Qfwfq Posted May 3, 2007 Report Share Posted May 3, 2007 That's pretty much what I had gathered, except I disagree that it leads to the notion of probability since, for each ramification, the others don't exist. More ramifications having one outcome isn't the same thing as greater probability, IMHO. Quote Link to comment Share on other sites More sharing options...

Simon Posted May 3, 2007 Report Share Posted May 3, 2007 More ramifications having one outcome isn't the same thing as greater probability, IMHO. I sort of agree and disagree. Looking at the probability from an observer's point of view, I would say this is a classic example of "a difference that makes no difference is no difference". Imagine a quantum roulette wheel. Before every spin, you are asked which is more likely - "zero" or "non-zero"? Suppose you're allowed to bet on either and double your money if you're right. Using the Copenhagen view of indeterminism, there will only be one ramification with 37 possible outcomes (on a single zero wheel). Before each spin, the probability of finding yourself in a "non-zero" ramification is exactly 36/37. This is what you would bet on. Using the Many Worlds view, there will be 37 ramifications each with a definite outcome. 36 of these will be "non-zero" while 1 will be "zero". Before each spin, the probability of finding yourself in a "non-zero" ramification is the same - 36/37. This is what you would bet on. Nevetheless I would agree that we have two different descriptions of reality. This might have implications as to whether you should play. If the Multiverse view is correct, it is a certainty there will be 36 ramifications where you win and 1 where you lose. So even if you experience being among the majority that wins, there will be one version of yourself that definitely loses. Knowing this might deter you from betting. You could argue that 36 people will gain at the expense of 1. Such concerns don't apply with the Copenhagen view. There will only be one person who either wins or loses. However, the probabilty for you as a player - before the event - remains exactly 36/37 in your favour with both interpretations. Simon Quote Link to comment Share on other sites More sharing options...

Qfwfq Posted May 4, 2007 Report Share Posted May 4, 2007 Now the subtlety, that it's essential to avoid missing, lies exactly in what I have bolded here:Using the Many Worlds view, there will be 37 ramifications each with a definite outcome. 36 of these will be "non-zero" while 1 will be "zero". Before each spin, the probability of finding yourself in a "non-zero" ramification is the same - 36/37.This is clearly inconsistent with the notion of the multiverse itself. What sense does it make to talk about said probability at all? The argument confuses these ramifications with being a sample of identical instances, in which the relative frequencies are 36 and 1 respectively. Only the deus ex machina sees all 37 outcomes. Indeed you go on to say:If the Multiverse view is correct, it is a certainty there will be 36 ramifications where you win and 1 where you lose. So even if you experience being among the majority that wins, there will be one version of yourself that definitely loses. Knowing this might deter you from betting. You could argue that 36 people will gain at the expense of 1.which is more to the point and doesn't show it as being the notion of probability, except for the detail that you don't normally reason on your 37 future selves like that. If you really and fully believed the interpretaition, there would be no point in "hoping" that you won't "be" the one unfortunate loser since it is certain that one of your selves will be. Now, if I do consider a sample of n wheels (or runs of the wheel, whatever), I should reason on the tensor product of distributions and I end up with the same thing over [math]\norm 37^n[/math] ramifications; in 1 of them the copy of myself will see all zeros and in this and a few others he will say "Well, so much for statistics!". Of course, there are more ramifications in which the relative frequencies are comparable to 1 out of 37, but to see all this translating into the notion of probability implicitly requires the assumption that only one ramification is what will actually happen. The multiverse as a purely mathematical construct, although I wouldn't quite call it by that name, is perfectly fine as a representation of all future possibilities and not just in QM, it's the same for roulette wheels and dice or what the weather will be like tomorrow. One could well rephrase quantum mechanics replacing any mention of probability with "portion of ramificaions" and believe that each has its own existence, consequently adopting a whole different "common sense" and resolving that none of his future self-copies in the worse ramifications shall complain. There is however a less obvious thing. Quantum formalism actually is a similar construct, except that instead of probabilities it is considering the complex amplitude of different possible evolutions. The Copenhagen school actually does consider these as being on the par, as long as we're talking about the dynamics of a coherent state. These are not, however, totally separate existences that shall never touch each other again; to the contrary they can all contribute to a total complex amplitude, determining what's ordinarily called probability. The "multiverse" of quantum formalism doesn't have real-valued numbers of ramifications. At this point, what's the difference between Copenhagen and multiverse? Apart from the above little distinction, it's all a matter of how far one carries the idea of time evolution occurring coherently. The Copenhagen school just considers that, when we observe the system, we will see one of the ramifications of the construct, each with a probability given by a modulus squared. Initially, talk was about the "conscious" observer but the focus has shifted onto decoherence. Where exactly does decoherence occur? How seriously do you consider the idea that, if we include everything in the chain of interactions (which means a heck of a lot unless you consider a smallish system in a zero Kelvin vacuum for a short time), the whole thing can be in a coherent state? Quote Link to comment Share on other sites More sharing options...

Simon Posted May 8, 2007 Report Share Posted May 8, 2007 Yes, I do appreciate the subtlety of your argument. Indeed you picked up that I already half agreed with it. The case you make is a very compelling one. You may recall what I acknowledged about the Many Worlds view earlier in the thread: ...it is a deterministic model of reality - perhaps the most deterministic model of them all. In a multiverse where time is constantly splitting and everything that can happen does happen, free will becomes hard to sustain, perhaps even logically impossible. I'm prepared accept the logical implication of this and draw the inevitable conclusion. The multiverse not only eliminates free will but probability too. It is curious that probability still remains the bible for Quantum Theory. Among those who now endorse the many worlds interpretation, I'm not sure that anyone has put forward the simple hypothesis that probability is an illusion. For me, the multiverse view, whether correct or not, does provide an explanation for quantum phenomena that would otherwise seem anomolous. All interpretations agree that twin slit interference occurs whenever the path of a particle isn't measured. The Copenhagen view regards such interference as evidence that the two possible events have no autononmous existence. The multiverse view regards such interference as evidence that both possible events occur in overlapping ramifications which separate when measured. It strikes me that of the two, the multiverse is the more realistic approach - not withstanding the fact that it does deny probability. If it is correct, then Einstein's remark to Bohr was right. We have a revised quantum theory applied to a fixed spacetime in which "God does not play dice". Simon Quote Link to comment Share on other sites More sharing options...

Buffy Posted May 8, 2007 Report Share Posted May 8, 2007 It strikes me that of the two, the multiverse is the more realistic approach - not withstanding the fact that it does deny probability.It doesn't "deny probability!" The probability is now simply which verse "you" end up in! Too many realities,Buffy Quote Link to comment Share on other sites More sharing options...

Qfwfq Posted May 8, 2007 Report Share Posted May 8, 2007 Among those who now endorse the many worlds interpretation, I'm not sure that anyone has put forward the simple hypothesis that probability is an illusion.Yeah, I find it surprising too. They would have to use a quite different terminology for the distributions. However, I'm not sure that the multiverse can really be regarded as an explanation, ifdeeply examined. The Copenhagen view regards such interference as evidence that the two possible events have no autononmous existence. The multiverse view regards such interference as evidence that both possible events occur in overlapping ramifications which separate when measured.I'm not sure what you mean by the wording, are "both possible events" meant to indicate the particle traversing either slit? Any view compatible with the formalism must consider both as contributing to the possibility of the particle being detected at a given final position. The probability is now simply which verse "you" end up in!Tee hee, :beer: but which of your selves is "you"? Split personalities, Q. Quote Link to comment Share on other sites More sharing options...

Simon Posted May 8, 2007 Report Share Posted May 8, 2007 Buffy said: It doesn't "deny probability!" The probability is now simply which verse "you" end up in! That's just the point. With the Many Worlds view, you know with certainty that you're about to split and end up in both verses. And as Qfwfq said: which of your selves is "you"? Since both versions after the split have an equal claim to being "you" before the split, any notion of probability has to be subjective. There are curious implications to this. Imagine the quantum roulette wheel again, but the stakes are much higher. Suppose that the moment any number except zero is spun, you will be wiped out. For the sake of argument, imagine that this will happen immediately. There will be no waiting period and no afterlife - just instant oblivion. However, if a zero is spun, you will survive and win £1 million. So what exactly are your chances here? With a single universe, the answer is clear. You have a 36/37 chance of dying and 1/37 chance of winning £1 million. What if the multiverse is true? Then there will definitley be 36 universes where you die and 1 universe where you win £1 million. Suppose you endorse the multiverse and ask yourself: "Which of the 37 verses will I end up in?" Answer: "the one in which I continue to exist!" You can't end up in the verses where you don't exist. Therefore, you are not risking your life. There will only be one outcome that you can possibly experience and it is a certainty! You can have complete confidence that a zero will be spun and you will win the money. Implications? With a single universe, when you face any situation where it is said your chance of survival is small, your death can be said to have a high probability. Facing the same situation in a multiverse, you cannot die. Your continued survival is guaranteed as long as there is always at least one ramification in which death does not occur. Whether this thought is comforting or disturbing is another matter. :) Simon Quote Link to comment Share on other sites More sharing options...

Queso Posted May 8, 2007 Report Share Posted May 8, 2007 Interesting intentions, Simon. Quote Link to comment Share on other sites More sharing options...

Simon Posted May 8, 2007 Report Share Posted May 8, 2007 Why only intentions? :) Simon Quote Link to comment Share on other sites More sharing options...

Buffy Posted May 8, 2007 Report Share Posted May 8, 2007 Facing the same situation in a multiverse, you cannot die. Your continued survival is guaranteed as long as there is always at least one ramification in which death does not occur. Whether this thought is comforting or disturbing is another matter. :cup:Ya wanna bet on that? :) No seriously, the notion of "you" is not the "entity that continues in all multiverses after a split" its "the path that you perceive". In Heisenbergian terms, your "observation" of "reality" (that is "the path you're perceiving") "collapses the wave function" and you end up with one reality. Your odds of which one of the 37 you end up actually perceiving is indeed still 1/37. Note also, that as with all things quantum, it doesn't matter whether *you* do the observing or someone else does, so the "you'll never die" is definitely *not* true.... Roulette, but not Russian,Buffy Quote Link to comment Share on other sites More sharing options...

Simon Posted May 9, 2007 Report Share Posted May 9, 2007 Buffy wrote: the notion of "you" is not the "entity that continues in all multiverses after a split" its "the path that you perceive". In Heisenbergian terms, your "observation" of "reality" (that is "the path you're perceiving") "collapses the wave function" and you end up with one reality. Your odds of which one of the 37 you end up actually perceiving is indeed still 1/37. Throwing out the main axiom of Quantum Theory - probability - appears like a radical proposition. However I'm now convinced that you can't retain objective probability with the Many Worlds view. Though some might regard this as a semantic quibble, I beleive it is a serious paradigm shift that should be taken on board by those who endorse the multiverse. I'll make another attempt to explain it. Each moment before a split occurs is one past instant that leads to all possible futures. Consequently, you - as you exist now - are certain to divide on to every possible path. After the split occurs, each version of yourself ends up perceiving one reality - but all make the same claim to having been "you" before the split. Is it then true to say "the odds are 1/37 that I - in the present - will end up in one version of reality"? You may argue "Well why not? The 1/37 odds apply to the single observation I will make when I collapse the wave function to one of the 37 futures." With the multiverse, there is no sense in which the wave function might be reduced to one future, not another. You will reduce the wave function to 37 different futures and you will become a different observer in each. However, not one of these separate 37 future versions of yourself can objectively be singled out as the one that 'you' end up as. So can you say: "There is a 1/37 probability that I will become a 'zero spin' observer"? No. It is a matter of certainty that 'you' in the present will become one 'zero-spin' observer and 36 'non zero-spin' observers. Subjectively, of course, you can only experience being one observer, but this changes nothing. Let's say you report the experience of spinning the wheel and becoming a 'non-zero' observer. It is still the case that before the split, the same you spun the wheel and then became a 'zero' observer. Objectively both can be considered certainties. They not only happened, they were always going to happen. I agree that from each observer's point of view, only one of the two events is experienced. Subjectively one outcome may appear to have a higher probability than the other. But these probabilities are not real if both events definitely occur. Nevertheless, it is also certain that your individual experience will be of one outcome or the other. Subjectively you will not experience both outcomes, even though objectively both experiences occur. Conclusion: given a multiverse, no expression of probability - except 100% - can ever apply to an observer ending up among any chosen sub-group of possible futures. In this case, the total number of possible future observers is 37. The number of 'non-zero' observers is a sub-group of 36. The number of 'zero' observers is a sub-group of 1. You could ask: "What are the odds that there will be one future version of myself who observes a zero spin? Put like that, the answer is clear. 100%. You could then ask: "Who will end up as this future version of myself?" Again, the answer is clear. "Me". Put those two answers together and you have replaced probability with certainty - assuming a multiverse. It would be true to say that 1/37 future observations will of a zero-spin - but that is not an expression of probability. It is simply a statement of fact. There will be 1 'zero' observation and 36 'non-zero' observations". Ultimately this describes a collection of pre-determined futures. I suppose you might attempt to rescue probability by saying: "Only 1/37th of me will observe a zero spin. 36/37ths of me will observe a non-zero spin." However, your future selves will surely be complete versions of you, not fractions. As for not dying, I stand by the following statement, rephrased for clarity: "Given a multiverse, you are guaranteed to continue to experience being alive indefinitely - as long as there is always at least one reality in which your death does not occur." Simon Quote Link to comment Share on other sites More sharing options...

Buffy Posted May 9, 2007 Report Share Posted May 9, 2007 Yah, I do call it semantic quibbling. All I'm saying is that "probability" has a slight semantic redefinition as "the chance of experiencing a *particular* timeline." I'd call your last conclusion a simple tautology, basically equivalent to saying: "If I can perceive that I'm alive then I'm alive." You can't just make the other verses "go away" by saying that only *your* observation counts: that's not how either interpretation works... Whoops I'm dead,Buffy Quote Link to comment Share on other sites More sharing options...

Qfwfq Posted May 9, 2007 Report Share Posted May 9, 2007 No seriously, the notion of "you" is not the "entity that continues in all multiverses after a split" its "the path that you perceive". In Heisenbergian terms, your "observation" of "reality" (that is "the path you're perceiving") "collapses the wave function" and you end up with one reality. Your odds of which one of the 37 you end up actually perceiving is indeed still 1/37.And which path do "you" perceive? Just as I thought, although you strive to defend the notion of probability in the multiverse, you are actually doing your thinking in Copenhagen. :lol: If you (or we, collectively) perceive one of the possible paths down the tree, then it ain't the multiverse at all... the other paths don't exist. A multiverse wouldn't be such, that allowed favouritism and priviledge. Note also, that as with all things quantum, it doesn't matter whether *you* do the observing or someone else does, so the "you'll never die" is definitely *not* true....Now this is the correct objection to Simon's Russian scenario. 36 out of 37 of Simon's friend's selves will see him vanish. Yah, I do call it semantic... but I don't call it quibbling:All I'm saying is that "probability" has a slight semantic redefinition as "the chance of experiencing a *particular* timeline."I mean, in the multiverse conception of reality, What the heck does the word "chance" mean at all? Circular dear, circular! I'd call your last conclusion a simple tautology, basically equivalent to saying: "If I can perceive that I'm alive then I'm alive."Rather than calling it a simple tautology, I see it as somewhat Descartian. Quote Link to comment Share on other sites More sharing options...

Buffy Posted May 9, 2007 Report Share Posted May 9, 2007 And which path do "you" perceive? Just as I thought, although you strive to defend the notion of probability in the multiverse, you are actually doing your thinking in Copenhagen. :lol:What's been left unsaid though is that with the multiverse interpretation its necessary to have an "outside" point of view in order to validate it! From this "outside view," "all outcomes are certain" without a doubt! I won't argue against that at all. What's cool about the outside viewer (OV) is that OV can then perceive all 37 paths and watch the 37 versions of you hitting different outcomes, and since the tree of paths has 1 You becoming 37 Yous, the OV can still say "You 37 sure was luckier than You's 1-36". You can also define Yous as any particular path from past along the ever branching tree into the future. Of all the paths that exist you can still state the "odds" of a particular instance of You being on a specific path in the tree. Now you may not like my definition of "probability" here, but I look at it as simply a mathematical ratio of path branches that present different possibilities. I'm not being "Copenhagen" I'm merely pointing out that this math--no matter what words you use--represents a useful set of data representing the ratio of "paths You're dead on" to "all paths" or whatever interesting "outcomes" you want to look at. That is, the math is *identical* to probability--when you think about it, it *has* to be--so if you want to call it the "kerfuffle index" I don't really care, but its a complete isomorphism in my book! Dangerous to hit me on probability right now because my kid is struggling with it in school at the moment and I've been throwing examples of applications of probability at her non-stop for the last 2 weeks.... Circularly isomorphic (jeez, just wait til she hits Abstract Algebra),Buffy Quote Link to comment Share on other sites More sharing options...

Qfwfq Posted May 9, 2007 Report Share Posted May 9, 2007 Left unsaid? What did I mean by:Only the deus ex machina sees all 37 outcomes.then? I'm not being "Copenhagen" I'm merely pointing out that this math--no matter what words you use--represents a useful set of data representing the ratio of "paths You're dead on" to "all paths" or whatever interesting "outcomes" you want to look at.Yep you are, when you consider the notion of "which path you end up in", which doesn't make sense in the multiverse. It makes sense to each of your selves, which is why each of them has the illusion of probability. That is, the math is *identical* to probability--when you think about it, it *has* to be--so if you want to call it the "kerfuffle index" I don't really care, but its a complete isomorphism in my book!Now obviously the math is the same, I've been saying it all along. That doesn't mean what's being described by the math is the same. Math is only math and, if my granny had eggs... Dangerous to hit me on probability right now because my kid is struggling with it in school at the moment and I've been throwing examples of applications of probability at her non-stop for the last 2 weeks.... Circularly isomorphic (jeez, just wait til she hits Abstract Algebra)Tee hee, I'm sure she'll do just fine on these things, 'cause she's your daughter! It isn't on probability that I'm hitting you, really. It's on the meaning of it, the concept. If 50-odd percent of Californians vote for Schwarzy, is that a probability? :) Quote Link to comment Share on other sites More sharing options...

Buffy Posted May 9, 2007 Report Share Posted May 9, 2007 Left unsaid? What did I mean by...then?Seriously, when was the last time I actually had to read one of your posts? Its easier just to read your mind, but it looks like there was some really good chianti involved last night! :)Yep you are [being all Copenhageny], when you consider the notion of "which path you end up in", which doesn't make sense in the multiverse. It makes sense to each of your selves, which is why each of them has the illusion of probability.That's what that OV is for though: to disentangle and observe all of youse (this is starting to sound like a bad mafia movie) separately! The "one" You at the branching point becomes 37 Yous afterward, and each of the 37 paths in the tree represents a "different you" that only experiences that one path. That's why if you want it to sound less Copenhageny, you star talking about the *paths* and not the *Yous* (and people will stop calling you a goodfella!): its no longer "which path *you* end up in" its "what's the ratio of path generation" which is--as you admit--still equivalent.It isn't on probability that I'm hitting you, really. It's on the meaning of it, the concept. If 50-odd percent of Californians vote for Schwarzy, is that a probability? :)Naw, its a result (and an outlier at that! ): I'm sure some of my diehard Democratic friends here in multiverse path 185638356453764538764 are wishing Simon was right and that they could be their replicates over on the Busty-won subtree. Consciousness in the multiverse is scarily limited! Hey, whaddya gonna do, nice college boy, Buffy Quote Link to comment Share on other sites More sharing options...

Simon Posted May 10, 2007 Report Share Posted May 10, 2007 I've been wondering if Qfwfq and I are really on such solid ground - and might even be protesting too much. :cup: We've both been emphasing the following point about the multiverse: While you are in the present - before a wave function collapses - every possible future is your future. For that reason, we've been assigning each one a probability of 100%. So when you ask in the abstract "which of the possible outcomes will occur?", the answer is "all of them". This is what appears to eliminate probability. All you have is a collection of pre-existing items which you can subgroup into ratios such as 'zero', 'non zero', 'life' and 'death' etc. All this time, I have been troubled with the same point that Buffy has been aware of. With each future that definitely occurs, you only experience one outcome. Suppose then someone asks before the fact: "how many of all those certain outcomes are about to be added to your personal experience and entered into your memory?" Answer: "Only one". Question: "Which one?" :shrug: If that last question is legitimate, then I'm tempted give Buffy his due and admit that, at the very least, probability has a valid subjective status of reality. And since the consensus of what we know about anything is no more than the sum of our observations, there is good reason to apply probability to everything we encounter - even though the mulitverse ultimately makes it an illusion. That is my compromise. :) Probability is not to be singled out here. The multiverse challenges both free will and the notion of time itself. Even before Everett postulated the multiverse, Einstein had started this revolution by endorsing the concept of "spacetime" - where every moment is not a 'when' but a 'where'. Trying to reconcile this pre-determined four dimensional "spacetime" with the Uncertainty Principle was what the debate between Einstein and Bohr was all about. Einstein was one of the leading architects of quantum theory but he couldn't accept the implications of the Copenhagen view. When he finally snapped: "God does not throw dice!" he was close to denying the existence of probability. The multiverse can be seen as the working solution to that argument - one that would have allowed Einstein to have his cake and eat it. It redefined the probabilities of quantum theory as a collection of definite outcomes - while still dubiously referring to them as probabilities. Thus revised, it became totally compatible with a fixed 'spacetime' - albeit one that required five dimensions instead of four. In any 'map' of spacetime, whether universal or multiversal, it is not only probability that seems to vanish. Past and future have no meaning - except as 'ad hoc' adjectives applied to points on the map. A past observer does not 'become' any future observer. They co-exist as separate entities. From this perspective, if you ask: "Which of the 37 possible observations will be added to my memory?", the answer is: "None of them. You exist only now. If there are 37 observers in the future, each will be as distinct from you as they are from one another." This reductionist map of 'spacetime' may in one sense be accurate, but it completely ignores our own experience. After-all when we look at a picture on a screen, are we just seeing a jumble of pixels with no relationships to each other? Or does their arrangement have meaning because our observations give them meaning? If so, the same must apply to any map of reality. At the risk of being Descartian again, "We constantly have the experience of becoming our future selves, therefore we do." :) Since these experiences also happen to be limited to one outcome, however many exist, there is - for all intents and purposes - uncertainty as to what those experiences will consist of. Relative to our experienced progressions between uncertainty of the future to knowledge of one past, both time and probability appear to have meaning. Free will is another matter. I would say we never actually experience a 'choice' that isn't based on some combination of probability or predisposition. It therefore remains an illusion. Neither the Many Worlds or the Copenhagen view can rescue it. :) Simon Quote Link to comment Share on other sites More sharing options...

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