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Help with Anti-particles?

  1. Nov 18, 2005 #1
    The definition i have read for what an anti-particle is, is that the only difference is the electrical charge from its counterpart particle.

    If this is true then why is it that an electron is already considered the anti-particle of a proton? The electron has a negative charge while the proton has a positive.

    What is the "oppositie" charge of the proton if not positive?
     
  2. jcsd
  3. Nov 18, 2005 #2

    jtbell

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    No, in addition to having opposite electric charge, antiparticles have opposite color charge (for the strong nuclear force) and flavor (for the weak nuclear force).

    Did you mean to say "not" in there somewhere? The electron and proton cannot be antiparticles because the electron is a fundamental particle whereas the proton is not a fundamental particle. Protons are made up of quarks which are fundamental. Change all the quarks in a proton to their corresponding antiquarks, by reversing their electric charges, color charges, and flavors, and you get an antiproton.
     
  4. Nov 18, 2005 #3

    James R

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    Particles and antiparticles also always have the same mass. The proton is 1836 times more massive than the electron.
     
  5. Nov 18, 2005 #4
    THANX SO MUCH :) so basically not only is the charge of the different, but color charge and flavor.

    so an electron isn't considered the proton's anti-particle because it has the same color charge and flavor??? while an anti-proton would have a different color charge and flavor. there is no need to take into the charge of the electron because it already has the "opposite charge" of a proton therefore the only difference can be with the color charge and flavor.
    Am i current so far.
     
  6. Nov 18, 2005 #5

    James R

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    The anti-particle of the electron is the positron, which has the same mass and charge as the electron, but positive charge rather than negative.
     
  7. Nov 20, 2005 #6
    i understand that. that wasn't my question. my question is what are ALL the main specific differences between an anti-particle and "normal" particle such as an electron, proton, and neutron.

    Also if neutrons have no charge what is the anti-particle of a neutron because anti-particles have to have opposite charges right.
     
  8. Nov 21, 2005 #7

    jtbell

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    I listed them in posting #2 above.

    The antiparticle of the neutron is the antineutron. A neutron is made of one up quark (with charge +2/3 e) and two down quarks (each with charge -1/3 e). An antineutron is made of an anti-up quark (with charge -2/3 e) and two anti-down quarks (each with charge +1/3 e).
     
  9. Nov 24, 2005 #8
    A neutron is made of one up quark (with charge +2/3 e) and two down quarks (each with charge -1/3 e). An antineutron is made of an anti-up quark (with charge -2/3 e) and two anti-down quarks (each with charge +1/3 e).

    These are nominal (unproven) values adopted in order to comply with the conservation of charge theory. They form part of an incomplete interpretation. We should never overlook the fact that while the Standard Model contains highly accurate predictive theories, it is sadly lacking when it comes to interpretation.
     
  10. Nov 24, 2005 #9

    ahrkron

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    There is expeimental evidence for quarks and gluons.
    Here's some: http://hyperphysics.phy-astr.gsu.edu/hbase/particles/qevid.html

    Can you be more specific? what part of the interpretation do you consider faulty or incomplete?
     
  11. Nov 26, 2005 #10
    particle and antiparticle compeletly annihilate each other. Is this possible in case of proton and electron? So there are some other differences, not just charge
     
  12. Nov 26, 2005 #11
    There is experimental evidence for quarks and gluons.
    Here's some.


    I agree, but there is no experimental proof of the fractional charge, the quantities were allocated to quarks simply to make quarks comply with the conservation rules.

    Can you be more specific? What part of the interpretation do you consider faulty or incomplete?

    The following quotes are typical of those that can be found in most Quantum Physics primers. They show that we know the numbers but not the words.

    Although considerable progress was made in the second half of the twentieth century, this has been largely a matter of accommodating interactions and second quantization into the theoretical framework. This progress has certainly sharpened the predictive power of the theory, but it has done little to sharpen our understanding of it. All the fundamental problems of interpretation remain.
    Jim Baggott (Beyond measure) 2004


    The laws of Quantum Mechanics are sufficiently different from the laws on Newtonian Mechanics which we experience in daily life to cause discomfort when studying them. Physicists usually cross this barrier using mathematics; you understand something if you can compute it.
    Martinus Veldtman. (Facts and mysteries in elementary particle physics).


    The simple truth is illustrated by the following statements
    2 + 2 = 4
    2 apples + 2 apples = 4 apples
    2 apples + 2 oranges = 4 fruits
    Quantum physics is in the position of knowing 2 + 2 = 4 but does not comprehend 'apples and fruit'.
     
  13. Nov 26, 2005 #12

    jtbell

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    See posting #2 in this thread.
     
  14. Nov 26, 2005 #13

    Astronuc

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    This phenomenon occurs in electron capture, in which a proton interacts (absorbs) an electron by which the proton is transformed into a neutron and releases and electron-associated neutrino.
     
  15. Nov 26, 2005 #14

    ahrkron

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    There are indeed findamental issues still to be clarified in QM. However, this does not preclude the study of other (we could say orthogonal) aspects of the phenomenology of particle physics.

    In particular, the charge values of the quarks have experimental support, and their interpretation (although necessarily sharing the fundamental problems of QM) is similar to that of other particles, which some may consider less controversial (like electrons or protons).

    Whe you say that

    You seem to imply that these charges are not as well established as those of electrons. In my opinion, that is not accurate.

    Regarding your last paragraph,

    I'd like to point out that such interpretational problems are shared by all particle properties, and not only those of quarks.
     
  16. Nov 27, 2005 #15
    ahrkron

    I believe you are saying in a professional manner, what I am trying to say in an amateur manner. Baggott does not agree with you entirely, he differentiates in quality, between what is known about quarks in comparison to what is known about electrons; but to continue debating on that basis would be splitting hairs.
    I hope my own contribution will appear elsewhere in PF, meanwhile I would like to say thank-you for taking the time to reply in a manner that I am sure will greatly help all of us who are simply trying to understand.
    many thanks
    jhmar
     
  17. Dec 9, 2005 #16
    thanx alot that helped a lot. but now something else has arisen. how can two particles annilate each other if energy can niether be created nor destroyed. as far as i know and reason, no two things completely destroy each other because duality doesn't actually exist because no two things are completely opposite. if two things were completely 100% opposite they wouldn't even be bound by the same laws of physics. to be opposite means to have no 0% similarties. doesn't just existing in the same universe mean u have something in common. but anyway thats just logically speaking. but according to Einstien isn't matter and energy infinite. doesn't that mean that nothing can ever be completely destroyed. it also makes logical sense. if matter and energy could be destroyed that would mean that "nothing" could exist. that doesn't even make any sense what soever. so how can two particles annilate each other?
     
  18. Dec 21, 2005 #17

    James R

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    Because when two particles annihilate each other, the mass energy is released as light (photons). Energy is not created or destroyed.

    That's wrong - particles and antiparticles completely destroy each other. Whether or not they are "completely opposite" depends on your definition of that term.

    You're not being very specific. Infinite in what way? Matter and energy can be converted into each other...
     
  19. Dec 22, 2005 #18

    When this happens, does this mean that the element changes because the mass of the nucleus changes?

    If a proton that absorbs an atom turns into a neutron,

    1) does the mass change between initial proton and resulting neutron?

    2) if so, where does the new proton come from?

    Thanks.
     
  20. Dec 22, 2005 #19

    Astronuc

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    In electron capture (EC), a proton in a nucleus absorbs one the electrons (usually one of the K-shell electrons, and IIRC sometimes but rarely and L-shell, s-electron) and the atomic number (Z) obviously decreases by 1 to (Z-1), and therefore the resulting atom is a different element of the same atomic mass (integer), however there is a slight difference in mass.

    http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact2.html#c3

    And looking at EC in Co-57 - http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/co.html#c3

    Co 57 - 56.936291373 +- 0.000000765 (amu) from http://wwwndc.tokai.jaeri.go.jp/cgi-bin/nuclinfo2004?27,57

    Fe 57 - 56.935393969 +- 0.000000736 (amu) http://wwwndc.tokai.jaeri.go.jp/cgi-bin/nuclinfo2004?26,57

    and Fe 57 is lighter than Co 57 by a small amount (despite the fact that a free neutrons mass is heavier than a proton). The difference has to do with the nuclear binding energy.
     
  21. Dec 22, 2005 #20
    No this is incorrect, please look up the definition of "opposite" in Webster. What you describe is best called antonymous--such as good vs bad--so opposed they negate each other. "Opposite" things have much in common, they just differ in position or direction, such as the statement, person A and person B sit on opposite sides of the table. Both A and B are in fact bound by the same laws of physics yet they are spatially 100 % opposite.
     
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