Is there life after death according to MWI theory?

[spidey]

Please correct me if i am wrong.

As per MWI,when an observer open the box,schrodinger cat will be alive in
one world and the same cat will be dead in other world. If we replace the cat with human,then the dead human and alive human will be different worlds.so,my curious question is does this mean even for normal death after we are old,the dead human will be in one
world and the other alive human will be other world? so MWI says that there is life after death in other world? since we are in one world,we are able to see only the dead human and couldn't see the alive human who lives in other world?

 

[neu]

Well, I'm out of my depth here to be honest, but my ignorant understanding of MWI is that each possible instance of a fundamental process is played out in a different universe, such that at every possible juncture where there are mutiple possible paths each one is played out in a separate universe. The upshot being that for every decision you make there are an infinite other "yous" in an infinite number of other universes living out all the alternative possible decision combinations.

Hence if you decide not to J-walk across a motorway, then another you will decide to J-walk and get killed, hence you may be alive in one universe and dead in another.

MWI does not say that there is life after death, as for the guy that died, he is still dead. It depends how you view the "you" in each universe. Up until that crucial life or death decision you were exactly equivalent objects, but after the decision the universe "splits" and you are entirely separate non-equivalent objects. Please correct me if I've misunderstood.

As for Schrodinger's cat analogy that is all that it is; an analogy. The cat is analagous to a non-macroscopic (quantum) system that is in a quantum superposition of states, such that observation causes it to collapse into one state or the other. This is not a property of macroscopic systems (such as cats or humans). In MWI it is this property of quantum systems that means that quantum processes (which must surely underly the macroscopic world) exist in an "apparant" superposition where each state of the superposition exists throughout the multiverse. This means that the unfavourable idea of wavefunction collapse is replaced by another unfavourable idea of a multiverse, although the multiverse concept is also proposed in other non related areas of Cosmology and the like.

 

[Ciokko]

absolutely not, human death has nothing to do with superstate.

 

[ShakyJake]

Fascinating stuff. I suspect you've already read this, but here's the Wikipedia article on MWI in regards to the Quantum Suicide experiment:

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

Quantum suicide remains controversial because a number of thinkers disagree on its success or failure and particularly its irrelevance to life expectancy and decision making. A variation of this thought experiment allegedly suggests a controversial outcome known as quantum immortality, which is the argument that if the many-worlds interpretation of quantum mechanics is correct then a conscious observer can never cease to exist.

 

[neu]

Sorry, I've made a silly mistake on my previous post. When I was talking about Schrodinger's cat I was incorrect. Ignore what I said. I actually forgot the set-up of the experiment where the death is caused by radioactive decay. In the proper sense therefore of course, schrodinger's cat, or indeed a human in the box can be dead in one universe and alive in another, just as the J-walker lives and dies in different universes

 

[ShakyJake]

just as the J-walker lives and dies in different universes

The question is what possibilities can be realized? In your example you have two universes: one where a person j-walks and the other does not (dead/live). However, push the point closer to where we have a j-walker getting hit by a bus. In one universe he dies and in the other universes he survives. From the surviving one we then have a multitude of variations of his injuries -- from paralyzed, to broken bones, to bruises, to mysteriously uninjured? If MWI is correct, then all possible scenarios will play out.

Like the quantum suicuide thought experiment, I had another that would allow you to "easily" win the lottery:

Make a machine that will kill you if you do not possesses the winning numbers on your lottery ticket. Since the losing "yous" will all be terminated, the only surviving "yous" will be the ones that won the lottery. Since the winning numbers are determined randomly and HAVE to be affected by quantum uncertainty on SOME scale -- it would stand to reason that every possible winning combination is realized thus allowing at least one of "you" to win.

 

[neu]

Make a machine that will kill you if you do not possesses the winning numbers on your lottery ticket. Since the losing "yous" will all be terminated, the only surviving "yous" will be the ones that won the lottery. Since the winning numbers are determined randomly and HAVE to be affected by quantum uncertainty on SOME scale -- it would stand to reason that every possible winning combination is realized thus allowing at least one of "you" to win.

I don't know why you've introduced a machine gun into the equation; whether you kill yourself or not the same number of yous will win and loose. The machine gun doesn't affect the probabilities. If you die in one universe you don't then become yourself in another universe.

Just buy a lottery ticket don't try and be clever about it, you'll hurt/kill/maim/blind yourself all at once

 

[ShakyJake]

I don't know why you've introduced a machine gun into the equation; whether you kill yourself or not the same number of yous will win and loose. The machine gun doesn't affect the probabilities. If you die in one universe you don't then become yourself in another universe.

Actually, you would. Remember, we're talking about the moment in time the branching takes place -- when the machine determines if you won or lost the lottery depending on your numbers. By killing the "yous" that lost (thus ending your consciousness) the only active consciousnesses are the ones that won. If the transition is smooth (as in you aren't laying there bleeding to death) then, from your point of view, you come out of the machine a millionaire.

 

[spidey]

is the normal death also a quantum event,if so, then there should be an alive human in another universe...
i heard that worlds cannot communicate because of linearity..is there anyway that different worlds can communicate...

 

[peter0302]

The thing you have to remember about MWI is that "you" are irrelevant. What matters are the states of your particles. In some states (worlds) your particles will be arranged in such a way as to make a live organism. In others, they won't be. This roughly can be thought of as multiple copies of "you" but not in any form that you could ever interact with or be conscious of.

And also keep in mind that "you" will be dead in every world eventually because even quantum randomness cannot make someone live forever. But from a quantum perspective, all that means is that your molecules are no longer interacting in such a way as to support life. They're just in different states.

Since consciousness is likewise a function of chemistry, the same analysis applies. In some worlds the electrons in your brain are working together to make a consciousness, in others they're not.

Sorry if this sounds particularly secular or solipsist. No quantum interpretation can address the soul, so there's no point in trying to work it in. :)

 

[ShakyJake]

Here's a fun Wiki article on the subject:

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

 

[spidey]

Here's a fun Wiki article on the subject:

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

yeah..this is cool one..Many worlds interpretation is giving bizarre results but seems to be valid..

 

[peter0302]

Well, please don't confuse mainstream MWI with thus "quantum suicide" nonsense. There's solid math behind MWI and legitimate research. The quantum suicide thing is 100% speculation.

 

[QMecca]

No offense, but how is it people treat MWI as a religion, it got no upper hand in the "competition" of interpretations.

"MWI gives some bizarre results but seems to be valid", please show me what exactly make it seem anymore valid than RQM/BOHM/TI etc.?
Nothing.
Infact, everything we can observe (which is where we get ALL our external information about the external world from: aka source of the science) is not pointing towards splitting, but rather a single universe.

Many Worlds is just getting the most hype because it fits people's scifi fantasies, like the Quantum Suicide "thought experiment" that will fail.

One thing I've noticed among MWI proponents it got all the nutjobs, thinking it advocates all type of pseudoscience.
+ Everyone insists it's correct, like a religion, which makes me pretty sure even it's proponents are very very unsure of it themselves or they'd let the interpretation speak for them.

 

[Alfi]

No offense, but how is it people treat MWI as a religion,
One thing I've noticed among MWI proponents it got all the nutjobs,

No offense, but ... ? *sheesh* First post eh?
what a lame phrase, used in attempt to excuse a person from being offensive, as they proceed to be offensive.

please show me what exactly make it seem anymore valid than RQM/BOHM/TI etc.?

please show me what exactly make it seem any less valid than RQM/BOHM/TI etc.?

 

[Coldcall]

I would not go as far as QMecca, but i think he does have a point about qm interpretations in general.

They are all different philosophical explanations for the same physical phenomenom - qm.

However i don't think its right to call anyone a nutjob just because of their favoured qm interpretation, which is just an intepretation after all, and it does not challenge the maths which i believe all versions agree on, more or less.

Of course i also think there are some perfectly rational objections to MWI which have never been satisfactorily resolved.

 

[neu]

The concept of many worlds is also thrown up in serval areas of cosmology, for example, I think the simplest rationale for a multiverse is the anthropic principle: http://en.wikipedia.org/wiki/Anthropic_principle

 

[ShakyJake]

I agree that the thought of the universe continuously splitting into all probable possibilities sounds ridiculous. But is it any more ridiculous than waveform collapse being dependent on an observer?

What other mainstream interpretations exist besides Copenhagen and MWI that explain the phenomena we observe?

 

[Coldcall]

I agree that the thought of the universe continuously splitting into all probable possibilities sounds ridiculous. But is it any more ridiculous than waveform collapse being dependent on an observer?

What other mainstream interpretations exist besides Copenhagen and MWI that explain the phenomena we observe?

In my opinion Copenhagen (with 1 universe) can be seen to explain collapse in one of two ways: a)obseveration/measurement or b) interaction between the microcopic and macroscopic. So this is why i think it still remains popular because it allows different philosophical implications depending on one's favoured view.

There are other more specific interpretations such a "Transactional" or for instance "Conciousness causes collapse" which is actually just like Copenhagen but its making a further philosophical leap. I'm not sure but i believe Zurek's "decoherence" works in conjunction with MWI as the causation for branch universe splits.

I think they are all "ridiculous" to some extent but that's not surprising since qm itself presents us with some shocking paradoxes, compared to how we use to think the universe worked under the classical/Newtonian mindset.

However, i would say that even though i am highly skeptical about MWI; i can admit that it appears to be the most rational explanation in the context of Schrodinger's cat where we are asked to believe that the cat is entangled with the atomic decay superposition. In that case, if the cat really is entangled it presents a real paradox about what it is like to be the cat before we've looked in the box. Forget the observer because its more important to understand this issue from the point of view of the cat. What is going on with it? Is it non-existent? Is it both alive and dead in some weird physical state? Or as MWI would have us believe it exists in both an alive and dead universe. So for all pratical purposes the cat experiences death and life but in different realities.

I find the MWI explanation easier to believe, but then again i prefer Copenhagen on the whole because i do suspect an observer plays a sort of defining role in the universe. I would prefer an observer-essential MWI where its the observer's choices shunting him from one reality to the next.

Of course i am talking about what i think would be a more pleasing outcome philosophically. I could be a nut-job as they say :)

 

[peter0302]

What other mainstream interpretations exist besides Copenhagen and MWI that explain the phenomena we observe?

- Bohmian Mechanics (in short, particles surf waves like in Baja)
- Transactional (a total mess, but nonetheless "mainstream", I guess - in short, the particles give each other a wave "handshake" first followed by the actual force, all happening forward and backward in time)
- Ensenble Interpretation (it's all just statistics - though that doesn't really explain much).

 

[ShakyJake]

b) interaction between the microcopic and macroscopic. So this is why i think it still remains popular because it allows different philosophical implications depending on one's favoured view.

Now my understanding is that the act of observation which causes the collapse is NOT due to the detecting device interacting with the particles. I think I remember reading in "The Whole Shebang" that they crafted experiments that removed that possibility and still got the same results. It literally seems as if the act of observation caused the particles to behave differently.

 

[Coldcall]

Now my understanding is that the act of observation which causes the collapse is NOT due to the detecting device interacting with the particles. I think I remember reading in "The Whole Shebang" that they crafted experiments that removed that possibility and still got the same results. It literally seems as if the act of observation caused the particles to behave differently.

Well I'll play devils advocate because in truth i actually agree with your understanding of the observer's role in wave collapse.

However, the difficulty in proving the role of the observer is that how does one check on the results of any experiment without someone observing it? Hence the wave collapse can always be associated with the observer - even if the observer's role is not essential. This is annoying as is in some ways its obstructing progress in qm because a) most phycists don't want to think we live in an observer-created/defined reality b) don't want to think observers play any central role in the universe.

So we have a problem and this is why its called the "measurment problem". Its really a philosophical issue and hence why many phycists don't like getting into it. The famous "shut up and calculate" says it all :)

Personally i can accept an observer defined reality, if only because it solves some other conundrums such as why the universe is so suitable for life. It could be the basis for a kind of looped, self-explanatory universe which gets rids of the "tower of turtles" problem with other theories. Re: Wheeler's Participatory Anthropic Principle.

The only problem i have with an observer's type interpretation is when its dealing with the situation of another observer or lifeform being entangled in a superposition. For instance is Schrodinger's cat also an observer? Because if that is the case then the wave must collapse according to the cat's perspective (is the cat an observer too?) before the scientist looks to see if the cat is dead or alive. In that case MWI appears more rational because the cat has two existences in two separate realities.

However if there is something special about *human* observers so that their interaction is "special" and the wave cannot be collapsed by the cat then that's a pretty heavy thought. Extraordinary claims require extraordinary proof!

Personally if observers do play a central role i would be much more comfortable with the idea that all biology are observers. Humans being a special type of observer would in fact be quite scary and i think it would force a major rethink about pretty well everything.

 

[ShakyJake]

You have to excuse me, I'm a layman with no university education in physics and QM -- but I find it fascinating.

Having said that, my understanding of WHAT a "waveform collapse" is:

I know particles also behave as waves as the famous two slit experiment shows. The video I watched regarding the two-slit experiment shows that you get an interference pattern on the backboard when you fire photons at the slits. However, when you try to observe which slit each photon goes through then the interference pattern goes away and you see two lines instead just as you would expect particles to behave.

My takes on this from the MWI perspective is that when an observer does this, he is "forcing" himself into the universe(s) where the particle is just a particle and that, for whatever reason, we cannot make direct observations of when they become a wave.

 

[Coldcall]

You have to excuse me, I'm a layman with no university education in physics and QM -- but I find it fascinating.

Having said that, my understanding of WHAT a "waveform collapse" is:

I know particles also behave as waves as the famous two slit experiment shows. The video I watched regarding the two-slit experiment shows that you get an interference pattern on the backboard when you fire photons at the slits. However, when you try to observe which slit each photon goes through then the interference pattern goes away and you see two lines instead just as you would expect particles to behave.

My takes on this from the MWI perspective is that when an observer does this, he is "forcing" himself into the universe(s) where the particle is just a particle and that, for whatever reason, we cannot make direct observations of when they become a wave.

I'm a layman too However, i think qm is intereresting to many folks - particulalry those philosophically inclined - because it appears to be saying something very fundamental about the nature of reality.

I'm not sure i know what a decoherence or wave form collapse really represents in reality. If we knew what the nature of reality consists of inside a superposition - other than an abstract set of probabilties - then i think we'd be sure about what the collapse was really all about. The problem is that at this point we just understand the output, and the probability wave; but we don't know what's happening within the superposition physically - if anything.

Whats amazing is how well qm functions when we still don't quite know why or how exactly.

 

[QMecca]

I'm sorry, I did not mean to offend anyone.
I didn't mean that every proponent of MWI is a nutjob, just that in the camp of proponents of MWI you got a few "nutjobs" like Frank J Tipler, hell he has published books like "THE PHYSICS OF IMMORTALITY" AND "PHYSICS PROVE CHRISTIANITY" and then you got Max Tegmark who believes QM = MWI = IMMORTALITY.
+ David Deutsch who must be the most close-minded stubborn proponent of any INTERPRETATION ever, he simply denies that MWI can be wrong and I can see him start a "blind-faith" religion on MWI if it's proven wrong beyond all doubts.

I just don't get the PASSION behind it, there's so many problems with MWI, NOTHING hints in that direction, it's simply a idea at this level, no more than a random hypothesis.

I'm not saying that any of the other interpretations are more or less likely to be true, but if your a proponent, the burden of proof lies upon you, not me.I hope I didn't offend anyone, I'm not that good in the English language, I might come off a little misunderstood when I write.

Anyway, yeah there are like 20 diferent interpretations out there.
I tend to use common sense, logic and occam razor.

Consciousness collapse = kind of too "solipsist" to me.
MWI = gets you into the same type of "self-refuting" science (read Travis Norsen's "against realism" paper)

I'm a agnostic, but must admit the only realist interpretation out there who resolves all the mystery is BohmShakyJake, read about Bohm, it makes it all pretty simple to visualize, it resolves wave/particle dilemma simple: it's both, as it's pretty much shows in every emperical observation of QM.
The particle is lead by it's pilot wave, it only goes through ONE slit, while the wave goes through BOTH slits, causing the interference pattern.

 

[QMecca]

The concept of many worlds is also thrown up in serval areas of cosmology, for example, I think the simplest rationale for a multiverse is the anthropic principle: http://en.wikipedia.org/wiki/Anthropic_principle

The anthropic principle isn't in anyway favouring MWI.
I hate when people use that, it's the same with people who advocate it for virtual reality.
Well hell, the other universes that we've "branched" from must be IDENTICAL anyway, so WTF?
AP slits it's own wrists with Occam's razor.
Same with virtual reality and AP, the universe must be identical to support life in which someone can run a simulation, Occam razor again.

Sorry, there is nothing in cosmology that I've encountered that is very helpful for MWI, actually Antony Valentini is investigating cosmology in attempt to show Bohm is correct and I've read people say Bohm might actually be needed to explain quantum cosmology.

You got proponents and opponents on all sides.

 

[spidey]

No offense, but how is it people treat MWI as a religion, it got no upper hand in the "competition" of interpretations.

"MWI gives some bizarre results but seems to be valid", please show me what exactly make it seem anymore valid than RQM/BOHM/TI etc.?
Nothing.
Infact, everything we can observe (which is where we get ALL our external information about the external world from: aka source of the science) is not pointing towards splitting, but rather a single universe.

Many Worlds is just getting the most hype because it fits people's scifi fantasies, like the Quantum Suicide "thought experiment" that will fail.

One thing I've noticed among MWI proponents it got all the nutjobs, thinking it advocates all type of pseudoscience.
+ Everyone insists it's correct, like a religion, which makes me pretty sure even it's proponents are very very unsure of it themselves or they'd let the interpretation speak for them.

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...

 

[QMecca]

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.

 

[Hurkyl]

I just don't get the PASSION behind it, there's so many problems with MWI

MWI gets a different breed of criticism than other interpretations. Opponents of Copenhagen might complain about the fact that collapse is too ad hoc. Opponents of Bohm might complain that it's nonlocal. Opponents of MW often complain that it's preposterous to even consider such a thing, and seem to deny that it has any motivation.

I submit as evidence

NOTHING hints in that direction, it's simply a idea at this level, no more than a random hypothesis.​

It's wrong to say that "nothing hints in that direction". Essentially everybody agrees upon unitary evolution. It's main technical problem is that pure states cannot unitarily evolve into mixed states, which led to people postulating other things, like wavefunction collapse. However, the relative state formalism suggested a way around that problem which was confirmed by decoherence: unitary evolution causes pure states evolve in such a way that they 'locally' approximate classical statistical mixtures of states.

All of the evidence suggests unitary evolution happens, and these theoretical results suggest that unitary evolution by itself is capable of agreeing with experiment -- in other words, there are fairly solid hints in the direction of MWI.

 

[Maaneli]

MWI gets a different breed of criticism than other interpretations. Opponents of Copenhagen might complain about the fact that collapse is too ad hoc. Opponents of Bohm might complain that it's nonlocal. Opponents of MW often complain that it's preposterous to even consider such a thing, and seem to deny that it has any motivation.

I submit as evidence

NOTHING hints in that direction, it's simply a idea at this level, no more than a random hypothesis.​

It's wrong to say that "nothing hints in that direction". Essentially everybody agrees upon unitary evolution. It's main technical problem is that pure states cannot unitarily evolve into mixed states, which led to people postulating other things, like wavefunction collapse. However, the relative state formalism suggested a way around that problem which was confirmed by decoherence: unitary evolution causes pure states evolve in such a way that they 'locally' approximate classical statistical mixtures of states.

All of the evidence suggests unitary evolution happens, and these theoretical results suggest that unitary evolution by itself is capable of agreeing with experiment -- in other words, there are fairly solid hints in the direction of MWI.

Actually, the criticisms of MWI are more severe than the others (spare CI which is just too vague to begin with). BTW, I've noticed an unfortunate tendency of people here to equate CI with textbook QM. They are not actually the same thing. Some people criticize MWI by saying that it is unlikely to be a self-consistent interpretation because there seems no clear way to ensure that "observers" in a "world" will always see the Born rule probability distribution. Many of the best philosophers of physics today such as Tim Maudlin, Guido Bacciagaluppi, David Albert, and others have criticized the interpretation of probabilities in MWI, and though I have not followed their critiques in great detail, I believe that is a plausible reason to be skeptical of MWI compared to other formulations of QM. Indeed, there is no such similar controversey about the derived quantum probabilities in pilot wave theory or stochastic mechanics or GRW collapse theory.

I agree with you Hurkyl that the existence of a linear, unitary evolution is a necessary condition for MWI, and to that extent, there is at least that evidence in its favor. But that still doesn't distinguish it from pilot wave theory or other unitary quantum theories. Moreover, to date there actually is no evidence that QM evolution MUST be unitary. In other words, there are theories with nonunitary collapse and nonlinear wavefunction evolution (the GRW theories), which are nonetheless currently empirically indistinguishable from the unitary and linear interpretations of QM. However, because of this nonlinear stochastic evolution law, GRW theories make slightly different predictions for the expectation values of POVM's, and Zeilinger has said "we will be able to do the experiments to test GRW collapse theories in 10 years".

In case nobody knows, there was a conference on Everett MWI last year, debating its merits and demerits:

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

 

[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?