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Galaxies of antimatter

  1. Oct 10, 2011 #1
    How modern astronomy/cosmology rules out the possibility that some of observable galaxies are made of antimatter? Or within the same galaxy some stars/solar systems to be made of matter while others from antimatter? Isnt light emitted by antimatter exactly the same as that from matter?
  2. jcsd
  3. Oct 10, 2011 #2


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    The problem arises when the two mix - hugely energetic bursts of energy for no other apparent reason. This is not observed. The question you must ask is why anti matter and matter would be so segregated as to rarely interact.
  4. Oct 10, 2011 #3
    And i ask why it wouldnt be so. For example in our solar system the only bodies we see within it that we can say that they might origin outside of it are the comets. Even if we had a comet made of antimatter how huge could be this energetic burst of this comet with other bodies of our solar system made of matter?

    And ok lets say we rule out the possibility of matter and anti matter stars within the same galaxy, why couldnt we have whole galaxies made of antimatter, we rarely see two galaxies colliding( correct me if i am wrong here ) in order to observe a galaxy of matter and a galaxy of antimatter colliding.
  5. Oct 10, 2011 #4


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    Actually, we see many examples of galaxies colliding. The link below shows just a few. If any of these were a mixture of matter and anti-matter, we would see huge energy releases, which we don't, as Chronos said. Also, intergalactic space is not empty, it is filled with low density ionized gas (Google ICM or intercluster medium). When this gas interacted between neighboring galaxies, we would again see the energy release if some of it were matter and some antimatter, which we don't.

  6. Oct 11, 2011 #5


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    And in the very early universe, matter was extremely uniformly-distributed. When the cosmic microwave background was emitted, for example, our universe was uniform to one part in 100,000. At that early time, there was simply no place for anti-matter to be separated from normal matter.
  7. Oct 11, 2011 #6


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    To really understand why this is so unlikely you would need to understand the overview of the history of the universe. Wikipedia and other online sources can give you a great overview of the subject and I suggest hitting them up and reading as much as you can about the subject. To answer it simply, there was never a point in time that antimatter could have stayed separate from normal matter in large enough quantities to form even small planetoids, much less entire galaxies. One of the leading mysteries is why our universe seems to be matter dominated. According to known laws matter and antimatter should have been produced in equal amounts and annihilated with each other, leaving nothing but photons I believe. Yet here we are!
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