Quantum Electrodynamics question
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Thread: Quantum Electrodynamics question

  1. #1
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    Quantum Electrodynamics question

    I have seen many Feynman diagrams, but I have only seen interactions between electrons, and anti-positrons between themselves and each other. However, I have never seen one done for Protons, is there a specific reason for this?

    Also, I have a little trouble understanding the maxwell tensor (aka field strength tensor, electromagnetic tensor, faraday's tensor, etc.). Is it supposed to work similiar to the stress tensor (I mean on paper, when I draw it out, not in theory).

  2. #2
    Right turn Clyde Nokia's Avatar
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    Yeah..........erm.....I'd say ... er...... format then reinstall windows and you should be OK!
    Drugs have taught an entire generation of kids the metric system.

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  4. #4
    They call me the Hunted foxyloxley's Avatar
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    until our more quantum aware guys get here :
    as this is more of an esoteric question than those normally postulated, I'll drop some links in for the reading herd
    Feynman diagrams
    quantum electrodynamics
    interactive Q+A
    more reading
    intro to particle physics

    quarks, strangeness, charm. it reads like a Hawkwind album
    from what I can find the proton proton scenario gives pions
    but as protons are made of quarks, which give leptons, I feel that the reason for a 'lack' of proton proton data, is because 'they' are too large, and several other components are observed too ...............

    Pax
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    OLDER yes
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  5. #5
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    Hi

    Arkimedes, considering the type of questions you usually ask here,
    I'd recommend you some physics-forum or math-forum. Check out
    this community[1]: usually 20-80 users online, 800'000 posts, active
    discussions.


    To your question(s):
    Foxyloxley, I am deeply delighted You got half the answer.

    As per QED:
    A quantum field theory, such as QED, deals with objects, which are
    fundamental fields. From these fields particles, like the photon, electron,
    quarks etc. emerge. Feynman-diagrams are drawn for fundamental field, or if
    you wish, the corresponding fundamental particles. Otherwise, you are
    dealing with some "effective theory".

    Since protons are composite particles (a mixture of quarks and gluons),
    they are not easily treatable withing QED. Their charge (and current,
    since relativistic) distribution has to be taken into account (see "form factors").

    The theory, which deals with quarks and gluons is called QuantumChromoDynamics (QCD).
    QCD is the theory of the so-called strong interaction, and is the dominant force within
    a nucleon, thus the more important one.


    As per maxwell tensor:
    It is just an object, defined to simplify the relativistic calculation. Just remember
    that F_{\mu\nu}F^{\mu\nu} ~ E^2 + B^2.

    Cheers


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  6. #6
    They call me the Hunted foxyloxley's Avatar
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    As per maxwell tensor:
    It is just an object, defined to simplify the relativistic calculation. Just remember
    that F_{\mu\nu}F^{\mu\nu} ~ E^2 + B^2.
    EXACTLY

    my eyes kinda glazed over a tad when I got to the colour bit, not that it actually carries a colour, that is just the name given to the property ......

    I have a friend, physicist, specifically a particle physicist
    he did his post grad work in this BECAUSE he 'thought' that there can't possibly be THAT much in such a small space ...............

    NOW there's virtual particles boson, meson AND their mirrors to contend with
    as stated earlier, I'm an enthusiastic amatuer, VERY amatuer............
    55 - I'm fiftyfeckinfive and STILL no wiser,
    OLDER yes
    Beware of Geeks bearing GIF's
    come and waste the day :P at The Taz Zone

  7. #7
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    Originally posted here by foxyloxley
    [B] ... BECAUSE he 'thought' that there can't possibly be THAT much in such a small space .... /B]
    There is a lot there in that small space because all the stuff gettin' busy there is really, really, really , really, really, really, really (technical term) small.

    I used to spend a lot of time thinking and worrying about such things.

    Now it just hurts if I try to think about it.


  8. #8
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    Arkimedes: College undergrad right, my guess is first or secaond year.

    Give it time guys, life will beat that esotaric inqusitiveness out of him in no time
    Who is more trustworthy then all of the gurus or Buddha’s?

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