is real, whereas the "realist" view is supported by MWI experts David Deutsch and Bryce DeWitt. However Stephen Hawking is on record as a saying that the other worlds are as real as ours[37] and Tipler reports Hawking saying that MWI is "trivially true" (scientific jargon for "obviously true") if quantum theory applies to all reality[38]. Roger Penrose agrees with Hawking that QM applied to the universe implies MW, although he considers the current lack of a successful theory of quantum gravity negates the claimed universality of conventional QM

If you take Tipler as a serious physicist I must disagree, but if you apply QM to the universe, any interpretation can be true, that's the problem.
As for Weinberg, read his e-mail exchanges with Sheldon Goldstein, he doesn't seem very much into the whole interpretational thing, he just don't bother with it.
I'm sure if you gave him all the information about other interpretations he would agree with them too, because all agree with QM.

 

[Coldcall]

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?

 

[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.