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How can electrodynamics prove the stability of electron

  1. Oct 24, 2005 #1
    in quantumdynamics, the stability of electron of H atom is a hypothesis.
    but if electrodynamics is right in quantum theories, electron circling a H atom will emit energy, then how can electroquantum theory give a sound prove of the stability of electron?

    thanks.
     
  2. jcsd
  3. Oct 24, 2005 #2

    DrChinese

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    Welcome to PhysicsForums, Apollothe!

    The electron is not in a classical orbit, and that is why it does not emit energy as it circles into the nucleus. The electron exists in discrete orbits corresponding to quantum (whole) numbers, where the innermost shell is 1. It cannot take on a value of 0, which would place it in the nucleus.
     
  4. Oct 27, 2005 #3
    I would say that the very notion of an electron tracing a well defined path arounf the nucleus is a misconception at this level. Perhaps the stability of atom may be explained by interferences beteween the radiating electron in one path with the radiating electron in other paths. Multiple path electron seems to be necessary in this discussion.

    Best Regards

    DaTario
     
  5. Nov 7, 2005 #4
    Let me try to give a many fingered answer to this question. I have some problems myself with the H atom especially in the Bohm-de Broglie approach where particles do have well defined orbits. The funny thing is that at the l = m = 0 level, the electron would just stand still ! Hence, the H atom would have a permanent electric dipole moment which I could measure in the Bohm-de Broglie approach by making a measurement with a CLASSICAL EM field. This measurement situation would not be possible in the Copenhagen setup since there I would have to go over to second quantization (but again, in my opinion, the Bohm approach allows for this). So in standard QM, you would have to couple the electron to a quantized Mawell field and study the stability of the stationary state (in general the issue is more delicate for the higher orbital momentum states). I remember having seen a recent paper where this difficult analysis has been carefully worked out, but I do not rememeber the reference anymore (perhaps Vanesh can help you out here).

    Now, a bit less conventional, the stability of the H atom with the correct energy level, has - I believe - recently been proved by Cole in the framework of stochastic electrodynamics. The idea here, is that the electron is a classical particle spinning fast around the nucleus and emmiting EM energy. However SED postulates the existence of classical vacuum field fluctuations (which is a prediction of second quantization) and one shows that this vacuum field is in equilibrium with the electron. That is, the electron eats as much energy as it radiates and the same does the ``vacuum´´ EM field.
     
  6. Nov 7, 2005 #5
    you happen to have the paper title and publication? :tongue2:
     
  7. Nov 7, 2005 #6
    The paper is written by Daniel C. Cole and Yi Zou : Quantum mechanical ground state of Hydrogen obtained from classical electrodynamics. Just type it in google, I did not check it yet myself to details however...
     
  8. Nov 7, 2005 #7
  9. Nov 7, 2005 #8
    Thank you Norman and Careful. :)
     
  10. Nov 7, 2005 #9

    ZapperZ

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    I don't get it.

    This paper is trying to mimick the Bohr/Rydberg model. I thought we have moved light years BEYOND such a thing? In other words, I am not impressed by anything that can duplicate a naive model.

    Why is this inadequate?

    (1) The atomic model has orbitals beyond what the Bohr model can describe.

    (2) Not only that, one of the most important aspect of the orbitals is the PHASE sign. For example, the d orbtal has several different symmetries with different phase signs. Is this a big deal? You betcha! The sign in the orbital phase is the origin of the bonding-antibonding bonds and bands! A huge chunk of Chemistry is based on this!

    And this is what is severely lacking in classical mechanics. It cannot explain superconductivity because the idea of "phase coherent electrons" is non-existent. And it cannot explain the bonding-antibonding phenomenon because its "atomic model" still mimicks the highly primitive Bohr atom. So this is why I do not get this. I suppose when you look at a cow very far, you can approximate it as a sphere and go away thinking you're on the right track. But the devil is in the detail (or was it god)? Up close, they don't look anywhere resembling each other.

    Zz.
     
  11. Nov 7, 2005 #10

    DrChinese

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    Would you say that the Cole paper oversells itself a bit? From the abstract:

    "These results, obtained without any fitting parameters, again raise the possibility that the main tenets of stochastic electrodynamics (SED) are correct, thereby potentially providing a more fundamental basis of quantum mechanics."

    :rofl: On the other hand, the *actual* conclusion is:

    "Without question, the simulations presented here do not 'prove' that SED
    works for atomic systems. There are far more tests and phenomena to still be
    examined, including relativistic corrections and high frequency effects, atomic
    spectra, many electron situations, spin, and an understanding of how 'photon' behavior arises."

    (One might even conclude that the author doesn't believe in photons from his quotes around the word photon.)

    Careful, if you have a problem with the standard quantum model of the hydrogen atom, perhaps you could tell us what problem that is? By most accounts, it has been a smashing success for 75+ years. It would make a more convincing argument if you compared SED to its most successful competitor (which is not dBB/BM).
     
  12. Nov 7, 2005 #11
    I said I did not read the paper yet (which I shall do now and you better would read the whole paper before you say something/the comments you make can be applied to almost every paper). What the author probably means when he says that he does not believe in photons is that he does not believe in second quantization of the Maxwell field and this might not be a bad idea at all (many people including nobel prize winners have doubted this). I already outlined ``the problem´´ with the model when I said that the Bohm de Broglie theory suggests that the H - atom should have a permanent electric dipole moment in the ground state, contrary to observation. I would be glad if someone could say something intelligent about this. What concerns the comments of ZapperZ: the Bohr model is exact for the H atom and the authors claim nothing more than treating the ground state of the H atom correctly. His further comments are exactly what you can expect from someone who does not want to think about realist explanations. It does not impress me at all that any of you are just repeating what you learned in textbooks (it actually shows bad research manners): I gave the standard explanation (as a good boy, and perhaps you as a quantum erudit know the reference I was talking about first) and added something I find interesting. It is up to the reader to decide what he thinks about it.
     
  13. Nov 7, 2005 #12

    ZapperZ

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    Bohr model is NOT exact for H-atom. It doesn't explain the degeneracy of the p,d,f,etc orbitals.

    Come again? Why is it "bad research manners" when asking "So what is new here?" Again, I will come back to the question in which ANY practicing physicist would face on any given day: It may be interesting, but is it IMPORTANT? Why is this severely-restricted model important?

    Why are we touting something that, at best, can only mimick the most naive picture of, not ANY atom, but just the H-atom. And it is also not "bad research manners" in questioning the SHORTCOMMING of any model, ideas, and theories. It is the main reason why we become physicists!

    And oh, I wasn't simply "repeating" what I learned in textbooks. I dealt DIRECTLY with bonding-antibonding bands in bilayer high-Tc superconductors AND had to figure out the spontaneous currents due to the overlapping of the [tex]d_{x^2 - y^2}[/tex] orbitals in the tricrystal ring experiments of Tsui-Kirtley. I would strongly suggest you do not make any personal characterization of people you hardly know.

    Zz.
     
  14. Nov 7, 2005 #13

    DrChinese

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    My question was: what problem do you have with the standard quantum model (which doesn't make that prediction) ? It makes no sense to compare dBB to SED that I can see, when the prevailing theory is neither of these. So I repeat that question, perhaps you might try addressing it specifically? Or if you don't have a problem with the standard model, why don't you tell us that too?

    The comments I made included quotes from the reference you cited, so I am not sure what you refer to when you say my comments apply "to almost every paper". They apply to the paper at hand. It purports to give a prediction for an atom in a ground state with one electron. This moves us back in time to 1913 (using a mere 55 computer-days of calculation to get the same answer). I would not call that an impressive feat.

    As to belief in photons, I would not say that this is an item that is seriously considered "in play" at this time. There are plenty of experiments which have demonstrated the existence of higher order effects in photons to very high levels of confidence. If there is a Nobel physicist alive who actually doubts this today, I would like to know who that is.
     
  15. Nov 7, 2005 #14

    DrChinese

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    A double standard?

    You cited the paper to support your contention - and now you admit without you haven't read it! (And you didn't say you hadn't read it, you said you hadn't checked the "details".)

    On the other hand, I quoted it verbatim and yet you insist that I must read it in its entirety before even commenting.
     
  16. Nov 8, 2005 #15
    I read the paper now and it is for sure interesting. The authors do not make any exaggerated claims whatsoever. This paper is largely improving upon any classical atomic model I know. Two things are mainly commented: (a) the author has substantial numerical evidence that in this approach the Schroedinger ground state of the H atom can be obtained from a statistical averaging procedure over realistic time scales of around 10^(-11) seconds of a stochastic Maxwell theory and (b) the circular orbit with the Bohr radius seems to be an attractor of this classical stochastic dynamics. This by itself is an interesting result given that students learn that classical physics already fails at this level. The author clearly mentions what should stil be done like (a) including more electrons (b) including spin. Unlike Zapper Z, I *do* see possibilities how to get an interference effect even at the classical level but I do not know for now if it will come out right (I have even thought of mechanisms which could deliver the other quantum numbers). The comments of Dr. Chinese concerning that the computational power needed for this would somehow invalidate the result, is entirely ridiculous. Any realist theory of the atom would be very complicated (much more than QM) such as the detailed dynamics behind every equilibrium phenomenon is. There is really no point in discussing these things with me : either you accept that there are creative realists around who want to reproduce the quantum successes (which is NOT a waiste of time for several GOOD reasons in my view), or if you think this is not possible then you shoud cook up airthight NO GO theorem. Everything besides this is religion and of no interest to the discussion.
     
  17. Nov 8, 2005 #16

    DrChinese

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    Careful, you have again ignored alll of ZapperZ's and my questions. I will take that as its own answer. It is clear you have a local realist agenda that you are trying to push under the guise of legitimate posts. If you are a local realist, why don't you simply tell us that to begin with rather than acting coy?

    For everyone else: this paper is a total red herring and has absolutely nothing to do with the original poster's question. An H atom is NOT a classical electron orbitting a classical nucleus. Even attempting to emulate the Bohr model (which it doesn't even claim to do) is nothing more than an exercise in rolling back the clock to 1913. As ZapperZ pointed out, attempts to describe it in such terms are pointless. The H atom is acts as a quantum system, and has been successfully described as such for over 75 years. Needless to say, it did not require 55 days :rofl: of computing power on a Pentium computer to get good predictions from quantum theory back then.

    The real purpose of the cited paper is to try to find ways to push SED as a viable alternative to oQM. So far, such attempts have had a very poor track record (this paper is such an example) and are mainly pushed by Santos, Marshall and a few others who are firmly in the local realist school. Since the scientific community has embraced Bell and Aspect+, this is considered a fruitless endeavor by all but a vocal minority.
     
  18. Nov 8, 2005 #17
    Look, I am seriously getting fed up with your dogmatic idiocy. I will give you the list of nobel price winners I know who have once refuted for long time the photon concept : Robert Millikan, Niels Bohr, Louis de Broglie (and since then it just became a habit). The physics in the paper I cited goes way beyond the Bohr model (recall: this was not stable, it did not include radiation). The paper is clearly relevant for this thread, it is just an alternative way of looking at things: you did not comment on the first (conventional) answer I gave on this question and from what I could read you were not even aware of this issue. As you probably noticed, I can talk very civilized and in a CONSTRUCTIVE and HONEST way to Vanesh even though are points of view are somewhat different. I give DIFFERENT answers to the same questions and I STRESS what is conventional and what NOT.
    It is up to the READERS to make out what they THINK of it, not what others say they should think about it.
     
  19. Nov 8, 2005 #18

    ZapperZ

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    This is misleading. Millikan STARTED not buying into Einstein's photon model, but read his Nobel prize speech. In fact, he acknowledges even in his earlier papers that ALL of his experiments validate Einstein's model. In physics, you cannot have a more convincing verification of your idea when a skeptic of yours produce EXPERIMENTAL observation that verifies your idea.

    And please do NOT forget the PF Guidelines regarding personal attacks.

    Zz.
     
    Last edited: Nov 8, 2005
  20. Nov 8, 2005 #19
    I know this Nobel lecture: my criterion was that there exist nobel prize winners which have doubted this for a LONG time (Bohr accepted it after a while but was never convinced), I did not say always. It is natural that people sometimes change of mind in their life, that is a sign of intelligence. The point is that such arguments should be of no value. Look, what you prefer to see as an ``explanation´´ or ``plausible´´ is entirely your business (I never use arguments based upon belief, I always argue), moreover it is possible to get particle like behaviour out of a classical maxwell field. I think that Dr Chinese could also be accused of stalking; my personal preference is entirely IRRELEVANT, I just offer scientific information (in the same way he should accuse 't Hooft to be a non-believer). Hereby, I would like to ask dr Chinese to stop doing this, it makes no sense and is annoying. I believe he is long enough around here for people to know his view.

    Cheers,

    Careful
     
  21. Nov 9, 2005 #20

    vanesch

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    Please, people, calm down (on both sides of the fence!).
    Personally, I find it interesting to discuss non-conventional views for several reasons:
    - first of all, they sometimes point out things about the more conventional views I didn't realize
    - second, it can be instructive for both parties to discuss this scientifically
    - it is not because something is "obviously" going to have difficulties in a certain respect, that it is uninteresting to discuss the aspects where it seems to work.
    I myself learn often more by trying to reply to an "alternative view" than by just reading yet another standard explanation.
    However, I want to do this on three conditions:
    - that the discussion is informative, eg, that the "opposing party" is willing to explain, and not simply to say that "if I were to read the relevant literature, all this would be already known and I wouldn't say such nonsense" ; I have to refrain myself from abusing from my supermentor status to shoot of warning points in such cases (which I would, if it were not myself who was the target).
    - that the discussion remains focussed on the subject and doesn't involve people, their reputations, ...
    - that the proponent of the alternative view shows that he knows the conventional view, its advantages and eventually its problems, and can respect the conventional view as much as I try to respect for the sake of argument, the alternative view.
    Honestly, I do find Careful respecting these things in general, so let us also respect his view (although my *personal* opinion is that he's fighting courageously, eh, windmills). We can all learn from the discussion as long as it remains cordial.
     
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