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Indrotucing me with a Problem

  1. Oct 11, 2006 #1
    Hi I'm Syed ,loving Physics from my childhood.I have no knowledge of hard core Physics,though I'm an M.Sc Physics.My area of interest is Theoretical Phyiscs,which needs Paper,Pen and Brain of which I have the first two and lacks third.So,Please help me to do better in this field.I'd be much obliged for that.

    Here is the question I persevere to know a Better Answer .

    What happens to an electron within a Potential barrier when it tunnels through it without enough KE to overcome it ?

    Can we observe an electron with negative KE within the barrier ? What is the Physical Meaning of this all ?
    (I am not satisfied with the answer David Bohm has given in his book)
  2. jcsd
  3. Oct 20, 2006 #2


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    Staff: Mentor

    What answer does Bohm give? I haven't read his book.
  4. Oct 20, 2006 #3
    "What happens to an electron within a Potential barrier when it tunnels through it without enough KE to overcome it ?"

    Nothing really. The electron exists within the barrier and outside of it at the same time.
  5. Oct 28, 2006 #4
    David Bohm basically formulated the following theory: Reality has 2 things - the wavefunction of all degrees of freedom, and the actuall current position (a classical point in phase space). The wavefunction evolves in time via the ordinary equations of QM, and completely ignores 'the actuall position', while the position evolves accourding to Newton's laws of motion with an addition of a quantum potential which is a non local functional of the wavefunction.

    This theory is compatible with all observations of QM, but it doesn't have any new predictions, so it's untestable.

    Bohm's answer to Syed's question is therefor that the kinetic energy is positive, but there is negative 'quantum potential' energy.

    The answer within the Coopenhagen's interpretation's viewpoint should probobly be just that the wavefunction is all that is, and that the tunneling particle never has 'negative kinetic energy'. The kineric energy operator is minus the laplacian, and that's a hermitian operator with a strictly positive spectrum.
  6. Oct 30, 2006 #5
    Those who have read Dirac,Feynmann and the All powerful Wheeler there is a simple answer to the question I have posted earlier concerning the tunneling of an electron through a potential barrier:

    We can still observe it but not as an electron but as a positron !
    I should like to discuss this.
  7. Oct 30, 2006 #6


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    Staff Emeritus
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    We don't discuss posting based on misinterpretation of basic physics except to say: get an education!
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