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Double Slit Explanation Overdue!

Regarding "why" questions:

The Feynman video I liked to above includes a bit where he talks about Mayan astronomy, about the fact that they could predict certain events, like eclipses, and used math to do this.

He then presents a hypothetical mayan "student" asking why it is that after so many days, mars will be at this place and not that, or whatever. The answer given could be related to the characteristics of some god or other, or perhaps it could simply be "that's how the calculations come out". Neither of these is really satisfactory though.

What would be a more meaningful answer is a deeper underlying mechanism. Ptolemaic astronomy offers such a mechanism (mars is moving around the earth in an orbit, with epicycles, in this particular way, and that's why we see it where we see it at any particular time, and why this particular mathematics can describe it's motion as seen from earth). That answer is wrong but I think it's an improvement over no answer at all: it offers a model that we can question, and from which we can attempt to deduce consequences that we might not otherwise have seen. That can lead to new predictions, and the possibility of falsification.

Of course it's true that such why questions only lead to new why questions. Once we've figured out that both Mars and the Earth itself are in elliptical orbits around the Sun, we can ask "why an ellipse?". But that's a good thing. Attempting to find an answer to the next layer of why questions can lead to new discoveries. In this case, enter Newton (I believe it was that very question that led, in part, to his theory of gravity, as an ellipse implies an inverse square law).
 
Alfie: take a look at Aephraim Steinberg's website. The blueish picture depicts one photon going through both slits interfering with itself. He's the leader of a team who used something called "weak measurement" to plot this. A guy called Jeff Lundeen led another team doing similar work. See physicsworld where they're number 1 and 2 in breakthroughs of 2011. The photon has a definite wave nature. It isn't actually a point particle. However it sometimes looks pointlike. For example you end up with dots on a screen. I don't think there's anything mystical to this, and am not keen on all the "surpasseth all human understanding" baggage that quantum mechanics attracts. Instead I'd hazard a guess that when you detect it, something like an optical fourier transform occurs, see this website:

"A great intuitive advance can be made in understanding the principles of the Fourier transform once you learn that a simple lens can perform a Fourier transform in real-time as follows. Place an image, for example a slide transparency, at the focal length of the lens, and illuminate that slide with coherent light, like a colimated laser beam. At the other focus of the lens place a frosted glass screen. Thats it! The lens will automatically perform a Fourier transform on the input image, and project it onto the frosted glass screen. For example if the input image is a sinusoidal grating, as shown below, the resultant Fourier image will have a bright spot at the center..."
 
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Farsight said:
Alfie: take a look at Aephraim Steinberg's website. The blueish picture depicts one photon going through both slits interfering with itself. He's the leader of a team who used something called "weak measurement" to plot this. A guy called Jeff Lundeen led another team doing similar work. See physicsworld where they're number 1 and 2 in breakthroughs of 2011. The photon has a definite wave nature. It isn't actually a point particle. However it sometimes looks pointlike. For example you end up with dots on a screen. I don't think there's anything mystical to this, and am not keen on all the "surpasseth all human understanding" baggage that quantum mechanics attracts. Instead I'd hazard a guess that when you detect it, something like an optical fourier transform occurs, see this website:
Click to expand...

It is a very cool experiment. An excellent explanation of what is going on in it can be found here:

Watching Photons Interfere: “Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer”
 
A Possible Non-Quantum Explanation

Hello,

To the original poster: I just submitted a paper to Nature Physics with a classical explanation for the single-particle double-slit experiment, which may be of interest to you. The idea is that the interference is constant (always present), but is somehow being negated or ignored when only one slit is used. This puts the onus, not on explaining the interference, but explaining how it is being suppressed, which is much easier to do. Below is the abstract; I can provide the complete manuscript by request (five page PDF).

Abstract: This paper attempts to outline a solution to the famous double slit experiment that allows the particles used in the experiment to remain particles from start to finish, but still produce the observed interference pattern. The solution only asks that we be allowed to change the particle’s initial shape before we use it in the experiment. We will show that this can allow the particle to ignore interference when only one slit is present, but still experience interference when two slits are present, which matches observation. No quantum mechanics or relativity are involved, only electrical charge; in fact, the proposed solution could easily be seen as classical.

Thank you,
Chris Martian
 
ChrisMartian said:
Hello, ...
Click to expand...
Hello ChrisMartian.
The problem is that your paper does not look like it addresses the single-particle double-slit experiment.
  • The single-particle double-slit experiment shows interference with photons which are not electrically charged.
  • We are not free to change the shape of a photon or an electron or C60 molecule or other particle before using them in the experiment.
  • In a single-particle double-slit experiment using charged particles like electrons, they do not interact with the silt other than being blocked. That produces beams, not interference patterns. As far as I can see, a beam of specially shaped charged particles treated classically would be unlikely to produce an interference pattern. They should be spinning at random and will classically produce broader beams than spherical particles. The beams might get wide enough to overlap but that is not an interference pattern.
 
Thank you for posting, ChrisMartian.

Even if your paper does not stand up to scrutiny here, I always find some value in the challenge-response cycle. There's so much to learn!
 
Thanks for the response, Reality Check. I apologize that it isn't clearer from the abstract, but the paper itself defines a new theory, then uses it to construct one possible explanation that doesn't introduce any more assumptions than the currently accepted explanation(s). It isn't designed to be the de facto answer, it's a thought experiment designed to show that we may not have to go to the extremes of completely warping a particle from a solid to a wave and back again. We may be able to get the same effect by assuming the observed interference pattern is what's normal for particles, and the absence of interference when we have only one slit is the mystery. Electrical, magnetic, gravitational, nuclear...the specific mechanism isn't the target, it's the idea that it may be more logical to come at this from the opposite side and see what, if any, weirdness shakes out. If it isn't as much of a stretch, then this type of solution may be preferable for some.

I don't know if it will be published, but it is still under consideration and has been for a full 3 business days, which I think is pretty good for a paper making such bold claims (delivered by an amateur at the kitchen table, with half the pages consisting of hand-drawn visual aides :) That might just mean they're taking their time to reject it, but still.

Kidding aside, thanks for your responses, and if there is interest, please let me know if it is within forum policy and I will post the paper itself. My comical attempt at drawing charge field lines makes it worth the read.

Chris Martian
 
ChrisMartian said:
Thanks for the response, Reality Check. I apologize that it isn't clearer from the abstract, but the paper itself defines a new theory, then uses it to construct one possible explanation that doesn't introduce any more assumptions than the currently accepted explanation(s).
Click to expand...
It looks like we will have to wait until you can post that paper because your description makes the paper seem even more invalid to me.

There is no "completely warping a particle from a solid to a wave and back again" that I can see in the QM explanation for the single particle double slit experiment.

Assuming the observed interference pattern is what's normal for particles is a wrong assumption because we observe that classical particles do not do this. Think about throwing balls or cubes or other shapes at a brick wall with two slits. Classically there is no difference at smaller scales.

Guessing at an unspecified mechanism ("the specific mechanism isn't the target") is not good science.

You are addressing the single particle double slit experiment. That means that every particle travels through one of the slits with no knowledge of the previous particles. An interference pattern either needs waves interfering or a probability of being detected (the Copenhagen interpretation of QM or one of the other interpretations of QM - multi-world, etc.) or maybe a specific time varying interaction with the slits that creates an interference pattern.
 
ChrisMartian said:
I don't know if it will be published, but it is still under consideration and has been for a full 3 business days, which I think is pretty good for a paper making such bold claims (delivered by an amateur at the kitchen table, with half the pages consisting of hand-drawn visual aides :) That might just mean they're taking their time to reject it, but still.
Click to expand...

You underestimate how long reviews can take. It may be several days before reviewers are assigned, another few days before the reviewers agree to review it, and a few more weeks before all the reviews make it back to the editor.

I have a question about your theory, though: can your theory calculate the angles for the diffraction maxima and minima?
 
AlfieGee said:
I think this is probably the most appropriate comment to my original post. I am indeed interested in the "why" behind all the maths. It doesnt seem any of the maths is really getting anywhere as to the "why" is it ?

So... Ive got Tom Campbells My Big Toe "why" regarding the double slit. What are my other options here? Are there any that are considered plausible?
Click to expand...

I consider the stochastic electrodynamics explanation a satisfactory explanation of 'why'. Of course, the word 'why' is a bit ambiguous. However, I like semiclassical explanations of 'why'. SED is a good explanation if you can accept classical relativity.

The SED explanation is that electrons are controlled by a background of electromagnetic radiation that permeates the universe. This 'zero point background' has a Lorentz invariant spectrum, and so is at equilibrium. The Lorentz invariant electromagnetic radiation is classical, in that the amplitude isn't quantized. The electrons are discrete particles but still classical in the sense they are affected by the Lorentz invariant radiation.

The pattern of motion for the electron (classical particle) is controlled by the Lorentz invariant radiation (classical wave), producing a statistical behavior with properties of both particle and wave. This provides as good an 'explanation' of wave particle duality as we are likely to find.

The two slits create an interference in the zero point background radiation. The interferance pattern observed after statistical averaging is really an interferan

I have studied the the Stochastic Electrodynamics (SED) theory of quantum mechanics (QM). I find it aesthetically pleasing. SED ‘explains’ many quantum phenomena including the double slit experiment. Here are a few links to get you started.


https://en.wikipedia.org/wiki/Stochastic_electrodynamics
‘Stochastic electrodynamics (SED) is a variant of classical electrodynamics (CED) of theoretical physics. SED consists of a set of controversial theories that posit the existence of a classical Lorentz invariant radiation field having statistical properties similar to that of the electromagnetic zero-point field (ZPF) of quantum electrodynamics (QED).


http://www.bu.edu/simulation/publications/dcole/PDF/SwedenCole2005.pdf
‘In the presence of a ìslitî, the ZP pattern will likewise be modiÖed. As particles pass through a set of slits, the rapidly áuctuating Öelds will have an average impact on the particle motion that should result in the di§raction and interference patterns seen in nature.’

http://cds.cern.ch/record/500707/files/0105054.pdf
‘Such indefinite status SED had for rather long time. On the one hand, its methods have found applications in new areas of researches such as gravitation theory [47], inertial mass theory [48-50] or in an explanation of a nature of the de Broglie wave [51-53]. On the other hand, it seemed impossible to find a connection between Maxwell’s distribution for particles and Planck’s distribution for a field. However, as it seems to the author of the present paper, after the historic-critical investigation above, there is an obvious opportunity of one more attempt to get rid of the internal contradictions in SED now.’


downloads.hindawi.com/journals/jcmp/2013/308538.pdf
‘Stochastic electrodynamics (SED) predicts a Gaussian probability distribution for a classical harmonic .... motion, it is argued that the introduction of electron spin ... in Section 2 Boyer's results on the SED harmonic oscillator.’

SED is only an approximation of the canonical QM. Experiment shows that real quantum mechanics is more accurate for multiphoton interactions. However, the two theories are equivalent for most of the phenomena that chemists and physicists use.
 
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