Sure, but the theory with the simplest sound-bite axiomatization may not be the most parsimonious theory at the end of the day. And your confidence in that starting point will depend heavily on how confident you are in the prospects for extracting the Born probabilities from the Schrödinger equation on its lonesome. A theist will claim that his starting point is maximally simple relative to its explanatory power—heck, one of his axioms is that his starting point is maximally simple! that’s how simplicity works, right? -- but the difficulty of actually extracting normality from theism without recourse to ‘deep mysteries’ undermines the project in spite of its promising convergences with the data.
I meant not simplest as in simplest sound bite, I meant in the way mr. Yudkowsky has painfully explained elsewhere when he treated Occam’s Razor. One single equation is always a simpler proposition than two; and a whole intelligent being that sparked Existence itself and is not made of parts is so far off the map it’s not even worth considering as a preliminary hypothesis.
The wave occurs at both positions (or with both spin components); the particle does not. Being made of particles, I have a determinate brain-state, not a superposed one; and I observe a determinate particle position, though the dynaymics of that particle (and of my brain-state) are guided by the wave function. Many Worlds seems to predict that I will both see a spin-up measurement result and a spin-down measurement result, when I observe the superposed state. But in fact I seem to either see spin-up or spin-down, not both. So at this simple stage, Bohm correctly predicts our observation, and Many Worlds does not. That’s why the challenge for Many Worlds is to make sense of the probabilistic element of QM. The Schrödinger dynamics leave no room for probability; they are, as you note, deterministic.
If you have any system that is in a given state A and that system interacts with another one that is in a superposition of states X and Y, it no longer makes sense to talk about the first and second system: the whole system is now in a superposition of states. Same thing with observing the measurement: what you actually observe is a computer telling you “spin-up” or “spin-down”. So that’s a gazillion atoms and molecules and particles and whatnot that’s different depending simply on the state of the electron. Now suppose you somehow isolated that computer completely from the outside, so that not a single photon left it, then you could say that the computer is in a superposition. And as soon as you looked, so would you. The fact that you don’t actually see the computer accusing both “spin-up” and “spin-down” or some combination is just a consequence of the fact that, while the whole system, including you, your brain, the computer, the room you’re in, the air you’re breathing, etc., is in a superposition, the amplitude for the two states to interact is infinitesimal. For all intents and purposes, these two states have decohered. That’s not to say superposition is gone; it’s just to say that the amplitude for those two states to interact is nearly zero.
A multiverser may respond: ‘But we’ve come so far! We’ve made such progress! Surely we deserve to be treated as the standard view by this point. All that’s left is the small problem of explaining the emergence of the real.’
Eh… I don’t know about that. I mean… well, I’ll come to that in a bit.
This is not to say that the quantum world is obliged to match our intuitions. It is only to say that for an interpretation to even qualify as an interpretation, it will have to give some content to its formalism. As content goes, ‘world-splitting’ and ‘Magical Reality Fluid’ is not much of an improvement, if improvement it is, over ‘particle’ and ‘wave.’
I’ll comment on it in a bit, too.
But I think most physicists who have a view on the issue assign a greater-than-.9 probability to their preferred variants of MW; and I haven’t seen evidence that they’ve grappled with the foundational questions enough to warrant that much confidence.
I think that is the same problem I had with any other theories. The very idea of non-locality triggers alarm bells all over my brain. That > .9 probability to MW, I believe, stems, at least partially, from an implicit < .01 probability to non-locality. So that really leaves very little room for other interpretations, and those, from what I’ve read, sound more bogus than Bohm.
[...] and in particular in challenging MW to become more rigorous and explicit in what it means with all this world-talk. Bohm may sound unfashionably 19th-century at times, but at least it never sounds mystical.
I, personally, don’t think MW sounds all that “mystical.” I guess that comes from having lived half my life in the 21st century, so even in fiction the notion of multiple universes has never been a scary, strange one. The existence of a multiverse has always been a… persistent idea in my mind, and once I started reading up on Q.M. and studying the subject I just gave form to that intuition. That being said, I do agree with you that, at least from Wikipedia’s list of interpretations, Bohm’s does look like the most solid alternative to MW.
And coming to my final point… the Born probabilities. I honestly, truly have not a clue where they come from. I am hoping that any final unified theory might be able to solve that little problem (HA, little, right), but it wouldn’t be bad if someone solved it from within Q.M. itself. Some have tried, and I haven’t yet gotten to the point where I believe I am ready to read their attempts and truly grok what they mean so I can myself judge my probability estimates.
I meant not simplest as in simplest sound bite, I meant in the way mr. Yudkowsky has painfully explained elsewhere when he treated Occam’s Razor. One single equation is always a simpler proposition than two; and a whole intelligent being that sparked Existence itself and is not made of parts is so far off the map it’s not even worth considering as a preliminary hypothesis.
Yes, I grok. My point was that some theists don’t just think that God is simple partwise; they think that in some unknown (perhaps ineffable) way he’s maximally conceptually simple, i.e., if we were smarter we could formulate God in something equation-like and suddenly understand why everything about him really flows forth elegantly from a profoundly simple and unitary property. (And if everything else flows forth inevitably from God, the theory as a whole is no more complex than its God-term. Of course, free-will-invoking variants will be explanatorily inelegant by design; sudden inexplicable ‘choices’ will function for libertarians like collapse functions for Copenhagenists.)
Obviously, this promise of being able to formulate God in conceptually (and not just mereologically) simple terms is not credible. But this was the point of my (admittedly unkind) analogy; we should be wary of theories that promise an elegant, unimpeachably Simple reduction but have difficulty connecting that reduction to normality even in a sweeping, generic fashion. MW is obviously much better in this regard than theism, but one of the problems with theism (it promises a simple reduction, but leaves the ‘simple’ undemonstrated) is interestingly analogous to the problem with MW (it promises a simple reduction, but leaves the ‘reduction’ undemonstrated). I don’t take this to be a distinct argument against MW; I just wanted to call it to attention.
I think that is the same problem I had with any other theories. The very idea of non-locality triggers alarm bells all over my brain. That > .9 probability to MW, I believe, stems, at least partially, from an implicit < .01 probability to non-locality.
Fair enough. This perhaps is the fundamental question: The naive interpretation of data from EPR-style experiments is quite simply that nonlocal causation (albeit not of the sort that can be used to transmit information) is in effect between distant entangled states. If your commitment to locality is strong enough, then you can recover locality by positing that you’ve imperceptibly fallen into another world in interacting with one of the particles, dragging everything around you into a somehow-distinct component of a larger, quasi-dialetheist (really, complex) reality. I don’t begrudge those who pursue this path; I only encourage careful scrutiny of exactly which priors we’re appealing to in taking that first step away from the naive, superficial interpretation of the experimental result that caused this aspect of the problem.
I, personally, don’t think MW sounds all that “mystical.” I guess that comes from having lived half my life in the 21st century, so even in fiction the notion of multiple universes has never been a scary, strange one.
I don’t find the idea of clearly distinct universes mystical or strange or scary. I do find it strange and very-nearly-incoherent to think of worlds ‘bleeding together’ at the edges; and I very much wonder what it would be like to fully inhabit that intersection between worlds.
the Born probabilities. I honestly, truly have not a clue where they come from.
Note that on BM, the Born probabilities emerge from stochastic initial particle distributions; probabilities are epistemic, not metaphysical (as they are in collapse). One can raise the further question ‘Why would a random distribution of particles yield the Born statistics as opposed to some other option?’ Durr, Goldstein, and Zanghi account for this distribution in Quantum Equilibrium and the Origin of Absolute Uncertainty. This specific point is a strong reason to take Bohmian Mechanics seriously.
BM requires some really unpleasant initial commitments, but there don’t seem to be any special interpretive problems, paradoxes, or unsolved problems in BM, aside from the ‘ordinary’ legwork required in any general microphysical theory (e.g., we need a Bohmian QFT). BM has solved the Measurement Problem; MW merely has some really suggestive hints that it might someday offer a more elegant solution of its own.
The sole difficulty BM faces, in contrast, is that it’s just kind of… ugly. Overtly, avowedly, unabashedly ugly. (That’s really what I respect most about the theory. It doesn’t hide its flaws; it defines itself in terms of them.) But until these same problems have been solved in at least one of BM’s competitors, we have no way of knowing that some analogous ugliness (like ‘magical reality fluid’) won’t be demanded in the end in any empirically adequate interpretation! Scary thought, eh? I also take seriously the pedagogical utility of BM (in spite of its inelegance in practice), as expressed in the above paper: “Perhaps this paper should be read in the following spirit: In order to grasp the essence of Quantum Theory, one must first completely understand at least one quantum theory.” Even if BM is false, using it as a naively concrete reading of the QM formalism may help us better grasp the general structural features that any empirically adequate QM interpretation will need to preserve.
MW is obviously much better in this regard than theism, but one of the problems with theism (it promises a simple reduction, but leaves the ‘simple’ undemonstrated) is interestingly analogous to the problem with MW (it promises a simple reduction, but leaves the ‘reduction’ undemonstrated). I don’t take this to be a distinct argument against MW; I just wanted to call it to attention.
I guess we’ll have to wait until we have interstellar travels to observe completely superposed civilisations so that we can actually see MW? That was a joke, by the way.
If your commitment to locality is strong enough, then you can recover locality by positing that you’ve imperceptibly fallen into another world in interacting with one of the particles, dragging everything around you into a somehow-distinct component of a larger, quasi-dialetheist (really, complex) reality. I don’t begrudge those who pursue this path; I only encourage careful scrutiny of exactly which priors we’re appealing to in taking that first step away from the naive, superficial interpretation of the experimental result that caused this aspect of the problem.
It’s not really “fallen into another world” as much as “being in a superposed state.” If you assume that superposition is a real effect of wavefunctions (particles), then you have to assume that you also belong in states. The only way of escaping that is not believing superposition is an actual, real effect, which to me looks like exactly what Bohm says.
Now I’m not saying that I give a > .9 probability to MW. It’s > .5, but I do not trust my own ability to gauge my probability estimates the way you did.
I don’t find the idea of clearly distinct universes mystical or strange or scary. I do find it strange and very-nearly-incoherent to think of worlds ‘bleeding together’ at the edges; and I very much wonder what it would be like to fully inhabit that intersection between worlds.
Point. I think mr. Yudkowsky mentioned something about a non-existence of worlds at that intersection? As in, the leakage from the “larger” worlds is so big that the intersection ceases existing, and then you have clearly distinct universes. Or at least that’s what I understood. I don’t think I like or even agree with the idea; it, too, sounds to me like trying to fit physics into intuition. But anyway, I agree with you that one of the main points in my head against MW is that intersection. That, and what I mentioned above, of completely impossible situations (like zombie Kennedy) never having happened in recorded history.
BM requires some really unpleasant initial commitments, but there don’t seem to be any special interpretive problems, paradoxes, or unsolved problems in BM, aside from the ‘ordinary’ legwork required in any general microphysical theory (e.g., we need a Bohmian QFT). BM has solved the Measurement Problem; MW merely has some really suggestive hints that it might someday offer a more elegant solution of its own.
Point. Which is why I agree with you that BM is the only other serious candidate. [whine]But those initial commitments are really unpleasant.[/whine]
The sole difficulty BM faces, in contrast, is that it’s just kind of… ugly. Overtly, avowedly, unabashedly ugly. (That’s really what I respect most about the theory. It doesn’t hide its flaws; it defines itself in terms of them.) But until these same problems have been solved in at least one of BM’s competitors, we have no way of knowing that some analogous ugliness (like ‘magical reality fluid’) won’t be demanded in the end in any empirically adequate interpretation! Scary thought, eh?
Scary indeed. Magical reality fluid actually terrifies me, and if it turns out that MW requires it… well, I think I prefer non-locality to that.
I meant not simplest as in simplest sound bite, I meant in the way mr. Yudkowsky has painfully explained elsewhere when he treated Occam’s Razor. One single equation is always a simpler proposition than two; and a whole intelligent being that sparked Existence itself and is not made of parts is so far off the map it’s not even worth considering as a preliminary hypothesis.
If you have any system that is in a given state A and that system interacts with another one that is in a superposition of states X and Y, it no longer makes sense to talk about the first and second system: the whole system is now in a superposition of states. Same thing with observing the measurement: what you actually observe is a computer telling you “spin-up” or “spin-down”. So that’s a gazillion atoms and molecules and particles and whatnot that’s different depending simply on the state of the electron. Now suppose you somehow isolated that computer completely from the outside, so that not a single photon left it, then you could say that the computer is in a superposition. And as soon as you looked, so would you. The fact that you don’t actually see the computer accusing both “spin-up” and “spin-down” or some combination is just a consequence of the fact that, while the whole system, including you, your brain, the computer, the room you’re in, the air you’re breathing, etc., is in a superposition, the amplitude for the two states to interact is infinitesimal. For all intents and purposes, these two states have decohered. That’s not to say superposition is gone; it’s just to say that the amplitude for those two states to interact is nearly zero.
Eh… I don’t know about that. I mean… well, I’ll come to that in a bit.
I’ll comment on it in a bit, too.
I think that is the same problem I had with any other theories. The very idea of non-locality triggers alarm bells all over my brain. That > .9 probability to MW, I believe, stems, at least partially, from an implicit < .01 probability to non-locality. So that really leaves very little room for other interpretations, and those, from what I’ve read, sound more bogus than Bohm.
I, personally, don’t think MW sounds all that “mystical.” I guess that comes from having lived half my life in the 21st century, so even in fiction the notion of multiple universes has never been a scary, strange one. The existence of a multiverse has always been a… persistent idea in my mind, and once I started reading up on Q.M. and studying the subject I just gave form to that intuition. That being said, I do agree with you that, at least from Wikipedia’s list of interpretations, Bohm’s does look like the most solid alternative to MW.
And coming to my final point… the Born probabilities. I honestly, truly have not a clue where they come from. I am hoping that any final unified theory might be able to solve that little problem (HA, little, right), but it wouldn’t be bad if someone solved it from within Q.M. itself. Some have tried, and I haven’t yet gotten to the point where I believe I am ready to read their attempts and truly grok what they mean so I can myself judge my probability estimates.
Yes, I grok. My point was that some theists don’t just think that God is simple partwise; they think that in some unknown (perhaps ineffable) way he’s maximally conceptually simple, i.e., if we were smarter we could formulate God in something equation-like and suddenly understand why everything about him really flows forth elegantly from a profoundly simple and unitary property. (And if everything else flows forth inevitably from God, the theory as a whole is no more complex than its God-term. Of course, free-will-invoking variants will be explanatorily inelegant by design; sudden inexplicable ‘choices’ will function for libertarians like collapse functions for Copenhagenists.)
Obviously, this promise of being able to formulate God in conceptually (and not just mereologically) simple terms is not credible. But this was the point of my (admittedly unkind) analogy; we should be wary of theories that promise an elegant, unimpeachably Simple reduction but have difficulty connecting that reduction to normality even in a sweeping, generic fashion. MW is obviously much better in this regard than theism, but one of the problems with theism (it promises a simple reduction, but leaves the ‘simple’ undemonstrated) is interestingly analogous to the problem with MW (it promises a simple reduction, but leaves the ‘reduction’ undemonstrated). I don’t take this to be a distinct argument against MW; I just wanted to call it to attention.
Fair enough. This perhaps is the fundamental question: The naive interpretation of data from EPR-style experiments is quite simply that nonlocal causation (albeit not of the sort that can be used to transmit information) is in effect between distant entangled states. If your commitment to locality is strong enough, then you can recover locality by positing that you’ve imperceptibly fallen into another world in interacting with one of the particles, dragging everything around you into a somehow-distinct component of a larger, quasi-dialetheist (really, complex) reality. I don’t begrudge those who pursue this path; I only encourage careful scrutiny of exactly which priors we’re appealing to in taking that first step away from the naive, superficial interpretation of the experimental result that caused this aspect of the problem.
I don’t find the idea of clearly distinct universes mystical or strange or scary. I do find it strange and very-nearly-incoherent to think of worlds ‘bleeding together’ at the edges; and I very much wonder what it would be like to fully inhabit that intersection between worlds.
Note that on BM, the Born probabilities emerge from stochastic initial particle distributions; probabilities are epistemic, not metaphysical (as they are in collapse). One can raise the further question ‘Why would a random distribution of particles yield the Born statistics as opposed to some other option?’ Durr, Goldstein, and Zanghi account for this distribution in Quantum Equilibrium and the Origin of Absolute Uncertainty. This specific point is a strong reason to take Bohmian Mechanics seriously.
BM requires some really unpleasant initial commitments, but there don’t seem to be any special interpretive problems, paradoxes, or unsolved problems in BM, aside from the ‘ordinary’ legwork required in any general microphysical theory (e.g., we need a Bohmian QFT). BM has solved the Measurement Problem; MW merely has some really suggestive hints that it might someday offer a more elegant solution of its own.
The sole difficulty BM faces, in contrast, is that it’s just kind of… ugly. Overtly, avowedly, unabashedly ugly. (That’s really what I respect most about the theory. It doesn’t hide its flaws; it defines itself in terms of them.) But until these same problems have been solved in at least one of BM’s competitors, we have no way of knowing that some analogous ugliness (like ‘magical reality fluid’) won’t be demanded in the end in any empirically adequate interpretation! Scary thought, eh? I also take seriously the pedagogical utility of BM (in spite of its inelegance in practice), as expressed in the above paper: “Perhaps this paper should be read in the following spirit: In order to grasp the essence of Quantum Theory, one must first completely understand at least one quantum theory.” Even if BM is false, using it as a naively concrete reading of the QM formalism may help us better grasp the general structural features that any empirically adequate QM interpretation will need to preserve.
I guess we’ll have to wait until we have interstellar travels to observe completely superposed civilisations so that we can actually see MW? That was a joke, by the way.
It’s not really “fallen into another world” as much as “being in a superposed state.” If you assume that superposition is a real effect of wavefunctions (particles), then you have to assume that you also belong in states. The only way of escaping that is not believing superposition is an actual, real effect, which to me looks like exactly what Bohm says. Now I’m not saying that I give a > .9 probability to MW. It’s > .5, but I do not trust my own ability to gauge my probability estimates the way you did.
Point. I think mr. Yudkowsky mentioned something about a non-existence of worlds at that intersection? As in, the leakage from the “larger” worlds is so big that the intersection ceases existing, and then you have clearly distinct universes. Or at least that’s what I understood. I don’t think I like or even agree with the idea; it, too, sounds to me like trying to fit physics into intuition. But anyway, I agree with you that one of the main points in my head against MW is that intersection. That, and what I mentioned above, of completely impossible situations (like zombie Kennedy) never having happened in recorded history.
Point. Which is why I agree with you that BM is the only other serious candidate. [whine]But those initial commitments are really unpleasant.[/whine]
Scary indeed. Magical reality fluid actually terrifies me, and if it turns out that MW requires it… well, I think I prefer non-locality to that.