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Thread: has ‘consciouness causes collapse’ (of wave function) been discredited?

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    has ‘consciouness causes collapse’ (of wave function) been discredited?

    regarding quantum mechanics...

    I thought that interaction with ‘the macroscopic world’ causes collapse of the wave function.... whether this is due to interaction with a mechanical detector or ‘conscious mind’.....
    .... but doesn’t the delayed-choice quantum eraser suggest that it is ‘knowledge’ of ‘which-path’ information rather than interaction with a detector which is critical to collapse...
    .. if so.. how does one explain/ understand the fact that minds are brains are made of quantum objects?
    ... can AI collapse?

    unfortunately, there is sooo much unscientific ‘wooo’ on the internet about this that it’s hard to sift through all the garbage....

    MANY thanks in advance!
    "It's only a model....?" :-)
    https://www.youtube.com/watch?v=m3dZl3yfGpc

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    The problem is, "collapse" can mean two completely different things, and people are always confusing them. The first form of "collapse" is well understood in quantum mechanics and even somewhat mundane-- it is what can be called "decoherence." This is what happens when you take a quantum subsystem in a pure state with relatively few degrees of freedom and couple it with an incredibly complex macroscopic measuring supersystem with so many untracked degrees of freedom that you have no choice but to treat the result purely statistically. Mathematically this means the pure state is replaced with what is called a "mixed state," which means the subsystem is treated as having a probability (and not a complex amplitude like wavefunctions have) of being in any one of a number of new pure states. The "decoherence" means that any coherences left between those possible pure states are so deeply embedded in the macro supersystem that they will never be tracked or extracted, so you may as well ignore them and say the subsystem has a probability distribution across all the possibilities, rather than a pure wavefunction (which has an amplitude with a definite phase across all those possibilities). There is no mystery here within the mathematical structure of quantum mechanics-- we are simply deciding not to treat the entire supersystem, we are taking a projection onto the limited degrees of freedom of the subsystem, and in taking that projection, a pure state looks like a mixed state. So that is a kind of "collapse"-- a projection and the creation of a mixed state with all coherences lost. Whether or not the supersystem was ever in a pure state is the issue that no experiment can determine, and is left as a kind of personal preference across all the different interpretations of quantum mechanics. All we know scientifically, because all we can test, is that it works to treat the subsystem (together with the associated observable outcomes of the supersystem) as a random projection from the spectacular degrees of freedom of the supersystem onto what we can actually perceive, a projection that involves averaging over all possible correlations, and that's what produces the "mixed state" we use to analyze the result of that testable projection.

    But that's not the "collapse" that distinguishes the interpretations of quantum mechanics, because all the interpretations can easily treat decoherence and projection from a supersystem onto a subsystem that does not track the buried coherences. The mysterious "collapse" doesn't appear until you register an outcome of the measurement, which forces you to replace the "mixed state" that covers all the possible outcomes, with a new pure state that picks out the result you actually registered. This is where the different interpretations all have a different description of what happened in the final and mysterious "collapse". And this is also where the role of consciousness is almost inescapable, because without consciousness, there is never a single outcome that gets registered, so there would never be any reason to replace the mixed state of all possible outcomes with any single result.

    But the unappreciated aspect of this is, this role of consciousness is not unique to quantum mechanics, it is endemic to all our experiences of daily life, and hence all aspects of scientific inquiry. The same situation really applies any time we regard some random or stochastic process as having occurred, whether it be tomorrow's weather or the shuffle that determines your next hand in a card game. These are also examples of "mixed states," where the best we can do is treat the situation as a probability distribution over the possibilities. So how do those hypothetical possibilities get turned into "what really happened"? There's ever only one way that transformation occurs, from the probable weather tomorrow to the actual weather, or the probable card your opponent is about to play to the card he/she actually plays: it's the role of consciousness, nothing else can do it.

    So the irony of this greatest mystery of quantum mechanics is that it really has nothing to do with quantum mechanics at all, because the quantum mechanics is over once you get to the mixed state, which is also the situation we are in when we look at a weather forecast or shuffle a deck of cards and wonder what possible hands we'll get. All of physics, and mathematics, and good planning and winning card strategy, all live in that generation of the mixed state-- none of any of those things affect or explain or in any way describe the experience of actually looking at the hand you actually got or actually feeling rain on your head. This role of consciousness is the deepest mystery in physics, but it's there in any aspect of physics that displays a stochastic character, whereas the generation of a "mixed state" is essentially just as mundane in quantum mechanics as it is in playing cards. So there's real mystery there, but it has nothing to do with quantum mechanics, and is very oversold in that context, in comparison to everywhere else it appears in applications much much closer to home.
    Last edited by Ken G; 2019-Mar-03 at 03:56 AM.

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    Quote Originally Posted by Ken G View Post

    So the irony of this greatest mystery of quantum mechanics is that it really has nothing to do with quantum mechanics at all, because the quantum mechanics is over once you get to the mixed state, which is also the situation we are in when we look at a weather forecast or shuffle a deck of cards and wonder what possible hands we'll get. All of physics, and mathematics, and good planning and winning card strategy, all live in that generation of the mixed state-- none of any of those things affect or explain or in any way describe the experience of actually looking at the hand you actually got or actually feeling rain on your head. This role of consciousness is the deepest mystery in physics, but it's there in any aspect of physics that displays a stochastic character, whereas the generation of a "mixed state" is essentially just as mundane in quantum mechanics as it is in playing cards. So there's real mystery there, but it has nothing to do with quantum mechanics, and is very oversold in that context, in comparison to everywhere else it appears in applications much much closer to home.
    I'm just not sure about this - it seems to me there is a distinction between quantum mechanics and unpredictable classical events that can be applied from the same perspective of needing consciousness. The part that consciousness may be needed in terms of our macroscopic experience in my opinion is huge, but that topic belongs to the reality thread - I think it suffices for this issue to take it as a given that consciousness is basically needed to simply discuss things like QM and what we observe microscopically and look at any differences between QM and the macroscopic from that vantage point. And it seems to me that there is a distinction to be made between a quantum mixed state and (say) a pencil resting on its point that falls in a direction that is undetermined. According to the laws of mechanics this direction is determined by a myriad small parameters. The latter (as Poncaire stressed for this is an example from him) are on the whole unattainable and irreproducible, but they do exist all the same. When a vertically falling ball close to a wall encounters a nail in the wall, the ball deviates to the left or right, the structure parameters that determine that direction of deviation are also unattainable and irreproducible. But they exist. Why these causal parameters exist within our macroscopic reality are a mystery, but we can rely on the fact that they do exist prior to the deviation to the left or right. Just before the pencil starts to fall, we can safely say that there existed a prior event before we discern the pencil just starting to tilt. And we can say the same about a prior causal event just before the just mentioned prior causal event and so on back in time. It is true that it would get more and more difficult for us to observe the end result of a prior causal event, but that is to do with our limited ability to measure such things rather than the whole train of prior events evaporating at some point leaving just the result with no assumption that there was a prior condition involved.

    But as I understand things, it is the case that at the Quantum level there are no such prior conditions present just before the state becomes known. If a particle is observed after exiting the Stern-Gerlach experiment as being "up", there is no suggestion that just prior to it being measured as "up" that there was a causal event turning it into an "up particle". And likewise as far back as you wish to go in that event of measuring an "up" - there is never any assumed prior causal mechanism going on in the particle that is rapidly turning it into an "up" particle prior to a measurement.

    In terms of the playing field on which our reality plays out, it seems to me that within the mystery that is consciousness there is a clear distinction between the quantum world and the classical world when looking at things like a pencil falling and the outcome from a Stern-Gerlach experiment. That distinction of course may ultimately belong in the same deeply mysterious melting pot of consciousness - who knows, but from where we are now, that distinction still seems to be very real. It doesn't seem to be the case that we can seamlessly project the macroscopic indeterminate nature of the falling pencil to the microscopic electron coming out of the apparatus in an up or down state - there still seems to be a dividing line between the two realms. And that dividing line illustrates the different kind of objectivity at the different levels, at the quantum level the outcome is part and parcel of the observation, we don't think of things going on in the particle independently of the observation, there is no prior "something" going on that will lead to the outcome, all we have is the outcome itself with no attributes doing their thing to get the particular outcome. The particle "needs" us and so the objectivity is very weak. At the classical level however, all of Poncaires myriad small parameters are going on without us watching the pencil falling - the objectivity there is strong, the pencil doesn't need us.

    Clearly this whole scenario of quantum and classical is playing out within a subjective environment of minds and so the pencil falling is not really strongly objective, without our minds there can be no pencil. But that's not my point, I'm just taking at face value our playing field of reality, and within that playing field it seems to me that we can reliably make a distinction between the quantum and classical based upon what seems to be the rules of that playing field. The falling pencil consists of existing small and unmeasurable parameters that determines the outcome and those parameters (in accordance with the rules of the playing field of our reality) do not require us to be looking at the pencil. On the same playing field, in accordance with the same rules, the quantum particle requires us to observe the outcome.

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    Quote Originally Posted by Ken G View Post
    But that's not the "collapse" that distinguishes the interpretations of quantum mechanics, because all the interpretations can easily treat decoherence and projection from a supersystem onto a subsystem that does not track the buried coherences. The mysterious "collapse" doesn't appear until you register an outcome of the measurement, which forces you to replace the "mixed state" that covers all the possible outcomes, with a new pure state that picks out the result you actually registered. This is where the different interpretations all have a different description of what happened in the final and mysterious "collapse". And this is also where the role of consciousness is almost inescapable, because without consciousness, there is never a single outcome that gets registered, so there would never be any reason to replace the mixed state of all possible outcomes with any single result.

    But the unappreciated aspect of this is, this role of consciousness is not unique to quantum mechanics, it is endemic to all our experiences of daily life, and hence all aspects of scientific inquiry. The same situation really applies any time we regard some random or stochastic process as having occurred, whether it be tomorrow's weather or the shuffle that determines your next hand in a card game. These are also examples of "mixed states," where the best we can do is treat the situation as a probability distribution over the possibilities. So how do those hypothetical possibilities get turned into "what really happened"? There's ever only one way that transformation occurs, from the probable weather tomorrow to the actual weather, or the probable card your opponent is about to play to the card he/she actually plays: it's the role of consciousness, nothing else can do it.
    But in the case of the delayed choice quantum eraser, surely all the hits on the various detectors could be recorded automatically, and the correlations between the signal and idler photons via the coincidence counter be checked by an algorithm, after the idler photons have all been detected, and the result would then be already sitting there in the data, ready to be observed by a consciousness, even if a consciousness never bothers to look at it?

    The fact that the idler photons (whose "which path" information was only erased in the experimental apparatus *after* their corresponding signal photons had already been detected) show an interference pattern when the results at their respective detectors are correlated via the coincidence counter would be sitting there, unchangeable after the fact, ready to be observed, or not, I would have thought?

    Does the waveform collapse when the results are correlated by a machine, or only when a consciousness looks at those results?







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    Quote Originally Posted by Len Moran View Post
    The part that consciousness may be needed in terms of our macroscopic experience in my opinion is huge, but that topic belongs to the reality thread - I think it suffices for this issue to take it as a given that consciousness is basically needed to simply discuss things like QM and what we observe microscopically and look at any differences between QM and the macroscopic from that vantage point.
    It belongs in the reality thread for both classical and quantum physics. All that separates them, in regard to consciousness, is how literally we take randomness as part of our model. Why should the person shuffling a deck take a random model any less seriously than something waiting for a nucleus to decay? If one has no answer to that, then one cannot distinguish the two.
    And it seems to me that there is a distinction to be made between a quantum mixed state and (say) a pencil resting on its point that falls in a direction that is undetermined. According to the laws of mechanics this direction is determined by a myriad small parameters.
    Actually, that isn't what mechanics says, that's what people who take determinism seriously say. Mechanics makes no such claim, because mechanics is a branch of physics, not philosophy, so mechanics is what we can test. You cannot test what makes a pencil fall any more than you can test what makes a nucleus decay. You can change the problem until it is something you can predict in the case of either a pencil or a nucleus (say, by bombarding it with neutrons to cause it to decay within a short time, or causing the nucleus to be stable and prevent it from decaying), but if you can predict it, then you are not going to describe it as a mixed state. A mixed state is always an expression of what you don't know, whether it is that you don't know when the pencil will fall, or you don't know when the nucleus will decay. You can no more claim that it would be possible to know that for the pencil than you could claim it would be possible for the nucleus. Particularly when we deal with fundamentally chaotic phenomena like the weather-- can anyone claim it would be possible to know with certainty the weather next week? Even if you could interrogate every molecule (and every butterfly), you still could not predict that. So where comes the claim that it would be possible in principle? That's simply extrapolating the deterministic quality of mechanics equations, a quality of a model that has not been tested to fit reality, it's not a quality of reality. The quality of reality is fundamental unpredictability, it's not reality's fault if the equations of some simplified model fail to capture that.
    The latter (as Poncaire stressed for this is an example from him) are on the whole unattainable and irreproducible, but they do exist all the same.
    How do you know? On what basis do you make that claim? All we have are idealized models, every physics equation is an idealized model that breaks down somewhere. How do you know the places where the models break down aren't the reasons what you claim exists does not in fact exist at all? It's all in how literal you take the equations, and how literal you take the need to average over what you don't know. We are averaging over what we don't know whether we are coupling quantum systems to macro devices, or shuffling a deck of cards-- and we need consciousness to break the mixed state in either description. We must learn to separate what we are doing, the way we are analyzing the situation, from any concept of what is "really happening." The latter is meaningless.
    When a vertically falling ball close to a wall encounters a nail in the wall, the ball deviates to the left or right, the structure parameters that determine that direction of deviation are also unattainable and irreproducible. But they exist.
    How do you know? You can say that if you look closer, you can predict better, so the mixed state you had before is now a deterministic condition because you looked better. But that's nothing new, you can peak at the deck as well, and collapse the mixed state that way. There is not what really is and what really isn't, there is only how you are analyzing the situation, what information you have access to. Since you cannot have access to enough information, you have a mixed state. That's as true in quantum mechanics as in classical mechanics, it's true any time you have a mixed-state description.

    What I'm saying is, we tend to think of mixed states as the stance that "something happened, but I don't know what yet, I can only know the probabilities as if the experiment were repeated many times." We can also think of quantum mechanical mixed states with that same language. And the way the mixed state is achieved is exactly the same-- we average over everything we don't know. That's how you get a mixed state, you average over what you cannot track, and project onto what you care about, and mathematically that's what you get. Nothing can ever turn that resulting mixed state into a statement of what actually did happen, the claim that something happened I just don't know what is completely empty and says essentially nothing at all. Certainly nothing you could ever use, and nothing you could ever test. Consciousness collapses the mixed state, that's all we actually experience and we can say nothing more about it whether it is quantum mechanics or classical mechanics.

    An important point that I think people overlook in quantum mechanics is that it is just as possible in quantum mechanics for people with different knowledge to make different predictions as it is in classical physics. This is natural, someone who has not looked at their opponent's hand in a card game makes a different prediction than a spectator who has seen all the hands. The spectator has the luxury of saying they know what the hands "really are", but all this means is they make predictions based on more information. And that's all we can ever say-- we make predictions based on the information we have, but there is always a statistical character. Even someone who has peeked at the hands knows they might have mistaken the king of clubs for the king of spades, and must accord some finite probability to that possibility. All predictions always come down to probability, and determinism is actually just a map from one probability distribution into another-- which is exactly how quantum mechanical determinism works as well. It is only consciousness that can turn a probability of an outcome into an actual outcome. The only difference is we take it more literally in quantum mechanics, because we can, if we choose, regard the wavefunction as real. And what is the track record of regarding elements of models as real things that somehow transcend the model? Is a proton a real thing, or are all protons indistinguishable parts of a universal proton wavefunction?
    Just before the pencil starts to fall, we can safely say that there existed a prior event before we discern the pencil just starting to tilt.
    All you are doing is watching outcomes unfold, and telling yourself they were inevitable consequences of what came before. That's postdiction, not prediction! It's a yarn you are spinning, you aren't testing it. We can rationalize everything that happens as if it was caused by something prior, that's a lot like when people believed tornadoes were the will of angry gods. Now we regard them as weather phenomena, but we still can only ever compute probabilities of where and when they will form-- and that would not change even if we knew the placement of every molecule an hour before.
    It is true that it would get more and more difficult for us to observe the end result of a prior causal event, but that is to do with our limited ability to measure such things rather than the whole train of prior events evaporating at some point leaving just the result with no assumption that there was a prior condition involved.
    The idea that prior conditions cause later ones is a popular model, but all we ever use is probability mappings. That's all you ever do from the moment you get out of bed in the morning-- assess probabilities that your consciousness then "collapses" into experiences. Anything else is just a yarn you are spinning, we can look and see what you are actually doing: winnowing down probabilities, but you still cannot predict a card shuffle any better than a quantum spin flip.
    But as I understand things, it is the case that at the Quantum level there are no such prior conditions present just before the state becomes known.
    Quantum mechanics is a prescription for making useful predictions, not a method for asserting "what is the case." There are elements of quantum mechanics that require we treat outcomes probabilistically, There are elements of weather prediction that require we treat outcomes probabilistically as well. There is no obvious distinction in how we make these predictions, there is only how literally we are taking our equations. And why should we ever take any equation literally anyway? An equation is, literally, instructions for making a prediction. If you apply an equation 100 times and get one outcome 75 times and the other 25 times, when you average over what you don't know, then you say the equation tells you there is a 75% chance of the first thing. That's just as true in quantum mechanics as in classical mechanics, we have no idea if there is any difference and no real reason to think there is other than excessive faith that equations are something other than what they are.

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    If a particle is observed after exiting the Stern-Gerlach experiment as being "up", there is no suggestion that just prior to it being measured as "up" that there was a causal event turning it into an "up particle".
    Actually, you could insert all kinds of observing apparatus into the experiment and try to watch the spin become determined. There could certainly be observations along the way that lead you to say "now I think it's 50% going to be up", "now I think it's 75% going to be up", "now I'm pretty sure it will be up", these are called "weak measurements." They exist in quantum mechanics just as much as they exist in classical mechanics, we must not mistake the fact that we have more experience with weak measurements in classical physics for some fundamental distinction in what is actually happening. We just have the luxury of being able to look more easily at macro systems, creating the illusion that "things happen for a reason." It's like, I always laugh when people say "the Dow Jones is up 0.1% on reports that the Fed might possibly lower rates." But the fact is, no one has the least idea why the Dow is up 0.1%, and in fact it is silly to even imagine that any reason is required in the first place for such a clearly random change. Causality is not really a physics notion, it is sociology-- we need the concept to function, but it's not in our laws of physics (which is why most physicists don't hold to superdeterminism, though some do).
    And likewise as far back as you wish to go in that event of measuring an "up" - there is never any assumed prior causal mechanism going on in the particle that is rapidly turning it into an "up" particle prior to a measurement.
    There's no such causality anywhere in physics. If you think you know why the pencil fell that way, all you did was wait until it was already clear which way the pencil would fall, and say that your information it would fall that way is why it fell that way. If you see someone blowing on it, you say you know which way it will fall, but it just means you already have the information to tell which way it will fall. What if they only pretend to blow, but don't actually blow? Then you don't have the information, and you still have only a probability. What causes it to fall in that situation? The decision to either blow or not blow. Well, what causes that? There is not cause, there is information. And when you cannot know, you average over what you can't know, and that's what creates the mixed state, in both classical and quantum mechanics.
    In terms of the playing field on which our reality plays out, it seems to me that within the mystery that is consciousness there is a clear distinction between the quantum world and the classical world when looking at things like a pencil falling and the outcome from a Stern-Gerlach experiment.
    And I claim you have not made that case. You have only said that you can look closely at a pencil falling and winnow down, as you watch, the probability that it will fall this way or that. When you have the information you need, you say you know, but that is always how it goes-- we say we know when we have the information, and before we have the information, we are a player picking up their hand to look. It's the same in quantum mechanics. Causation is a sociological story (and a very useful one-- in sociology).
    That distinction of course may ultimately belong in the same deeply mysterious melting pot of consciousness - who knows, but from where we are now, that distinction still seems to be very real.
    Ah yes-- seems to be real. That's exactly right-- there are many sociological stories we tell that seem to be real. People who thought angry gods made tornadoes thought that seemed quite real also. But there's no evidence that gods did that, and there's no evidence that the randomness of weather is any different from the randomness of a Stern-Gerlach experiment, because neither are in the reality, they are in how we analyze the reality. They are in how we think, which is also how the concept of a collapse from a mixed state to a sure outcome emerges. It's always consciousness, it's no different in classical physics.
    It doesn't seem to be the case that we can seamlessly project the macroscopic indeterminate nature of the falling pencil to the microscopic electron coming out of the apparatus in an up or down state - there still seems to be a dividing line between the two realms.
    Then tell me what the dividing is. What can you do with the pencil you can't do with the electron in the Stern-Gerlach? (In fact, people who hold the Bohm interpretation, which I do not, maintain that the two are precisely the same, and the electron is just as caused as the pencil. I maintain the opposite-- neither are in any absolute sense, it's just how we are analyzing the situation.)

    And that dividing line illustrates the different kind of objectivity at the different levels, at the quantum level the outcome is part and parcel of the observation, we don't think of things going on in the particle independently of the observation, there is no prior "something" going on that will lead to the outcome, all we have is the outcome itself with no attributes doing their thing to get the particular outcome.
    It's merely the degrees of freedom you are tracking. Take a classical system and treat the analog of an "up" or "down", like flipping a coin without looking at any other degrees of freedom. It turns into the Stern-Gerlach. If you start to look closely at the hand flipping the coin, you see why the coin flipped as it did. So what? You don't know why the hand did what it did, so it's still random. Just because you can track more degrees of freedom allows you to tell yourself the sociological "causation" story, but the even it still just as random.

    The particle "needs" us and so the objectivity is very weak. At the classical level however, all of Poncaires myriad small parameters are going on without us watching the pencil falling - the objectivity there is strong, the pencil doesn't need us.
    Particles don't go through the equivalent of Stern-Gerlach machines without us? They do, it's the same.

    But that's not my point, I'm just taking at face value our playing field of reality, and within that playing field it seems to me that we can reliably make a distinction between the quantum and classical based upon what seems to be the rules of that playing field.
    The rules are, you predict based on what you know, and average over what you don't. That's it, that's the rules, we use all the time. Then consciousness "collapses" our predictions into what actually happens. Nothing else ever does that-- not even macroscopically. You can tell yourself it would have happened just the same without you, but you can say that as easily for an electron in Stern-Gerlach as for a coin flipping. But you still never get an outcome without a consciousness to "collapse" all the things you cannot possibly know and would always have to treat probabilistically.
    The falling pencil consists of existing small and unmeasurable parameters that determines the outcome and those parameters (in accordance with the rules of the playing field of our reality) do not require us to be looking at the pencil. On the same playing field, in accordance with the same rules, the quantum particle requires us to observe the outcome.
    The quantum particle does not need us to observe it, it only needs us to analyze it. It only needs us to average over all the things we cannot track and are outside our information. Just like when you play a game of poker.

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    Quote Originally Posted by speedfreek View Post
    But in the case of the delayed choice quantum eraser, surely all the hits on the various detectors could be recorded automatically, and the correlations between the signal and idler photons via the coincidence counter be checked by an algorithm, after the idler photons have all been detected, and the result would then be already sitting there in the data, ready to be observed by a consciousness, even if a consciousness never bothers to look at it?
    Let's say you set up that very experiment, and I ask you, so what is recorded? You would always have to describe what is recorded as a mixed state-- a probability that this got recorded, a probability that that got recorded. There's nothing else you could say about it. So it makes no difference if the mixed state exists in what is recorded, or in what happens to the particles, it's still a probability distribution. That is all you could ever use to describe it. The only possible way to replace that probability distribution with an actual experimental result is to look. And then it's consciousness that makes the change. If no consciousness ever registers it, it can never be distinguished from that very probability distribution that you would always use to analyze it.
    Does the waveform collapse when the results are correlated by a machine, or only when a consciousness looks at those results?
    The waveform collapses into a mixed state due to the way we choose to treat its interactions with the apparatus (which is what is meant by "decoherence", the different outcomes destroy crosstalk between each other but they are all still there in the probability distribution that we get from our analysis technique that is prescribed by quantum mechanics). We cannot talk about what is actually happening, we can only talk about how we will analyze it. This is quite fundamental in physics, for example we have the second law of thermodynamics that says entropy always rises. But entropy appears in how we are analyzing the system, what we are choosing to know and what we are admitting we don't know and must average over. The "actual state of the universe" would always have to be just what it is, so would always have to have zero entropy and so could never rise. But entropy is not about the actual state, it is about our treatment of it. And so is the rest of physics.
    Last edited by Ken G; 2019-Mar-06 at 12:08 AM.

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    I'm confused.

    It seems to me that's like saying no quantum event ever definitely happened in the universe until there was someone around to analyse it.

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    Quote Originally Posted by speedfreek View Post
    I'm confused.

    It seems to me that's like saying no quantum event ever definitely happened in the universe until there was someone around to analyse it.
    Well, I would say that it is quite clear that nothing at all, quantum or otherwise, ever definitely happened anywhere or anywhen without someone to analyze it (someone not necessarily there and then), because "definitely happening" is a concept of an intelligence. It simply doesn't appear anywhere else, that's an example of language that intelligence must give meaning to. But you mean this is as a window into quantum mechanics, so I'll address it from that perspective.

    We first have to establish what you mean by "a quantum event." If by that you mean, "something that is ruled by the Schroedinger equation," then there pretty much isn't any quantum event that ever definitely happened, which is why Bohr said "there is no quantum world." It's entirely up to your analysis to even say if those events actually happened! If you mean "a macroscopic measurement of something ruled by the Schroedinger equation, but the outcome of the measurement was not ruled by that equation" (because the Schroedinger equation never has a particular event happen except if the system is in a "stationary state" of that measurement, which is like saying that nothing is happening at all), then you are talking about "collapse" and the role of consciousness, because there is never any need for a concept of "what actually happened" if there is no consciousness to perceive it-- without conscious perception, mixed states of probability would always suffice. The bridge expert can deal entirely in probabilities, what "actually happens" is an incidental that matters only because the player is conscious and so will experience some particular thing.

    None of the interpretations of quantum mechanics give any accounting of that last bit, none of them describe how a consciousness perceives an outcome whose statistical tendencies (only) are predicted by the Schroedinger equation. So in effect, each of the interpretations must give its own interpretation of the role of consciousness. And that's just what they do-- you can go through each interpretation and conclude what each is saying is the role of consciousness, and the only one that gives no particular role is the Bohmian interpretation, but that interpretation has a quasi-mystical "pilot wave" that sort of artificially replaces the need for a role of consciousness by a need for a role of a pilot wave-- which is no less mysterious and no easier to incorporate in a predictive model. In short, they all boil down to "and then something mysterious decides which outcome actually occurs," and whether you interpret that mystery as a role of consciousness, or a role of a pilot wave, or a role of many consciousnesses living in "many worlds," is all a matter of personal preference.
    Last edited by Ken G; 2019-Mar-06 at 02:57 PM.

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    Perhaps a good way to clarify what I am saying about consciousness is that consciousness is the place where information comes to roost. If I have a mixed state description of some situation, and I have an apparatus that is not conscious but is capable of registering a definite outcome, then all I get is a new mixed state. The old mixed state was just of the outcomes, the new mixed state couples each outcome to each pointer reading on the apparatus. I still have no definite outcome, I just have the information I used to create that mixed-state description, and adding the registering apparatus has not added any new information at all, so it has not changed the description at all. The description is my description, and it changes only when my information changes. The place where we can tell when my information changes is in my consciousness, that is the place where I compile the information I am going to use to describe the situation and enable testable predictions. So the role of consciousness, and the role of information, are inseparable, they come together because the conscious mind is where information gets assessed.

    Now I realize you can say that computers can be programmed to assess information without being conscious. But that's just like the registering apparatus-- if I program a computer to have information input to it, and make a statistical prediction of an outcome, then set up a robotic experiment and register the outcome and check if the statistical description was correct, then my own description of what happened there will always be that same mixed state again. I will have a mixed state of computer programs calculating probabilities and doing many repeated tests and finding that the probabilities worked, but the mixed character of the state will be that I won't know how the experiments actually came out, instead I will have a probability they came out one way and a probability they came out some other way, but both ways will satisfy my computer program, so my mixed state will include a collection of a bunch of satisfied computerized analyses. Since all the computerized analyses will be satisfied, I will be able to predict that the computer will assess the theory as being correct, and if I test that by interrogating the computer I will see that my prediction was correct. If I don't ask the computer what the outcomes actually were, then I will only test my correct prediction, and the outcomes will remain in a mixed state description. If I do ask what the outcomes were, only then are those outcomes "collapsed" into something specific, but then it's again the role of my consciousness to achieve that collapse. We see all this when we simply restrict our language to being about how we would describe the reality, and avoid any essentially meaningless claims about what the reality "actually was." Again, it is perfectly natural for different consciousnesses to assess different information, and thereby use different mixed-state descriptions, but none of the descriptions will completely eliminate all probabilistic character and achieve knowledge of "what really happened," and indeed that last concept is itself merely a model created by intelligences (and one that works quite well until you look too closely, whereupon it all falls apart and leads to silly language like "a butterfly can change the weather").

    Everything I just said applies perfectly well in classical physics, so where does quantum mechanics come in, and why do so many people think that quantum mechanics imposes some kind of special problem in regard to the collapse of mixed states into specific outcomes? It's because quantum mechanics makes the distinction between the uncertainty you just happen to have given the information you possess, and the Heisenberg uncertainty principle that stipulates fundamental limits on what you can know. That's it, quantum mechanics discovers there are fundamental limits. But so what? We should have already known there are limits, it was always a kind of pretense that "complete information" exists when no analysis anywhere includes such a notion. So who cares that there are fundamental limits, all we need to know is that there are always limits. We always will have to average over what we don't know, that was just as true before the invention of quantum mechanics as now. Every description of every reasonably complicated reality will always have to average over what we don't know, until we know it, so will always use mixed-state descriptions that collapse into more definite states. That is the nature of intelligent analysis, and the role of consciousness is to experience an outcome, not just make a prediction and test it statistically the way a computer could do. The consciousness does more than say what happened, you could program a computer to say what happened-- the consciousness experiences what happened, which is a form of information that culls the "many worlds" of Everett's interpretation of quantum mechanics into the single world that consciousness inhabits. In short, your consciousness is your perspective, it is a vantage point for creating a description of the situation. You could program a computer to do that, but even if you did, your own perspective could not include the computer perspective as anything other than a mixed state until you experience it yourself. So you could replace "consciousness" with "personal perspective" and it's all the same issue. All Everett's "many worlds" does is allow there to be lots of different consciousnesses experiencing all the possible outcomes, when your consciousness only experiences one, and we could have had the same thing in weather prediction using purely classical physics.
    Last edited by Ken G; 2019-Mar-06 at 06:13 PM.

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    That last point is a good way to see what I mean. We can easily construct a "many worlds interpretation of classical physics" that contradicts no experiments, we simply assert that given all the information (and its uncertainties) that I have in some classical physics calculation applied to a complex or chaotic system, there are many possible outcomes of future observations that would be consistent with that information, so I will simply assert that all those possibilities actually do occur, and my consciousness only picks out one to perceive. What observation contradicts that interpretation of classical physics?

    All I can use classical physics to do (and all I can test about classical physics) is to calculate probability distributions, and test with many repetitions that the probability distribution was borne out. But here's the reason we didn't recognize this: that's not at all what most classical physics calculations look like! Instead, the classical physics calculations you will see at the ends of chapters of books look like mapping of complete information into complete information. But that was always a pretense, a shorthand way to talk about the analysis that was actually happening, which was always a mapping from an uncertainty into an uncertainty, a mapping of a neighborhood of possibilities into another neighborhood of possibilities, and that's all we ever actually test. Determinism was never a characteristic of reality, it was always a characteristic of a mathematical model that satisfies certain rules about how it maps neighborhoods into neighborhoods. In particular, it allows the center of the new neighborhood to be calculated from the center of the previous neighborhood, and the new neighborhood must not grow in size so badly that it becomes essentially unpredictable-- that's all determinism ever meant. It never meant that the future of our reality is completely determined by its past, that was always a lie, an overextrapolation of what the laws of physics are actually able to say, and well beyond anything physics could ever test.

    All we could actually do is knock down the size of the uncertainties and make the neighborhoods smaller, but we never knew we were getting down to anything that looked like complete or exact information. All quantum mechanics does is give us a model of the limits of complete information, but we never had any reason to think there was any such thing as complete information when we had no idea of how to define or establish such a notion. So if one simply escapes the radical overextrapolation of classical physics that pretends macroscopic uncertainties could ever be extrapolated down to any arbitrarily small scales without any difficulties, then one doesn't even need quantum mechanics to understand that physics has always been about the generation of mixed states, and has always only tested those mixed states, and has never had any description or explanation for why we encounter specific outcomes instead of those mixed state descriptions that physics creates and manipulates.
    Last edited by Ken G; 2019-Mar-06 at 06:30 PM.

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    The falling pencil is an illustration of an avalanche effect because whatever physical force disturbed the metastable state it is very unlikely although possible that the reverse force comes along at just the right moment to cancel the minute perturbation and becomes immediately less likely when several times larger force would be required just a tiny time later. The metastable state therefore always falls under Brownian perturbation. Stable states have restoring classical forces which make returning from every perturbation the most likely outcome yet still we see evaporation where an atom or molecule leaps out of its bonds.

    If you wanted to stabilise a pencil on its point you could devise a machine and sensors to do that overcoming the perturbations with energy from outside or you could just stack many other pencils adjacent like an atomic lattice on , for example a curved base, and then all the pencils would become stable. That's how we engineer the world to be stable for us. If we start to look at details as KenG says, then we cannot tell which leaf will fall from the tree first or exactly where on the wall the furthest drop will arrive when we drop our cup of soup. We casually accept those kind of events as random and unpredictable until they can be observed. Before Quantum ideas, we could lazily assume that if we knew enough, we could predict everything, i.e. determinism, but now we know better, (perhaps!)
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by Ken G View Post
    The idea that prior conditions cause later ones is a popular model, but all we ever use is probability mappings. That's all you ever do from the moment you get out of bed in the morning-- assess probabilities that your consciousness then "collapses" into experiences. Anything else is just a yarn you are spinning, we can look and see what you are actually doing: winnowing down probabilities, but you still cannot predict a card shuffle any better than a quantum spin flip.
    So if we think of probability mapping rather than prior conditions causing later conditions, what is the best way to figure in a bias to a particular likely outcome? I find it difficult not to think of cause and effect between x, y and z if I note that x occurring gives a greater than 50% probability of y occurring and y occurring gives a greater than 50% probability of z occurring and so on to the outcome that the sunny spells predicted at some previous time based upon measurements turns out to be the case at some later time more than 50% of the time.

    There seems to be at play probabilities that have a somewhat reliable bias that map onto other reliable biases that eventually gives us a somewhat reliable weather prediction.

    And what we find is that as we get better at collecting data, get better and faster at computing all of the probabilities, we find that the bias becomes stronger and hence more reliable.

    Are we allowed to discern some kind of causal trend running through this biased mapping - a "something" that says for some reason x will give us y which gives us z more often than not? Is that bias not a sort of cause and effect? I don't pretend to know why that bias occurs, all I know is that we represent it as cause and effect. And if we can represent it in that manner and we can rely on it to give us some kind of usable prediction, then can we also say that there does exist usable prior conditions that form a history of an event like the weather? And once we have an event that can be predicted to some degree then it becomes a kind of descriptive notion - x causes y which causes z and perhaps that does draw a line in the sand between classical and quantum - at the quantum level we can never predict events (and hence we have no descriptions) leading to outcomes, we can only ever predict observational outcomes.

    I'm not saying that cause and effect exists in the way we imagine it to - as something really happening independently of phenomena. I'm just looking at the phenomena of cause and effect, the way we can reliably use it and the way it allows us to build a time line of events that lead to outcomes in a descriptive manner - i.e. we can safely describe an event of throwing a ball and watching it fall to the ground. That's a nice and reliable event, we can predict everything about it and we can say it is going to happen in the same way tomorrow and in a thousand years from now. I doubt that the way we see that event represents anything about the event outside of phenomena, but within phenomena, it gives a different picture to that which we can expect from QM from within that same phenomena. We can build cause and effect events classically and even to some degree within chaotic systems, but we just can't do that at the quantum level.


    I found this from Bernard d'Espagnat: (Page 110, "On Physics and Philosophy")

    As already noted, what most basically differentiates quantum mechanics from classical physics is not (as often believed) the fact that its axioms involve intrinsic probabilities. It is the fact that it is not descriptive but essentially predictive and, more precisely, predictive of outcomes of observations.


    Edit to add:

    I have only just read post 11, it does clarify some of the questions I posed here.
    Last edited by Len Moran; 2019-Mar-06 at 08:55 PM.

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    Quote Originally Posted by profloater View Post
    If we start to look at details as KenG says, then we cannot tell which leaf will fall from the tree first or exactly where on the wall the furthest drop will arrive when we drop our cup of soup. We casually accept those kind of events as random and unpredictable until they can be observed. Before Quantum ideas, we could lazily assume that if we knew enough, we could predict everything, i.e. determinism, but now we know better, (perhaps!)
    Well perhaps this is the most interesting aspect of this thread rather than the QM bit. If determinism as a classical notion appears to break down in that in principle there is no information available, ever, that would allow us to predict which leaf will fall from the tree first, then that does sort of suggest that the determinism that we take for granted such as (say) a magnetic field will always result from a flow of current in a wire is a macroscopic construct. There must be probabilities that there won't be a magnetic field, it's just that we don't get to see those probabilities occurring. Is there a scale of probabilities that go from 99.99999......9% that a magnetic field will follow from a current flow to (say) 0.0000.......1%) that water at sea level will not boil at 100 degrees C? Having a high degree of probabilities allow us to construct repeatable historical events, we join the dots of the probabilities to make a smooth continuous event time line made up of causes and effects. This it seems fools us conclusively with reliable things like electric currents producing magnetic fields, but starts to unsettle us when we get into chaotic systems, we sense a breakdown in familiar cause and effect. And perhaps at the quantum level, it's not so much phenomena fooling us, it is more a case of phenomena laying bare the basic building blocks of our macroscopic reality with no pretensions of ever joining up the dots to give us our familiar notion of predictable cause and effect events. Perhaps it is the macroscopic world that is the weird realm rather the quantum world!

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    Does that mean we can start to look at collapse on a macro scale as we have learned to model in a particle experiment? I have seen a solution go super saturated for a very long time and then literally collapse in a fraction of a second with kilograms of salt falling out when it should have trickled out at the evaporation rate. We have macro explanations for that which boil down to an avalanche from a single microscopic event. Like crystals forming at a nucleation site. If there were to be no such micro event would the state ever collapse? This raises questions about the division between micro and macro which are too complicated to model from particles to the cosmic loom of interconnectivity. In another thread the notion of distant supernova changing outcomes for humans via thunderstorms is challenged but it is possible that the links can be seen just as Molibdenum is essential and arose in a distant star explosion. ( the 42 atom) . The reality thread had all of this without the detail of observation being central to our model in detail and in aggregate.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by Len Moran View Post
    I find it difficult not to think of cause and effect between x, y and z if I note that x occurring gives a greater than 50% probability of y occurring and y occurring gives a greater than 50% probability of z occurring and so on to the outcome that the sunny spells predicted at some previous time based upon measurements turns out to be the case at some later time more than 50% of the time.
    Yes, you would think of cause and effect, even moreso if you took 90%. But that's just my point-- you think of cause and effect. Cause and effect is a useful model, it's a way you can think about what is happening. We use it all the time, a small child who knows not one single deterministic equation of physics has no trouble coming up with the concept of cause and effect without it even being prompted for them. It just means that we learn to predict what will happen, with varying degrees of confidence, based on the information we have. The more you know, the better your success at predicting the future, it doesn't mean anything else. Cause and effect means we can map between neighborhoods of possibilities, but it does not mean discrete states map into discrete states because classical physics doesn't have discrete states it just has the bins we can resolve with our instruments. It is quantum mechanics that has discrete states (like spin up or down), and lo and behold, we find we lose the determinism that we never had in the first place (we only imagined that we would, with no good justification-- just wishful thinking). And as for the present causing the future, I find it quite significant that in physics, it is never easier to predict the future from the present than it is to predict the past from the present. What does that tell you about cause and effect?
    There seems to be at play probabilities that have a somewhat reliable bias that map onto other reliable biases that eventually gives us a somewhat reliable weather prediction.
    Certainly, that's what cause and effect really means, reliability of prediction. And it works just fine both directions in time. The murder detective is trying to figure out the past based on the evidence, they are not trying to figure out the future. The concept that the murderer "caused" the death of the victim is sociology, and it's not the reasoning the detective uses, the detective uses the evidence to infer whodunnit-- the evidence in effect causes the guilty party. But the jail time will be determined by issues of "premeditation," returning to our usual sociological model of cause and effect.
    And what we find is that as we get better at collecting data, get better and faster at computing all of the probabilities, we find that the bias becomes stronger and hence more reliable.
    Yes, the probabilities get narrowed down, but only because the bins are very coarse. In quantum mechanics, they are very fine, so of course we find it harder to predict beyond statistically. Imagine spinning a pencil on the table and trying to predict its angular momentum to within Planck's constant-- it was only ever wishful thinking that Newtonian mechanics could actually do that, we should have been skeptical long before the Heisenberg uncertainty principle.
    Are we allowed to discern some kind of causal trend running through this biased mapping - a "something" that says for some reason x will give us y which gives us z more often than not? Is that bias not a sort of cause and effect?
    Yes, that's exactly what cause and effect is-- prediction bias. It doesn't mean the precise outcome is caused, it means the outcome can be predicted in the form of some kind of probability distribution. The question remains in classical physics-- what determines the actual outcome and not just the probability distribution? No physics equation ever did that.
    And once we have an event that can be predicted to some degree then it becomes a kind of descriptive notion - x causes y which causes z and perhaps that does draw a line in the sand between classical and quantum - at the quantum level we can never predict events (and hence we have no descriptions) leading to outcomes, we can only ever predict observational outcomes.
    Actually, quantum mechanics is just as predictive as classical mechanics, because at its heart we have a mathematically deterministic equation-- the Schroedinger equation. But that equation doesn't act on the observables the way classical equations do, it acts on something we don't observe-- the wavefunction. The wavefunction does the same thing that classical observables do though-- it provides a probability distribution that our next observation will fall into. That's just what we get out of Newton's laws as well, it's no different. It's just that quantum mechanics provides a very clear meaning of an "orthogonal" measurement, a measurement whose outcome is completely unpredicted by the present state of the system. That's not something we encountered in classical physics, but only because we never could look closely enough to see it. It provides a fundamental limit on how predictable the future can be, but only when very tiny quantities are measured, quantities so small they fall way within the error ranges of all classical measurements. What I'm saying is, in either classical physics or quantum physics, all we ever do is map probabilities into probabilities, and test the results with repeated measurements to show that the predicted probability distribution was correct. It's just that in classical physics, we usually use such coarse bins that we only bother to do it once-- we call it a success if the outcome falls in the bin, we ignore the probability distribution we'd get if we repeated the experiment over and over.
    I'm just looking at the phenomena of cause and effect, the way we can reliably use it and the way it allows us to build a time line of events that lead to outcomes in a descriptive manner - i.e. we can safely describe an event of throwing a ball and watching it fall to the ground. That's a nice and reliable event, we can predict everything about it and we can say it is going to happen in the same way tomorrow and in a thousand years from now.
    But look at the assumptions you are making: "we can predict everything about it." Is that really true? Don't you mean we can predict everything we care to predict? The idea that we can predict everything is exactly the "lie" of thinking that classical physics describes a world where the exact information of the future is precisely caused by the exact information of the present. But we never have exact information, and classical physics is not a theory about what happens to exact information (since no such theory has ever been tested), it is a theory about what happens to imprecise information, how we map an uncertainty into an uncertainty, a mixed state into a mixed state. But when we do one measurement, we say "this happened", even though the next measurement in a similarly prepared ensemble will yield something somewhere different within that probability distribution. Classical physics is also about predicting mixed states but experiencing definite outcomes, this is my point-- not that we don't find cause and effect a useful sociological model within which to frame our existence. And simply widening the bins so wide that the entire probability distribution is swallowed into a single bin to achieve certainty in the outcome is something you can do in quantum mechanics also, we just don't do that in quantum mechanics like we do it in classical physics. In a sense, we have always been misrepresenting classical physics by simply widening the bins that we choose to care about, and we don't do that in quantum mechanics. That is the cause of the "difference", not anything special about collapse in quantum mechanics.
    We can build cause and effect events classically and even to some degree within chaotic systems, but we just can't do that at the quantum level.
    Yes we can, we can build cause and effect sociology just the same way in quantum mechanics. The Schroedinger equation is deterministic, but it acts on the wavefunction. For those who hold to Everett's many worlds view, that's the reality-- it's entirely deterministic. They think our consciousness only samples a very tiny fraction of what is. We could hold to the exact same view in classical physics, when we predict weather. It all stems from the fact that determinism only predicts the generation of mixed states of probabilities, like the probability it will rain. If we simply take that state as the literal reality, we are forced to say that some consciousnesses get the rain and some get no rain. That's all Everett does, mixed states are the actual reality projected onto the substates corresponding to the outcomes experienced by the non-overlapping consciousnesses.
    I found this from Bernard d'Espagnat: (Page 110, "On Physics and Philosophy")

    As already noted, what most basically differentiates quantum mechanics from classical physics is not (as often believed) the fact that its axioms involve intrinsic probabilities. It is the fact that it is not descriptive but essentially predictive and, more precisely, predictive of outcomes of observations.
    I'm not completely sure what he means by that. I would have said that both involve intrinsic probabilities, and both are predictive rather than descriptive.

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    Quote Originally Posted by profloater View Post
    Does that mean we can start to look at collapse on a macro scale as we have learned to model in a particle experiment? I have seen a solution go super saturated for a very long time and then literally collapse in a fraction of a second with kilograms of salt falling out when it should have trickled out at the evaporation rate.
    Yes, that's a good example of impossible to predict macro behavior. All we could have used classical physics to do would be to predict the possible outcomes there, the exact one you actually experienced would never have been predictable. So where comes the common belief that whatever happened was "caused," and we just don't know the details of how, versus saying that what happened was just what we perceive happening there-- a kind of "collapse" into a specific outcome that is essentially and fundamentally random, and could never be successfully modeled any other way, so why do we imagine it was something else, yet are surprised when we see the same kind of "collapse" in quantum measurements?
    This raises questions about the division between micro and macro which are too complicated to model from particles to the cosmic loom of interconnectivity.
    I would like to argue that the "division" was never between micro and macro, it was always between precise and coarse treatments by us. In a coarse treatment, you say it will take 1 second for a rock to fall 4.9 meters, and when it takes 1.01 seconds, you claim success. In a precise treatment, you are measuring if the spin of a single electron is up or down. It only sounds like a completely different outcome because you are looking so much more closely.

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    Well on a slightly different tack concerning macroscopic cause and effect, it seems to be generally considered that there is a massive conflict between QM and GR and one of the reasons appears to be connected to the incompatibility between the discrete nature of QM verses the smooth and continuous nature of curved space and the equations that represent that. But, in the light of what is being discussed here, perhaps that particular incompatibility is nothing of the sort. If a predictable path of a free floating object through curved space is only different to a chaotic weather system in terms of the bins containing our possible measurements then perhaps we can go all the way and say that the determinism of GR is not incompatible at all with the discrete nature of QM, the so called incompatibility is more to do with the way we sociologically make a distinction between a nice smooth and predictable path through curved space and the very discrete (for example) up or down spin of QM. If nature is a continuum of probabilities as we move from QM to GR with no abrupt dividing line, why introduce such a dividing line between QM and GR?

    Of course there are a number of other reasons cited for the incompatibility between QM and GR, so I'm not suggesting there isn't such an incompatibility, but in terms of this one particular aspect, I would perhaps say there are grounds for crossing it off the list based upon this discussion.

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    Quote Originally Posted by Ken G View Post
    Yes, that's a good example of impossible to predict macro behavior. All we could have used classical physics to do would be to predict the possible outcomes there, the exact one you actually experienced would never have been predictable. So where comes the common belief that whatever happened was "caused," and we just don't know the details of how, versus saying that what happened was just what we perceive happening there-- a kind of "collapse" into a specific outcome that is essentially and fundamentally random, and could never be successfully modeled any other way, so why do we imagine it was something else, yet are surprised when we see the same kind of "collapse" in quantum measurements?I would like to argue that the "division" was never between micro and macro, it was always between precise and coarse treatments by us. In a coarse treatment, you say it will take 1 second for a rock to fall 4.9 meters, and when it takes 1.01 seconds, you claim success. In a precise treatment, you are measuring if the spin of a single electron is up or down. It only sounds like a completely different outcome because you are looking so much more closely.
    Yes i see that is a better distinction.c
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by Len Moran View Post
    Well perhaps this is the most interesting aspect of this thread rather than the QM bit. If determinism as a classical notion appears to break down in that in principle there is no information available, ever, that would allow us to predict which leaf will fall from the tree first, then that does sort of suggest that the determinism that we take for granted such as (say) a magnetic field will always result from a flow of current in a wire is a macroscopic construct. There must be probabilities that there won't be a magnetic field, it's just that we don't get to see those probabilities occurring. Is there a scale of probabilities that go from 99.99999......9% that a magnetic field will follow from a current flow to (say) 0.0000.......1%) that water at sea level will not boil at 100 degrees C? Having a high degree of probabilities allow us to construct repeatable historical events, we join the dots of the probabilities to make a smooth continuous event time line made up of causes and effects. This it seems fools us conclusively with reliable things like electric currents producing magnetic fields, but starts to unsettle us when we get into chaotic systems, we sense a breakdown in familiar cause and effect. And perhaps at the quantum level, it's not so much phenomena fooling us, it is more a case of phenomena laying bare the basic building blocks of our macroscopic reality with no pretensions of ever joining up the dots to give us our familiar notion of predictable cause and effect events. Perhaps it is the macroscopic world that is the weird realm rather the quantum world!
    I find the macro world so leaky! Electrons choosing to zip through copper but not rubber is fascinating but if you have a meter some leak to the outside. Leaves will grow according to tropisms yet no full tree is identical to any other, just like snowflakes. Plastics creep when they should be stable, control systems achieve better accuracy than hysterisis predicts because they are always vibrating, And i have repaired machines by giving them a severe talking to when they “should” work. That last example is weird but i have witnesses!
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Thanks everyone so far for the great answers... it will take me some time to read them all through carefully!
    "It's only a model....?" :-)
    https://www.youtube.com/watch?v=m3dZl3yfGpc

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    Quote Originally Posted by speedfreek View Post
    But in the case of the delayed choice quantum eraser, surely all the hits on the various detectors could be recorded automatically, and the correlations between the signal and idler photons via the coincidence counter be checked by an algorithm, after the idler photons have all been detected, and the result would then be already sitting there in the data, ready to be observed by a consciousness, even if a consciousness never bothers to look at it?

    The fact that the idler photons (whose "which path" information was only erased in the experimental apparatus *after* their corresponding signal photons had already been detected) show an interference pattern when the results at their respective detectors are correlated via the coincidence counter would be sitting there, unchangeable after the fact, ready to be observed, or not, I would have thought?

    Does the waveform collapse when the results are correlated by a machine, or only when a consciousness looks at those results?

    Sent from my ALE-L21 using Tapatalk

    I've seen a proposed experiment, here goes:

    The experiment is run a large number of times. The pattern on the screen is automatically photographed each time but without anyone observing it or there being any audit trail. Statistically it should be about 50:50 whether there is an interference pattern or not.

    Immediately, the photos are automatically sealed into envelopes by machine and no person observes the process.

    When experiment complete, burn half the envelopes.

    A conscious person then opens the remaining envelopes.

    The proposer thinks the remaining photos will show only one pattern.

    The question then being, what was in the envelopes before half were burnt?

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    Quote Originally Posted by Len Moran View Post
    Well on a slightly different tack concerning macroscopic cause and effect, it seems to be generally considered that there is a massive conflict between QM and GR and one of the reasons appears to be connected to the incompatibility between the discrete nature of QM verses the smooth and continuous nature of curved space and the equations that represent that. But, in the light of what is being discussed here, perhaps that particular incompatibility is nothing of the sort.
    Yes, I agree. We should never interpret our theories as the exact truth, so if GR uses a smooth manifold, we should not be surprised if this is only an effective treatment after some smaller scale physics that we don't know yet has been averaged over. In particular, we have no idea if GR applies inside an atom, because the effects in there are vastly too small to measure. Are electrons black holes? In GR, they'd have to be if they are point particles, the way QED treats them. But electrons have mass way below the Planck mass, maybe GR doesn't work at such small mass scales. How would we know? It's just ignorant to take our theories as the literal truth on all scales, given how many times we've had to learn that lesson.
    If a predictable path of a free floating object through curved space is only different to a chaotic weather system in terms of the bins containing our possible measurements then perhaps we can go all the way and say that the determinism of GR is not incompatible at all with the discrete nature of QM, the so called incompatibility is more to do with the way we sociologically make a distinction between a nice smooth and predictable path through curved space and the very discrete (for example) up or down spin of QM. If nature is a continuum of probabilities as we move from QM to GR with no abrupt dividing line, why introduce such a dividing line between QM and GR?
    I agree. Indeed, the final conclusion Hawking had about black hole event horizons is that they are as chaotic as weather. The thought was dismissed by the literalists, but I don't see on what basis.
    Last edited by Ken G; 2019-Mar-07 at 02:14 PM.

  24. #24
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    Quote Originally Posted by kzb View Post
    The experiment is run a large number of times. The pattern on the screen is automatically photographed each time but without anyone observing it or there being any audit trail. Statistically it should be about 50:50 whether there is an interference pattern or not.

    Immediately, the photos are automatically sealed into envelopes by machine and no person observes the process.

    When experiment complete, burn half the envelopes.

    A conscious person then opens the remaining envelopes.

    The proposer thinks the remaining photos will show only one pattern.

    The question then being, what was in the envelopes before half were burnt?
    If what you mean here is, use the paired photon results to separate the original non-interference pattern into two subsets, it is true that this culling procedure can result in two patterns that both show the two-slit interference pattern, they just don't when combined (the two patterns are spatially offset from each other). So then the two envelopes contain the two interference patterns prior to being burned, there's no particular issue there. The key point is, you would already need access to the paired results before you put the photons in those envelopes, because that's the only way you could put them in envelopes and get what you claim. If you put them in the envelopes before you knew what happened to the paired photons, the envelopes would just be random subsets of the original pattern.

    But the point is, whether you use something as fancy as quantum erasure, or something as mundane as a shuffle of a deck of cards, before you look your treatment of the outcome will be as a "mixed state" of probabilities. There is never any need to describe it any other way, and the choice to claim "the cards are already determined, I just don't have access to that information yet" was always just an untested interpretation of classical physics, akin to the untested interpretations of quantum mechanics. Another possible interpretation that makes all the same testable predictions is that after the shuffle, whatever information you have and whatever probability distribution that creates, represents an actual partition of "many worlds" in which all those outcomes actually do occur in one of those many worlds. When you look, it means that in all those worlds a consciousness picked up the cards and continued on their merry way, and all that gets decided when you personally look is which one of those consciousnesses is "you".

    That interpretation passes every objective test, it's just not at all popular. So why is essentially that same approach taken by many in quantum mechanics interpretation? It's because quantum mechanics cannot hide its machinery behind imprecise observation the way classical physics does. The machinery of quantum mechanics operates not on observables, but on mathematical entities that produce only expectation values of observables. The machinery of classical physics operates on the observables themselves, which come with much larger uncertainties than in quantum mechanics, yet are pretended to be exact values of observables, as if that wasn't a clear contradiction in terms. But if you look "under the hood", you see that classical physics is also merely a prescription for mapping information into probabilities, just like quantum mechanics is. It merely does a better job of creating the illusion that it is describing "what really happens" because it operates directly on observables, but it is never tested that it describes what really happens, so we should not have been surprised to discover that it never actually did that.
    Last edited by Ken G; 2019-Mar-07 at 02:54 PM.

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    ^ Ken G
    I suspect I have not understood the experiment description myself.

    It uses a scrambler to randomly switch the quantum eraser on or off.

    The proposer says that there are two possible photos, one showing an interference pattern, and one not showing an interference pattern.

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    Quote Originally Posted by kzb View Post
    ^ Ken G
    I suspect I have not understood the experiment description myself.

    It uses a scrambler to randomly switch the quantum eraser on or off.

    The proposer says that there are two possible photos, one showing an interference pattern, and one not showing an interference pattern.
    That's not quite how quantum eraser works. You never see the effect in a photo of the detector screen, that always shows no two-slit pattern. The only way to get a two-slit pattern is to correlate the outcomes for the paired photons with the photo, culling out the dots in the photo that are associated with a given outcome of the paired photon. Then you will see, if the eraser is in effect, that the two sets of dots each make up their own two-slit pattern, but it doesn't show up in the entire photo. You can look at the photo of the detector screen long before the paired photons go through their apparatus, and nothing about the quantum eraser experiment is any different. It is often described incorrectly to make it seem even more mysterious than it actually is.
    Last edited by Ken G; 2019-Mar-07 at 07:24 PM.

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    Perhaps it would also help to summarize how each interpretation copes with the consciousness phenomenon:

    Copenhagen: what the consciousness objectively perceives is reality by definition, so in that sense consciousness does collapse the wavefunction but it's not an actual happening. Quantum mechanics and its wavefunctions are just mathematical models we use to make that connection. "There is no quantum world," so there's actually nothing "to collapse". Objective perception is the sole authority on what happened, and consciousness is there to do the perceiving. (This is the approach if you think reality is whatever observation and measurement can access.)

    Many Worlds: consciousness doesn't collapse the wavefunction because the wavefunction never collapses, and mixed states don't exist-- they are merely projections of the true wavefunction onto the analysis we use, and then the consciousness only perceives a tiny fraction of that mixed state. Hence each of our own consciousnesses exist in a tiny tiny fraction of what actually exists, and our unique perceptions are not privy to most of the true story. So that ultimate collapse into experience is not a real event, but it is what consciousness perceives, so it is responsible for the illusion of collapse. (This is the approach if you think reality is just the mathematics of the Schroedinger equation.)

    Bohmian: Consciousness is a fly on the wall of the true reality. There is never any collapse, reality is just what happens and was always predetemined. We are simply not privy to the information the universe uses to determine what happens, and we don't see the invisible machinations of the "pilot wave" that connects all that inaccessible information to whatever happens (and those connections go both forward and backward in time in any way necessary to make what happens be the only thing that was possible to happen). Our consciousness exists in the sole reality, and the nature of that reality is not changed whether we know about it or not. (This is the approach if you demand that reality be accessed by classical thinking must access.)
    Last edited by Ken G; 2019-Mar-08 at 02:31 PM.

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    Part of consciousness is agency or the illusion of agency. Indeed the feeling of agency is perhaps the most important part of human consciousness and this applies to observations within this thread, I guess. So how do those three interpretations handle agency? I think in at least two it must be an illusion.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    I just want to be sure that I have the essence (in a very basic manner) of what is being said in this thread concerning the marrying up of chaotic systems and predictable systems such that they are seen actually to be both part of a spectrum going from a hugely chaotic system to a hugely predictive system where the dividing lines are more to do with the sociological way we view them.

    If A has an effect on B that gives six possible random outcomes we cannot say that A has had a direct casual part to play in producing the actual outcome, that outcome is a product of something mysterious in B. All we can say is that if A interacts with B, there will be a one in six chance of it being any particular B1 to B6.

    But if the effect of A on B is to produce a B2 outcome every single time the interaction with A occurs, then we have a very predictable relationship between A and B.

    Are we still saying that there is something mysterious going on in B in both cases, but in the first case it produces six possible outcomes after A interacts with B and in the second case it produces just one outcome after A interacts with B? Are we saying that just because we only get the one outcome in the second case, that doesn’t at all imply that there is a direct causal link from A to the solitary outcome at B, rather B, with all its mystery, is the “thing” producing that outcome?

    Prior to this discussion I might have said that the first instance is a case of a dice producing a random outcome of one to six. But I might have said that the second case illustrates a “real” causal effect, maybe for example by passing an electric current through a wire and producing a magnetic field every single time the switch is pressed. And I might well have said the two cases are entirely different aspects of the physical world – the first case represents a kind of unpredictable chaotic physical world, the second a reliable and predictable cause and effect world.

    But if I understand things here we would say that in both cases B takes over once triggered by A and then B may produce outcomes that are probabilistic or it may produce just one outcome. But in neither case can we say that the outcomes produced by B have a direct casual link to A, B is an independent “something” acting in terms of its own “remit”, in the first case the remit allows for six possible outcomes at all times, in the second case the remit allows for just one possible outcome at all times. The difference is simply one of degree, if we put a weight in the dice we would notice a bias towards one particular outcome and perhaps if we were very clever with the weight we might even get the dice to produce the same outcome over very many interactions with A such that it would seem to become identical with the second case. And perhaps if we did the test with the current and wire an unthinkable and unimaginable number of times we might just find that on one occasion, no magnetic field was produced and perhaps we might then start to compare it with the dice scenario.

    If this is the gist of what is being said, the real mystery seems to involve the “mechanism” by which B “decides” what its intrinsic bias is going to be – in the first case, without any weight in the dice, the intrinsic bias is presumably zero percent and in the second case the intrinsic bias is 100%.

  30. #30
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    Well, it seems we have a bias, if we experience a high number of positives we form a model of causality and then we start to ignore the failures of our model. I can believe i could never win a lottery at a million to one yet every week someone wins. Probabilities cluster towards zero and one in consciousness. Midway is uncomfortable so we look for more subtle influences or more variables until we can see cause again. A mind that thrives on useful predictions abhors the idea of random. It is really hard to accept randomness when we need reliable prediction to feel in control, to feel the comfort of agency.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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