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Antimatter: how they exist in matter?

  1. May 21, 2012 #1
    I was wondering about antimatter. Antimatter & matter anihilate when they combine. But how they exist in matter? Why matter anihilate due to the presence of antimatter & matter? Also scientist are thinking about antimatter that where it had gone after big bang but i think that this antimatter exist in matter in our surroundings. Matter do not exist without antimatter! Am i right in this regard?
     
  2. jcsd
  3. May 21, 2012 #2
    Re: Antimatter?

    Correct.

    I don't understand what you're asking, please clarify.

    Simple. That's what we've observed.

    They're wondering why there was more matter than antimatter at the beginning of the Universe, not where it went. And how could antimatter exist in matter in our surroundings? Also, wouldn't it annihilate?

    Why would matter not be able to exist without antimatter?
     
  4. May 21, 2012 #3
    Re: Antimatter?

    It's not some kind of the darkness cannot exist without light kind of thing (although iirc it was once thought of in this way), right now we know that there is more matter than antimatter.

    I'm really not too sure what you mean about 'But how they exist in matter?' or the rest of your question really... :confused:
     
  5. May 21, 2012 #4

    Ryan_m_b

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    Re: Antimatter?

    Just to take a step back to square one, are you sure you know what antimatter is? Particles have antiparticles with opposite charges e.g. the negatively charged electron's antiparticle is the positively charged positron. Antimatter is simply matter made out of antiparticles e.g. antihydrogen is composed of positrons orbiting the nucleus (instead of electrons) within which are neutrons and antiprotons.
     
  6. May 23, 2012 #5

    mfb

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    A particle can annihilate with its corresponding antiparticle.
    - there are bound states with an electron and a positron (the antiparticle of the electron). They are unstable and the two particles annihilate after a while, but not necessarily instantly.
    A positron will not annihilate with a proton, for example, as they are different particles.

    No permanent antimatter exists within matter. It is possible to store antimatter in accelerator structures, but you have to avoid contact with matter to do so.
    Antiparticles can exist as virtual particles, but they have a very short lifetime and annihilate quickly.

    It is a result of the theory, and experiments confirm it. There is no real "reason" why things are like this.

    Matter can exist without antimatter.
     
  7. May 24, 2012 #6
    Ok.thnx for rplying everyone! But let me make my question clear.first of all, how antimatter is produced. Is it produce from matter? If yes! Then how both antimatter & matter exist together since antimatter is extracted from ma tter. Why they do not anihilate when they are together in the form of matter.if it exist in matter then to balance matter every matter-antimatter pair should have to exist in atom .i.e. electron & positron. Which makes the matter & antimatter in equal quatities in universe. Now explain this!
     
  8. May 24, 2012 #7

    ZapperZ

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    Antimatter can be made in many different ways.

    For example, look up "pair production". You'll notice that the electron-positron pair is created out of a gamma photon.

    Your other question on the matter-antimatter amount in the universe is a bit more complicated, and it is still an active research area. The popular candidate to explain why our universe is predominantly made of matter and not antimatter is our observation of what is known as CP-violation in certain elementary particle decay. I don't know to what extent or to what level of details you are capable of understanding, so I'll stop here. But you can always do a search on "CP-violation" to find further explanations.

    Zz.
     
  9. May 24, 2012 #8
    Antimatter also exists in nature. In radioactive beta minus decay, an anti-neutrino is also emitted, which is the anitparticle of the electron neutrino. (BTW, the neutrino and anti-neutrino are both weakly interacting, so the probability of them interacting is relatively small, isn't it?)
     
  10. May 24, 2012 #9
    The other "problem" that anti-neutrinos have is that they can't just annihilate with ordinary neutrinos. This is because the only particle that could be produced by such an annihilation - the Z0 boson - is heavy, almost invariably much heavier than the COM energy of the neutrino/anti-neutrino pair. This is in stark contrast with "ordinary" [baryonic and charged leptonic] matter and antimatter, which have electric charges and can therefore annihiliate easily into massless photons.

    A virtual Z0 could, once in about 4 x 10x blue moons, extremely fleetingly pop into existence from a neutrino/anti-neutrino collision, but the only decay channel then open to it (unless the available energy were at least 2me) would be ... to decay back into a neutrino and anti-neutrino.

    As a result, many anti-neutrinos, including those from the cosmic neutrino background, exist and pass through us regularly every day, and we don't even notice them!
     
  11. May 25, 2012 #10
    matter and antimatter do not coexist,so during a possess you break something up . I mean, it's not like everything consists of antiparticles and particles.
    You can have just 2 particles, collide them, and BANG several things to appear.... antimatter is made to conserve certain quantities that are needed to be conserved. How are they made? Because energy and matter are one and the same, so particles and antiparticles can be made out of energy (or fields if you want to speak in modern terms).

    Dirac's equation proposed antimatter.
    At first it was a laughable theory, because it proposed negative energies.
    After some hard time Dirac gave the explanation-model of the sea of antiparticles, which of course is not a real "sea" but it is a model explaining his theory.
    Antimmater was discovered.
    Thanks to Feynman's diagrams we can see better the possesses during such interactions.
     
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