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    Modest Agnostics Expect A Multiverse And Hold Many Worlds True
    By Sascha Vongehr | November 29th 2011 04:56 AM | 87 comments | Print | E-mail | Track Comments
    About Sascha

    Dr. Sascha Vongehr [风洒沙] studied phil/math/chem/phys in Germany, obtained a BSc in theoretical physics (electro-mag) & MSc (stringtheory)...

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    There is a widespread antipathy against Many World and Multiverse concepts, especially if the latter come with Extra Dimensions. But these concepts are self-evident and always were to me, even before knowing any physics, let alone quantum physics. Many Worlds and the Multiverse are obvious because nothing else can make sense. So is the expectation of there being probably extra dimensions: “Teacher, why only three?” I remember sketching four dimensional water melon slices in order to figure that one out. [I only discovered that two eyes are sufficient to see stereoscopically in any type of dimensional space (We would have three dimensional retinas in 4D space anyway) and how a 4D propeller plane or helicopter may look like.]


    However, many educated people are belligerent when it comes to deriding such concepts:


    “Physicists ad hoc add dimensions to everything these days – get back to reality!!!”

    “Multiverse? Are you kidding me? Come back when you can explain this universe, then go on to explain others!”

    “Oh sure, assume infinitely many worlds and call it science if we cannot say anything anymore because everything is possible. Flush parsimony and Occam’s razor down the drain.”


    Tegmark’s four level Multiverse seeks to include Many Worlds as the third level which “adds nothing new” to the second – an obvious and fatal problem with this scheme.

    What is strange about this hostility: These people are usually self described atheists and agnostics out to defend scientism.


    Let me tell you why there “are” Many Worlds (1) and likely a Multiverse (2), without even drawing on empirical science in any essential way. The last section (3) will rephrase the Multiverse argument to include "hidden stuff" like extra dimensions.


    1) Many Worlds:

    Many Worlds is not the multiverse. Many Worlds is not even quantum physics! Quantum physics is the fact that different worlds are entangled, which for example allows that the “parallel existence” of other possible worlds, can be inferred from within any one world. Without quantum mechanics, other self-consistent worlds are just parallel worlds that never interfere.


    The Many Worlds concept includes the other worlds where you wear a differently colored shirt while reading this right now for example. I could now argue with high brow stuff like the ‘Principle of Plenitude of actualization’, or draw on the authority of philosophers like David Lewis, Bas Van Fraassen, or as far back as Anaximander [610-546 before "the one"]. However, I will not soil a self-evident concept with arguments from academic authority.



    A fundamental description aims to take account of the whole of totality, of all that is physically possible. If you refused Many Worlds in such a description, you will do the following ridiculous thing:

    You would assume that in the very foundation of totality, the very most fundamental laws of nature, the absolute rock bottom core of physics in its most profound and general symmetries, there is something inside there that ensures that you, yes you personally with name and address, wear that silly color shirt today!


    I may be the reincarnation of Jesus, but going as far as thinking myself and the color of my socks on a Tuesday afternoon being somehow part of the very foundation of everything? Nah!


    Actualism versus probabilism: Those are for academic “philosophers” securing themselves a job via verification transcendent terminologies. All self-consistent possibilities are fundamentally equivalent and just as ‘alive from their inside’ as those actualized for you right now. Surely, this was self-evident to many long before Parmenides of Elea. Psychoactive substances tend to trigger such epiphanies and have been ingested for 25 thousand years!


    [Remark: The Many World Interpretation (MWI) of quantum physics suffers normalization problems. Claiming that all Everett branches together are one entangled totality forgets that outside observer independent universal wave functions are highly suspect. Quantum physics is the single description (not single world) of the totality of worlds/minds! “World” in this context means the world of observers, not a cosmos inside a certain physical model (see “multiverse”).

    UPDATE: For Many Worlds, what they are and about experimental verification, please see the article dedicated to these problems: Many Worlds Tautological Truth]


    2) Multiverse:

    The Multiverse concept claims that there are many more universes that must be added to a consistent description of totality. “Universe” means here not totality (the Universe) but the kind of place like our observable cosmos. The Multiverse concept claims that many more of those look totally different from ours: different physical constants, different numbers of space dimensions, different shapes of space.



    You should expect this. Why? Well ask yourself some questions. Where do you find life? Life needs a lot of just right ‘Goldilocks’ conditions! Consider time: There was no life for most of time, then there is a little bit of life right now, and then our universe will go on for an incredibly long amount of time (in a sense infinity) without any life again.


    Consider space: There is no life in the middle of earth, then there is a tiny little bit of surface called biosphere where there are mostly bacteria and of course you and me in an even much narrower layer, and then above that there is again nothing but a few viruses perhaps stuck to a rock hurling through space after having been chipped off Mars a long time ago.


    Consider spatial scale: There are no life forms in the nanometer range, none in the picometer range, none in the … probably all the way down. Nor do we see life forms as big as the moon, as big as the sun, as big as an galaxy, as big as a galaxy cluster, as big as ….


    In fact, you can describe our universe along any parameter, say gravitational field strength or temperature, and you will find that even after transforming the scale logarithmically, there is only a tiny region where you find life. What about sheer numbers? Most planets have likely no life. Only a tiny fraction has their surface moldy like earth.


    Now imagine all kinds of universes that all have a consistent physics and order them all according to whatever parameter you like, say number of dimensions or size. Naturally, you should expect life only in a tiny region, a miniscule proportion of that space of all consistent universes.


    Of course, if we ask in terms of which ones are observed by conscious minds and in that sense “o-exist”, then only the ones that have life inside do. But apart from this distinction, all these universes are equivalent. You would need to believe in divine supernatural intervention in case only one of these perhaps infinitely many consistent universes in some ill-conceived sense “really actually ontologically exists”. You would need a god to have picked your world out of the huge amount of dead as well as alive competitors, blowing some ghostly glow of “absolute-exist”-pixy dust on it.


    Even if you believe in god, whatever amazing thing that is, what makes you think he finds you so amazing?

     

    3) Multiverse and Hidden stuff like Extra Dimensions?

    We can start the multiverse discussion from most living beings' point of view - that would be microbes. Take a bacterium in some sort of environment for its 20 minutes of life before it splits into two. Take one that lives inside a bio-film on some surface, say inside the fold of a filling inside a cavity of one of your teeth. Here is the attitude “Multiverses and hidden dimensions are nonsense” translated to bacteria:



    “The universe is a fundamental liquid space and a two dimensional end-surface on which I am stuck. The properties of space and that “given plane” are really rather curious but they allow me to thrive. The universe looks large, I cannot see the end, and it looks everywhere I can see the same, so that is all there is to it. A hidden space below the end-surface and other worlds with different properties are nonsense.”


    The curious properties of the universe that the bacterium is talking about derive partially from the properties of the material of your tooth-filling and so on. That filling only has such curious properties because it is not fundamental, because of the fact that it is actually an environment that came itself into being in a bigger universe that is not just very much bigger than the bacterium can grasp, but that also contains very many more and to the bacterium unimaginably strange places, some of them are universes to very different microbes and animals and ... . If that were not the case, there would not be such strange places like tooth cavity fillings.


    The properties of our vacuum are also quite strange. There is handedness for example, and more matter than antimatter, and so on. What makes you think that you happen to be so special that your universe has these properties because they are the most fundamental properties rather than just the properties of some tiny dirty niche in a vastly bigger picture?


    Again – the argument is not about academic physics or even the eager atheist blathering about anthropic principles. It is about not being a megalomaniac with your head up your own behind, irrespective of there being a god or not.


    Below the fundamental “end-surface” there is something, something hidden that the bacterium cannot ever get at, but if the bacterium wanted to come up with a good physical theory that explains that surface, it should not be surprised if a lot of strange worlds have to enter the description.


    --------------------------------------------

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    Comments

    Sascha
    I am also a modest agnostic physicist who likes the Everett interpretation out of aesthetic pleasure more than anything else. Neverrtheless you have to concede that to get solid empirical proof is something alse and even if it may eventually happen you and me may not be around to enjoy that.
    One problem is that the speculative talk over extra dimensions and 'other planes' is hardly new: it became popular in the nineteen century at the time of the non-euclidean geometries when imaginary multidimensional cosmologies 'a la Blavatsky were popularized in the media by an army of mediums, charlatans and occultists....

    vongehr
    solid empirical proof is something alse and even if it may eventually happen you and me may not be around to enjoy that.
    Empirical proof for interference from counterfactual worlds we have via the experiments known under the heading of "Elitzur-Vaidman bomb testing".



    But even without such, we do not need empirical proof for tautological truths. There is no consistent terminology (where terms have significant meaning in the sense of logical positivism) in which one can express that other possibilities are not actualized relative to their observers. Such is strictly language gone wrong and not physics.
    Thor Russell
    Thats a pretty impressive experiment, I was not aware of it before.On a different note, evolutionary biology clashes with creationism to a significant extent because biology is obviously flawed, e.g. the eye is not perfect and evolution predicts that, creationism of course does not. Do you think a similar thing will happen with physics anytime soon? E.g. some law, force or measurement in our universe is shown to be "ugly" with no good reason? 
    Thor Russell
    It can't be too ugly or we wouldn't be here. And if it's not so ugly as to wipe us out then we'll have evolved to enjoy or endure it and regard it as normal.  So how about "death and taxes" for a start?
    Anyway, you're wrong about creationism. Creation must not be perfect otherwise it wouldn't leave room for faith. And the "mere appearence of age" mustn't be perfect or the pure unbiased minds of creationists would not be able to spot the deliberate mistakes and call their findings "creation science". Haven't you ever talked to these people? I tell you, five minutes with a creationist and you'll be on a contact high of the most unpleasant kind. Ten minutes and you'll wish you were dead. Fifteen minutes and you'll think you are dead and have gone to hell. Twenty and you will really be dead - and probably gone to hell for good measure.
    Thor Russell
    Ha, no I havn't bothered to talk to a creationist for a long while. I will try to clarify what I mean by ugly a bit more. Say for example what if particle "X" is discovered and it has almost no effect on how our universe appears, and is not needed by most consistent theories, it just happens to be there. Theories without it are more elegant, would allow us to exist without us noticing a difference in our everyday lives and would appear to be more statistically likely (but not excessively so). So you would then have to ask why is it there? The only sensible answer you could give would be our universe isn't perfect or unique, and the random initial conditions caused it to be present in our particular one, even though it isn't needed, expected, and universes without it are more mathematically simple and still support life. I don't think our understanding of the universe is at that stage yet given we don't have a theory of everything etc. However I have seen it suggested somewhere that the weak nuclear force is unnecessary and life could be supported in a universe without it if you tune other parameters. Do you see what I'm getting at?
    Thor Russell
    Good post, Sascha.

    I recently read a pop sci article on a PRL where the authors assemble measurements of spectra from distant quasars and assert that alpha varies as a function of distance from Earth. The startling part is that it gets larger in one direction and smaller in another. This to me screams of some sort of mistake, but let's suspend disbelief for a moment.

    Assume that it's true and alpha is a slowly varying function of space - within our observable cosmos. Could that not explain the apparent fine tuning of the constants (at least e, h-bar and c) without the need for a multiverse?

    - Phil

    vongehr
    Assume that it's true and alpha is a slowly varying function of space ... Could that not explain ... without the need for a multiverse?
    1) A previously thought fundamental "constant" changing is in the sense of this article a multiverse already. There is no point in saying "within our observable cosmos", because for somebody in a galaxy far to the left, the observable cosmos is a different one and so the "constant" already varies also outside of the observable cosmos.
    2) Much physics can be explained without a multiverse. There is perhaps no need for a multiverse. Nevertheless, a modest naturalist will expect one and be rather surprised if against all expectation, there should be only exactly this type of universe. What an amazing luck we had that the only existing type of cosmos allows us.
    MikeCrow
    When presented with the incredible odds for the constants to be what they are, I always have to point out we don't know how many other (type 2) universes there are.


    Never is a long time.
    Bonny Bonobo alias Brat
    1) A previously thought fundamental "constant" changing is in the sense of this article a multiverse already. There is no point in saying "within our observable cosmos", because for somebody in a galaxy far to the left, the observable cosmos is a different one and so the "constant" already varies also outside of the observable cosmos.
    Please can you explain this a bit more? Aren't you contradicting yourself by saying 'somebody in a galaxy far to the left' is outside the observable cosmos?

    My latest forum article 'Australian Researchers Discover Potential Blue Green Algae Cause & Treatment of Motor Neuron Disease (MND)&(ALS)' Parkinsons's and Alzheimer's can be found at http://www.science20.com/forums/medicine
    There is no contradiction in what he's saying.

    Suppose you're an observer in a galaxy 13 billion light years away - to our left. You can also observe galaxies 13 billion light years to your left, which would be 26 billion LY away from us - which is outside our observable cosmos.

    Presumably alpha would be varying all the way out to those 26 billion light years - and beyond.

    I don't like the Multiverse concept and I especially don't like the Many Worlds idea, but I know that my likes and dislikes do not affect the universe.

    "Even if you believe in god, whatever amazing thing that is, what makes you think he finds you so amazing?"

    Possibly the fact that He finds everything amazing.

    "It is about not being a megalomaniac with your head up your own behind, irrespective of there being a god or not."

    Exactly. But theists got there before physicists - where do you think the expression "world without end" came from?
      
    Come on Sascha, you are the man for thinking out of the box! Since when did "amazingness" depend on size or complexity or cleverness? Perhaps God finds some of the little things of life which we can do something about a lot more interesting than stuff that just obeys one equation. Even Bruce Almighty got that right.

    I'm quite surprised, actually, that you can get away with your constant assertions that science has disproved God. 20 odd years ago, biologists were the most atheistic of all scientists, no doubt largely because of attacks from creationists. (Creationism is a meme complex that is parasitical on theism: don't blame the host.)  Astronomers were inclined to believe in God at least as frequently as the general population and I think physicists came a close second: they were not outstandingly atheistic anyway. What's happened since? I genuinely would like to know!
    vongehr
    Even if you believe in god, whatever amazing thing that is, what makes you think he finds you so amazing?" Possibly the fact that He finds everything amazing.
    The sentence you quote is right after pointing out a competition with even other living universes that he not actualized. So your answer makes no sense at all. If he found everything amazing, he actualizes everything, that is the whole point.
    But theists got there before physicists - where do you think the expression "world without end" came from?
    I never claimed that physicists got anywhere early. I clearly stated that these concepts were probably clear to reasonable people 25 thousand years ago.
    I'm quite surprised, actually, that you can get away with your constant assertions that science has disproved God.
    What other sciences did was to attack a certain god that may well exist. We do not know whether all this is not in somebody's laboratory, and he would be our god. I am unsure why you claim I constantly assert something about god. What I said once (many posts since then by now), is that god does not know anymore than we do, and if he is not in a quite classical sense interacting with us, he would be in a certain sense decoupled (no influence on us, since he is the superposition of all possible gods).
    Then my answer stands. He actualizes everything :) What's the problem with that? Lots of different Saschas all wearing different socks. Don't forget, souls don't exist in this universe even according to some theologians.

    Why should God not know more than us? Are you saying that the only "real" things are things that conscious beings other than God observe?   I thought that was the point, they are no more real for having been seen than they are if they're not.  If I've mistaken your meaning or the theory, my apologies, please have another go, this stuff is do-able but not exactly obvious.

    And I don't undertand " superposition of all possible gods" even slightly. I was doing fine with "and if he is not in a quite classical sense interacting with us, he would be in a certain sense decoupled (no influence on us,... " and then it all turned into noise. Please elucidate.

    Cheers.
    rholley
    Sascha quote:
    what makes you think he finds you so amazing?
    David quote:

    מָה-אֱנוֹשׁ כִּי-תִזְכְּרֶנּוּ;    וּבֶן-אָדָם, כִּי תִפְקְדֶנּוּ.

    What is man, that Thou art mindful of him? and the son of man, that Thou thinkest of him?
     
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    As far as the many worlds, multiverse, and hidden dimensions, a skeptic might point out that, until there are testable predictions made for either model, the concepts are meaningless.

    To say that beyond our universe there are which do not and cannot interact with our universe with the possible exception of the initial creation of our universe is not verifiable, whether you replace with "universes", "gods", or "LOL cats". Note that this does not apply to multiverse theories which allow some interaction, generally via collisions, although the predictions made by these theories have not been verified or negated.

    While hidden dimensions seem to more formula dense, especially when it comes to string theory, again there are no testable predictions (that I am aware of) which would lead to the verification or negation of any of these theories.

    As far as the many worlds theory, you say: "I may be the reincarnation of Jesus, but going as far as thinking myself and the color of my socks on a Tuesday afternoon being somehow part of the very foundation of everything? Nah!" But is it any more believable, or meaningful, to say that there are a near infinite number of worlds created every time you put on your socks versus saying that there is a single world where every sock choice is predetermined and your consciousness is merely navigating through that world and discovering what happens next. Again, without testability, the theories are meaningless (unlike quantum uncertainty, which has been tested, and which many worlds attempts to explain).

    Personally, many worlds seems far too messy, multiverses seem as logical as multigalaxies, and I'll stay agnostic on hidden dimensions for now but I'd really like to see some prediction that we could at least theoretically test.

    vongehr
    I think you need to question your understanding of "verifiable". Such makes only sense inside a consistent terminology. If you could at all consistently express that other possibilities are not actualized for their respective observers (meaning, see logical positivism, so that the words have verifiable (!) meaning), then of course you would be right. However, what you basically did is taking on an inconsistent terminology with terms that have no verifiable distinction (absolutely actualized versus relatively actualized) and then ask science to please verify. That is not how it works. Tautologies are in no need of verification.
    BTW, see comment above, where the WMI can be verified at all (namely whether or not parallel worlds interfere), it has been actually verified.
    The Stand-Up Physicist
    Teacher, why only three?
    Too bad your teacher didn't learn about special relativity. I am pretty sure you understand there are three dimensions of space and one for time that are unified, yet different, since on other topics you claim to understand special relativity better than most.


    For the record, I am with HildyJ, that I insist on a testable hypothesis that gets confirmed by data. Here is my list of things not yet seen I don't believe in:
    1. The Higgs boson (up or down vote in a few months!)
    2. Supersymmetric particles
    3. More than 3 spatial dimensions
    4. Dark matter
    5. Dark energy
    6. The multiverse
    7. Black hole singularities
    8. Inflation 
    The first two have a chance of being address within a year. The other six may remain open for quite some time.





    vongehr
    I am pretty sure you understand there are three dimensions of space ...
    I am pretty sure you heard of that special relativity also works in stringtheory for example, where there are ten such dimensions?
    I am with HildyJ, that I insist on a testable hypothesis that gets confirmed by data.
    The you should also start to ask yourself whether you actually understand the concept of verification at all. You do not verify tautologies and you you definitely never verify artifacts due to faulty terminology.
    I'd say I pretty much adhere to your list :)

    Apart from that, I gather that Mr Vongehr says that it's evident that there are many worlds (not MWI). This flies way over my head, I must confess. I'd say it's evident that there's one world. There may be more, but I don't see that as evident, even if it's true. I also think that it's possible that we live in just one world (both MW & MWI) without predetermination.

    At least a number 4 in your list is completely bogus. The CDM (cold dark matter) paradigm in astrophysics did make a lot of predictions and they were confirmed. I guess there is a question about the exact "temperature"/mass of DM, but otherwise it is well established tested result (despite the particle itself being unkown to particle physicists).

    The Stand-Up Physicist

    What has been confirmed by observation is that Newtonian gravity theory does not work for many extremely weak gravitational systems. There is a hypothesis to explain the observations known as cold dark matter (CDM). You cite two current limitation to the research efforts:

    1. The unknown temperature

    2. The unknown particle

    I think the second one is more important than the first. Physicists have tried and keep trying to name that CDM particle. Every candidate has been rejected for various technical reasons, the creation of the currently known particles being one of the harder tests to pass.

    If this situation were to persist, then my completely bogus prediction that there is  no dark matter, cold or not, would be correct. One would need a new, dark-matter-free hypothesis that could explain all the problems with Newtonian gravity theory. It is tough to find alternatives.

    If in the future we know the basic properties of the CDM - its rest mass and spin for starters - then that model will have matured nicely.

    This is about the future, so either possibility could be true. It is respectable to bet on CDM. I don't.

    Dark matter, the stuff in other dimensions?

    Those constants that have no particular reason to be a certain value, if we forced them to change would we enter another relm? Not entirely sure that is even theoretically possible.

    James Ph. Kotsybar

    HIGHER  DIMENSIONS    

     -- James Ph. Kotsybar


    From point to line to plane to sphere

    there’s only three dimensions here, 

    and each dimension has a name 

    that we can easily proclaim.

    If we would further interact, 

    we must devise the tesseract – 

    a cube that turns its outsides in, 

    spinning in imagination – 

    and thus we have dimension four – 

    the future and what came before.

    Three of space and one of time, 

    our theory’s still short of sublime. 

    We have to make this leap again

     to five, six, seven, eight, nine, ten ..., 

    but they’re curled up so very small 

    they’ve not been given names at all.

        

    blue-green
    Extra Dimensions .... How about all of the dimensions that are at the foundations of quantum mechanics? I am referring to orthogonal functions, eigenfunctions, eigenvectors, eigenvalues and good old fashioned Fourier Analysis. 
    I still find it rather enchanting to learn that different harmonics are perpendicular to each other .... 
    And to think that all these dimensions were discovered by studying something as basic as the transfer of heat from hot bodies to cold bodies.
    Theoretical quantum mechanics is the mathematics of Hilbert Spaces, metrics and all. 

    This is where the fertile fields have been concerning extra dimensions. 
    Fundamentals like the uncertainty principle fall right out of the mathematics once you realize/construct conjugate variables as potentially infinitely dimensional objects in a Hilbert Space.


    ... delta ...






    vongehr
    Cough cough, extra space-time dimensions.
    blue-green
    Yes i know, that's what you are emphasizing, and yet, the real meat for some two hundred years has been in these orthogonal vectors .... One would never know it from reading popular press articles on physics. 
    And what about those ubiquitous complex-valued numbers that are rotating us out of familiar real-valued space-time dimensions? Can say enough here about phases ....
    blue-green
    The use of superpositions and complex numbers in quantum mechanics has more to do about how it is wonderfully silent on things for which there is no information. The wave functions are a reflection of an entire experimental setup and inherently non-local. There is very little agreement as to whether they point to extra space-time dimensions, as one can easily see in the talk section of the wiccapaedia article on the clever Bomb testing experiment (mentioned in the 2nd comment). Penrose has a nice description of it in a couple of his books. It all hinges on the use of complex phases and the superposition of orthogonal states.

    It has nothing to do with religion or a lack of or disinterest thereof. Religion is a social affair ~ culture.
    Hi Sascha,

    A question: If the multiverse model is true, does that mean that *anything* that could happen does happen in some universe? For example, is there a universe where everyone on the planet is 2000 years old (and is really, really disliking the indignities of old age) or where everyone has 10 legs and 8 arms, etc? Or are there restrictions on what can occur?

    Thanks,
    -M

    vongehr
    You are confusing multiverse and many worlds. Even if there is no multiverse, there are still "many worlds" as long as "worlds" is not inconsistently defined as some "really existing" stuff.
    Your question about what is self-consistently possible at all is a very important one indeed! But that question is not directly to do with multiverses, nor is it necessary to discuss it in terms of many world models.
    I'm not sure who you are replying to, the threading doesn't show up clearly on my screen. Assuming it is me - which is quite likely since most posts you address to me start with "you are confusing bla-bla-blah" - no, I am not. There was no mention whatsoever in the OP's post (so this goes for him too) nor in my reply of "many worlds". You might as well say I am confusing multiverse with a fried egg.
    vongehr
    You are confusing ... replies; the reply was to anonymous, but you nevertheless are also confusing many worlds and multiverse. Anonymous asked for suicidal 6000 year olds, not for different constants of nature (for example). Such so called "freak" scenarios (e.g. Boltzman freak observers and their QM 'tunneling into crazy land' analogues) are many world, not multiverse issues.
    I know you are used to dealing with a population of stubborn absolute realists, but I do understand the difference between multiverse and many worlds - thanks largely to you as it happens. But a lot depends how you define the words - I have always assumed "multiverse" was a generic term which would encompass "many worlds" - a view apparently shared by Wikipedia which boldly states: "MWI [many worlds] is one of many multiverse hypotheses in physics". And, before you have an apoplectic fit, I am also well aware that you believe "many worlds"  to be a necessary paradigm for all workable theories, not one of many competing "interpretations of quantum mechanics" as Wikipedia evidently does.

    It is quite possible that I misunderstood the poster's question, but even after disentangling your comments from speculations about my state of understanding :) I still don't think I did. I don't think his questions were carefully contrived to indicate "many worlds" for the simple reason that he would have used that term instead of "multiverse" if he was serious about it. I prefer the "repugance and horror" theory. IDEA !! We could ask him.

    edit - 
    Ah - seems like he has already answered. Heh-heh. I'm right, and you're wrong. :)
    vongehr
    Well, see below. ;-) Hope you don't have an apoplectic fit - whatever that is.
    Okay, so in the many-worlds model, it seems that anything allowed by the laws of biology (or physics, if you want) could and would occur in some world. My question was indeed regarding such "nightmare" worlds and whether, under this model, they must exist. Can you elaborate on this?

    Thanks,
    -M

    vongehr
    This is a very serious problem indeed, the one that keeps me awake at night, no joking, because it is even more serious if quantum mechanics is truly linear and there is no more "corrections" between the quantum description that we already have and phenomenology of conscious minds: QM as we know it makes everything possible, even what is impossible according to biology.

    You call it "nightmare" worlds, I called them "terrible states", those where you tunnel into a microstate that seems to be an inconsistent macrostate, one where you find yourself raping your only beloved child using a fetish that you never had, in your memory perhaps a blank ten minutes. Would there be any verifiable difference between quantum tunneling and plainly having gone mad?

    That problem is the next one that people have not even grasped yet how deeply troubling it is. I hope that rational minds make an impact on this question before the religious and occult embrace it. I personally consider ideas of how to get around this, but perhaps I am fooling myself and there is no way around this. I am forcing myself to keep my mind open - too many have tried to prove what they want to believe.

    Bringing in conscious experiences is always a big step. QM is about knowledge, not consciousness. The hard problem is not how many souls there are in many-worlds but how many there are in just one. I don't, as a matter of personal opinion, believe in p-zombies, but, until you can derive a way to distinguish them from conscious beings without question-begging, a theory within physics has to treat the observer as a device for knowing things, not for experiencing them. If I've got that wrong please enlighten me! I should be delighted to learn how an account of interfering states comes up with conscious experiences. Bridge that gap with qualia and such-like incoherent nonsense and I'm sure you'll be able to find enough non-linearities surrounding your observer to make the picture anything you want. 

    vongehr
    The hard problem is ... how many [souls] there are in just one.
    Good point - it seems in QM Many World models there is just one (making it Many Minds) or else the models do not work at all. In classical worlds, there are as many as you like, but I doubt that there are any.
    within physics has to treat the observer as a device for knowing things, not for experiencing them.
    That seems to be your own delineation of "physics".
    I should be delighted to learn how an account of interfering states comes up with conscious experiences.
    Working on it. Give me a few more years ;-)
    I'm sure you'll be able to find enough non-linearities surrounding your observer to make the picture anything you want.
    Ahh - now you hit hard where it hurts. It is true - that is basically what many hope for and I would not be surprised if you charged my attempts with similar. Think about it like this: Otherwise QM would be the only theory ever that never developed beyond its linear beginnings. How likely is that?

    Consciousness of the Gaps. Ha!

    Thor Russell
    OK things seem to have gone from annoying confusion about multiverses and quantum many worlds to pretty quickly over my head. Can you please explain what is meant by "corrections" and "truly linear"? in relation to QM. Also what is the big issue with "terrible states" surely they are so incredibly rare in some sense that a lot more suffering comes from normal random things that are biologically possible.  Wouldn't you also be more likely to have a random pleasurable experience than do something complicated and horrible? Sure it may make a depressing post to explain this, but I'm still curious ...Finally why does consciousness relate to QM? Even though a car engine is governed by quantum rules it can be explained clasically quite well, without needing to go to the lowest most fundamental level of reality. Why should a conscious brain be different?
    Thor Russell
    vongehr
    Can you please explain what is meant by "corrections" and "truly linear"? in relation to QM.
    QM is a linear theory, with its state vectors (see linear algebra) and its boring time evolution. You may get something reasonable on wiki or so if you search for "linear quantum unitarity" or some such. Non-linear corrections would be like going from special relativity to general relativity. Things do not add up linearly anymore because gravity interacts with itself.
     Also what is the big issue with "terrible states" surely they are so incredibly rare
    They are rare in a classical box-lever-pulley world interpretation with frequentist probability. But look at how many odd possibilities there are (chair jumps to the left, jumps to the right, makes a loop and sings a song) and how many usual ones (chair does nothing). Also ask yourself why a few unusual ones should have any less life just because there are a million times more usual ones.
    likely to have a random pleasurable experience than do something complicated and horrible?
    If you ask for the chair jumping up and suchlike, you may laugh in some situations, but there are a hole lot of jumps that end on your head.
    Finally why does consciousness relate to QM?
    It doesn't in the way Penrose etc wish. The relation is the other way around: All physics relates to self-consistent consciousness, however many measurement devices come inbetween.
    Thor Russell
    Thanks.
    Thor Russell
    Can you please explain what is meant by "corrections" and "truly linear"?

    I take Sascha to mean adding bits and bobs to Schrodinger's equation. Either because you are forced to by experiment (which would be a correction if it were ever necessary) or because you want it to perform new tricks as in Penrose gravity-induced decoherence. 

    Also what is the big issue with "terrible states" surely they are so incredibly rare in some sense that a lot more suffering comes from normal random things that are biologically possible. Wouldn't you also be more likely to have a random pleasurable experience than do something complicated and horrible? Sure it may make a depressing post to explain this, but I'm still curious ...

    Incredibly rare to us doesn't really count if they 100% exist in their own world. Without the benefit of Sascha to enlighten them they will certainly think it's the only world that exists and they will be right

    However I am entitled to say they do not exist because I am in this world and if I do not observe the terrible state when I look for it then it does not exist, it's not hiding somewhere. I somewhat reject the implication that I should always say "It is true that it doesn't exist - to me" as that sounds more like newage effluent than science. The whole question is, whether the fact that they would be entitled to claim existence if they were around to do it obliges us to do it for them if they are not. Like a Shakespear character: should we assert that Hamlet is real just because, if he was, he would be entitled to say so?

    The issue would not arise, of course, if that were all there is to it. There would be just one reality, perhaps chosen at random. But the fact is, these other worlds do have some sort of existence as they interfere, quite literally, with each other and us.

    Can a coherent theory of "degrees of existence" be devised that will rescue the idea of a reality? 

    Finally why does consciousness relate to QM?

    No idea. It seems to me to be a way of explaining a small ontological conundrum with a massive non-sequitur, hoping the two will cancel.. 

    Even though a car engine is governed by quantum rules it can be explained clasically quite well, without needing to go to the lowest most fundamental level of reality. Why should a conscious brain be different?
     
    Exactly.

    too sleepy to work it out any better. HTH.
    Within the limits of the 10^500 possible universes as outlined in the string theory landscape.

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

    vongehr
    And once again: Many Worlds does not equal multiverse does not equal stringtheory!
    But the 10^500 number puts a limit on how many possible different universes you can have in the multiverse. If string theory is correct.

    10^500 number is convenient in another way in that it can help explain how we ended up with a universe with such a low value for dark energy. 10^500 is big enough that if the amount of dark energy a universe has is randomly determined when the universe forms then there should be a huge number of universes with a similar amount of dark energy as ours.

    blue-green
    This is all getting pretty silly. Knowing that there are multiverses as Sascha uses the term is as simple as knowing that there is something different over the horizon, or over the hill, or beyond the community in which you happen to be raised. No biggie there. Too many plays have already been written about couples trying to break through cultural barriers.

    The many worlds angle is not near as cut and dry as Sasha presumes. For example, decoherence is often considered to be an explanation for how Everett's branching state functions collapse to a SINGLE state. The whole problem with Everett's program (which he did not follow through on after developing it for his thesis) is that it is framed in a vacuum and not in a real world in which everything is immersed in a thermal bath. Contrary to what Sasha is implying, and also contrary to what the poster in the article states, decoherence does the very opposite of proving the existence of many-worlds. 

    Decoherence disproves many worlds without even using gravity in a direct way. If you put in the obvious fact that gravity is present and accumlative, then with gravity you have additional ways for wave functions to collapse. At least that is what Penrose taught me in his books.

    Nor does the fact that quantum mechanics remains unitary at all scales imply many worlds. 
    Instead, quantum mechanics is silent about a great many things, including what color of shirt I am going to wear tomorrow. It is not anywhere as tight and restrictive as is classical physics. We see that in its fundamental admission of random processes .... and in its use of a type of logic which isn't the usual Venn Diagram logic you learned for classical realism. QM has a different methodology for common words like AND ... and OR. Its Hilbert Space math with complex-valued vectors is not just an extension of ordinary vector analysis. The objects in it are different and behave differently. 

    Perhaps my confusion comes from psychoactive substances, like these mushrooms I photographed in my yard. Or maybe it's Sascha who is working through his youthful psychoactive experiences.



    ~ Cheers ~
    vongehr
    Knowing that there are multiverses as Sascha uses the term is as simple as knowing that there is something different over the horizon
    Wrong - using it in my way means that there is nothing determined beyond the horizon.

    The many worlds angle is not near as cut ... For example, decoherence
    You forget that Many Worlds has nothing directly to to with QM. QM Many Worlds as in MWI puts in additional assumptions.
    Decoherence disproves many worlds
    Decoherence according to almost all people working on it is FAPP (for all practical purposes) and not "objective collapse".
    Nor does the fact that quantum mechanics remains unitary at all scales imply many worlds.
    Who claims such? You are fighting straw men.
    Sorry for being so vague, let me try to rephrase my question more clearly:

    Do you believe that you Sascha Vongehr "split" into different states?
    So now there is a Sascha Vongehr reading these exact words, but there is also almost an infinite amount o other Saschas equally real in other "worlds" doing every other possible outcome of the wavefunction?

    When I say real, I mean that they exist just as much as you exist right now reading these words.

    vongehr
    All self-consistently possible Sascha Vongehrs are fundamentally equivalent even without considering wavefunctions or assumed splitting. Quantum mechanics is not the foundation of self-consistency; self-consistency is the foundation of QM.
    That is disputable, but I do not want to enter that debate right now, maybe tomorrow.
    First I watn to clarify to be sure of your position because one could get the impression that you did not believe these other worlds really existed from this comment section.

    But your last comment here seems to suggest that yes, you do believe that right now you are sitting here replying to my message while in another "branch" you are eating your computer. Correct?

    But if this is so, why do you say "I do not believe in MWIs" ?

    vongehr
    other worlds really existed ... Correct?
    Depends on your usage of "really exist".
    why do you say "I do not believe in MWIs" ?
    As I said before, MWIs have frequentist probabilities, those moreover cannot always be normalized (measure problem) and MWIs mostly assume universal wavefunctions that nobody ever observes.
    My usage of "really exist" is pretty straight forward: it exists beyond thought/math, it is actual entities in reality, just like you are.
    So my question is do you believe that these other Sascha Vongehr's that you can find in the math of the wavefunction really exists just like yourself? Only in different branches?

    (forgot to ask this question as a reply, so just delete the other comment)

    vongehr
    Well, if it were that easy with the definitions. ;-)
    Again - I have never found any Saschas anywhere in a wavefunction. In a truly fundamental description, all possible Saschas are equivalent. Why do I have to soil it with "really" and "exist" - there are no two people who use those words the same way.
    Poor multiverse and many-dimension theorists are persecuted, persecuted i say! Sorry, but aint that the most non-issue ever, not like the majority of people of the internet even knows QM, let alone can meaningfully hold a many-worlds-opinion.

    Meaningfully holding the opinion that there are many-worlds means that you need to know how it splits, 'when the box is opened'? what if i drill a hole in the box and fart in it? The worlds also need to split in the correct fractions.

    vongehr
    not like the majority of people of the internet even knows QM, let alone can meaningfully hold a many-worlds-opinion.
    That is what science columns are there for
    Meaningfully holding the opinion that there are many-worlds means that you need to know how it splits
    No - many worlds is not necessarily QM many worlds interpretation (MWI), nor does it necessarily have to split.
    You are being way too vague in your definition of "many worlds" some of your posts imply the Everettian reading of QM, some seem anti-MWI and some are just too vague to categorize.

    How would you solve the measurement problem if there is no split taking place?
    How is it then a Many Worlds model?

    It seems to me almost like you are talking about the Mathematical Universe Hypothesis by Tegmark, where every structure exists, but this is VERY different from MWI and should NEVER be referred to as "many worlds"

    Interesting article and discussion, but there are some important foundational questions that need to be asked and answered before we can consider the notions of extra-dimensions and multiverse. For instance, at no point do you define precisely what constitutes a dimension. And I'm not talking the intuitive ideas of up and down, left and right, back and forth, or even the mathematical definition of a dimension (or the correspondence we can establish between points in mathematical space and points in physical space). I'm talking about the physical dimensions. As far as we know, dimensions can be merely human concepts we use to relate to space. And space, as an observer independent aspect of reality is a single continuous or discrete structure that has no dimension in the sense we understand it. In other words it cannot be broken down into dimensions the way we can break down matter into it components.

    Could be interesting to consider dimensions, extra-dimensions or the multiverse from a more fundamental point of view.

    Daniel L. Burnstein

    Your postings have no place in a Science blog as they consist only of arguments such this one where you say "Let me tell you why there “are” Many Worlds (1) and likely a Multiverse (2), without drawing on any deep theory whatsoever." So one reads further to learn about the "why."

    #1 How is this in anyway a statement of either physics theory or data data: "If you refused Many Worlds in such a description, you will do the following ridiculous thing: You would assume that in the very foundation of totality, the very most fundamental laws of nature, the absolute rock bottom core of physics in its most profound and general symmetries, there is something inside there that ensures that you, yes you personally with name and address, wear that silly color shirt today!I may be the reincarnation of Jesus, but going as far as thinking myself and the color of my socks on a Tuesday afternoon being somehow part of the very foundation of everything? Nah!" Nah, as in "no meaning to your rant."

    #2) Then you go further off data by saying: "You should expect this. Why? Well ask yourself some questions." If reality could be know by having folks ask them selves questions, no need for any experimental data. Ranting on the internet would be enough. I'll wait for the data.

    #3) Now you fall off the end when you say "What makes you think that you happen to be so special that your universe has these properties because they are the most fundamental properties rather than just the properties of some tiny dirty niche in a vastly bigger picture?" To which I answer, "why not?"

    vongehr
    To which I answer, "why not?"
    Ha ha, you made me laugh. I won't again go into that tautologies are logic (science) and do not need empirical verification, but you telling me that looking at physical systems in order to form an educated expectation (see title of post!) is not science but "why not" is the proper thing: LOL!
    "... do not need empirical verification."

    When you start posting about the data you collect, I'll start reading your posts again. No data -- you've got nothing but arguments no different than any political BS, like "make the rich richer in order to create jobs." Might be true, might be false. Wake me when you have the data either way.

    Yes, there is a role for theory in science, but when the theory is so crazy as to be inherently untestable, you are into "monads" and other crap from minds operating in a game of logic with no constraints. To every "why" there is an equally possible "why not?" It's like kids screaming at each other "tis true" and "tis not."

    You just don't get science. Perhaps because it seems you don't DO science for a living in a real lab with the instrumentation required to TEST your thoughts about reality.

    PS: I'm not saying your ideas are wrong -- only that you have no data on which to convince anyone. Which is why I said "why not" to your speculations.

    vongehr
    After you show me the empirical data for 1 + 1 = 2 and other tautologies, with proper statistics please, and after you read this here once more explaining Many Worlds and what scientific verification actually means, you can come back and comment again.
    political BS ... crap ... kids screaming ... You just don't get science ... it seems you don't DO science ...
    This is not how it works. Come back with arguments after you understand what the problems are.
    I didn't read the rest of the comments (and most of the article actually), but drawing from my personal experience almost all theorists who support string theory and the multiverse are religious. To be exact, among those whose stance on the matter I happen to know, there is not a single one who is not a believer.

    Hank
    Maybe 'religious' in the anthropomorphic sense.  M-theory is clearly an example of human centrism.
    Daniel Burnstein
    "Maybe 'religious' in the anthropomorphic sense.  M-theory is clearly an example of human centrism."

    Very true. I also feel the same way about observer dependent theories.
    Daniel L. Burnstein
    vongehr
    M-theory is clearly an example of human centrism.
    I have no idea what you mean. M-theory is the framework that combines all five different string theories.
    vongehr
    I didn't really read your comment, but drawing from my personal experience almost all commentators who do not read the article write stuff that has little to do with the post.
    I have read your article, but you haven't answered some very crucial questions that I have posed to you.

    vongehr
    You mean the new article (specifically written to address the kind of questions you ask)? Maybe we can discuss more there. In the end, not all sentences that seem like questions are questions that have an answer. I only care about questions that are scientific in the sense of being like a lock. Analysis of the lock tells you how the key must be shaped. If a lock allows no key at all or all kinds of keys, it isn't a good lock.
    "I didn't read the rest of the comments (and most of the article actually), but drawing from my personal experience almost all theorists who support string theory and the multiverse are religious."

    As odd as your statement is, it certainly is clear that it would take a huge leap of faith to even think about a multiverse. Coming up with such an idea is on a par with thinking of a anything supernatural. I've got to say at no point in my life did I think there was anything supernatural. It was obvious to me there was no god. Before imagining a multiverse I'd just go with Jesus. At least he is historically real. And, being "saved" provides some comfort.

    A multiverse? Extra dimensions? These are things teenagers ponder. Then some grow up and build an LHC so they can provide data-based limits to their wondering. Looks like others just get lost in their own minds.

    I do not understand you at all, Sascha. Why don't you answer straightforward questions with straightforward answers?

    If you ask the average person in the pub what they mean by reality, they will quickly pass through the stages of puzzlement, amazement, horror and then laughter: it takes a couple of seconds at the most for their ontological certainty to reassert itself even if they understand the question in the first place. "Reality? All this!" they say, waving their arms around to indicate the room. Then, nine times out of ten they rap the table with their knuckles as if the solidity of the wood somehow settles the matter. You will be lucky if nobody turns the question right round and aims it at you: "Are you telling me you don't believe this is real?", they say, making as to pour a cup of coffee over your head.

    And they are right. Existence is a primitive concept, why bother to define it - it's a label for the fact that, well, things exist don't they? You are getting the same response here.

    If you want to help people understand MW it is no use being all mysterious - and very irritating - by suggesting that words like "real" and "exist" have no agreed meaning. Clearly they do - children learn to distinguish between reality and fantasy very early, otherwise they get themselves killed. I don't know how people who grow up in a culture where they are exposed to the Hindu concept of Maya integrate it with Darwinian realism, though when I asked an Indian friend about this, she just looked puzzled and said they leave it to the priests to worry about things like that.

    Your ability to grasp MW from an early age may very well be at the expense of not being able to understand the immense hold that naive realism has on most people. Yet I would have thought you would have learned by now. It's no use ranting against what is effectively human nature, people here are not puzzling about a theory about physics, they are reacting to having a very disturbing ontology thrust upon them without any apparent recognition of how radical it is. You yourself find it hard to swallow that the terrible states are just as real as "this" one, and yet you jeer at words like "real" and "exist", saying they "soil" the austere cleanliness of a beautifully symmetrical theory. Some people might think that such pristine cleanliness is synonymous with sterility.

    Science makes few statements about reality itself. I have argued with philosophy teachers about this and have to concede that there is no actual assumption of reality in the scientific method. There is, however, an assumption of regularity if the method is going to work and it seems like hair-splitting to say we observe consistent data but we can't prove there is anything there to produce it! You may as well waste your time on Hume's argument against induction: that "just because it was consistent yesterday doesn't mean it will be consistent tomorrow - unless you assume that consistency is consistent".

    So stop dodging the questions! Yes, a priori, all worlds are equally real. 

    Next - If you consider the particular worlds where there are observers - not all worlds have anyone to observe them - then you must examine a system comprising an observer and the particular variable being observed. That creates a phase space of many dimensions - and it looks very much as if the "probability distribution" that has always been a puzzle is simply due to ignorance of the observer's microscopic state. I am pretty sure that the reason you have never observed Saschas in any wavefunction is because you don't know the "Sascha operator". Actually making the observation is trivial. Cogito ergo sum. Of course there are an ensemble of possible Saschas in an ensemble of superpositions as far as everyone else is concerned - this is just a way of breaking down the hypothetical universal wavefunction, no physics involved whatsoever.

    People like myself, who are vague about most of the maths, want to know whether this approach gets rid of all the nonsensical collapsing of wavefunctions and splitting of universes that some of the neo-classical interpretations of QM entail. I think it does - I would be happy to be plunged back into confusion if I am wrong about this. Suffice it to say that, as I understand it, combining the observer and the observed into one system means adding the dimensionalities of their respective phase spaces. Bell's inequality grows exponentially with the complexity of the subsystems. Call it "entanglement" if you must but that sounds like a minor correction to be made when you have let a couple of particles interact. Entanglement terms dominate the physics of even quite small systems, making decoherence another probabalistic result of not knowing the precise state of the observer, nothing actually random going on. It just gets better the more you look at it.

    But like the quantum hippies, you then muddy the waters by declaring the worlds that observers observe "real to them" and talk about modal reality. Quit the philosophy already! It does not help. The observation is observer-specific and one may guess that the observer psychologically constructs an opinion about the world they see.

    In the end there remain two questions. Firstly, is the wavefunction itself the ultimate reality in the theory or is it an aid to calculation that emerges naturally from something else? No need to talk about "who observes the universe?" - QM determines that the only possible observer is the universe itself: with a probability of finding itself of unity.

    The other question is what people here are asking. Which of these states is real, like I am? You are right to exclude such questions from the maths. However people are entitled to apply their own ontological prejudices. Which they will do if they understand how the maths works. This is why I muttered "symmetry breaking". You were quick enough to point out that the early universe could not come up with an invariant probability distribution for the CMB's inertial frame. So you brought in a symmetry-breaking first particle to help it make up its mind. There is no reason why people should not do the same with many worlds. We do, after all, know that we exist. Thus at least one world exists. You can consistently assert the unique reality of "this" world as long as you accept that the unreal ones interfere in the maths. This makes most of the wavefunction a calculating device, not a description of reality. Well, we've known that ever since Schrodinger whinged about "all this damn' quantum jumping".

    If you want to help people understand, say where intuitive ontology CANNOT be applied, don't just assert that orthogonal states have just as much a right to claim to exist as we do. You might as well argue that a fictional character is just as real as you or me because they are "real to the other characters". Great fun if you like Pirandello, not much help in getting your head around QM.


    By the way, despite everything, your efforts have paid off, at least one person here now has some slight clue about what "many worlds" might mean. But I expect I am confusing "many worlds" with "many words" or something like that. I usually do.


     

    Gerhard Adam
    Existence is a primitive concept, why bother to define it - it's a label for the fact that, well, things exist don't they?
    Unfortunately, things aren't quite that simple.  Do numbers exist?  Do sets exist?  Does infinity exist?  These are all concepts that we feel quite comfortable employing despite there being no "reality" associated with them. 

    Even in less esoteric terms, we recognize historical figures as having "existed" and postulate about future figures that have yet to "exist" and we have no problem recognizing that they aren't "real".  So it's quite legitimate to question what one means by words like "real" or "exist" when considering such propositions.

    Ultimately the point of modal realism is to consider whether there is any legitimate reason to exclude many worlds from logical consideration simply because we can't physically interact with them.  Most people aren't concerned about whether many worlds exist ... they want to know if they can go there ... if they can interact... if they can experience alternate realities.  The answer is NO, they cannot.

    In that respect it doesn't matter whether many worlds exist or not.  It doesn't have to mean more than whether we want to argue about whether set theory represents reality.  If many worlds provides utility in logic, then there's no compelling reason to exclude them because our sensibilities argue that there can't be any such thing.  We already nullified that idea in our use of non-real objects in mathematics simply because they have utility.

    Mundus vult decipi
    Do numbers exist? Do sets exist? Does infinity exist? These are all concepts that we feel quite comfortable employing despite there being no "reality" associated with them. 

    Why would anyone mistake an abstraction for a physical entity?

    So it's quite legitimate to question what one means by words like "real" or "exist" when considering such propositions.

    Yes it's a legitimate question. That's what I mean.  When I say existence is a primitive, I don't mean we can't qualify it and say things like "they probably did exist" or "well, they may exist or may not, we don't know yet" (English has no proper future tense). But the essential concept of existence is not being chopped up.

    Most people aren't concerned about whether many worlds exist ... they want to know if they can go there

    I doubt that very much. Most people want to feel comfortable with their concept of reality.
     
    And the answer, by the way is YES. Not, maybe as an additional person in that world appearing out of nowhere, but in the sense of tunneling into one of Sascha's "Terrible States". We can even choose where we end up as long as we scrape together all the entanglements that they've left behind and recohere ourselves. Which doesn't sound too likely but seems to be the idea behind "Sascha's photon".

    In that respect it doesn't matter whether many worlds exist or not. It doesn't have to mean more than whether we want to argue about whether set theory represents reality. If many worlds provides utility in logic, then there's no compelling reason to exclude them because our sensibilities argue that there can't be any such thing. We already nullified that idea in our use of non-real objects in mathematics simply because they have utility.

    It's not a valid comparison.
    Derek Potter said: it looks very much as if the "probability distribution" that has always been a puzzle is simply due to ignorance of the observer's microscopic state.
    ...
    is the wavefunction itself the ultimate reality in the theory or is it an aid to calculation that emerges naturally from something else?

    A recently published gedankenexperiment suggests that such a statistical interpretation is difficult to square with the predictions of any consistent quantum theory. Unless one is willing to cling to the assumption that some sort of outside, "objective" viewpoint has any real meaning (or that everything is correlated with everything else) it seems impossible to escape the conclusion that quantum states are real, physical states and not merely representations of incomplete knowledge.

    Hey Derek, Thanks for helping me understand this significantly better. Now, I really only have a couple questions.
    One, why can't we assume different degrees of reality like Aristotle did? You can either make an actual vs potential distinction or maybe you can say the "realness" of a thing is dependent on how much energy that thing has and say the other "worlds" are simply too low energy to count as real in the sense that we are real (correct me if I am wrong, but I am pretty sure that is how decoherence sort of works). Both ways, other "worlds" (though possibilities makes more sense for this term) can interact casually in the way described by quantum mechanics without really doing any damage to realism.
    Two, why would we assume, a priori, that these "worlds" exist? Accepting that alternatives are equivalent (which is literally the exact same thing as saying they are possible) does not mean that there is no difference between an alternative which is actualized and one that is not. If anything, if you accept all alternatives are actualized, then that would mean it was impossible, a priori, for any to not be actualized, which is a) obviously unintuitive and b) seems to get the problem backwards (I can see no good reason for it to be weirder for it to be metaphysically impossible to wear anything other than the socks I wear today than for it too be logically impossible that I not wear all possible socks, both are obviously ridiculous).
    Three, do you personally buy into Sascha's framework? Most of the time it sounds like you advocate decoherence alone as the best way to interpret quantum mechanics, but decoherence and MWI are two different things.
    Thanks for the response

    vongehr
    Seems to me that you need to become clear about what you mean by "actualization". Can you, for example, differentiate absolute and relative actualization in your own framework (like I do in posts on tautological modal realism and those on the EPR resolution).
    Also: My framework is not a QM interpretation! It is valid also classically and should lead to QM (e.g. Bell violation) via considering what correlations are necessary for the emergence of "reasonable" stochastic laws.
    Because actualization is intrinsically an objective fact about something (eg it is not something like beauty which is ultimately subjective) relative actualization does not seem like a coherent concept (it is not that something is actualized relative to all observers that count, it is just actualized. If you would like actualized things exist relative to ultimate reality) thus, in my framework what you mean by "actualized relative to observer a" actually means that the thing that is relatively actualized is an effect on observer a rather than its own independent existence. While observer a is absolutely actualized, meaning it has it's own existence in the same sense that you or I obviously exist. So the distinction can be made. However, actualized itself is a mode of being "real" so possible worlds are real (because they exist as potential) but not actualized (they haven't happened,but can happen) contingency (the fact that you don't have to where those socks) is therefore saved and totality (what is ultimately possible) is also saved

    vongehr
    While observer a is absolutely actualized, meaning it has it's own existence
    You confuse relative actualization (also called "indexical") with absolute actualization.
    One, sorry about the longer post after this one that you also replied to, I did not thing that my first one was posted, so they are actually both replies to the same question. I'm new here so I didn't really get the reply system.
    oh, I'm sorry, I didn't know for sure what you meant by the term. But after you gave me another name look for it, I was able to analyze it a bit better.
    so now I can safely say that indexical "actualization" as defined by David Lewis simply has no place Aristotle's framework of actuality and potentiality. This is a strength in my opinion because like I said, actuality is supposed to be an objective concept, eg not a relational one. Having relations without absolutely actual entities to pin them down is, quite frankly, incoherent and a little bit ridiculous. The concept stinks of anti-realism (I can almost hear some hippie going "reality is what you make of it maaaaaaaaan"). Even if you say that a world is actualized "relative to itself", if that world is not absolutely actualized, or at least objectively real in some sense, that is the same thing as saying that "nothing is actualized relative to nothing" you are either real or your not. Even if every possible world was real , or even actualized in the fullest sense, this would still be an objective fact, not a relative one.
    Now, you can still talk about relations, so if you'd like you can say that observer a casually interacts with this world and not another one (even if those worlds probably don't exist). So something like your idea of indexical actualization can hold, but only if you understand that this is not itself a foundation for reality but a relation between things that are already real.
    As for absolute actualization not being coherent, or not making a verifiable distinction with "relative actualization" that is simply false. The reason you have trouble understanding this (I have already read the "to be or not be is not the question post" you are referring to) is because you do not understand that a) relative facts NEED absolute facts to exist and b) absolute actualization does not need a definition because it is itself such a basic, fundamental definition. You don't need to talk about "really real", there is real or there is not real. There is actualized (happening, in action) and there is potential (could happen, could be in action). If you refuse absolute actualization, then you literally refuse ALL OBJECTIVE FACTS, it is the problem that relativism faces literally all the time. Even if you can't make an experimental difference the two, there is an a priori difference, a difference in definition. If your TMR relies on indexical actualization, than it is tautologically false (so you can keep the T after all).
    People don't shy away from models like this because they are intuitive or they are programmed not to by evolution, they reject relativism about actuality because it literally does not, and in principle cannot make any sense. It is also equally ridiculous to think that you can go from "certain facts are contingent" to "every possible world is real-- but not real-- but only real according to itself." that is called circular causation, and it is dumb.
    Ultimately, David Lewis and the Possiblists already made these arguments quite a while ago (even your rejection of absolute actualization is just David Lewis's indexical argument for modal realism mixed with a blatant misunderstanding of what a regress argument is).
    That said, thank you for clarifying your position, my main problem up until this point was that I couldn't agree or disagree with what you were saying because I was not even sure what you were saying. I don't mean any disrespect with anything I have said (I like to say what I say bluntly, I would rather not have any confusion about what I mean), whether or not I think your argument is bad (I do) I obviously consider you smart (smarter than me probably) if I care about your ideas on reality. I also appreciate you giving the time to respond.

    vongehr
    Having relations without absolutely actual entities to pin them down is, quite frankly, incoherent and a little bit ridiculous. The concept stinks of anti-realism (I can almost hear some hippie going "reality is what you make of it maaaaaaaaan").
    That there are other people who may be ridiculous ("hippie") does not mean that your position is any better.  You have apparently no idea about what "anti-realism" is.
    your rejection of absolute actualization is just David Lewis's indexical argument for modal realism mixed with a blatant misunderstanding of what a regress argument is
    Wow - you read my EPR paper in about a few minutes and even understood it better than I do.  What about you admit that you have no clue about how "actualization" differs from "real"?
    My answer to that is "sort of." Actualization itself refers only to objective facts, eg reality independent of observers (it is important to understand that just because observing A is the reason why A exists, it does not mean that A exists only relative to observer B, it exists absolutely but B observing A is the cause for A's actualization). In the same way that I don't ask "relative to whom does 1+1=2?" because 1+1=2 is an objective fact, I wouldn't ask relative to whom something is actualized. If it is actual it is actual. However, Aristotle's framework does deal with what I think you mean by "relative actualization". Things that are relatively actualized exist as effects on observers, so that while observer B has absolute actualization, A might exist only as a effect on observer B while there not being an A independent of B. However, before you can have a relative "actualization" you first need something (the observer) to be absolutely actualized. An analogy can be made between absolute and relative facts, if I say this stick is twelve inches long, this is an absolute fact about that sticks length, if I say stick A is taller than stick B, I am now stating a relative fact about the relation between two absolute facts. Unactualized alternatives therefore cannot be actualized "relative to themselves" because actualization is not relational property anyways, and it was just established that these are UNactualized alternatives, which cannot support relative actualization anyways.
    Also, it is important to realize that "real" and "actual" are not the same thing (it's like squares and rectangles, all actualized things are real but not all real things are actualized). Possible worlds are real (in that they exist as real potential, and not just abstract concepts) but are not actualized (they are not happening or existing in the same that we are existing right now). Thus, because potential is a real casual factor in the world, this framework plays well with quantum mechanics, which deals with how potentials (or possible worlds) interact with each other.
    Now, when I say a thing is actualized, I cannot provide a useful description of actualization because it is a basic property, so I just say "actualized in the same sense that we are right now" so if you are asking for a "actualization is A" type definition, I, in principle, can't really give it to you. This does not mean that I don't know what actualization is, or that it is an incoherent concept, merely that defining it would only bring in new more basic concept that I then could not define, defeating the purpose of trying to define actualization in the first place.
    Finally, I am sorry if I came across as misunderstanding what you said about your TMR not being a QM interpretation. I was sticking purely to your own definition of the term. I can see why equivalence of alternatives is obviously true, because it is literally just saying, with different words, that certain facts are contingent, and it is possible for things to be or not be a certain way. However, then you add that unactualized alternatives are also "real" which is you adding your own ontology which is a) very broad, as I just explained and b) does not necessarily follow from equivalence of alternatives, and is not really tautological. So while QM (not TMR) does suggest that "possible worlds" are real in some sense of the word simply because they seem to interact casually in the wave function, there is no a priori reason to assume your definition of TMR is true because, unless you drop the part about "worlds" being labeled as real, it is not tautologically true like equivalence of alternatives is.
    Finally, if you do in fact believe that all possible worlds are actualized in the sense that I have described, then your entire point about equivalence of alternatives is lost, because you completely destroy the concepts of contingency by saying that it is literally true that you HAD to wear those socks today and that other Sascha's HAD to wear those other socks. Your only intuitive point goes down the drain in that scenario, so it would be better to look for alternative frameworks that, while still holding true to TMR, also preserve the One True World instead of Many True Worlds. I think that Aristotle's distinction between actuality and potential could be that framework. Correct me if you don't agree with what I have said.

    vongehr
    My answer to that is "sort of."
    Not sure who you are answering
    Actualization itself refers only to objective facts, eg reality independent of observers
    You do not understand "actualization", sorry.  It is anyway not on topic here.  Why do you not read my posts on the EPR paradox and put these comments where they are on topic, namely for example where I show that absolute actualization fails where the EPR-MW model grows new branches when Alice worlds match up with Bob worlds?
    then you add that unactualized alternatives are also "real" which is you adding your own ontology
    No - I do not "add" anything.  "Real" means "necessary for explaining the observed".  The "real" is forced upon us in this sense via the quantum interference/correlation between worlds being necessary in probability calculations for example.   I do not "add" anything by admitting to other people that yes, we may agree on calling such "real".  "Modal realism" is an established term - I have to deal with that somehow.
    sorry about this, but I just wanted to check that this was the right link for the EPR=MW model you mentioned.
    http://www.science20.com/alpha_meme/einstein_podolsky_rosen_paradox_reso...
    Also, I think there was a misunderstanding. When you say "absolute actualization fails" are you referring to local realism only? Because as far as I know EPR does not disprove nonlocal versions of realism.
    Thanks for your response

    vongehr
    The EPR-MW paper is on the archive (needs revision though), and here you get more links to related content.
    Absolute actualization, which can be made to be meaningful in a "local realism", strictly fails due to QM. "Nonlocal realisms" are pretty much nonsense. Once you have "non-locality", it is no longer a "realism" in the sense inplied inside of "local realism" anyway. This is not worth discussing, since realism is not well defined anywhere. Just stick to what you want to discuss (counterfactual definiteness, modal realism, relativistic micro causality, non-separability, ...)
    Fair enough. This is ultimately a discussion of semantics then. Most of the "realisms" (or whatever you would want to call them) I am interested in defending don't particularly need locality (for instance, I am willing to consider the possibility that place might not exist in the conventional sense near the bottom of the physical world, or that there are other forms of interaction that are able to "skip" space, sort of like teleportation) or counter-factual definiteness. When it comes to quantum mechanics I usually agree with the intuitions of Heisenberg.
    I wonder if you will ever write anything about the Kochen-Specker Theorem, after all it gets rid of Naive versions of realism (aka, noncontextual versions of hidden variable theorems) before EPR does.
    If I have any more questions on this subject I will go to one of the articles that are about EPR, since this discussion does not really have much to do with this article (sorry about that). Also, sorry about misunderstanding your EPR arguments earlier, I read the wrong article :P There are quite a lot.

    vongehr
    You are correct; Kochen-Specker and Hardy paradox are even more important than EPR, however, those are beyond lay people.  Everything in EPR can be grasped by highschool students.  EPR allows me to prove modal realism with a hands on, intuitive space-time splitting model where one can discuss for example a little arrow that actualizes worlds.  And still, people do not get it (refuse to look at it mostly).  So, in that sense, Kochen-Specker is impossible for somebody who still desires to communicate to a wider audience (I mean communicating insight, not the usual science writer message about that science is awesome and therefore we are awesome and cool but you are too silly to understand it so just buy our books so you can dream about how awesome we cool guys are). ;-)
    KRA5H
    @HildyJ Sorry for responding to this very old post, but I stumbled upon the article and chose to read it. Everette's MWI is not even in principle testable nor does it make predictions. It is not a theory. It is a just convenient way of thinking about quantum superposition. The multiverse concept is also not testable nor does it make predictions so it is not a theory either. Since January 2012 the existance of a multiverse has been ruled out: http://www.jserra.org/ourpages/auto/2012/5/25/48343117/2012%201%20New%20...