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Solar Neutrinos vs. Photons

  1. Feb 17, 2012 #1
    Hi guys, I have a question about the difference in the time it takes a neutrino to escape the core of the sun compared to the time it takes a photon to escape from the core of the sun.

    Basically, my question is: what is the difference between photons and neutrinos that makes neutrinos very unlikely to interact with atoms, while photons are very likely to interact with atoms?

    I know that neutrinos are very small compared to the sizes of atoms and electrons, but aren't photons very small too? They don't really have a size, right?

    I've thought about it a bit, and maybe I've answered it myself: since electrons "orbit" the nucleus of an atom in the electron cloud, they are effectively "everywhere" in their orbit at once, right? And then since the atoms are so tightly packed together in the core, the electron clouds are very close together too, right? So then basically it comes down to the fact that the neutrino hardly ever interacts with electrons and other particles, while photons end up getting sucked into an atom all the time.

    I'm not 100% certain on that though, could someone help clear this up?
  2. jcsd
  3. Feb 17, 2012 #2


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    Hi SHISHKABOB! :smile:
    photons feel the electromagnetic force (and the weak force), but neutrinos only feel the weak force …

    and the electromagnetic force is a lot stronger than the weak force

    (the clue's in the name! :wink:)​
  4. Feb 17, 2012 #3
    that makes sense, thanks

    so then when a photon is emitted, it is attracted by the electromagnetic force of the atoms around it? I guess I am confused about how exactly the photon or neutrino "hits" the atom...
  5. Feb 17, 2012 #4


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    oooh, I'd rather let someone alse answer that. :redface:

    I think it has more to do with the photon and the atom behaving as waves than as classical particles
  6. Feb 17, 2012 #5
    that sounds reasonable, thank you very much anyways
  7. Feb 17, 2012 #6
    How are uncharged photons attracted by electromagnetic force?
  8. Feb 17, 2012 #7


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    A photon practically IS the EM force. It's electric and magnetic fields oscillate back and forth so it is overall uncharged, but every time it gets to a peak in it's electric field it is either positive or negatively charged.
  9. Feb 18, 2012 #8
    OK, thats informative! Thanks, Drak!
  10. Feb 18, 2012 #9


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    The big deal is neutrinos are nearly collisionless. A neutrino can penetrate a light year of lead with relative ease, photons are far more sociable. Dark matter is even more anti social than neutrinos.
  11. Feb 18, 2012 #10
    Okay so I went back and read some stuff on it again, and I think I found the solution to my puzzlement. Photons only go a few millimeters, apparently, before being absorbed and remitted. A few millimeters of incredibly dense star core matter is still a lot of hydrogen atoms that it "missed". It makes sense conceptually to me now, thanks for the help guys.
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