• Martin Krumins
    15
    The slit experiment seems to be reviving idealism given that we supposedly change the universe by observing it.
    First a point of observation: the construction of the device that observes the phenomenon is manmade, although it can reveal much more, the instrument itself holds no special external place in the universe, it is a product of man.

    Now we are idealists in the sense that we do indeed construct the world as to how we wish to perceive it
    But also, we have evolved to perceive it in a way that keeps us out of trouble
    And most importantly we perceive it in a frame that helps us grow.

    The extent of our relationship to the external world can be described as a mirroring process which evolves idealism into something that is almost ‘real’ although imperfect.
    But we are perfectly capable of diminishing the relationship with the world outside that our process over evolutionary time has established.

    We are likewise capable of utilising this diminution as a revision and thus through difficult theoretical exactitude, improve the usefulness of the mirroring process and enhance our relationship to the world outside for our growth and gain.

    The split experiment is no more than a philosophical transition which causes the materialist (in itself an extreme perception) scientist to regress into pure idealism. For the instruments that he creates reflect his mind. They are so wrapped up in the search for truth they have forgotten that the very means by which they search for truth is only a heavily refined idealism that has been externalised into an object.

    What is true, is not affected. This is their mistake. As they are confused by the transferrence of ego into an object, they posit their own flaws (idealist basis) upon the world outside. But the world outside is not actually affected of course.
    You can see the development as a reversal of perspective but one done through the medium of the instrument which the scientist in his naivety has taken to be more real than his own perceptions when in actual fact they could only ever be an extension of those perceptions.

    I hope I’ve explained it ok, basically scientist convinces himself instruments are real, instruments are fallible as their makers, scientist decides the world is affected by the instrument, scientist is mistaking his origin in idealism for the world outside. World outside never effected. the idea that we can percieve two things is correct, the idea that if we percieve, the outside world changes, is stupid.
  • Marcus de Brun
    450


    Now we are idealists in the sense that we do indeed construct the world as to how we wish to perceive it
    But also, we have evolved to perceive it in a way that keeps us out of trouble
    And most importantly we perceive it in a frame that helps us grow.

    Martin

    No offense but this reads like jibberish. the Double Slit Experiment represents perhaps the single greatest mystery in Physics... at least according to Feynman.

    I think Philosophy is better placed to provide a sound answer to the conundrum, better placed than Physics or QM.

    Perhaps you might formulate your idea into a clear paragraph of plain english.

    M
  • Martin Krumins
    15
    yeah ive got a terrible habit of expressing my self at the beggining of formulating an idea rather than at the end. ok but its going to take me a while. ill work on it and try again.
  • Dfpolis
    1.1k
    The slit experiment seems to be reviving idealism given that we supposedly change the universe by observing it.Martin Krumins

    Of course we change the universe by observing it. We are part of the universe and our observations change both us and the objects we observe.

    The idea that we somehow stand apart, that what we do, including our observations, doesn't matter is, and always was, simply wrong. Our observations on the human scale may not change things much, and so we can often neglect the changes we make. But, on the quantum scale, the interactions necessary to make an observations cannot be neglected. So, there is no difference in principle between the observations we make in everyday life and those we make at the quantum level -- it is simply a matter of when it becomes impossible to ignore the disturbance our observations invariably make.

    This does not mean that we must become idealists. We are observing physical reality, and its intelligible features inform us -- reducing what is logically possible to what is actually the case.

    The problem is that before we observe reality is sensible, intelligible and perhaps measurable, but not sensed, known and a set of measure numbers. Thus, in physics, the actual measure number depends not only on what we are measuring, but also on the process we employ to measure it. None of this should be surprising, or make us reject realism.

    To be a realist is to hold that what we observe informs us, but it informs us in a way that is limited by our perspective, senses and so on. It does not inform us exhaustively.
  • Relativist
    1.5k
    You seem to be talking around the topic, but not addressing it directly. Can you please succinctly tell us how you interpret the results of the double slit experiment, taking into account the perspective you have described. In particular, what (if anything) does the experiment tell us about objective reality.
  • Martin Krumins
    15
    i think your mistaking observations for actions.
  • Martin Krumins
    15
    ok i dont know why your talking about love particularly but im glad you agree that observations don't change anything.
  • Dfpolis
    1.1k
    All observations are actions. Not all actions are observations.
  • Martin Krumins
    15
    observations are not our actions though right? I always knew there was some passifying quility to it lurking beneath.
  • Dfpolis
    1.1k
    Sure, I have a few videos on my YouTube channel on quantum theory if you care to know more.

    I assume that we are discussing the quantum version of the experiment. As with Young's optical version and the water version, the observed interference pattern confirms the wave theory and definitively falsifies the particle theory.

    So, what about the "dots" in the screen? Don't they show that we are dealing with particles? No, not at all. We have to remember that all detectors are made of bull matter, all bulk matter is made of atoms, and all atoms have quantized energy levels occupied by their shell electrons. Detection events all involve electrons transitioning to higher energy states. This happens in atoms that are localized by the electric potential well of the nucleus, and it happens in individual electrons.

    So, when a wave impinges on a detector, it excites the electrons in a number of atoms' electrons and those electrons interact, exchanging energy, just as they do in thermal energy exchange. These interactions are non-linear and so chaotic in the mathematical sense. Eventually one electron accumulates enough energy to effect what we interpret as a detection event. Since the atoms of the detector are localized, so are the detection events -- giving us the dot pattern we observe.

    Because electron-electron interactions are nonlinear, they cannot sustain a linear superposition of states, and so the wave function (which previously did not involve nonlinear electron-electron interaction terms) collapses.

    How does this reflect my philosophical approach? Just as I look at sensation and knowledge by considering the interaction of the object with the sense or the intellect, so I consider quantum observations by giving equal weight to the physics of the system being observed and of the detection process.

    Also, as Aristotle noted, physical states do not involve numbers. At most they are countable and measurable. The measure number that we obtain, then, depends on the details of the measurement process and does not pre-exist in nature. Only a potential to be measured is found in nature. The actual measure depends jointly on the system state and the detector state.
  • JamesG1951
    3
    The double slit experiment forces us to step outside the box so we cannot define and create the result we want and expect to find. The laws of physics are defined as being "in a closed system" while the physical universe is a closed system because what you have observed has already been created, our sapience is outside that system or we would not have the ability to change the course of an object apart from where the laws have already defined where it is going. We can use our sapience to direct our sentience into doing something apart from what the laws of PHYSICS meaning physical existence has to abide by. The observation is the moment something becomes part of the closed system. The NOW is the defined creative moment of defining that system. the double slit experiment separates the now from the past
  • Dfpolis
    1.1k
    No, observations all involve action. In seeing, for example, the object is illuminated (light acting on it), scatters light (the object reacting), and our eye receives some of the scattered light (reacting to it) and sending off a neural pulse which involves complex interactions in and between neurons. So there are all kinds of actions going on.

    And this does not even touch upon the act of will directing our attention and the sequence of acts that initiates.
  • EnPassant
    483
    The slit experiment seems to be reviving idealism given that we supposedly change the universe by observing it.Martin Krumins

    This, to my mind, is a confusion of terms. When a scientist observes a quantum event, that whole process involves

    1. Planning the experiment.
    2. Implimenting it = detection.
    3. Observing the results.

    All this comes, loosely, under the heading 'observing'. But, for clarity, these three parts need to be separated. Observation is not important in terms of what physically happens. What is important here is detection. A particle can be detected without observation (the observation can take place months after the fact.)

    Detection must be defined as follows:

    Quantum particles live in their own spacetime, which is not classical spacetime.
    When a quantum event interacts with a classical experiment it leaves a trace effect on the experiment. A spot on a photographic plate is a trace effect.

    These trace effects are NECESSARILY classical objects because they exist in classical spacetime. Detection then is defined as a quantum event leaving a classical trace effect on classical spacetime.

    Consequently, these trace effects are measured in classical terms. It cannot be otherwise. So the scientists are reduced to interpreting quantum spacetime, in classical terms; the measurements are according to a classical ruler.

    The trace effects exist at the interface between quantum spacetime and classical spacetime. But they are classical objects.

    If detection is defined in these terms it can be seen that the effect on particles is produced not by observation per se, but by detection; the 'collision' of a particle with a classical object (ie the experimental apparatus, which is a classical object). It is detection, not observation, that effects the change. Changing reality by 'observing' it is a confusion of terms; a confusion between detection and observation.
  • Relativist
    1.5k

    Thanks for the description. Do you agree with the Quantum Field Theory view that quantum fields (waves) are fundamental, while particles are "disturbances" in a field? Your description sounds consistent with this view.
  • Dfpolis
    1.1k
    Pretty much. I think that so-called particles are quantized wave structures, as modeled by QFT. I think that annihilation and creation operators mask more fundamental nonlinear processes.
  • Martin Krumins
    15
    Thank you very much, detection and observation are two hugely different things and many people use observation in their description. thanks for clearing that up, you should copy paste it to like a hundred youtube videos, haha.
  • Wayfarer
    10.4k
    Our observations on the human scale may not change things much, and so we can often neglect the changes we make. But, on the quantum scale, the interactions necessary to make an observations cannot be neglected. So, there is no difference in principle between the observations we make in everyday life and those we make at the quantum level -- it is simply a matter of when it becomes impossible to ignore the disturbance our observations invariably make.Dfpolis

    I recall in Brian Greene’s book, The Fabric of the Cosmos, he discusses whether the observer effect is due to literally interfering with the object of analysis:

    The explanation of uncertainty as arising through the unavoidable disturbance caused by the measurement process has provided physicists with a useful intuitive guide as well as a powerful explanatory framework in certain situations. However, it can also be misleading. It may give the impression that uncertainty arises only when we lumbering experimenters meddle with things. This is not true. Uncertainty is built into the wave structure of quantum mechanics and exists whether or not we carry out some clumsy measurement.

    So it's not as if the act of measurement literally alters the subject - I think if it were that simple, then it would not be regarded as the great mystery that it currently is.

    As I understand the conundrum surrounding measurement, the electron exists 'in a super-position' which is described by the wave function. That is literally a description of a range of possibilities.

    Prior to it being measured, it can't be said to be in a particular place. But that doesn't mean it exists in a particular place but hasn't been located - it is literally not in any particular place until it is measured. The point that the act of measurement seems to be implicated in ‘creating’ the object is what is behind 'the measurement problem', is it not?
  • Relativist
    1.5k
    Can you describe how you think the classical world (with apparent particles and large scale structures) emerges from the quantum world (of wave function and superposition)? For example, when entanglement occurs is there always a quantum collapse such that the other eigenstates disappear - and the "object" takes on more classical properties? I've read descriptions in terms of Many Worlds, but my impression is that you reject that, so I'd like to understand your view.
  • Dfpolis
    1.1k
    It may give the impression that uncertainty arises only when we lumbering experimenters meddle with things. This is not true. Uncertainty is built into the wave structure of quantum mechanics and exists whether or not we carry out some clumsy measurement.

    So it's not as if the act of measurement literally alters the subject - I think if it were that simple, then it would not be regarded as the great mystery that it currently is.
    Wayfarer

    There is no intrinsic mystery. I talked about both types of uncertainty mentioned by Greene in my response, but perhaps not with sufficient clarity.

    There seems to be no argument that observing changes the prior state in an indeterminate way. The problem here is not that quantum dynamics are indeterminate. Orthodox quantum theory tells us that all quantum processes other than measurement ate completely deterministic. The problem is that we know neither the detailed prior state of the system being observed nor that of our measurement/detection apparatus. Without knowing the initial state we cannot apply deterministic laws to calculate deterministic outcomes. So, this type of indeterminism is obviously epistemological, not ontological.

    I mentioned a second way in which physical states can be said to be "indeterminate" when I raised Aristotle's observation that, in physical reality, quantity is not an actual number, but countability and measurability. I went on to say that the measure number we actually get depends on the details of the measurement process. This is the explanation of the second kind of indeterminism Greene mentions. As you can see, this is not new either, but has been known in principle since mathematical physics was founded by Aristotle.

    So, why is this a problem? Because many people, including physicists, approach quantum phenomena with two misconceptions:
    (1) Quanta are, sometimes at least, particles that can be adequately conceived of as point masses. This is a prejudice that goes back to the baseless speculations of the Greek atomist. It has never been adequately supported by observational data. Sometimes we can get away with thinking of quanta as particles, but doing so invariably leads to paradox and contradiction.
    (2) Physical quantities have determinate values before being measured. This is a prejudice that goes back to the Pythagorean view that physical things are made of numbers and geometric figures. Even those physicists who haven't read Aristotle should have been disabused of this belief with the advent of special relativity. It showed that the values we measure for physical quantities as basic as space and time depend on the details of the measurement process.

    So, if you think that quanta are particles then you are going to think that they ought to have well-defined positions and momenta, in any given frame of reference, anyway. Since quanta are not particles but waves, it is not surprising that this leads to immediate difficulties. We have known since 19th century developments in hydrodynamic wave theory and the acceptance of Maxwell's electrodynamics that the energy and momentum of waves is not localized, but distributed over the entire field. It should also be obvious that waves do not have a well-defined position that can be adequately dealt with by conceiving of them as point masses. So, it should be no surprise that when we try to measure the position and momentum of a quantumconceived of as a particle we get puzzling results.

    These results are not due to any mysterious, ontological indeterminacy. We know that when we measure the momentum of a quantum with a narrow range of wave lengths the resulting momentum number is inversely proportional to the wave length. We also know that localizing a wave structure requires a wide range of wave lengths (and hence of "momenta"). This is the basis of Heisenberg's uncertainty relation for position and momentum. Still, the relation between localization and range of wave lengths is not a quantum phenomenon. It applies as much to water waves as to quanta. It is simply a consequence of the Fourier integral theorem in mathematics.

    As I understand the conundrum surrounding measurement, the electron exists 'in a super-position' which is described by the wave function. That is literally a description of a range of possibilities.Wayfarer

    There is no reason to think superpositions are not fully actual in themselves. What is potential is the number a measuring process will yield, but, as Aristotle noted, that is potential for all physical quantities.

    Prior to it being measured, it can't be said to be in a particular place.Wayfarer

    Right, because waves are intrinsically extended.
  • S
    11.8k
    I hope I’ve explained it okMartin Krumins

    No, I don't think you have. I almost don't know where to begin. There's a lot which is unclear or makes little sense. Like, at the start, I'm struggling to get my head around why you seem to think that it's relevant to point out that the device is man-made? We already know that. Are you suggesting that if the device sprung up naturally, instead of being man-made, then the results would be different in a nontrivial way?

    basically scientist convinces himself instruments are real, instruments are fallible as their makers, scientist decides the world is affected by the instrument, scientist is mistaking his origin in idealism for the world outside. World outside never effected. the idea that we can percieve two things is correct, the idea that if we percieve, the outside world changes, is stupid.Martin Krumins


    • Instruments are real.

    • That they're fallible, as we are, doesn't mean that they're faulty or unreliable, and it isn't reason enough to conclude that the results of experiments involving them should be discounted or rejected.

    • The scientists didn't just arbitrarily decide that the instrument itself is effecting the results of the experiment, that is a conclusion based on what happens with and without the instrument doing its job. If it's not the functionality of the instrument which is effecting the results, then what is it that is causing the different result when the instrument is not functioning or removed?

    • As for the rest, you've lost me. Some parts, I don't know what you're saying, other parts, I know what you're saying, but not why you're saying it. You mention the double-slit experiment, and you contradict conclusions from that experiment, but you don't really explain how you reach these conclusions which clash with what is suggested by the details of the experiment. I think that it's stupid to call these conclusions stupid, when, although there is still much to be explained, it is clear that the observation device in some way relates to the two different sets of results, and that the relationship seems to be causal. When it's not observing, you get X, and when it is observing, you get Y. Do you think that you have a better explanation? Because I haven't seen one from you. I'll go with what the scientists say over what you say. What's your expertise?
  • Dfpolis
    1.1k
    Can you describe how you think the classical world (with apparent particles and large scale structures) emerges from the quantum world (of wave function and superposition)?Relativist

    Sure. As I have said, we need to look at the detailed physics of the measurement process, instead of treating it abstractly. When we do, we see how the transition from the quantum to the classical world occurs. The associated philosophical problem is falling prey to Whitehead's fallacy of misplaced concreteness -- treating an abstraction as though it is a concrete reality.

    Detectors are made of bulk matter, which is held together with electron-electron interactions. The two electron problem in quantum field theory involves nonlinear dynamics. It is easy to understand why. Each electron generates an electromagnetic field which affects the other, which, in turn, affects the original electron. Since the E-M field is caused by the charge and current densities, it is quadratic in the wave function. That means that electron-electron interactions are intrinsically nonlinear.

    The nonlinearity is easily overlooked, because as soon as it is discovered, it is replaced by a linear perturbative approximation. This is done because we don't know how to solve nonlinear equations, but we can solve the approximating perturbation series.

    If the two electron problem is nonlinear and impossible to solve exactly, imagine the complexity and difficulty of solving the interactions of about 10^23 electrons in a detector. Even problems with as few as eight electrons test the capacity of supercomputers. Because the exact quantum treatment of a detector is impossible, they are treated classically, or at best, semi-classically.

    So, we have the abstraction of quantum existing in isolation, and therefore subject to linear dynamics, and the abstraction of detector treated classically. In reality, we have a free electron approaching 10^23 or so bound, interacting electrons. As it approaches the detector, its interactions with the detector electrons ceases to be negligible -- meaning that the nonlinear terms in the free electron's wave equation become increasingly important.

    Superpositions of solutions of linear equations are also solutions of those equations. Superpositions of solutions of nonlinear equations not solutions of those equations. Thus, once the nonlinear terms in the free electron's wave equation become important, the superposition will become unsustainable, and the wave function must collapse to a single solution of a set of (~10^23) nonlinear equations.

    Once we see why the wave function has to collapse on detection, it is clear how the classical world emerges from the quantum world. When we have enough atoms interacting so that their nonlinear interactions cease to be negligible, superpositions will no longer be sustainable, and we will have one well-defined solution at a time -- not a superposition of a live cat and a dead cat.
  • Martin Krumins
    15
    ok so the depth of the problem is based in idealism, you may have to read about it to understand why I would link the fact the instruments are man made to be of any relevance to the problem. Its just an extension of the idealist philosophical problem from us to our instruments. but there is someone that has already outlined the difficulty I was having so no need to worry. thanks
  • Wayfarer
    10.4k
    Prior to it being measured, it can't be said to be in a particular place.
    — Wayfarer

    Right, because waves are intrinsically extended.
    Dfpolis

    So do you think it's correct to say that there are no actual atoms in the original sense of 'indivisible particles'? In that, what is perceived as 'particles' is not something that is actually a particle but for which the term 'particle' is a kind of analogy?
  • S
    11.8k
    ok so the depth of the problem is based in idealism, you may have to read about it to understand why I would link the fact the instruments are man made to be of any relevance to the problem. Its just an extension of the idealist philosophical problem from us to our instruments. but there is someone that has already outlined the difficulty I was having so no need to worry. thanksMartin Krumins

    I'm already familiar with idealism. I doubt that further reading on idealism will help explain your reasoning about instruments being man-made and the supposed relevance of it all. I think that that would have to come from you. After all, you're the one making this link. But it's alright, you don't really have to attempt to explain yourself, because I already know that the fact that instruments are man-made says nothing much about anything. I was just curious as to how you'd go about trying to make something of nothing.
  • Dfpolis
    1.1k
    So do you think it's correct to say that there are no actual atoms in the original sense of 'indivisible particles'? In that, what is perceived as 'particles' is not something that is actually a particle but for which the term 'particle' is a kind of analogy?Wayfarer

    Exactly
  • Banno
    10k
    This OP is not in touch with reality.

    So what is worrying here is that it attracts attention.
  • andrewk
    2.1k
    There are a number of different double-slit experiments, and all of them (or at least, all the ones I know, including several 'delayed choice' and 'quantum eraser' versions) are completely explained by the mathematical analysis, which does not hold any mysteries, beyond the mundane technical difficulty of working through them. They do not necessitate the adoption of any particular interpretation of QM or any particular philosophical position.

    Without knowing which double split experiment the OP was thinking of, and what aspect he thinks requires an idealistic worldview, one can't say much more. The idea that observation changes the world because of something to do with consciousness is not supported by QM. What causes the interference pattern to disappear when particles are detected going through one of the slits is the interaction between the detector (including the recording apparatus connected to that) and the particles, not the fact that a conscious entity looks at the results of the interaction. The interference pattern would still disappear if nobody looked at the screen or the detector.

    I write that as somebody with strong idealistic leanings. Those leanings stand on their own and have no need of a misconstrued version of QM to justify them.
  • Wayfarer
    10.4k
    ....which does not hold any mysteries...andrewk



    What is the consensus regarding the factuality of this video? Because if it is accurate then the mystery is that you can create a radical change in the outcome of an experiment simply by looking at it. And if that is NOT a mystery, then why are so many people defending the 'many-worlds interpretation'?
  • andrewk
    2.1k
    The video is a classic example of science being so oversimplified as to make nonsense of it. A number of the key claims are nonsense, including the one that an electron 'interferes with itself'. It does no such thing. What the electron gun does is create a probability field at the screen. Consequently, flashes appear on the screen, which we think of as electrons hitting the screen, in accordance with that field. The probability field is undulating, so we see the patterns of bright and dark bars.

    What is 'interfering with each other' are (is?) the two probability fields emanating from the two slits. It is not electrons interfering with each other or with themselves. When there is only one slit there is no interference because there is only one source of the probability field.

    When the electrons are observed passing through a slit, a device needs to be used that physically interacts with the probability field near one of the slits, as that's the only way to get an electron observation near the slit. It is that interaction that changes the field, not the fact that 'the electron knows it's being watched'. The change to the field causes the probability field at the screen to be one of a large smudge rather than interference bars. The mathematics of this is quite straightforward, and not at all mysterious.

    The attraction of the many-worlds interpretation is that it introduces a straightforward way of explaining why QM has probability distributions in it. In a sense it is a way to uphold Einstein's 'God doesn't play dice' objection. I don't think it really has any bearing on what is called the 'measurement problem'.
  • Wayfarer
    10.4k
    A number of the key claims are nonsense, including the one that an electron 'interferes with itself'. Iandrewk

    I think the video is OK. I posted a question about this experiment on Physics Forum and that is exactly what I was told there.

    And as for the claim that the device ‘physically interferes’ with anything, this is the subject of the Brian Greene quote that I mentioned [utl=https://thephilosophyforum.com/discussion/comment/210930]above[/url].

    As for your last claim that the Everett interpretation doesn’t have anything to do with ‘the measurement problem’, I can’t see how that could be any further from the truth. It is all to do with interpretation of what’s behind the measurement problem, which is the subject of Sean Carroll’s blog post, the most embarrassing graph in the world.
  • andrewk
    2.1k
    I've read that blog post by Sean Carroll more than once in the past. As far as I can recall it is about which are the most popular interpretations of QM, and doesn't even mention the measurement problem. Its point is simply that there is no consensus interpretation of QM. I don't know whether he was being facetious when he called it an embarrassing graph. I suspect so. I don't see anything embarrassing about it. Since interpretations are metaphysics, not science, I see the diversity of interpretations as a healthy sign.

    this is the subject of the Brian Greene quote that I mentionedWayfarer
    I would say "don't believe everything written by physicists in non-peer-reviewed books" but I don't think I need to tell you that, given your disdain for Stephen Hawking's non-peer-reviewed writings, which I share.

    I think the video is OK. I posted a question about this experiment on Physics Forum and that is exactly what I was told there.Wayfarer
    It depends what you mean by 'OK'.
    Does it give a good general idea of how the basic double-slit experiment is conducted and what is seen? Yes.
    Does it demonstrate that a Laplacian view of the world as consisting of small hard billiard balls bouncing around is unviable? Yes.
    But does it accurately represent how the interference pattern arises and why it disappears when we take measurements next to one of the slits? No.
    If you think you've read a credible technical argument to the contrary, and you wanted to discuss that, you could post a link to it here.
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