Contra MWI (Many World Interpretation) I had mentioned to Jeff Schwartz and to Ken Augustyn that I was thinking about writing a paper about the problems with MWI, and they both encouraged me to focus my energies on that project, rather than on other matters that seem to be soaking up my time. This message is not that paper, but is rather a first informal chat about the subject. A first point is too obvious and oft-mentioned to bear repeating in the literature, But I'll mention it here: If every possible experience occurs in parallel then what does it mean to say that the relative probabilities of two alternative possible experiences is not unity? The initial argument that I made to myself back in 1959, when the reading of von Neumann's book caused me to imagine a many-minds solution of the measurement problem, was this: Imagine flipping a coin a hundred billion times. Simple calculations show that, although the possibilities range from all heads to all tails, a huge proportion of the possible sequences will lie in the interval in which the ratio of heads to tails is unity to within 1%. The fraction of the possible sequences in which the ratio is, say, 6:4 to within 1% is very-very tiny. But suppose the coin is "loaded" so the relative probability of heads to tails is 6:4. Then the huge proponderance of the actually occurring sequences will in all likelihood be concentrated in the interval where the ratio is 6:4 to within 1%, even though only a tiny-tiny fraction of the possible *sequences* lie within that interval. Thus if we have a situation in which each outcome is either a head or a tail one can form a clear idea of what the consequence would likely be if the relative probability of heads to tails is 6:4. But if heads and tails BOTH occur in parallel then what is the meaning of saying that the ratio of heads to tails is 6:4? What one needs in order to explain the (quantum) data is this: The "experience of the observer" in a quantum situation where the predicted relative probability of "heads" to "tails" is 6:4 will almost certainly be that the ratio of heads to tails in a run of one hundred billions flips lies within 1% of 6:4, even though only a miniscule fraction of the possible sequences lie in that interval. There is not much difficulty understanding this result if each flip gives either a head or a tail. But how does one understand that one's experiences will almost surely be 6:4 heads to tails to within 1% if ALL possible experiences occur in parallel, and the experiences of finding the 6:4 ratio to within 1% are only a minute fraction of the possible experiences? It all comes down to the question of what does "statistical weight" means in a situation where all things happen in parallel. What does it mean to say that my experience will almost surely be `such and such' when the contrary experiences are occurring in parallel, and are vastly more numerous. The MWI answer is simply: THAT is the mysterious quantum postulate! And this mystery is preferable to instantaneous action at a distance, and the need for new rules associated with the entry of consciousness into the dynamics of conscious systems. However, this MWI postulate IS mysterious, whereas the idea of the existence of a temporal "now" extending over the universe, even though we do not have direct empirical access to it, was clear enough to generations of eithteenth and nineteenth century scientists: that idea is not intrinsically mysterious. Nor is it intrinsically mysterious that there should be rules for how our minds work, and how minds are connected to brains. Another thing about the MWI that IS mysterious is that, because this multi-morld is micro-deterministic, there is no logical or dynamical need for anything not strictly entailed by the micro-physical conditions, and hence no need for, or causal role for, what our feelings seem to us to be. Consciousness, as we directly know it, becomes an inert spectator: experiences per se have no functional role in nature. As in the *classical* deterministic case there is no reason for the "seemings to be" that we directly experience, and call "pleasure" and "pain", to exist at all, or, if they do exist, to be associated, in general, with physical activities that benefit and injure our survival prospects, respectively. Nor can the "seeming to be" that we call "effort" make any difference. The MWI, like the classical model governed completely by microlocal dynamical laws, leads to the conclusion that these most immediately and directly known aspects of reality, namely pleasure, pain, and effort, either are fundamentally different from the "seemings to be" that they are defined to be, or can have no effect upon our physical actions. The effort to build science on micro-deterministic physical theories that either contradict the empirical evidence (as in the case of classical physical theory) or that postulate infinitudes of forever empirically inaccessible parallel branches of reality (MWI) both lead directly to the invalidation of the foundations of our conscious dealings with the world, whereas the alternative of building our conception of reality on a formulation of physical theory that maintains close contact with the empirical data (vN/W), provides both a natural place for us in reality, and a way for us to know reality, and for our knowings to act upon the rest of reality. And it does these things without invoking any fundamental mysteries. A basic technical problem with MWI [which really should be called MMI (Many Minds Interpretation) because the problem is to explain the statistical structure exhibited in our human experiences] has to do with the characterization or definition of an "observing system" within a physical universe that evolves always in accordance with the Schroedinger equation. The basic problem is that in a universe that evolves with no collapses the state of the universe is going to be an amorphous glob: any state of a human being will be part of a continuum of similar human beings with slightly different states, maybe with more or less particles, with slightly different histories, with slightly shifted locations, etc., in an amorphous superposition or mixture. These states, since they form continua, will overlap: they will not be orthogonal. To make the statistical formulas of quantum theory work we need to have projection operators that are associated with human experiences. But if the state contains a continuum of human-body possibilities, all existing in parallel, and if each projection operator P in some *physically defined* class corresponds to an experience, and each (1-P) corresponds to an associated contradictory experience, then the set of pertinent P's must form a continuum, as do the (1-P)'s. But then the probability formula Prob P = Tr PS/Tr S will give FINITE values for a continuum of P's, which gives a wildly infinite total probability. The whole quantum probability calculus breaks down. This difficulty is avoided in the vN/W QT, as I define it, because experiences are taken as primary realities, rather than mere re-expressions of physical structures. This allows one to talk first of a set {E_i} of experientially distinct experiences, and then define the associated set {P_i}={P(E_i)} of orthogonal P_i's: P_i P_j = P_j P_i =0. I do not believe that it makes sense to introduce such P_i's in an amorphous universe just building on physical properties alone. For there is no lattice or discrete structure defined by the physics alone in an amorphous universe. [As I have just described it, the vN/W QT would seem to require a sort of Platonic Realm of pre-existing ideas {E_i}. However, it is possible to maintain the idea of co-evolving realms of mind and matter by supposing that each distinct E_i in the set {E_i} came into existence in conjunction with an existing physical correlate. But once an E_i is created any subsequently added E_j must correspond to a P_j that is orthogonal to all those P_i's already specified.] Anyone who thinks that decoherence (coupled perhaps with consistent histories) gives a coherent well worked out MMI or MWI ought to consider the problems described by Zurek in Prog. Theor. Phys 89, 281-312 (1993) The more recent review by Zurek (Phil. Trans. R. Soc. Lond. A (1998) 356, 1793-1821) also stresses the incompleteness of the program. He stresses the problem of how the universe is to be split into systems (observing systems and 'the environment') in a unique way. That problem is connected to the problem that I emphasized of extracting the discrete "basis states" required for the application of the probability calculus from an amorphous glob. He describes his report as "still only a report of partial progress". So the growing aura that MWI is somehow already satisfactorily worked out is not based on fact. Of course, people working on quantum computation are not involved with the basic problem of collapse, which comes in unavoidably only at the level of the interface between human brains and human experiences. But they ARE acutely concerned with environmental decoherence, which acts very much like a collapse, but in principle can be suppressed. When they assert that they believe that the Schroedinger holds (no collapses) they are probably speaking primarily about the world of quantum computers, not primarily about the vastly different, and vastly more problematic, realm of human brains, or they have not really examined the problems that Zurek has been trying (still not successfully) to resolve. Or maybe they are just blissfully optimistic. But Zurek has been doggedly trying to make it work for two decades, so it must be admitted that there are some deeply nontrivial problems with MWI. From stapp@thsrv.lbl.gov Thu Apr 12 20:54:25 2001 Date: Thu, 12 Apr 2001 20:51:18 -0700 (PDT) From: stapp@thsrv.lbl.gov Reply-To: hpstapp@lbl.gov To: Stanley Klein Cc: hpstapp@lbl.gov, kleinlist , bdj10@cam.ac.uk, brucero@cats.ucsc.edu, ghrosenb@ai.uga.edu, hameroff@u.arizona.edu, Jeffrey M. Schwartz , keith@imprint.co.uk, Kathryn Blackmond Laskey , phayes@ai.uwf.edu Subject: Re: EPR-Bohr-Bell and nonlocatity On Thu, 12 Apr 2001, Stanley Klein wrote: > > 2. Could you remind me briefly why Bohm and many minds (many worlds) > aren't also ontologies (quite ugly ones I'd say, but still > ontologies). > > They are ontologies, but neither has a real theory of consciousness. Neither one has any place for "free will", since no questions are put to nature. The known laws determine the course of events, and there is no possibility for efficacious mind because there are no collapse events. These theories were designed to keep mind from having any effect: they are efforts to extend the epiphenomal character of mind found in classical mechanics into quantum theory. Bohm theory had no place for mind, but Bohm tried to bring it in, in some later papers, by introducing an infinite tower of Guider waves, each controlling the one below it. Somehow the infinity gave consciouness. But I believe that a satisfactory theory of consciousness should not replace consciousness by something else! A satisfactory theory of consciousness must have the experiences that we directly feel, and report in psychological language, as elements of the theory. And these elements must be tied into the mathematics of quantum theory. This is possible in the von Neumann formulation because the mathematics of quantum theory is about bits of information, and thoughts are felt, or mentally grasped, informational structures. Many-minds theory is nominally about "mind" in the sense that it resolves the "collapse" problem of quantum theory by denying that there are collapses, and thus places the whole burden of reconciling that with the fact that we do not experience all the things that are then present in the universe, by appealing to a theory of mind, which, however, has never been worked out. The first question is why does mind exist at all in that theory since everthing else is determined without acknowledging mind. But the real problem is to recover the results of the von Neumann theory, which gives the empirically validated prediction about experiences, given an observer/participant who askes well defined questions that are supposed to correspond to well defined experiences, when the full dynamics is given by the Schroedinger equation. The problem, there, is that the projection operators P, which are needed to make the computations, define SUBSPACES. An example of a subspace is the plane containing the x and y axes in a three dimensional space. One can see that, given any vector in the subspace, the tiniest shift of that vector in certain directions will move that vector out of the subspace. But the evolution of the state of the universe since the beginning of time, under the control of the Schroedinger equation is going to be a smeared out structure with no sharp boundaries or edges. How, therefore, can the state of the universe itself, evolving in this way, ever lead to well-defined subspaces? The whole mathematical structure needed to get the validated predictions collapses in ruins. In the von Neumann theory one has projection operators, which have two eigenvalues, 0 and 1, and hence two answers to the associated question, according to the basic rule of quantum theory. One has therefore "bits" of information, and the notion that a potential experience that grasps this bit of information either occurs or does not occur. But this whole structure depends on the supposition that something picks out a definite projection operator P. It seems obvious the Schroedinger equation cannot do it. Stated differently, if the state of the universe is the result of an uninterrupted Schroedinger evolution since the big bang then the problem even defining individuals is already enormous, and the further explaining of how the set of orthogonal projection operators P corresponding to a definite set of mutually exclusive possible experiences is going to be determined by the amorphous structure of the state vector alone is daunting task that has not yet been performed. So I claim that the many worlds/mind interpretation throws the whole interpretational problem onto the problem of creating a theory of mind, or minds, without real collapses, but the huge difficulties in doing this have not even begun to be solved. von Neumann's formulation is, I claim, the only quantum theory that gives an adequate theory of consciousness and the brain. Henry From stapp@thsrv.lbl.gov Fri Apr 13 20:51:31 2001 Date: Fri, 13 Apr 2001 20:47:42 -0700 (PDT) From: stapp@thsrv.lbl.gov Reply-To: hpstapp@lbl.gov To: Stanley Klein Cc: hpstapp@lbl.gov, kleinlist , bdj10@cam.ac.uk, brucero@cats.ucsc.edu, ghrosenb@ai.uga.edu, hameroff@u.arizona.edu, Jeffrey M. Schwartz , keith@imprint.co.uk, Kathryn Blackmond Laskey , phayes@ai.uwf.edu Subject: Re: same predictions? On Fri, 13 Apr 2001, Stanley Klein wrote: > [Stan] > > > 2. Could you remind me briefly why Bohm and many minds (many worlds) > > > aren't also ontologies (quite ugly ones I'd say, but still > > > ontologies). > > > > >[Henry] > >They are ontologies, but neither has a real theory of consciousness. > > > Thanks Henry. That's what I had thought about them being ontologies. > I think some people strongly feel that Bohm has implications for > consciousness (e.g. either the Bohm point or the 'pilot wave' being > the mental). > > Now let me ask whether the three ontologies (Bohm, many minds, vN/W) > make the same predictions. I had previously thought that they do. > However, now I'm not so sure. In 'many minds' the choice of branch is > random. In vN/W the choice doesn't seem to be random but rather comes > from the mental realm. So maybe the two predictions regarding the > outcome of mental effort are different. Or do you think they have > same predictions? > > Stan > Dear Stan, Bohm's original nonrelativistic model was designed to make the same pedictions as vN/W. It does so, however, only if supplemented by an extra postulate that associates consciousness with the classical universe defined by the moving "Bohm point". This is a bit of a problem because classical physics does not have any "rational" connection between mind and matter. The great virtue of the quantum approach to mind/matter is that the two aspects are naturally entwined right from the start in mutually supportive roles. The original Bohm model does not have this feature. Also, all the classical universe enter co-equally into all of the dynamics, and hence it is unnatural to single out ONE of the infinite ensemble as completely different from all the others, in that it has this mysterious consciousness attached to it, with this attachment having no effect on anything. But in any case, that model is nonrelativistic: its PREDICTIONS do not satisfy the empirical facts. Thus it is ruled out. Bohm recognized this, right from the start, and noted that one would have to do just what was done in the orthodox approach: go over to field theory. It sounded at first plausible that, just as ordinary quantum theory could be made relativistic by going over to a relativistic field theory, so could his addendum to it. However, the attempt to actually do so, made in his book, "The Undivided Universe", revealed problems: He did not fully demonstrate that he could apply his ideas to our basic relativistic quantum field theory, QED. For this reason one cannot claim that Bohm theory gives the same predictions as the relativistic vN/W-Tomonaga-Schwinger theory. Bohm theory has, I believe, not really been fully defined at the level of QED. But let me pass over that point, and suppose the Bohm model is well defined for the case of a human brain How do we test the idea that of the billions of classical brains that, according to Bohm's theory, effectively combine to make the quantum state of the brain, exactly one carries (epiphenomenal) consciousness? Let us think of the problem in the context of the OCD patient whose brain is overwhelmed with the flood of signals that are impelling him to wash his hands still one more time. A competing rational thought briefly breaks through: "it would be better, in the long run, to tend to the roses in the garden." Now there is at least in principle a big difference between what Bohm would say happens and what vN/W-QZE says happens. Bohm theory would say that since this thought has flashed into the mind the "preferred" Bohm point (or trajectory) must be in a particular position, within the cloud of positions that consitute the brain [let us ignore the rest of the universe]. The rest of the brain trajectories are still present, but engender no consciousness. The fact that the "consciouness-trajectory" is off in one corner does not influence the motions of any of these virtual worlds. But in the vN/W theory the fact that this thought has flashed means that the actual (quantum) world is a world that is compatible with the fact that this thought has occurred. In nV/W the QZE effect, generated by the thought, can now "hold in place the theraputic idea of moving to the garden", and thereby actually change the evolution of the state of the brain from what the Schroedinger equation specifies, whereas in Bohm's theory the presence of consciousness on the trajectory has no effect on anything. So the actual evolutions will be different in the two theories. But suppose the evidence supports the vN/W QZE prediction that the theraputic thought can hold itself in place. The Bohmist can say that due to the complexity of the brain one cannot actually compute what the Schroedinger equation would say. Thus he could say that the brain was, due to its prior conditioning, holding part of itself in place, and that the thought that "I shall, by the force of my will, resist the OCD urges, and hold in place the thought of moving to the garden", which Bohm's theory would say is attached to the trajectory, would be an effect of the brain on the stream of consciousness associated with the consciousness-bearing trajectory. Of course, it is totally fantastic that the brain should create this epiphenomenal illusion. What is point such silliness? What I expect to happen is that as neuroscience and psychophysics develop, and more and more information begins to accumulate about the differences in the way the brain behaves when consciousness and conscious effort is present, as contrasted to brain behavior when conscious processes are not present, it will become evident that a lot of details are in accord with what would be expected from vN/W QT. So the theory will become a useful tool. [I am suddenly reminded of Gell-mann's early pronouncements that the idea of "quarks" was merely a useful tool---that quarks should not to be construed ontologically---and the present-day blurring of that distinction by physicists] If the behaviors of brains "seem" to be such that thoughts affect brain actions in certain specific ways, and the alternative proposal that this "seeming to be" is some sort of illusion, which cannot "yet" be explained, and if the "seeming" connections are naturally explainable as "true" connections within the framjework of basic physics, then it becomes reasonable at some point to start talking as if the seeming connections are real connections, and drop the inane search for an explanation of the mysterious "illusion". So I am saying that the brain is such a complex system that it is too much to demand that some single clean "crucial" experiment will decide between the vN/W QT and Bohm's model, even though the predicted brain behaviours differ. The vN/W QT specifies a direct linkage between mind and brain that seems to fit both the empirical facts and the basic principle of QT, whereas Bohm theory needs to explain why it is that the presence of the "consciousness trajectory" SEEMS to influence brain behaviour when the equations do not entail it. [How does the presence of the "consciousness trajectory" account for the "seeming" power of the thought to keep attention focussed on the garden, when the attachment of consciousness to the trajectory was just a ad hoc epiphenomenal add on?] [Bohm was undoubtedly aware of these problems, because he later tried to bring in consciousness in ways that were very different from the original simple ideas that some single trajectory was real, and hence specified the branch that was "observed" by the observer. He tried later to give consciousness some overlording power. A guider field to guide the field that guided the field that .... guided the classical universe. But this deeper theory of consciousness was never worked out in enough detail to permit clear predictions. Nor is it clear how these "higher fields" are related to our conscious thoughts, which is what a theory of consciousness ought to be about.] Similar problems arise in the many-minds case. This theory pushes all the interpretational difficulties onto a theory of mind, which is not provided. It is the vN/W theory that directly relate the mathematical formulas of QT to experiences and that is validated by the empirical data. So THAT theory is the touchstone to reality, and the many-minds theory must connect onto that theory, and justify it without using anything other than the Schroedinger equation. That's a tall order. The many-minds theory must deduce the relevance of the projection operators P on which vN/W QT [and Copenhagen QT] is based, and explain how the state of world that is really the amorphous structure that has grown out of the Schroedinger evolution since the big bang manages to generate realms of experiences that conform to the vN/W rules. Decoherence helps a little bit, but not enough to do the job. The state of a system that are naturally defined by environmental decoherence effects are the so-called coherent states, which are beautifully connected to classical physics. That is an encouraging first step. But closely neighboring coherent state are far from being orthonormal. And if two such states are each coupled to an environment and the combined system evolves unitarily then the inner product of the two states remains what it was. So there always remains continuums of overlapping states: environmental decohence does not separate the amorphous state on the universe into distinct realms to which the vN/W rules of interpretation apply. So the many-minds interpretation does not exist. To make it exist one needs a whole superstructure to place on top of the Schroedinger evolution, a superstructure that will justify the vN/W-Copenhagen rules of computation and interpretation. I very much doubt that any such superstructure can be constructed that does not smuggle in ad hoc rules that go beyond what the Schroedinger equation entails. So the details of the predictions could depend on those other features. So in answer to the question of whether vN/W QT and Many-Minds QT make the same predictions I answer that the latter does not curently exist. To the exent that it could be made an adequate theory it would have to justify the vN/W rules at the practical level, at least to a good approximation. But I do not see how the theory is going to be able to avoid bringing in the outside question poser; I do not believe that the state of the universe evolving via the Scroedinger equation can, by itself, justify of the vN/W rules. without admitting an outside "question poser", or something equivalent to it. Since the vN-Tomonaga-Schwinger relativistic quantum field theory is the fundamental relativistic quantum theory that gives a clear basis for the interpretation of the formulas, and since the yet-to-be-created many-minds interpretation must presumably justify it, at least at the pragmatic level, I propose taking the former theory as basic, at least until the latter theory becomes well defined.