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A Poll about Quantum Tunnelling

  1. Classical Electron Tunnelling

    3 vote(s)
    27.3%
  2. Quantum Electron Probability

    8 vote(s)
    72.7%
  1. Nov 14, 2004 #1
    In the quantum tunnelling process, where an electron tunnels though the potential barrier, we known this to be true by always seeing the electron we test for.

    We have always found what we were looking for and therefore have NEVER considered or thought about any other vallid or acceptable solution, such as the quantum electron.

    There are two solutions to QT.

    Classical electron QT, where the "real" electron's tunnels through the barrier.

    Or

    Quantum electron QT, where the "virtual" electron's probability is greater than the barrier.

    Did the classical electron tunnel through the barrier or does the quantum electron simply appear, according to QM?

    Which process do you think is taking place?

    Regards

    Terry Giblin
     
  2. jcsd
  3. Nov 15, 2004 #2

    chroot

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    I frankly don't think you have any idea what you're talking about, Terry.

    Tunneling is a quintessential quantum phenomenon with no classical analogue. Furthermore, the electron is not "virtual" in a tunneling scenario -- at least not if you're using the word "virtual" to mean the same thing that particle physicists mean.

    - Warren
     
  4. Nov 17, 2004 #3
    Conservation of energy does not apply to QM?

    Am I insane for not joining the club?

    If I have to accept a theory, who's first rule is that "Conservation of energy" does not apply, I would rather not join the club.

    When I proposed my solution to the DSE, by replacing the electron gun with a quantum tunneling electron.

    I could not understand why no body had thought of it sooner, so I was concerned that I might be wrong.

    However I have now learnt that the reason no one else thought of the same simple experiement, was because in Physics you are not meant to understand QM only accept it, without question.

    so they don't learn that QM is purely an accepted probability theory.

    There is a very small but acceptable probability that an electron can appear at random somewhere beyond the barrier, it does not tunnel through the barrier it is a statistical probability that it will appear, which is known to work.

    In my solution to the DSE I was trying to prevent the classical approach and replacing it with another probability solution. Unfortunately everyone else simply assumed the classical electron tunneled through the barrier. Where as my intentions was to think of the QM probability wave, which can go through the two slits at the same time.

    Quantum Tunnelling electrons in the world which I live in to not break the conversation of energy, they follow and obey accepted rules of probability.

    Nothing I have said is knew - I have simply remember the approximations and assumptions originally made when the theories were being developed .

    We have to learnt to accept and try to understand better that probability plays an important part in Physics whether we like it or not.

    Its our lack of understanding of probability not QM which is holding us back.

    Regards

    Terry Giblin
     
  5. Nov 17, 2004 #4

    chroot

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    Well, now that you've gone firmly off the deep end and have decided to invoke some kind of scientific conspiracy theory, let's make some things clear -- again:

    1) There is no such thing as "classical tunneling." Classically, a particle that does not have enough energy to get over a barrier will never get over that barrier.

    2) Your statement that "There is a very small but acceptable probability that an electron can appear at random somewhere beyond the barrier" is a phenomenon which has been given the name tunneling. Perhaps you have some kind of misunderstanding about what the word tunneling means. Perhaps you're confusing the physicist's definition of tunneling with the general english definition of tunneling.

    3) Your notion of a particle's wavefunction as being non-zero even on the other side of a barrier is precisely the way QM interprets tunneling. You seem to be saying the same things QM says, but then you go on to say you don't believe QM.

    4) QM does not "break" the conservation of energy -- in the macroscopic limit, it is recovered from the theory.

    5) "We have to learnt to accept and try to understand better that probability plays an important part in Physics whether we like it or not." Spoken like a true physicist, Terry. That's exactly correct. Probability is at the very heart of QM. Do you think QM does not deal with probability? Do you know anything about QM?

    - Warren
     
  6. Nov 17, 2004 #5

    jcsd

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    Terry- quantum mechanics does contain the conservation of enrgy, it says for a 'closed' system the Hamiltonian operator is not a function of time. Now the implications of this statement in quantum physics are not exactly equivalent to the implications of the conservation of energy in classical physics, but quantum physics isn't equivalent to classical physics so big suprise.
     
  7. Nov 17, 2004 #6
    Terry, as chroot pointed out, there are so many things inconsistent with your argument.

    QM does not violate the conservation of energy...

    You say that you do not buy QM but your proposal states something no different than quantum mechanics.

    Classical electrons do not tunnel.

    Do you have the slightest clue what QM is about? It seems safe to assume the answer is no. Your post is filled with many inconsistencies and errors and thank god no one else accepted your argument.
     
  8. Nov 19, 2004 #7
    you speak too soon yxgoo!! of course the electron tunnels through classically and this can be expressed via quantum mechanics, no big deal!! quantum mechanics can be derived from a classical basis anyway! i'd rather not vote 'cos there's no way to choose both 'cos both are true both give the right answer
     
  9. Nov 19, 2004 #8

    EL

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    ??? What do you mean?
     
  10. Nov 19, 2004 #9

    russ_watters

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    You guys aren't thinking of the Rutherford gold-foil experiment, are you (most electrons fired at a thin gold foil go straight through, some get deflected or reflected)? That isn't quantum tunneling.
     
  11. Nov 19, 2004 #10
    what the probabilities do is 'smear' reality over time and or space depending on how the statistics are being organized mathematically, but each 'dot' in the probability map is a real orbit, you see, some DO get through because the dynamics at that point in time and space ALLOW a direct tunnel through, really quite elementary mr dear watson; you all seem to find this sooo difficult to understand; i do beleive you must like to live in a time warp of the 1920's, wake up to the 2000's guys, we're moving on!! and all with good maths, and how reality is based on good maths, including QT you just need to understand what its doing mathematically, so as i say, BOTH are correct!!
     
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