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What is photon emission

  1. Mar 26, 2009 #1
    k my physics background is limited , I know that photon emission is when the electron moves down in energy level thus releasing a photon but how does the photon get inside the electron , the energy that moves the electron into a higher level when this energy
    moves the electron out their is this how the photon gets into the electron , please clarify
     
  2. jcsd
  3. Mar 27, 2009 #2

    jtbell

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    Electrons do not contain photons. The photon is created at the moment of emission.
     
  4. Mar 27, 2009 #3
    ok , where is it created from or how is it created .
     
  5. Mar 27, 2009 #4

    Danger

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    Let me preface this by saying that I am not in any way an authority in the field. As far as I know, though, you get down to the range where everything consists of wave packets.
    Thinking of sub-atomic particles as... well... particles... is counter-productive.
     
  6. Mar 27, 2009 #5

    malawi_glenn

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    The photon is produced by the excitation of the electromagnetic field, in the theoretical framework that describes electrons and photons (Quantum Electrodynamics) the photons are quanta of the electromagnetic field.
     
  7. Mar 27, 2009 #6
    so the field is already there it just hasn't been excited
     
  8. Mar 27, 2009 #7

    malawi_glenn

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    well at this level, yes :-)
     
  9. Mar 27, 2009 #8
    so would I need to understand QED to completely understand this
     
  10. Mar 27, 2009 #9

    malawi_glenn

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    well here is a web course: http://www.phys.ualberta.ca/~gingrich/phys512/latex2html/node1.html [Broken]

    It assumes that you have done advanced Quantum mechanics, at the level of Sakurai's book "modern quantum mechanics"

    It is a difference of understanding and understanding. Since the language of physics is math, the understanding is almost always contained in the formalism. So for a complete understanding, yes, one needs to know the theory - otherwise it would not be a complete understanding.
     
    Last edited by a moderator: May 4, 2017
  11. Mar 27, 2009 #10

    Danger

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    Nobody completely understands it. That's the beauty of science. Keep investigating.
     
  12. Mar 27, 2009 #11

    malawi_glenn

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    yeah that is true, it is also a difference of understanding nature and understanding a theory that describes nature ;-)
     
  13. Mar 27, 2009 #12
    thanks for helping guys , i at least have a better understanding and ur right i cant think of a photon like a pool ball i need to think of it as a wave packet.
     
  14. Mar 27, 2009 #13
    Photon is timeless, it's not created... It just is in the electron (as energy, if you wish), or around it (as the field, again, if you wish), and it is transmitted or absorbed.

    There is quite a nice explanation about this on Hecht's Optics.
     
  15. Mar 27, 2009 #14

    malawi_glenn

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    that is the classical explanation, i.e classical electrodynamics
     
  16. Mar 27, 2009 #15
    Is it true that photons have no mass/weight? Please clarify this, I may be misinformed.
     
  17. Mar 27, 2009 #16

    malawi_glenn

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    Photons have zero mass
     
  18. Mar 27, 2009 #17
    so if photons are not created and are timeless , then the universe has been around forever .
     
  19. Mar 27, 2009 #18
    That's what I thought, thank you.
     
  20. Mar 27, 2009 #19

    HallsofIvy

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    A photon does, however, have momentum.
     
  21. Mar 27, 2009 #20
    right and they have a force too. Photons always seem to capture people's imagination
    and invoke interesting debates , nature is cunning an Einstein would put it.
     
  22. Mar 27, 2009 #21
    Being timeless is not the same as being forever. Or, as an illustration, being massless is not the same as nonexistence (or, at the other end, omnipresence).
    Timelessness just says that you can't measure the existence of a photon with a clock (why?)
     
  23. Mar 27, 2009 #22
    You could think of it like this:

    Imagine that you are holding one end of a slinky and have attach the other end to a wall. When you suddenly lower your hand 10 cm, a wave travels along the slinky. Lowering your hand is like an electron dropping an energy level and the wave is like a photon.

    The wave wasn't in your hand. Ya, dig?
     
  24. Mar 27, 2009 #23
    so ur saying the field is always there just not excited.
     
  25. Mar 27, 2009 #24
    Hmm, yes, it is there, but you will never know that it is there, unless you excite it. But, if you excite it, some might argue, aren't you creating it?

    I hope this has helped you departure from your initial picture where photon was a thing that can enter electrons. It might be so, but that thing is a very very strange thing, and absolutely not similar to the real things, which are made of electrons, protons and other stuff.
     
  26. Mar 27, 2009 #25
    it has definitely opened up my mind
     
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