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Orientation of virtual particle pairs in local fields?

  1. Jun 2, 2004 #1

    turbo

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    Can the presence of gravitational, or electro-magnetic fields cause virtual particles to arise with a preferential physical orientation?

    Logically, the virtual particles should not emerge in a preferred orientation if they arise spontaneously, and can't be acted upon by local fields until they exist, but there is much in quantum mechanics that seems *illogical*, and this may be another wrinkle (the presence of a local field increases the probability that the virtual particles will emerge with a preferred orientation). To me, tunnelling seems equally odd, but without that effect, we wouldn't be using personal computers. Yes, I am old enough to have meekly submitted huge stacks of IBM punch cards to the acolytes of "The Computer" at our state university, hoping that the green-and-white striped output would vaguely resemble the result I so dearly wanted....

    Anyway, if quantum mechanics does not allow the virtual particles to emerge in a preferred orientation, does the uncertainty principle allow the pairs exist for long enough to take on some degree of preferential orientation due to the presence of local fields?

    Again, my apologies if this question has been beaten to submission in the past... Pons Asinorum...
     
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  3. Jun 3, 2004 #2

    Labguy

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    In the presence of any strong electric or magnetic field, an alignment would take place except for the very short lifespans of the particles. All black holes and neutron stars have strong magnetic fields.

    They (virtual particles) always come in pairs; one particle and one anti-particle, like an electron and a positron, quark and anti-quark or a photon and another photon with opposite spin and impulse. They only exist for a very short time; ~range of 30 to 100 atoseconds.

    If restricted to these short time scales, the uncertainty in the energy can be very large. In the intermediate stage of virtual pair production, conservation of energy appears to have been violated, but the particles are created and annihilated on such short time scales as to agree with uncertainty. We (usually) get virtual particles from Hawking radiation, where the particles annihilate or seperate, with one falling back into the event horizon to return the "borrowed" energy. Another source is from an electro-magnetic field where both particles can become "real" particles with the energy for that provided entirely by the field.

    The electro-magnetic field tends to separate the charges. If the field is strong enough, the particles tunnel through the quantum barrier and materialize as real particles (as above). The field strength necessary to accomplish this is achieved when the work done to separated the charges by a Compton wavelength equals the energy necessary to create the particles.

    Bottom line is that your assertion that virtual particles would "align" is correct except that the lifespan is so short that (1) there would not be enough time for alignment orientation or (2) alignment could happen but the time scale would be so short that the effect couldn't be observed.
     
  4. Jun 3, 2004 #3

    turbo

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    Thank you for your reply. I didn't assert that alignment would occur due to the presence of local fields, though. I asked if alignment might occur. I thank you again for the explanation that due to the short time scales, any trend toward alignment couldn't be observed. Is there some experimental or theoretical work that you can point me to? Googling hasn't gotten me anywhere.... 8-P Intuitively, it seems to me that even minutely unmeasurable trends toward alignment might be significant in total when considering the size of the vacuum, but maybe that's a cognitive shorcoming on my part.

    To follow up, are you aware of any studies investigating the effects of local fields regarding the probability that virtual particles might arise with a preferred orientation within those fields? I'm drawn to these questions because of the nature of my training and inclination. From an engineering standpoint, I know that a small motive force in just the right place (like air pressure to the controller of a pneumatic valve) can have a HUGELY multiplied effect. It seems to me that forces that can cause even very small pertubations in the behaviors of virtual particles must have enormous effects on the macro world.
     
  5. Jun 4, 2004 #4

    Labguy

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    When you say the "size of the vacuum", I don't know if you are still referring to "local" fields or large-scale vacuum fluctuations...(?) The virtual particles that arise from vacuum fluctuations (only) usually annihilate quickly and produce photons since there are no other energies (like magnetic) to seperate them.

    Sorry, I'm not aware of any such studies, but somebody out there must be thinking about it... :confused:
     
  6. Jun 4, 2004 #5

    turbo

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    My reason for this question

    The reason I posed this question initially is in part because the pervasive seething sea of virtual particles in what is otherwise "vacuum" has measurable effects on macro-world objects. (Casimir effect) It follows that the macro world, including local fields MUST have effects on the virtual pairs. Interaction is not a one-way street.

    It also seems logical (a sometimes ineffective approach to quantum physics, I realize) that even if local fields aren't strong enough to produce the Hawking effect (line an "evaporating" black hole), they may impose some preferential alignments by either:
    1) their effects on the virtual pairs during their brief existence,
    or:
    2) by causing virtual pairs to arise (and anihillilate) in statistically preferred orientations.

    I am sorry that I used the phrase "size of the vacuum" - it was inconcise. I meant to express the fact that empty space occupies the vast preponderance of our universe, while observable matter occupies such a tiny fraction of it. Logically, if these all-pervasive virtual particles are NOT randomly aligned, that could have huge consequences for the macro world.
     
  7. Jun 7, 2004 #6

    Chronos

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    the planck constant gives a basis to make those predicitions.
     
  8. Jun 7, 2004 #7

    Labguy

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    How? Especially with any respect to the Casmir effect which requires "boundaries".
     
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