Re: MWI question for the physicists...
Pierz wrote: I wonder if someone with a good understanding of QM can answer this question, which has been troubling me. Let us imagine the case of a single particle, and let us imagine we know its position at time 0. Now my understanding of the evolution of the wave function for the position of the particle, according to a Deutsch-ian version of MWI, is roughly as follows: The position wave function of the particle represents the distribution of universes in which the particle is at a certain position. As an observer, I don't know which of those universes I am in, until I make a measurement of the particle's position. There is one eigenvalue for each universe (or better, branch in the multiverse), and the probability of that eigenvalue is a measure of the underlying universe 'count', or proportion. This may be Deutsch's take on MWI, but it is idiosyncratic to the point of incoherence. The wave function for a particle is, in general, a superposition of eigenstates of the position (or momentum) operator. But this does not represent a distribution of universes. The problem with such an account is that the basis states for the superposition are undetermined. For a single particle, there are an infinite number of possible bases for position space, and an equal infinity of possible bases for the representation in momentum space. This is known as the basis problem -- why is it that when we make a measurement, one particular basis is picked out, and the same basis is picked out consistently every time. If it were merely a matter of self-location in a multiverse, there would be no way of ensuring that the same basis eigenfunctions were selected every time. The basis is actually determined dynamically by the process of einselection, where the preferred basis is that which is stable against environmental disturbances. Separate universe do not emerge until decoherence has dissipated the interference terms into the environment in an irreversible way. Thus universe emerge only after interaction (measurement); they are not present beforehand. So the terms in the superposition do not represent separate universes -- they are just elements of a mathematical representation of the quantum state. As an aside, quantum probabilities as given by the Born Rule do not come from branch counting -- the probability is not a measure of the underlying universe count. So far so good. The explanation seems coherent, even if we haven't explained the distribution of those universes. However, I am puzzled by the case of spins. Consider a set-up in which a photon is polarized in the z direction, so that we know that the particle will, with probability 1, pass through another polarizer also oriented in the z direction. However what of the situation where the second polarizer is oriented at 45 degrees to the first one? In that case, the probability is 0.5 that the photon will pass through. If it does, then obviously the probability is 1 that it will also pass through a third polarizer also oriented at the same angle. This is a good illustration of the problem with thinking of the elements of the superposition as separate worlds. Every state, even an eigenstate of momentum or spin, is a superposition of eigenstates in different bases -- in fact, an infinite number of different superpositions. When you see it this way, you realize that the components of the superposition can't be worlds, because then you would have to say that the world in which we find ourselves is actually an infinite number of different superpositions of different worlds -- a set for each possible basis of the Hilbert space. The notion of a world then becomes incoherent. The photon polarized in the z-direction is a superposition of polarization states in any other direction. It is an equal mixture of 45 degree polarizations, but unequal mixtures of polarizations at any other angle. It is these coefficients of the expansion of the state in a particular basis that give the probabilities (as absolute values of the coefficients squared). Since any real value is possible, branch counting is ruled out. So what is going on in the multiverse in this scenario? Clearly, prior to the photon hitting the 45 degree polarizer, it can't be the case that half the universes have photons polarized at 45 degrees to the z axis, because in fact 100% of them are polarized in the z direction. Yet after the hitting the polarizer, half do. So in this case the discontinuity between quantum state and measurement, which MWI saves us from in the case of a continuous variable like position, seems to persist. What is going on at the point of the photon's interaction with the polarizer in an MWI account? Clearly, the multiverse differentiates into two branches corresponding to the two spin eigenvalues, each with measure 0.5. But does MWI have anything to say about the the weirdness of the jump between the z polarization and
Re: 1P/3P CONFUSION again and again
On 09 Aug 2015, at 22:53, John Clark wrote: On Sun, Aug 9, 2015 Bruno Marchal marc...@ulb.ac.be wrote: would be silly to ask the amoeba before the division if *you* will swim to the left or to the right after the division, almost as silly as asking which of the 2 amoebas was THE one true original amoeba that had THE 1p you. But no-one in this list has ever pretend than there is only one such the. Someone on this list has. In nearly every post Bruno Marchal says that from THE 1p *you* will see this but from THE 1p*you* will not see that; but if there is more than one then the statement becomes meaningless. Not at all. Because the question is on the 1-p you, and you know (in advance, in Helsinki) that there will be only one 1-view from any of the two 3-1 p view available. You look like trying to be wrong on purpose. We always use 3-you or 1-you, or we use 1-JC and 3-JC, or 3-1- JC. So in Bruno's unusual peepee notation 1-JC is John Clark's subjective experience and 3-JC is John Clark's objective actions, but what the hell is 3-1-JC and how does it differ from regular old 3-JC? 3-JC is refers to the bodies which in this case are in the two cities. 3-1 refers to the subjecyive experience, of frst person view ascribed to both bodies, which is different from the 1p view lived by the person attached to such bodies. 1p are always single solitary and definite. 3-you can be in W and M. But 1-you cannot. Maybe maybe not, it all depends on what you means, but neither JC nor 3-JC nor 3-1JC nor 1-3-1JC knows what Bruno Marchal means by that pronoun, and by now it's pretty obvious that Bruno Marchal doesn't either. In the math translation, eventually, we get a meta-definition of the 1p-you, more precise than the one who remember .., but for the UDA reversal, the first definition is quite enough. if you argue that 1-you can be in both place, it means you talk about the 3-1-you. Is Bruno Marchal you, or the 1-you, or the 3-you, or the 3-1- you? For *any* creature, you can consider its you in the 1p sense, or the 3-1p sense, or the 3p sense, etc. If Bruno Marchal has an headache, this is pure 1p, if he send a mail, that is 3p (at first). Much later, if we ever arrive there, we will see that the body is not really a 3p thing, but an 1p-plural object, but this is not relevant here(it is relevant for after-life type of question, though, but useless and confusing to accept at this stage, despite QM suggests it (but we can't use QM). you have the following belief: I will [...] The word will implies the future and if you thinks that computationalism is true, that is to say that you is rational, then you thinks that the subjective future will bifurcate. That is the point. And if you agree it bifurcates, a simple reasoning (that we have done many times) shows that you are unable to predict the 1p outcomes of that bifurcation. If you is not rational then you could believe anything, but you's beliefs in what will happen, true or false, will in no way effect what will in fact happen. push the button, open a door and see [...] What I believes I will see depends entirely on what I means by I when dealing with the future in a world with I duplicating machines. But as we assume computationalism, there is no ambiguity at all, and the result depends only on the maning of I or you on which we have already agreed, but of course we need to take into account the 1p/3p nuances to get the answer right, given that the question bears on that 1p perspective. The English language in general and in person pronouns in particular was never designed with this sort of thing in mind . Sure, but computationalism makes what happens crystal clear, unless you forget that the question bears on the subjective experiences. your argument suppress the indeterminacy in Everett QM. I though you were the guy who kept saying that Everett's MWI was deterministic. In the 3p view, but for the 1p (and here 1p-plural) we have to derive and use the Born probability rule, like in the WM-duplication we have to use the P(W v M) = 1 and P(W M) = 0 rule. Nobody can figure out what your theory predict Computationalism predicts that after the bodies have been duplicated photons from Moscow will turn the Helsinki Man into the Helsinki Man who remembers seeing photons from Moscow (aka The Moscow Man). And computationalism says that after the bodies have been duplicated photons from Washington will turn the Helsinki Man into the Helsinki Man who remembers seeing photons from Washington (aka The Washington Man). What remains indeterminate? The experience that the guy will who undergone such duplication can expect to live. Obviously, given the protocol he must expect to wake up in W or in M, and not in both.
Re: 1P/3P CONFUSION again and again
On Mon, Aug 10, 2015 at 4:50 AM, Bruno Marchal marc...@ulb.ac.be wrote: there will be only one 1-view from any of the two 3-1 p view Oh no, now we have the two 3-1 p view ! 3-JC is refers to the bodies which in this case are in the two cities. OK, or in non-peepee notation the objective actions of John Clark's body or bodies. 3-1 refers to the subjecyive experience In non-peepee notation the subjective experience. of frst person view That is redundant because the first person is the only type of subjective experience there is. ascribed to both bodies, which is different from the 1p view lived by the person attached to such bodies. I have no idea what that means and think your peepee notation really sucks.. Ascribed by who? If it's the by a third person then the 3-1 view is just the 3 view, and if it's the first person then the 3-1 view is just the 1 view. 1p are always single solitary Are? I t should be 1p is always solitary but I think the idea and not just the grammar is wrong. I can't prove it but I have a hunch that solipsism is untrue, so right now I think there are about 7.1 billion 1ps on planet earth and maybe more if animals are conscious and many probably are. In the math translation, eventually, we get a meta-definition of the 1p-you, more precise than the one who remember . Regardless of how advanced the mathematics precision is not achieved if the symbols used (like *the* 3-1you) don't mean anything. if you agree it bifurcates Of course I agree that the subjective experience bifurcates when looking along the timeline in one direction, and it unites when looking along the opposite direction. And that is why personal identity can only be defined by looking toward the past and not the future. a simple reasoning (that we have done many times) shows that you are unable to predict the 1p outcomes of that bifurcation. Not true the outcome is perfectly predictable. The guy who intercepts a photon from Moscow will turn into the guy who experiences Moscow and the guy who intercepts a photon from Washington will turn into the guy who experiences Washington. I honestly don't know what more needs to be predicted. I though you were the guy who kept saying that Everett's MWI was deterministic. In the 3p view, but for the 1p (and here 1p-plural) we have [...] I REALLY don't understand your homemade peepee notation! You just said 1p are always single solitary . What your computational theory of mind fails to predict is the outcome of the result of pushing on the button from the first person perspective That is gibberish. In looking toward the future in a world with person duplicating machines there is no such thing as *THE* the first person perspective; such a term is only meaningful in looking toward the past because things bifurcate going in one direction and converges going in the opposite direction. John K Clark -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Idiot Test
OK - perhaps this post is not entirely serious. I don't actually know. There appears to be no reliable test of idiocy. Even people who invite others to participate in games of running along a lawn while a drone fires rockets at them may not actually qualify, ultimately, as idiots. It may be that the true definition of an idiot (in the theological, not medical sense) is one who is incorrigible in their beliefs. If you never change your mind, why have one? The hallmark of a true idiot is one who never admits they are wrong about something even in the face of massive counterfactual evidence and the weight of opinion thrown against them. So what, I hear you say. Idiots clearly exist. Trouble is, we need this test as I said above. You don't want idiots in government you don't want idiots as scientists and you certainly don't want idiots running your local church. On the basis of this argument you would, for example, still want to keep drugs illegal - for idiots. Anyone who could reliably prove they were not an idiot could still use drugs. Idiots get orange juice and huge injections of vitamins. Or something. The test would therefore be to administer a standard dose of Salvia Divinorum after which the person would be interviewed. The box marked 'idiot' would be ticked in the case where the subject maintained with the same or increased fervour, the beliefs they held prior to taking the test. Those who come through the experience with changed or clearly modified beliefs would be classed as normal. Obviously the people conducting the interview would be 'normal'. Any takers? Kim Jones B. Mus. GDTL Email: kimjo...@ozemail.com.au kmjco...@icloud.com Mobile: 0450 963 719 Phone: 02 93894239 Web: http://www.eportfolio.kmjcommp.com I'm not saying there aren't a lot of dangerous people out there. I am saying a lot of them are in government - Russell Brand -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
MWI question for the physicists...
I wonder if someone with a good understanding of QM can answer this question, which has been troubling me. Let us imagine the case of a single particle, and let us imagine we know its position at time 0. Now my understanding of the evolution of the wave function for the position of the particle, according to a Deutsch-ian version of MWI, is roughly as follows: The position wave function of the particle represents the distribution of universes in which the particle is at a certain position. As an observer, I don't know which of those universes I am in, until I make a measurement of the particle's position. There is one eigenvalue for each universe (or better, branch in the multiverse), and the probability of that eigenvalue is a measure of the underlying universe 'count', or proportion. So far so good. The explanation seems coherent, even if we haven't explained the distribution of those universes. However, I am puzzled by the case of spins. Consider a set-up in which a photon is polarized in the z direction, so that we know that the particle will, with probability 1, pass through another polarizer also oriented in the z direction. However what of the situation where the second polarizer is oriented at 45 degrees to the first one? In that case, the probability is 0.5 that the photon will pass through. If it does, then obviously the probability is 1 that it will also pass through a third polarizer also oriented at the same angle. So what is going on in the multiverse in this scenario? Clearly, prior to the photon hitting the 45 degree polarizer, it can't be the case that half the universes have photons polarized at 45 degrees to the z axis, because in fact 100% of them are polarized in the z direction. Yet after the hitting the polarizer, half do. So in this case the discontinuity between quantum state and measurement, which MWI saves us from in the case of a continuous variable like position, seems to persist. What is going on at the point of the photon's interaction with the polarizer in an MWI account? Clearly, the multiverse differentiates into two branches corresponding to the two spin eigenvalues, each with measure 0.5. But does MWI have anything to say about the the weirdness of the jump between the z polarization and the 45-degree polarization? -- You received this message because you are subscribed to the Google Groups Everything List group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
