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feynman video and photons

Discussion in 'Electronic Design' started by Jamie Morken, Apr 18, 2006.

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  1. Jamie Morken

    Jamie Morken Guest

    I was watching a video of Richard Feynman:

    "http://video.google.com/videoplay?docid=6586235597476141009"

    and he told of how his dad had asked him to explain where the photon
    comes from when an electron in an atom drops its orbital energy state
    down, and Feynman said that he couldn't really explain where the photon
    comes from that made sense in a way of thinking of the photon as a
    particle. This seems really basic to me as I don't think of photons as
    particles, and so when the moving charge (electron) changes it orbital
    state, this is a movement of charge which will create an electromagnetic
    field, and because the amount of charge movement is quantized by the
    allowable states of the electron orbits around an atom, it will emit a
    characteristic amount of electromagnetic energy. Labeling an amount or
    frequency of electromagnetic energy to be a photon particle makes no
    sense to me. I think a photon is really only a definition of magnitude,
    not an actual particle.

    cheers,
    Jamie
     
  2. Guest

    Do you feel the same way about electrons?
     
  3. Jamie Morken wrote:
    I think a photon is really only a definition of magnitude,

    Problem with that-- put a candle one foot from a square meter sized
    photocell. The photocell has a bazillion little particles of some
    photosensitive metal, say calcium, in ultra-fine powdered form. Each
    calcium particle is isolated form all the rest.

    Let's say you get 10^18 electrons per second out of the photocell.

    Now put a x10 filter between the two. So far so good, you now count
    10^17 electrons per second. But then harbor-freight-physics has a
    sale, and you buy 16 more x10 filters. You put them between the candle
    and the photocell.

    Now you're getting around one electron per second out of the photocell.

    For a Nobel prize, please explain how an electromagnetic wave, spread
    out evenly over a square meter, can cause one electron to jump out.

    For a second prize, explain why the electron sometimes jumps out after
    1/10th of a second, when the electromagnetic wave hasnt delivered a
    full second's worth of energy,
     

  4. out of a photocell... you lost me


    martin
     
  5. ooops, was think of photons , coming out of the photocell



    martin
     
  6. Bill Beaty

    Bill Beaty Guest

    You're wrong; those aren't Nobel-grade discoveries... and apparently
    both
    were made decades ago and are long known by physicists. The
    photoelectric
    effect is not proof of photons. Heh. Everything we know, is wrong.
    See:

    Lamb W E and Scully M O 1969
    The photoelectric effect without photons
    Polarization, Matiere et Rayonnement edn
    Soci´et´e Fran¸caise de Physique
    (Paris: Presses Universitaires de France)

    That "Lamb" is WIllis Lamb, who got the Physics Nobel in 1955

    Some physicists even complain about the misconceptions spread by
    undergrad
    texts, such as the misconception that "Einstein's photoelectric effect
    proves
    the existence of photons." In fact the photoelectric effect can be
    explained by
    Classical EM fields if we allow vacuum fluctuations to exist. Photons
    may
    exist, but it takes a much more subtle experiment to prove this. A
    good article
    on this topic is by the author of the textbook "Quantum Optics" and is
    found
    in the collection below:

    The concept of the photon-revisited
    A. Muthukrishnan, M. Scully, M. Zubairy

    Found in "The Nature of Light: What Is a Photon?"
    Oct 2003 Optical Soc. of Am, Optics/Photonics News
    http://www.osa-opn.org/abstract.cfm?URI=OPN-14-10-49

    Other papers in the above collection are excellent. The discuss the
    real
    evidence for photons, and get us questioning the old incorrect textbook
    stuff
    were taught never to question ...and force us to (gasp) Actually
    Think!

    Lest you assume that Lamb's paper was the last on this topic, please be
    aware that physicsts are STILL arguing over whether EM fields are
    quantized
    (whether photons actually exist,) and are still looking for experiments
    which
    supply an unequivocal answer. Zubairy mentions that these issues are
    discussed in Quantum Optics, but I've never tracked that one down. The
    whole OPA/OSN collection above has lots on this. And a quick google
    search turns up a recent paper from 2001:

    Proposed experiment to test photon anticorrelation with quantitatively
    controllable source emission rate
    http://ej.iop.org/links/q50/5U25DXuTmMzsTPFxBvezCg/ob1411.pdf
    Abstract
    We describe a proposed experiment that will establish whether or not
    the
    optical field is quantized. We argue that previous attempts to
    establish this
    have not been conclusive. Quantum optics and Maxwell electrodynamics
    predict different outcomes for the experiment which is an improved
    version
    of that performed by Brown and Twiss in 1956 (Nature 177 27-9). The
    Brown-Twiss experiment did not distinguish between the two theories
    because its source was classical. In the proposed experiment, a weak
    light
    signal is achieved without selective deletion, and it can be either
    Poissonian
    or sub-Poissonian.


    Myself, I believe in photons 90%, but have learned enough that I
    wouldn't
    be suprised if EM fields turn out to be real, and photons turn out to
    be
    a big and long-running mistake. The last big mistake was the Aether
    theory which was shot down by photons. It would be quite ironic if
    the physicists of a hundred years hence become convinced that neither
    Aether nor photons exist. :)

    ((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
    William J. Beaty Research Engineer
    UW Chem Dept, Bagley Hall RM74
    Box 351700, Seattle, WA 98195-1700
    ph425-222-5066 http//staff.washington.edu/wbeaty/
     
  7. Photons, EM fields, Electrons, Temperature Gradients, Laplacian, Vector
    Fields, etc... have nothing to do with nature. Nature was here long before
    man and is not constrained by how man interprets the world and defines
    things. Definitions are always circular, Systems can never be completely
    understood, etc...

    The fact of the mater is that EM fields and photons are just our way of
    making something simple out of something that is infintely complex. Its
    your choice to choose which one you want to use to try and understand
    something or you can even try and come up with another model. Obviously
    though what we have today in science is a set of models that have worked
    very well... they could be totally off and just by chance we are able to get
    something out of them(well, the scientific method is what makes the
    difference between science and non-science).

    One might define all things in the world as phenomena then find ways to
    "understand" that phenomena. The whole point is to predict future outcomes
    of similar phenomena so one can use that to there advantage. Quantum
    mechanics is based in the realm of probability theory(ofcours along with the
    theories it builds off of which involv other branches of math) applied to
    real world. Its a model one uses to help predict things.... does it say that
    it knows what reality is? It shoudln't. If it does then it is jumping into
    the world of philosophy or metaphysics. Its whole purpose is to explain
    phenomena. Classical mechanics uses calculus(although a bit of other
    branches of mathematics here and there) to explain the world. Both do a
    good job but neither has been perfect. As we learn more about the structure
    of representation(= math) we can then apply it to the real world(science).

    The main thing I'm trying to get across is that all these theories are just
    models and try and explain how things work but cannot ever explain how
    things really are. We has humans have limited knowledge and are trying to
    make sense of the world in whatever way we can.... simplifications make this
    possible. If you are working on the theory of elasticity then it doesn't
    matter what a real photon is(if you could even know that). If its a small
    elf like creature then your crude approximation that it is a spherical
    massless particle might be good enough. Ofcourse it a photon could be
    totally different but the approximations we give it happen, for some unknown
    reason, to work. No one, EVER, will be able to definitively define what
    anything is. Some people act like they have a monopoly on intelligence and
    in those cases you gotta be careful about what they say. I studied physics
    for 4 years and I always thought that what I read and was told was how the
    world really was.... I could never except the quantum mechanical based
    reality(for obvious reasons because it is based on probability which by its
    nature allows is uncertain). When I took quantum mechanics I learned how
    probability theory was applied but I still had problems believing that was
    how reality really played its game. I finally learned through a prof that
    its just a model and they are not claiming that it is really what nature
    does(which I always believe but I never heard anyone else say).

    So, if you didn't read all that the conclusion is that its up to you to
    choose which model you want to use to try and understand things better. The
    field interpretation may or may not work better than the discrete element
    method. You might even have to come up with your own definitions of things
    to get somewhere. In 99% of the cases you will be able to use the
    established theories to do what you need. You can rest comfortably knowing
    that millions of humans have worked over many centuries to build up these
    theories and test there validity. While I personally don't believe in
    quantum mechanics being a good approximation to reality I think it is a
    natural method to probe deeper into the universe(in the sense that we will
    be able to have better predictors).


    i.e., LEARN BOTH DEFINITIONS!!!!


    Jon
     
  8. ok, Mr Lamb was a big name. So were Newton, Kepler, Shockley and
    Pauling and they all went far off the deep end near the end of their
    careers. Lamb's article has dang few references to it on Google, so
    I'll assume it wasnt widely accepted.

    Planck, Bohr, Einstein and Feynman all liked the photon theory, I'll
    take their word over J. Random Crank Theorist.
     
  9. For light, E=h/f. The relevant factor is the "h", Planck's Constant.
    That's why we talk about "photons".


    Mark L. Fergerson
     
  10. While I personally don't believe in quantum mechanics
    Pardon!!!! This makes no sense in relation to what you wrote.

    Of course its a good *approximation* to reality. Indeed, its an
    excellent approximation. It predicts what is measured in reality
    extremely well. Thats why QM exists.

    Kevin Aylward

    http://www.anasoft.co.uk
    SuperSpice, a very affordable Mixed-Mode
    Windows Simulator with Schematic Capture,
    Waveform Display, FFT's and Filter Design.

    "There are none more ignorant and useless,than they that seek answers
    on their knees, with their eyes closed"
     
  11. What I ment is that quantum mechanics is not a good approximation to reality
    in the sense that it is not how nature really works. Not that it isn't a
    good experimental predictor but that it doesn't "approximate" natures TRUE
    methods. Although you might say that they are one in the same it is easy to
    give examples where good predictors only look good on some scale but in the
    "long run" they fail. If quantum mechanics was one in the same as
    nature(i.e., nature used quantum mechanics) then on any scale it would be
    the same. Maybe approximation was a bad word to use there but not sure what
    else I could use. There are two concepts going on here though... one is the
    approximation to nature itself and one is the approximation to the
    experiment and predictions. Quantum mechanics surely does do a good job on
    the later but this is inherent in its methods(it uses probability and
    probably always, when used right, does more good than harm). We can never
    hope, at this point atleast, to understand the complexities of, say, a drop
    of water by modeling all its particles using the equations of fluid dynamics
    yet we can easily model it by using statistical methods. Ofcourse I doubt
    the particles themselfs care what method we use or how we think they work...
    they will do what they do... its our job to find out how they work and not
    there job to work like we want them to.

    Note though even though QM predicts SOME things extremly well it doesn't
    predict all things well. But sure, if I didn't mention this then I should
    have, Theories are used to predict! If they can't predict well then they
    tend to be useless(although we can never be sure how close to nature the
    theory really is).


    For example, Lets suppose you come up with a theory that explains some
    phenomena extremly well... lets say 99.9999%. Now I come up with another
    theory that explains the same phenomena only to about 30%. Does this mean
    your theory is a better representation to what nature uses? Maybe.. maybe
    not. My theory could be incomplete or have some errors that make it a bad
    predictor yet it could be exactly what nature does(hypothetically atleast).

    QM is a bad representative of the what nature does UNLESS you really believe
    nature bases itself in the realm of probabilty... I doubt this though but
    who knows.

    The point is that just because something is a good predictor of experiment
    doesn't mean it is how nature works(I might have already said that but). I
    do not believe, and it is my personal oppinion, that QM is how nature
    works... I doubt it even works by newtonian mechanics. It might even be
    impossible to know how it works. My point was to get across the idea that
    these are just theories that work well for some things and not explinations
    of how reality works. Is it a photon or an EM wave? probably niether...
    maybe both... Use what works to get somewhere. If its not working then try
    something else...


    Jon
     
  12. Jamie Morken

    Jamie Morken Guest

    I think you mean h*f :)

    The apparent quantization of aether waves (aka "photons") is a result of
    the harmonic states of electron vibrational states in matter atoms.
    This doesn't mean that there are particles called photons, this only
    means that when matter emits aether waves from electron harmonic state
    changes (orbital changes of electrons) it emits the aether waves at
    a characteristic frequency based on the geometry of the atom, so it
    makes no sense to think there are particles of energy transmission
    called photons just because matter emits characteristic energy
    signatures. It is like saying that sound is quantized into "speech"
    particles because it so happens that there exists humans that emit
    sound waves at quantized frequencies.

    cheers,
    Jamie
     
  13. Rich Grise

    Rich Grise Guest

    So, howcome, if you surround an atom with photomultiplier tubes, and
    stimulate the atom to "[emit an] eather [wave] from electron harmonic
    state changes", only one of the PMTs registers?

    Thanks,
    Rich
     
  14. No, I wanted to type the usual "Energy equals Planck's constant times
    'nu'", but Greek characters don't usually show up properly in
    everybody's newsreader. Whatever; we all know how the units have to come
    out.
    The quantization isn't "apparent", it's "real". To quote your OP:
    Since the electrons' orbital energy states _are_ quantized (which is
    where Planck's constant actually comes in) the energy of the emitted
    photon must also be quantized.

    We don't usually see this clearly and consistently because the
    orbitals' "natural" quantizations are thermalized, but that's another
    quibble. ;>)
    There can be, but don't _have_ to be, harmonic relationships.
    Nobody ever claimed that "particles of energy transmission called
    photons" have any objective existence, they're just a convenient way of
    parsing what we measure. And since the matter that emits them does so
    from quantized energy transitions, it's quite a natural way to parse
    those observations.

    Did you have another source of time-varying, self-propagating EM
    waves in mind?
    No. It's more like saying we can quantize the energy of phonons
    because the available energy levels for a lattice that supports them to
    vibrate in are quantized. But analogizing between light and sound is a
    Very Bad Idea for many reasons. Photons in free space are _not_
    analogous to phonons in a lattice.


    Mark L. Fergerson
     
  15. Oh, come on Rich, do you expect an "aether wave" addict to be able to
    come to grips with wavefunction collapse?


    Mark L. Fergerson
     
  16. Who really knows? It could be some other factor involved that makes it
    "appear" this way.
    I wouldn't be so sure. Many people claim a lot of stuff about physics that
    isn't quite true... Some of these people even have phd's in physics. There
    are "many" physicists that believe in negative probabilities.. quite
    nonsense. Probabilities are taken to be between 0 and 1 by
    definition/axiom... so its absurd to say there can be negative probabilities
    when we "define" them to be between 0 and 1.. but I've seen several
    physicists claim to the contrary. (and its a different story if you want to
    define probabilities to be between -1 and 0 or something like that... this
    is not what they do though.)
    Or it could be that space and time itself is quantized!?!?!


    Jon
     
  17. Rich Grise

    Rich Grise Guest

    Well, maybe it's more like the atom emits a ray of light, but you don't
    know which direction until after you detect it. ;-)

    Cheers!
    Rich
     
  18. Jamie Morken

    Jamie Morken Guest

    Hi Rich,

    I think its because the electron orbitals are lobes and rings and so
    they emit directionally.

    cheers,
    Jamie
     
  19. Tim Williams

    Tim Williams Guest

    Oh, now you've gone and done it.

    Besides quantum atomic theory that works quite nicely, what do you have to
    say about accelerated electrons? On a bulk scale, sure, you just get
    synchrotron radiation, but on a subatomic level, a magnetic force photon
    comes in from the magnet, kicks the electron aside (ala Feynman diagram) and
    a radiation photon poops out for the change in kinetic energy.

    Although I haven't done anything formal with Feynman diagrams, at least
    yet... but hey, that's the nice thing about the crucible of Usenet, if I'm
    wrong some flamer will correct it ;-)

    Tim
     
  20. Jamie Morken

    Jamie Morken Guest

    Ya I am having too much fun, I will stop now :)
    If you shoot a stream of electrons through an alternating magnetic
    field, like in a free-electron laser, there is an analog relationship
    between the oscillation of the free electron and the intensity of the
    magnetic field. It makes no sense that a free electron would only
    be influenced by quantum amounts of magnetic field energy.

    You can change the gap between the two magnet arrays to change the
    magnetic force on the electrons to any field intensity, so the
    magnetic field energy is not quantized.
    (see: "http://en.wikipedia.org/wiki/Free_electron_laser")
    I wasn't aware you could do anything formal with Feynman diagrams? :)

    cheers,
    Jamie
     
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