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Cosmic horizon.

  1. Aug 13, 2015 #1
    Hello everyone,

    Questions keep on rushing through my mind. If we can see light from 300,000 years after the big bang (THE OLDEST LIGHT EVER) then why can't we see beyond our cosmic horizon??? We are seeing the oldest light ever... then why do we have a cosmic horizon?
     
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  3. Aug 13, 2015 #2

    Orodruin

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    Because light travels at a finite speed and the universe has a finite age.

    There was light before the CMB, but we cannot see it because the universe was opaque and that light scattered.
     
  4. Aug 13, 2015 #3
    And the universe is expanding as well is that correct? So that's why we have a cosmic horizon?
     
  5. Aug 13, 2015 #4

    Chalnoth

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    The rate of expansion over time determines the distance to the cosmic horizon.
     
  6. Aug 13, 2015 #5

    Orodruin

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    Note that there are several different horizons in cosmology, see https://en.wikipedia.org/wiki/Cosmological_horizon
    The particle horizon would be there even if the universe was not expanding, but had a finite age. If you want specific answers you will need to specify which horizon you are talking about.
     
  7. Aug 13, 2015 #6
    Alright got it
     
  8. Aug 13, 2015 #7
    Yeah thanks a lot. I get it now.
     
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