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Antimatter in Universe

  1. Jan 22, 2005 #1
    I'm told that most of the observable universe is made up of "normal" matter. How did physicists come to this conclusion? There is no difference between matter and antimatter when observed.
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  3. Jan 23, 2005 #2
    This is the way I think and it might not be correct. The assignment of "matter" and "anti-matter" are arbitrary since we do not have a standard reference. We could simply call one of them "matter" and the other to be "anti-matter". This is similar in the situation to assign "left" and "right".

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  4. Jan 23, 2005 #3
    We do, which is exactly why I'm puzzled by the claim that the observable universe is made up of one type, the one of which you and I are made. i.e. protons and electrons, as opposed to antiprotons and positrons.
  5. Jan 23, 2005 #4


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  6. Jan 23, 2005 #5
    So it's just "chances are." I thought there was a way to detect antimatter (other than annihilation) that I was not aware of.
  7. Jan 23, 2005 #6


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    If there were large amounts of anti-matter in the universe, we would see enormous emissions of energy where they meet. Hellfire gave a link explaining that.
  8. Jan 26, 2005 #7


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    One could, but it is certainly sensible to name the kind of matter that makes up 99.99999% of what you obserb matter and the rest anti-matter. It saves a heckuvalot of typing.
  9. Jan 26, 2005 #8


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    Because we would expect to see fireworks at a matter-anti-matter horizon which we don't see. A mixed matter-anti-matter system is unstable.
  10. Feb 4, 2005 #9


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    Observing at a distance, I can't think of any way of detecting antimatter (other than annihilation), except (possibly) rather indirectly. Up close & personal, antimatter particles reveal their 'true colours' in several ways other than by annihilation (e.g. estimates of charge and mass -> clean distinctions); however, this isn't much help, as all it does is tell you there is little anti-matter in cosmic rays (and none, to speak of, where spacecraft have ventured).
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