# The Double Slit Defraction Experiment

Discussion in 'Physics & Math' started by Erring Flatley, Apr 18, 2004.

1. ### PhysMachineMALLEUS SCIENTIARUMRegistered Senior Member

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Well, if you want to modify the uncertainty principle then you have to completely change the theory, since it is absolutely required for consistency with the theory of quantum mechanics. It comes from the noncommutativity of various operators, and if you get rid of the uncertainty principle the entirety of quantum mechanics as it stands would collapse. The whole theory is pretty much built so that uncertainty is a requirement of the formulation, and if there was ever an experiment that flat disproved this uncertainty then the whole theory would need reformulating.

3. ### OmnignostRegistered Senior Member

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I am still struggeling with the white light question. What is is you don't understand of the previous explanations on why thermal noice gives a continous signal? You are correct when you say that a phase difference of 180 degrees gives a cancellation and zeroo signal. It is just that it doesn't occur very often. You make some very confident statements that are simply wrong. Take a moment trying to figure out what I am trying to say, ideally do some simulations. Have you got Matlab? Then I could send you some code to show you how it works. There is no way you can make progress in your theories until you figure this out.

5. ### Erring FlatleyErring FlatleyRegistered Senior Member

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When an atom has an electron thermally excited, the electron goes into what is called a metastable state. The time in a metatable state varies with the molecule. Fluorescent molecules have a very long metatable state. When a photon passes through the field of an excited electron, the electron releases its photon with the passing photon in a coherent manner. This is called stimulated emission. The resulting photons are coherent, that is to say they are in a single package. Both photons occupy the same x,y,z space, but the value of the electromagnetic vector is doubled. It is the priciple upon which the laser is built. This action of stimulated emission of metastable electrons is happening on the sun as much as it is happening in a laser. But on the sun and in other sources of mixed wavelength light, the resulting waveform is not a pure sine wave. It is entirely possible for a mix of wavelengths to be coherent. The square wave is an example. (It is composed of a fundamental with its odd harmonics.) It is wrong to assume that photons are not coherent simply because they are not of the same wavelength. White light is as coherent as it can be for a mix of wavelengths. Please remember, Young did the original double slit experiment using sunlight. Both sunlight and a laser produce a diffraction pattern, showing they are fundamentally the same.

Last edited: May 11, 2004

7. ### Erring FlatleyErring FlatleyRegistered Senior Member

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I am not trying to modify the uncertainty principle. If the Double Slit experiment with a single photon source does not yeild a diffraction pattern, the facts will modify it. It is the nature of truth to be continually refined. I do not see quantum mechanics collapsing. The energy levels and transition of electrons in orbitals is a very real phenomenon.

8. ### PhysMachineMALLEUS SCIENTIARUMRegistered Senior Member

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Yes, the transition of orbitals and such are real phenomenon, but they come from the same basic postulates as the uncertainty principle. You seem to be missing that if the uncertainty principle is wrong, then so too is all of quantum mechanics, since it is so fundamentally tied with the first postulates.

9. ### 1100fBannedRegistered Senior Member

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You should learn a little bit of logic:
A implies B is equivalent to (not B) implies (not A).
The Postulates of QM implie the HUP. If the HUP is wrong then QM is wrong. You cannot have QM without the uncertainity principle.
The HUP is not a postulate of QM. It is a result of QM.

Last edited: May 12, 2004

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11. ### NasorValued Senior Member

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This entire thread is ridiculous. It’s trivially easy to check whether your photon source is emitting single photons or groups of photons. The easiest way would be to use a monochrometer and a powerful photomultiplier tube. Check any introductory textbook on instrumental analysis for plenty of information on photon-counting techniques.

Additionally, the double slit experiment can be done with any particle, not just photons. You can use electrons, atoms, anything that has a reasonably long wavelength. Again, see any introductory textbook on modern physics. You can find actual pictures of single-electron interference patterns here: http://physicsweb.org/box/world/15/9/1/bologna-image

12. ### 2inquisitiveThe Devil is in the detailsRegistered Senior Member

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I thought current research indicated that a single photon can be split to form an
entangled pair of photons. Does this happen every time a photon is split or only
when a photon is split by a specific method, such as a crystal? In either case,
the entangled pair verifies that a photon can be split.

13. ### James RJust this guy, you know?Staff Member

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No. Pairs of entangled photons can be created by various methods, but none of them involve physically "splitting" a single photon into two.

14. ### HelloweenRegistered Senior Member

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The reason the two-slit expirement exhibits interference, is that light cannot be viewed as particles. Light is fundamentally a wave with some particle like properties.

15. ### PhysMachineMALLEUS SCIENTIARUMRegistered Senior Member

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Or a particle with wave-like properties. Calling something a particle of wave properties or vice versa is an inadequate statement, and honestly there needs to be invented a new word to describe such a thing.

16. ### HelloweenRegistered Senior Member

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yeah, but either way, you cannot view light as being a stream of photons. that view is itself the primary flaw in the question addressed.

17. ### 2inquisitiveThe Devil is in the detailsRegistered Senior Member

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3,181
I found the article I remembered reading, James. It was from the Los Alamos National
Lab in the U.S. I don't know the exact scientific terminology for how the entangled
pair were produced, but a single photon is sent through crystals to produce two
daughter entangled photons, hince I assumed they were split. A cut:

"In the Los Alamos implementation of Ekert’s cryptography protocol,
researchers used a pair of special optical crystals placed in a beam of
ultraviolet light from a laser. Occasionally an ultraviolet photon from the
laser is converted into two infrared photons. These daughter photons
share the almost magical correlations of entanglement."
http://www.lanl.gov/worldview/news/dateline/Dateline1100.pdf

18. ### Erring FlatleyErring FlatleyRegistered Senior Member

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Quantum mechanics is a probabilistic mathematical description of electrons and photons. Its probabilistic nature is related to and based upon the uncertainty principle. If the uncertainty principle were removed the wave mechanical nature of quantum mechanics would go on, but it would be reformulated, and reformulated more precisely, more deterministicly. The simple wave equation is a mathematical reality without even looking at physics. (And, it is a starting point for the unified field equation (which no one is even looking at right now).) Newtonian mechanics is highly successful, but that does not make Einsteinian mechanics wrong. Quantum mechanics is highly successful, but that will not make a more accurate new quantum mechanics wrong. It is not my objective here to argue the correctness of the uncertainty principle. I am saying the double slit experiment needs to be done with a source of light genuinly designed to produced single photons.

19. ### Erring FlatleyErring FlatleyRegistered Senior Member

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This experiment is done with a laser which by design produces coherent photons in packages. This experiment is not done with a source of light designed to produce single photons. I repeat: I am saying the double slit experiment needs to be done with a source of light specifically designed to produce single photons. Such a photon source would not yeild a defraction pattern.

Last edited: May 15, 2004
20. ### Erring FlatleyErring FlatleyRegistered Senior Member

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This experiment was done with a beam of electrons, not with a source of single electrons. Electrons are as capable of being coherent as photons are. That electrons can form coherent packages should be obvious from their ability to form electron clouds in atoms. The double slit experiment needs to be done with a source of photons or electrons that is designed to produce single electrons or photons. To cut down a coherent source of such with filters only produces single packages of such. Using filters to decrease a coherent beam does not produce single photons or electrons. A package of photons occupies the same x,y,z space as a single photon. And the package can pass through the filter on the same path as if it were only one photon. Filters produce single packages of photons, not single photons.

21. ### geistkieselValued Senior Member

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2,471
In the spirit of pushing aside some fluff, let me describe a rational alternative to any "physical description" of the trajectory of an electron immediately before entering one or two holes in the diffraction experiment, which is otherwise desribed quantum mechanically. I claim the result here id drastically variant from a QM pont of view. Feynman used the phrase in Vol III "Lectures on {hysics" that of the QM model was not true then we would ahve to assume the electron picked the hole it would ultimately travel through before i arrives at he hole.

The electron be shrouded in a negative charged field is repulsed by the reflection of its own negative charge fileld as the electron approaches the surface containing the diffraction holes. Assuming as even distribution of forces over the exposed surface of the reflected negative field force, except the lowered force potential well marking the path from hole to approaching electron. The elecron will, fro momentun considerations direct itself into one of the possible holes used for the experiment. Here we do not have to split the charge field of the electron as it transform into a "wave" during transit. Mor must the electron "split as" abstracted by, not quantum theory, rather by quatum contrivance (excuse the venting_.

We know th weelectron is a two state particle which is assumed to mean the partile is in one or the other of the states before entering the diffraction conditions. This would simply mean the electron, prior to oarization in a satte of rapidly varying spibn states and only upon poalrization, when entering the hole, is the poalrized state determined such th ethe observed state is invariant to t further variation until acted upon by sufficient force. Like the spin-1 Stern-Gerlach transition expeiments described by Feynman the nonlocal state, nonlocal by polarization "default", takes the "other hole" and performs the function it does while transitioning from a parallel direction alongside the electron. For one hole diffraction the nonlocal element i is dragged into a trailing position behing the electron, hence the different observed patterns on the scintillating screen.

This appears heretical, and I suppose it is, but it is a rational alternative, orders of magnitude less obtuse and contrived than the current standard model.

22. ### Erring FlatleyErring FlatleyRegistered Senior Member

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I disagree. The electron is not repulsed by the wall. If the wall is a metal the electron is very likely to enter the wall and give the wall a charge. And I do not accept that the electron is a two state particle as I have described above. I view the defraction pattern as being the result of a source of photons or electrons that contains coherent particles in packages and it is the packages that go through the device and break apart and recombine on the screen to form the pattern.

23. ### PhysMachineMALLEUS SCIENTIARUMRegistered Senior Member

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So basically you're talking about an entirely new theory of matter to explain the diffraction patterns?