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December 15th, 2005, 04:49 AM
#1
Senior Member
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).
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December 15th, 2005, 09:53 AM
#2
Yeah..........erm.....I'd say ... er...... format then reinstall windows and you should be OK!
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December 15th, 2005, 10:44 AM
#3
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December 15th, 2005, 11:13 AM
#4
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
so now I'm in my SIXTIES FFS
WTAF, how did that happen, so no more alterations to the sig, it will remain as is now
Beware of Geeks bearing GIF's
come and waste the day :P at The Taz Zone
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December 15th, 2005, 01:10 PM
#5
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
[1] http://www.physicsforums.com/
If the only tool you have is a hammer, you tend to see every problem as a nail.
(Abraham Maslow, Psychologist, 1908-70)
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December 15th, 2005, 02:55 PM
#6
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............
so now I'm in my SIXTIES FFS
WTAF, how did that happen, so no more alterations to the sig, it will remain as is now
Beware of Geeks bearing GIF's
come and waste the day :P at The Taz Zone
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December 16th, 2005, 01:46 AM
#7
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.
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December 16th, 2005, 04:02 PM
#8
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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