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My argument against the double-slit experiment in physics.

Martin Krumins September 04, 2018 at 15:13 13875 views 52 comments
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.

Comments (52)

Marcus de Brun September 04, 2018 at 19:48 #210242
Reply to Martin Krumins

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 September 04, 2018 at 20:18 #210243
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 September 06, 2018 at 16:23 #210826
Quoting Martin Krumins
The slit experiment seems to be reviving idealism given that we supposedly change the universe by observing it.


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 September 06, 2018 at 20:04 #210850
Reply to DfpolisYou 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 September 06, 2018 at 20:10 #210851
Reply to Dfpolis i think your mistaking observations for actions.
Martin Krumins September 06, 2018 at 20:14 #210852
Reply to JamesG1951 ok i dont know why your talking about love particularly but im glad you agree that observations don't change anything.
Dfpolis September 06, 2018 at 20:25 #210854
Reply to Martin Krumins All observations are actions. Not all actions are observations.
Martin Krumins September 06, 2018 at 20:30 #210855
Reply to Dfpolis observations are not our actions though right? I always knew there was some passifying quility to it lurking beneath.
Dfpolis September 06, 2018 at 20:54 #210860
Reply to Relativist 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 September 06, 2018 at 20:58 #210862
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 September 06, 2018 at 21:01 #210863
Reply to Martin Krumins 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 September 06, 2018 at 23:36 #210893
Quoting Martin Krumins
The slit experiment seems to be reviving idealism given that we supposedly change the universe by observing it.


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 September 07, 2018 at 01:11 #210903
Reply to Dfpolis
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 September 07, 2018 at 01:32 #210908
Reply to Relativist 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 September 07, 2018 at 02:54 #210920
Reply to EnPassant 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 September 07, 2018 at 04:26 #210930
Quoting Dfpolis
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.


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 September 07, 2018 at 14:08 #210999
Reply to Dfpolis 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 September 07, 2018 at 15:16 #211007
Quoting Wayfarer
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.


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.

Quoting Wayfarer
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.


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.

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


Right, because waves are intrinsically extended.
S September 07, 2018 at 16:05 #211011
Quoting Martin Krumins
I hope I’ve explained it ok


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?

Quoting Martin Krumins
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.



  • Instruments [I]are[/I] 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 September 07, 2018 at 16:19 #211016
Quoting Relativist
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)?


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 September 07, 2018 at 22:23 #211069
Reply to S 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 September 08, 2018 at 00:34 #211081
Quoting Dfpolis
Prior to it being measured, it can't be said to be in a particular place.
— Wayfarer

Right, because waves are intrinsically extended.


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 September 08, 2018 at 01:59 #211101
Quoting Martin Krumins
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


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 September 08, 2018 at 02:57 #211111
Quoting Wayfarer
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?


Exactly
Banno September 08, 2018 at 04:08 #211118
Reply to Martin Krumins This OP is not in touch with reality.

So what is worrying here is that it attracts attention.
andrewk September 08, 2018 at 04:32 #211121
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 September 08, 2018 at 05:20 #211130
Quoting andrewk
....which does not hold any mysteries...




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 September 08, 2018 at 05:48 #211142
Reply to Wayfarer 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 September 08, 2018 at 06:10 #211145
Quoting andrewk
A number of the key claims are nonsense, including the one that an electron 'interferes with itself'. I


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 September 08, 2018 at 06:28 #211148
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.

Quoting Wayfarer
this is the subject of the Brian Greene quote that I mentioned

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.

Quoting Wayfarer
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.

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.
Wayfarer September 08, 2018 at 06:32 #211150
Quoting andrewk
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.


But doesn’t the whole question of ‘which interpretation’ - Copenhagen, MWI, etc - revolve around ‘the measurement problem’? Isn’t the ontological status of the wave-function collapse the basic interpretive issue?


Quoting andrewk
But does it accurately represent how the interference pattern arises and why it disappears when we take measurements next to one of the slits?


Is it possible to represent that graphically, or only mathematically?
andrewk September 08, 2018 at 06:39 #211152
Quoting Wayfarer
But doesn’t the whole question of ‘which interpretation’ - Copenhagen, MWI, etc - revolve around ‘the measurement problem’

To get into that I think we'd first need to take a step back and try to reach a shared understanding of what 'the measurement problem' is. It is often talked about but rarely defined. It is often presented just in terms of a vague gesture towards quantum weirdness in general.

My closest guess is that, rather than being a problem, it is a question, the following one:

'Does conscious observation change the physical universe?'

One can adopt an interpretation of QM in which the answer is Yes, or another in which it is No. QM itself is silent on the issue. For me the question is moot because I see consciousness as primary and the 'physical' as an artifact of our consciousness.

What do you consider the measurement problem to be?
Wayfarer September 08, 2018 at 06:55 #211155
Quoting andrewk
What do you consider the measurement problem to be?


[quote=Wikipedia]The measurement problem in quantum mechanics is the problem of how (or whether) wave function collapse occurs. The inability to observe this process directly has given rise to different interpretations of quantum mechanics, and poses a key set of questions that each interpretation must answer. The wave function in quantum mechanics evolves deterministically according to the Schrödinger equation as a linear superposition of different states, but actual measurements always find the physical system in a definite state. Any future evolution is based on the state the system was discovered to be in when the measurement was made, meaning that the measurement "did something" to the system that is not obviously a consequence of Schrödinger evolution.[/quote]

That 'something' is the 'act of observation' which reduces all the probabilities to one particular one, namely, the observed one. Prior to that observation, there is no objective 'particle' but then after it's been measured, there is. Hence Bohr's famous aphorisms on this problem, such as 'When we measure something we are forcing an undetermined, undefined world to assume an experimental value. We are not measuring the world, we are creating it' and more succinctly 'nothing exists until it is measured'. This was the source of the long debates between he and Einstein, ever the scientific realist. It is why Einstein was obliged to ask the question 'does the moon continue to exist when nobody's looking at it?' This is all covered in Manjit Kumar's book Quantum and David Lindley's Uncertainty. (The first is better.)

Incidentally my view is that the so-called probability wave exists in reality - but purely as literal distributions of possibility, i.e. it’s not a physical wave, but a distribution of likelihoods. That’s why, whether you fire one particle per x second or eighty thousand per x seconds, you get the same pattern - because the rate of emissions doesn't affect the distribution pattern, then whatever determines the distribution is not time-bound. That strikes me as profoundly significant. I asked this question on physics forum and also on Stack Exchange. (Notice the reaction on Physics Forum, post #14, when I suggest that it's not time-bound.)

This also ties in with an interpretation by Ruth Kastner et al, which says that '“This new ontological picture requires that we expand our concept of ‘what is real’ to include an extra-spatiotemporal domain of quantum possibility.' In other words, there are real possibilities. I don't think that modern ontology allows for that, however, as I think that part of what happened in the transition to modernity was the 'flattening' of ontology so that something either exists (1) or doesn't (0). Whereas here we are dealing with 'things' (loosely speaking) that have various 'degrees of reality'; when the particle is observed, it is 'actualised' by the observation. And we don't like that because it undercuts scientific realism - hence, Einstein's question.
andrewk September 08, 2018 at 07:22 #211158
With the problem as expressed in your quote, the widely-accepted solution is decoherence, which is mentioned later in that wiki article. There are other suggested solutions, which I am not familiar with, and which I haven't bothered to investigate, because decoherence provides such a satisfying answer to the question of why we observe only one of the outcomes that were regarded as possible before the measurement.

As the article explains, decoherence is not tied to a particular interpretation. It can be used in both Copenhagen and many-worlds, and maybe in others too (but not in Bohm, I suspect).

I read your discussion on PF, and I agree with the answers, although I would not have used the word 'gobbledegook' myself.

As to whether wave functions or probability fields are 'real' I prefer to leave those questions to ontologists. They have no meaning to me. For me, what is 'real' is subjective experience, and everything else is speculative theorising.
Martin Krumins September 08, 2018 at 08:00 #211161
Reply to S belief in a real world is dubious because our perception is based on our own created life values. science uses experiment to validate theories about the real world but they only validate it to other beings that share the same values. In that process the idea of the real world sneaks by without resolving the fact that we are basically making up the world to conform to our values. Scientific instruments are not real in the sense that there is no possible way to ascertain the real world from a being that cannot objectively ascertain the real world external to their values. Why do values pose such a problem? well look at how we behave economically and politically. Saying this I do believe that science is our best shot and also that our value created world is still a valid mirror of the external world and not some pure simulation, but it is not special,external or real. But the point I was trying to make was only made if there was naivety that our observations could change the external world. i raised my point because if you forget yourself and philosophically merge your perceptions to the objective world you are trying to accurately mirror, you forget that your creating what you percieve to conform to a value matrix; you believe the mirror of your perception is flawless (for that is one of our values in operation, self aggrandisement). Now one off shoot of believing this is that because the truth is, that your 'making it up', is that you can also effect the real world, you can make up the external world, you can manipulate it by knowing it. We can of course manipulate the external world through our knowledge of it, but not by observation alone, this would definitely be an error. but someone already pointed out that it was detection not observation that interfered with the experiment. That means to me that we are still respecting our perceptual boundaries. well the scientists are, the commentators, not so much.
Wayfarer September 08, 2018 at 08:36 #211162
Quoting andrewk
As to whether wave functions or probability fields are 'real' I prefer to leave those questions to ontologists


Well, this being a Philosophy Forum, we would rather hope to find some here, would we not?

Then again, if everything is ‘subjective experience’, maybe it doesn’t matter.
Martin Krumins September 08, 2018 at 08:43 #211163
Reply to Banno you mean I am not in touch with reality? My name is there, you can say it. So by way of minimal comment and abbreviation you suggest to the other members that you of course are in touch with reality. The internet gives young people a means to express themself and all they do is act like their institutions are all that should matter. Don't think I don't notice your tone is borrowed from the current political climate in the U.S. Look, Philosophy is about escaping from the pressure to always think and do what will be accepted. I know that my every expression is not defined clearly for others and do not think that any failure to express elevates what I say, but if you were a real thinker and not just a child determined to be accepted, you wouldnt mind a little confusion in an expression.and you certainly would not mind a point of view that does not conform correctly, be it by error or otherwise.
Wayfarer September 08, 2018 at 10:43 #211175
Quoting andrewk
I read your discussion on PF, and I agree with the answers, although I would not have used the word 'gobbledegook' myself.


Please see Post # 16, which says:

A simple way to see it is that it means that each particle is interfering with itself, not with other particles.


Which you yourself have already dismissed. So, interesting that you agree with an answer there, which you dismissed here.

I think I'm raising a serious and possibly novel argument in that thread, and I don't think the person there I was discussing it with understood it.
Wayfarer September 08, 2018 at 10:56 #211177
Quoting Martin Krumins
belief in a real world is dubious because our perception is based on our own created life values. science uses experiment to validate theories about the real world but they only validate it to other beings that share the same values. In that process the idea of the real world sneaks by without resolving the fact that we are basically making up the world to conform to our values


What is being called into question through QM is the independent reality of atoms as material particles. If you believe that the world ultimately comes down to atoms, then it's a challenge for that view, and for scientific realism, generally. That was the main bone of contention between Einstein on the one side, and Bohr and Heisenberg on the other. Einstein was very much a scientific realist, whereas Bohr and Heisenberg had much more philosophically nuanced views.

The whole subject is very controversial for a number of reasons. One the one hand, physics in general and quantum mechanics in particular are the Crown Jewels of science. But on the other they seem to throw common-sense and even scientific realism out the window. Actually not a lot of people know how to deal with that. But from a philosophical point of view, if you're not committed to scientific materialism or scientific realism, then it's not that big a deal.

You're raising some interesting points, but could I ask, have you done any readings or formal study on the topic? There are many interesting titles on the subject for the non-physics specialist. Some of them are crap, some of them are not, although in this field, it can be quite hard to differentiate them. But one thing is for sure, don't let anyone tell you it isn't mysterious. Richard Feynmann said 'I think it's safe to say that nobody understands quantum mechanics', and he understood it better than almost anyone. Likewise Neils Bohr said 'if quantum mechanics doesn't shock you, then you haven't understood it'.

(By the way your posts really would benefit from some more line-breaks. They're quite intelligible but posting them in large paragraphs make them hard to read.)
S September 08, 2018 at 14:38 #211211
Quoting andrewk
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.


Which is why I attempted to draw out his thinking about this link he has made with idealism through the seemingly trivial fact that the equipment in the experiment is man-made. But apparently someone here has already outlined the difficulty he was having and there's no need to worry.
S September 08, 2018 at 14:57 #211215
Quoting Martin Krumins
Belief in a real world is dubious...


Only madmen and philosophers say such things and expect to be taken seriously. The world is real, I can vouch for it. My life values won't alter the results of the double-slit experiment, nor would they shield me from getting hit by a bus if I were to suddenly walk right out in front of one driving at speed.
Dfpolis September 08, 2018 at 17:49 #211247
Quoting andrewk
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,


Yes. The paradoxes are the result of refusing to let go of Greek atomism and insisting, against all the evidence, that quanta are both particles and waves. The math, which works perfectly, represents quanta as waves.
andrewk September 08, 2018 at 21:17 #211273
Reply to Wayfarer Quoting Wayfarer
I think I'm raising a serious and possibly novel argument in that thread, and I don't think the person there I was discussing it with understood it.

You raised a question, which was whether the particle rate (BTW more accurately characterised as the field strength) determines the degree of undulation in the bars. The answer to that was No, and that answer is correct. In your later posts you tried to articulate a point about time and space but the point was not expressed clearly enough to understand. I too could not understand what point you were trying to raise. I thought the way people said the point was not understandable was regrettably curt.

I hadn't noticed DrClaude's comment about a particle 'interfering with itself', so I do not include that amongst the statements that I said I agree with. On a literal level the statement is not truth-apt. It just points towards a way one might think about something. I think that way is unhelpful, because it de-emphasises the probability field, which is the key to understanding.

Perhaps you could have another go here, at explaining what the argument was that you were trying to make in the PF thread.
Wayfarer September 08, 2018 at 21:34 #211277
Reply to andrewk The point I tried to articulate was about whether this means that time (being 'rate') is not a factor; which also that means that space (i.e. proximity of particles) is not a factor (as proximity is an aspect of space-time.) So, what is causing the interference pattern is not a function of space-time. (That was what was described as 'gobbledygook'.)

In the Stackexchange thread I put it like this: if the interference pattern is not rate-dependent, then it means that time is not a factor in the generation of the interference pattern i.e. if the same pattern can be generated in 1 second as in 24 hours, then 'time' is not a variable.

Part of the exchange was as follows:

It's the fact that it is not time-dependent which is of interest. I don't think you could replicate this outcome using a physical medium like water waves in a tank, because in that situation, 'time' would be a boundary condition. That is the sense in which 'waves' and 'interference' might actually be a metaphor for the effect; the effect is not the consequence of actual waves, but of the interaction of probabilities only. The interpretive challenge is then that it appears to demonstrate 'real possibilities' i.e. possibilities that have physical consequences. – Wayfarer Dec 5 '16 at 2:29

It is not time dependent because the boundary conditions, which in the end define the probabilities, are not time dependent is what I am saying. It is the particular use of wave equations. with operators on psi, that makes the difference between material waves or energy waves and probability waves. – anna v Dec 5 '16 at 4:49


So just as electrons are not really particles, the so-called interference patterns are not really ‘waves’ either. Actual waves are carried in a medium and are time-dependent. Here time is not a factor.
andrewk September 09, 2018 at 00:35 #211321
Reply to Wayfarer I don't have a clear idea of what you mean when you say time is not a factor. When the experiment begins, there is no pattern on the screen, and when it finishes, after some time has elapsed, there is a pattern. So the experiment cannot be done without time. I suppose that goes without saying for any experiment, or indeed any action at all because to 'do' something is to arrange things so that a property of the world that did not hold at time t1, holds at t2.

Similarly space must be a factor because the pattern on the screen can only be understood in terms of spatial measurements. The pattern is a mapping from the spatial coordinates of points on the screen (a pair of real numbers) to a real number that indicates brightness.

I think the problem is that the statement that something is or is not 'a factor' in an event is too vague. I get the sense that you have a strong idea of what you mean by it but unfortunately it is not coming across.
Wayfarer September 09, 2018 at 02:24 #211341
Quoting andrewk
I don't have a clear idea of what you mean when you say time is not a factor.


I'm referring to the amount of time taken, the duration of the exposure. So it's not 'vague'. One of the posters who responded to the thread on Physics Forum said it: '24 hours at 1 per second would give the same pattern as 1 second of 86400.'

Consider if you were actually doing the experiment with water and not with photons. Would you produce the same interference pattern regardless of the rate of flow? I would think obviously not. The interference in the case of water is literally a matter of collisions between molecules - actual interference. But here, there's an interference pattern when you're firing the photons one at a time! Hence the expression that 'the photon interferes with itself', which you already said is nonsense (and it seems so to me).

So no matter how long you take, you will get the same pattern (with the caveat that 'only up to the point where the rate is so high that the interaction between different electrons can no longer be neglected'.) Hence: not a matter of time. And as the pattern is not being caused by actual physical collisions, then it's also not a matter of physical proximity, i.e. space. So whatever is showing up, is not 'inside' time and space. That's the claim that was called 'gobbledygook' but I think the correct term is actually 'metaphysics' ;-)
andrewk September 09, 2018 at 02:46 #211342
Quoting Wayfarer
Consider if you were actually doing the experiment with water and not with photons. Would you produce the same interference pattern regardless of the rate of flow?

If by 'flow' you mean wave height then Yes, subject to irregularities caused by turbulence.

Water does not flow in a linear manner when the water has waves. Each particle executes a roughly circular motion. It is only the wave that flows, not the water. A better sense of this can be gained by considering the wave in a cracked whip. The whip cord doesn't flow from the handle to the tip. Only the wave does.

In the water analogy, the analog of the 'rate' of the electron gun is the height of the wave. The technical term across both cases is the amplitude of the wave. The wave amplitude affects only the brightness, not the shape, of the interference pattern. The shape depends only on the wave frequency and the distance between the sources.
Quoting Wayfarer
with the caveat that 'only up to the point where the rate is so high that the interaction between different electrons can no longer be neglected'.

I saw that caveat on the PF discussion, and I suspect it's wrong. But it doesn't affect the discussion here, so we needn't bother investigating whether it is.
Quoting Wayfarer
whatever is showing up, is not 'inside' time and space

I reiterate that I think to call this gobbledegook is uncharitable and, I think, bordering on rude. But I have to confess that I cannot imagine what it would mean for something to show up that is not inside time and space.
Wayfarer September 09, 2018 at 03:06 #211345
Quoting andrewk
But I have to confess that I cannot imagine what it would mean for something to show up that is not inside time and space.


And I suggest that is because it is a metaphysical issue, not a physics issue.

I don't if you glanced at the article I mentioned by Ruth Kastner, but it really does seem [s]to address this:[/s] related

Werner Heisenberg, the quantum pioneer famous for his uncertainty principle, considered his quantum math to describe potential outcomes of measurements of which one would become the actual result. The quantum concept of a “probability wave,” describing the likelihood of different possible outcomes of a measurement, was a quantitative version of Aristotle’s potential, Heisenberg wrote in his well-known 1958 book Physics and Philosophy. “It introduced something standing in the middle between the idea of an event and the actual event, a strange kind of physical reality just in the middle between possibility and reality.”


Martin Krumins September 09, 2018 at 13:06 #211380
Reply to S look i agree with you but im using the term real as if real is variable and relative to our evolution. I totally believe there is an external world for which sense is in relation, but i dont think its real as in the universal concrete version chosen by abstract thought, which i believe has no special place, like we can ascertain a reality that is totally accurate universally simply because we use a culture of mathematics and experiment. the thing is you don´t either, at present nobody does.

our senses are susceptible to illusion and ignorance, and so is our abstract world. but that is a good thing because the external world is always there, even though its changing, we can change with it and always keep our relation to it as close as possible.

usually when you give the argument people agree with you in essence but they still want to believe in the possible universal validity of their senses or abstract thought. they want this so bad because its a social value to be closest in the relationship to the external world, so the value real means that you are at that pinnacle of accuracy. but this drive to be accurate is always in danger of being mistaken to make the world we experience as the real one. or that science has achieved a universal perception that can clarify the senses and thought for eternity.

but what would happen if believing that we had finished the job has a negative effect on us for we have evolved to perceive a changing world and not a static one. so if science says we know whats going on maybe that degrades our relationship to the external world rather than enhancing it. that is the route and reason for my skepticism, not that i think we live in a dream.
Martin Krumins September 09, 2018 at 18:05 #211424
Reply to Wayfarer yeah thanks, I'll try to make it less spewy. Its really just laziness, i spend a lot of time crafting writing either for legal work or lyrical prose. Both of those disciplines are time consuming, so I get online and want to chug espresso and spew ideas.

Im approaching the topic by reading a book by Schrodinger called 'what is life' because apart from just observing the world in my way, i have only really read philosophy (mostly nietzsche) some biology and the rest novels and plays etc. so im hoping shrodengers book will be a window into modern physics for me. I like abstraction but just havent any time to develop my math.

If you can recommend other books that do not explain through math, that would be good. but i totally understand if you simply cannot understand modern physics without math.
Wayfarer September 09, 2018 at 20:59 #211458
Reply to Martin Krumins I had a great Listmania! list on Amazon but Amazon has nixed those lists and it’s disappeared. But titles for non-mathematicians are Quantum by Manjit Kumar (review here); Uncertainty by David Lindley (here); The Quantum Enigma, Bruce Rosenblum.

There’s an [in]famous book called Tao of Physics, by Fritjof Capra. This was published in the early 1970's and is still in print. I think it's well worth reading, even despite its critics (although also good to read the critics of course). That and a book called The Dancing Wu Li Masters by Gary Zukav initiated a minor social movement based on the popularisation of quantum mysticism. You would have to read them to really get the picture, but the basic idea is that the ‘consciousness causes collapse’ theory, which was at one time popular in QM, restores consciousness to the central role that scientific materialism has tried to banish it from. Of course this is wildly controversial and even political. But if you go to Amazon and enter Quantum Consciousness in the search bar you will find hundreds of titles on it and not all of them are rubbish. Oh, and How the Hippies Saved Physics by David Kaiser, which has this great photo of San Francisco's 'Fundamental Fysiks Group':

User image
Left to right: Jack Sarfatti, Saul-Paul Sirag, Nick Herbert; bottom corner: Fred Alan Wolf.

Also have a read of Quantum Mysticism: Gone but not Forgotten.

Bernard D'Espagnat What we call reality is a state of mind

Richard Conn Henry The Mental Universe.


Martin Krumins September 10, 2018 at 11:04 #211552
Reply to Dfpolis yes it gets very complicated as it pertains to a being in the world. Should we bother to differentiate reactions? I think we should so I see observation as not effecting will (maybe guiding and persuading it but not effecting it), which i percieve as work from more primordial/fundamental reactions.

I do not see sense reactions as structurally as important as digestive reactions, or digestive reactions as important as fertilization and the work that proceeds them. I think a natural hierarchy of reactions is important. therefore i think differentiation is important, so although indeed observation is reaction as is digestion or fertilisation, i do not think it honest to say that we have rearranged their hierarchy in any true sense to call observation action.