The Double Slit Defraction Experiment

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

  1. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    OK, PhysMachine, I will get personal here, You are at Georgia Tech. You are over generalizing. I am not going to throw out everything that has been thought for the past 3000 years. After all, who was it that first proposed the atom? Was it Plato? What I am saying is that if the double slit defraction experiment was done with a source of light that was truly designed to produce single photons, it would not yeild a defraction pattern. To do that experiment would result in having to reform current thinking in particle physics. But science only advances by constant reform and refinement. Right? Right. You are at Georgia Tech. You have at your finger tips whether you realize it or not the facility to do the very experiment I am talking about. Would you like to talk about this further?
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Helloween Registered Senior Member

    Messages:
    40
    I'm not sure that you would'nt get a diffraction pattern if you sent one photon through at a time. I think I remember an experiment where someone tried that with electrons and still saw a diffraction pattern. I'll try to find it later though, I've got Exams to work on

    Please Register or Log in to view the hidden image!

     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    I have checked every source pointed out to me in both photons and electrons. Every work uses a beam of photons or a beam of electrons. (see www.advancedphysics.org under optics for more) Beams produce single packages of photons or electrons and send the single packages through the slits. We need a true source of single photons we know is producing single photons by design.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. geistkiesel Valued Senior Member

    Messages:
    2,471
    You do not want to be too hasty with concluding that multiple photons are necessary for interference effects. A little knw quantum theory "postulate" dictates that quantum models void in nonlocal forces are incomplete. The quantum mechanical industry is stilll trying to have their theory and avoid the nasty subject of nonlocality, its "too spooky".
     
  8. beta Registered Senior Member

    Messages:
    129
    I am interested to see what your understanding of a single photon is.
    Do you regard it as having a time dependant frequency.Do you consider it to be a particle, wave, both neither.
    Perhaps there is some misunderstanding (not necessarily yours)
     
  9. PhysMachine MALLEUS SCIENTIARUM Registered Senior Member

    Messages:
    208
    First of all I do theory research right now, so I don't have access to a lab. Second of all, I don't think I could convince somebody to build one of these things to emit one photon at a time to test the diffraction pattern since they are predominately busy with their own research.
     
  10. geistkiesel Valued Senior Member

    Messages:
    2,471
    If you are responding to geistkiesel, the answer is yes.
    See a graphics rich, math poor Stern-Gerlach assessment

    Caveat emptor, the web site is hereical.
     
  11. Nasor Valued Senior Member

    Messages:
    6,230
    Please explain in detail how the behavior of electrons around atomic nuclei demonstrates their ability to form 'coherent packets'. This ought to be pretty hilarious.
     
  12. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    May I remind you they laughed at Mickey Mouse too. And, look at all that he achieved, and with only three fingers on each hand. If you want something funny, may I recomend mafia.com, you car driver you.
     
  13. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    I do not see the photon as a particle but strictly as a wave phenominon produced by the energetic acceleration and deceleration of an electron. I see a single photon as being a "lineal wave". (But, a single photon is a rare thing in the universe. They have an extraordinary tendency to be coherent. Most photon emission is by stimulated emission. Think of the surface of the ocean, the waves are caused by gusts of wind randomly hitting the surface of the water, but through coherency these gusts are turned into rollers.) A lineal wave is a wave that is three dimensional but symmetric about a linear axis and that axis is on the direction of propagation, the direction of movement. The photon, like the electron, is a manifestation of the electromagnetic field (let us ignore gravity, which does play a role but is almost trivial, it is so small here). The electromagnetic field is a vector field. At each point in the field there is an associated vector of magnitude and direction. Imagine the axis of the photon. The value of the vector at each point on the axis is increased and decreased like the values of a sine wave. And, each of these points also has a direction, perpendicular to the axis. This gives the photon polarity. Electrons too have polarity and this enables the manefestation of magnetism when enough electrons are oriented in the same direction. (Current thought calls this spin.) Off of the axis the value of the vector decreases with distance from the axis. (May we have a black board here? And some chalk, too?) Most view the electron as a dimensionless particle with an associated field. I see the electron as a field with a center point and the field of the electron extending to infinity at 1/r^2. So too does the photon extend to infinity. I see the electromagnetic field as very much being an ocean of interaction, and in that there is so much matter in the universe, it is very, very deep. At any point in the universe the value and direction of the electromagnetic vector is the sum of the effect of all the matter in the universe at a rate of 1/r^2 from the point. (That is: 0ne over r squared.) I hope that last line made sence to you. The universe is an extraordinary mathematical occurence, with it all interrelating at the speed of information, c. So, the photon is a lineal wave, propagated by the movement of an electron.

    Yes, photons have a frequency, like a sine wave does. And, that frequency can be Dopler shifted by frame of reference. They are time dependent only in that they have a speed.
     
  14. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    I am sorry, Nasor. You are a brilliant light in the universe and have achieved the perfection pursued by Buddha, Jesus, and Muhammad. My apologies.
     
  15. beta Registered Senior Member

    Messages:
    129
    OK, the relevant part of your response is that you regard a single photon as being a wave.
    It has an amplitude that is seen to vary with time and it has a spacetime dimension. It results from the electron transition from an excited to stationary quantum state, that effectively results in a dipole moment of charge distribution about the nucleus.
    If you have accepted that a single photon can be a wave, then I don't understand why you cannot accept that a single photon can interfere with itself in the double slit experiment. (or are you suggesting that single photons don't actually exist).
     
  16. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    The electromagnetic field is a vector field. The photon is a wave phenominon of the vector in the field. The electron is a type of standing wave in the field and when it is moved a ripple in the vector values occurs. This ripple is a photon. It is a wave of the electromagnetic vector occuring in a lineal path. Its wavelength varies. Its amplitude does not. If two photons of the same wavelength are coherent the resulting double photon has a total vectorial value double that of a single photon. That is to say its amplitude is doubled over that of a single photon.

    No, there is no dipole moment, not if the atom is nobel and in a stable state. Whether or not there is a dipole moment in the excited state is not relevant here. (Some molecules do have dipole moments but it has nothing to do with electron excitation.)

    I do not accept that a photon is a "wave", as most currently define it. I accept that the photon is a lineal wave. A single photon which is a lineal wave cannot pass through two holes simutaineously. The lineal wave must follow one linear path of movement. In the double slit experiment a package of photons is broken into smaller packages and some of these smaller packages then pass through the double slits and form an interference pattern on the screen. Filters used to break down a beam of photons do not produce single photons as is commonly assumed, but single packages of photons.

    As you sit before the screen of your web transceiver, there are radio waves passing through your corporal self. These radio waves sum at any point in space. They are not separate phenomenon. Any photon passing by you is summed along with all the other intersecting photons including the longer radio wave ones. You are sitting in a "bubbling broth" of electromagnetism. Because out in space there is no place free of photons of many wavelengths, the occurrence of a single photon is very, very rare. To create a single photon we would have to create a special space in the lab for it. But, we should be able to create one. In a lab experiment it would be sufficient to produce a photon distict from any photon of near wavelength. It really does not matter if there are radio waves present. But a radio wave could trigger an electron in an excited metastable state to produce a photon and that might enter into the experiment. So single photons can exist, but because there is so much "interference", they are very rare.

    (How do you get the italic out of your quotes? They look so much better without it.)
     
    Last edited: May 21, 2004
  17. beta Registered Senior Member

    Messages:
    129
    Sorry, I don't share your views on photons. I had an excellent reference site for you to read, but they've disappeared

    Please Register or Log in to view the hidden image!


    I suggest some reference should be made to reputable information regarding the quantum analysis of evolution of a photon.

    Just copy text from the relevant post, then paste into the 'wrap-quote-tags' option. Actually, I don't know how to select italics for a quote ?
     
  18. PhysMachine MALLEUS SCIENTIARUM Registered Senior Member

    Messages:
    208
    So a "lineal wave" is what is usually called a "plane wave" in my experience? If so, what you are quoting is the classical free space solution of Maxwell's equations. The problem with that solution is that it treats classical light as being continuous, when we can observe that it is discrete. So we treat it like we treat quantum particles; with wave-like and particle-like properties. Photons aren't "waves" in the sense that they are oscillations in a medium since they can propagate through the vacuum, but they aren't "particles" in the sense that they interfere with each other like waves. I really don't see how you can argue that a photon, being a plane wave, cannot interfere with itself in a double-slit diffraction experiment, since you argue that photons are plane waves and plane waves to interfere with each other in that type of experiment.
     
  19. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    Alright, Nasor, I am sorry again, I have not answered your question. It is intuatively obvious to me but perhaps I should expain a bit about electrons so that it is more obvious to you. The electron is better thought of as a standing wave in the electromagnetic spectrum. Like any friction free wave when it is confined it will resonate. As any resonant structure has harmonics of greater frequencies, so too does the electron. When the electron resonates about the nucleus of an atom, it has the capability to resonate in a harmonic. It is moving from one harmonic to another that we think of as changing orbitals. And as it moves from a lower harmonic to a higher, it absorbs energy which may come via varying pathways. When it moves from a higher harmonic to a lower, it may release a photon at a specific wavelength. It is from this movement that we record emission spectra. As the nucleus becomes larger and the number of electrons orbiting in the atom becomes larger, the possible number of harmonics becomes larger, and the resulting emission spectrum becomes more complex. Is that clear so far?
     
  20. geistkiesel Valued Senior Member

    Messages:
    2,471

    I have a problem with the situation you describe. That the source of light is producing packages of photons follows your logic that something must be going through two holes. Maybe so, but absent in your discussion is the mention of nonlocal forces, or any reference to quantum transition physics. I may err here, but I see a situation described in100% classical terms, which to me implies the reader, myself included, must not only fill in their own blanks, the must create the blanks in the first instance.

    Some have characterized light as coming in two flavors (Feynman "Lectures on Physics") having to do wih polarization inferences. Half the light gas is shared by E fields oscillation 90 degrees in rotation. This is somewhat unsatisfactory by its implcation that each photon is keeping track of all those surounding it to maintain its proper identity. This plus the unbelievability in mother nature producng photons exatctly alike with the exception of the E field direction scheme.

    A possible solution to all the objections is the recognition that the polarization experiments imposing the 'dual nature of light', is infact a demonstration of the +/- oscillations of single photons at some natural frequency, probably the measured frequency. When a photon enters a polarizing medium the current state of the oscillations defaults as a measured state. As we are discussing directions of fields and as the polarizing medium is spatially oriented (like Stern-Gerlach arrangements oriented by the direction of the field/gradient direction of the segment) 1/2 half he photons will point outside the angle of their window and become absorbed by the filter, allowing all ohers, now localized to angles determined by the polarizing channels inside the polairizer mass.

    In two hole diffraction transitions the "wave-particle duality of electrons" is manufactured to hide an ignorance of what is physically occuring. The electron also with two "spin states" is oscillating such until reaching the plane containing the holes at which time what ever state is "observed" this is the polarized state, with the unobserved state assuming the new task of nonlocal force center.
     
  21. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    Continuing: In a space containing only two electrons the two will repel each other. In an atom this does not occure. The presence of protons in the nucleus neutralizes the repulsive forces of the electrons. (The stucture of the proton is more than I want to go into here so let us leave it at that.) This reduces the electrons wave nature to something more like that of the photon. And as such they may be coherent and form the "cloud" of electrons that orbits the nucleus. In an electron gun producing a beam of electrons, the cathode is pumped with excess electrons by applying a strong voltage to the cathode. At the anode, electrons are pulled from the anode to produce a net atomic positive charge. At a great enough voltage the electrons leave the cathode and are propelled in a stream toward the anode. Ordinarily the electrons would repulse each other and fly in all directions away from their collective charge center. But in an electon beam they do not do this. Why? As in a nucleus the charge on the electrons is nutralized by the nuclearly positive force they are experencing from the anode. (Why did they name "positive and negative" oppositely in atomic physics verses electronics? As I recall it had something to do with Ben Franklin?) In effect the situation created by us in an electron gun is exactly the same as in the atom. The positive force of the nucleus nutralizes the electron's negative force and allows coherency of the electrons like that found in photons. In the electron gun, the positive force on the anode nutralizes the negative force on the electrons, again allowing the electrons to form a coherent beam. The electrons in an electron beam are coherent with each other in the same way electrons orbiting in an atom are coherent with each other. And, this coherency is of the same nature as that found in photons.
     
  22. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    [/FONT]
    I made a spelling error in my original post not to mention misspelling diffraction! Please reread the original post now that I have corrected it and it may make more sence to you.
     
  23. Erring Flatley Erring Flatley Registered Senior Member

    Messages:
    95
    No, no, no. A lineal wave and a plane wave are not the same thing. A plane wave is a spherical front of wave moving through space. A lineal wave is a wave that is moving on a line through space. Because the electromagnetic field is a vector field it can support a wave moving on a lineal trajectory. Imagine a wave pulse moving down a line something like a pulse of electricity moving down a wire. The lineal wave is three dimensional though. At each point of the wave on the line there is a vector value of the electromagnetic field. Going transversely from the line the value of this vector decreases. So that the wave is spherical in structure moving down a line of trajectory. Imagine you are at a circus. The human canonball is about to be shot from the canon. At the last minute he panics and jumps from the canon. But! The fusilier ignites the canon just as the human canonball jumps to safety. Bang. In a moment the flags and banners above the band at the far end of the tent flutter. A puff of air traveled across the tent to ruffle the flags. The lineal wave is like the puff of air that crossed through the tent. It is a spherically symetric vector wave and it moves through space on a lineal trajectory.
     

Share This Page