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Photon Exchange - Frequency? And uncharged antiparticles

  1. Aug 9, 2011 #1
    I wondered about the photon exchange mechanism when my AP physics teacher taught about it. Essentially, it's like shooting a basketball back and forth. I don't see the attractive part, but's that what the analogy was on the internet thing used. I assume it's in the math, anyway.

    But my main question is, do these photons have a frequency of 0? In order to be constant repel or attract, would the photon not have to see on the same cycle to keep the charge correct(EM radiation is a cycling electric field, oscillating between positive and negative). To be constantly positive or constant negative, the photon would have to not oscillate, hence 0 Hz. The main contradiction with accepting this is that photons ARE oscillations in the electric field(magnetic arises from the changing electric, I believe), causing EM radiation. So am I envisioning in incorrectly, or can photons sometimes have frequency and sometimes not have frequency, depending on the source?

    Since I'm also in the quantum mechanics section, which covers antimatter(I think), what is it that attracts neutrally charged particles/antiparticles together, like a neutron/antineutron pair? I think I've read somewhere that neutrons are polarized somehow, so this is the only thing I can think of, aside from the other opposite features attracting(like quarks or the other things)

    Thank you for your help.
     
  2. jcsd
  3. Aug 10, 2011 #2

    naima

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    Gold Member

    For the question about attraction have you ever read http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html" [Broken]
     
    Last edited by a moderator: May 5, 2017
  4. Aug 10, 2011 #3

    clem

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    That analogy is completely false. You need to use the mathematics of QED.
     
  5. Aug 10, 2011 #4
    As Clem posted, the details of electromagnetic interactions go way beyond photon characteristics.

    Photons have different frequencies depending on their energy....E = hf....

    So a photon from one frequency (color) of light will exhibit a different energy from a photon of another color....gamma rays, for example, are very high energy high frequency....

    Check the first few paragraphs here: http://en.wikipedia.org/wiki/Photon

    and skip down to see PHYSICAL PROPERTIES.

    Not also that photons DO exhibit wave particle duality...

    You can also check:
    http://en.wikipedia.org/wiki/Electromagnetic_radiation#Particle_model
     
    Last edited: Aug 10, 2011
  6. Aug 10, 2011 #5

    Drakkith

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    A neutron is only neutral overall. It is composed of 3 quarks, of which 1 of them has a charge of + 2/3 and the other 2 have charges of - 1/3. An antineutron would actually be composed of an anti-upquark and 2 anti=downquarks. It is a similar situation like (but not exactly like) an anti-hydrogen atom contacting a normal hydrogen atom I believe. I don't believe that a neutron and antineutron would attract each other from a distance, but if they do get close enough to contact then they should annihilate.
     
  7. Aug 11, 2011 #6
    Ah, so a virtual photon is like the ball passing only for repulsion, but for attraction, the photon goes away from the attracted/ing object and back in time, enabling it to be absorbed by the other particle. This seems certainly plausible considering the bizarrely twisted logic(at first glance, at least) of quantum mechanics.

    For the uncharged antimatter pair then, they aren't attracted. I assume they can't be captured or used or whatever because they can't be stopped electromagnetically from flying into normal matter in their path.

    Thanks for the help
     
  8. Aug 11, 2011 #7

    Bill_K

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    That is bizarre all right, but neither plausible nor correct. And yet that is exactly what John Baez said, isn't it. :frown: John is an excellent mathematician, but this explanation of his of Coulomb attraction/repulsion is completely made up, and I can only suggest you look elsewhere.
     
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