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Question about distant galaxies

  1. Sep 9, 2009 #1
    It is often stated that observation of the most distant stars inform us about the early universe because the light we observe now was emitted from the stars when the universe was young. In fact this is a quote from space.com:

    "The universe is about 13.7 billion years old. Light reaching us from the earliest known galaxies has been travelling, therefore, for more than 13 billion years."

    I, as a lay person, am puzzled by this because I would have expected those stars to have been much closer to us when the universe was young (than they are now) and only moved away with the expansion of the universe. So in the example above, why did it take light 13 billion years to get to earth? Would not those stars have been much closer to us when the light was emitted?
  2. jcsd
  3. Sep 9, 2009 #2


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    Staff: Mentor

    The galaxies were closer then than they are now, yes. The quote doesn't say either how close they were then nor how far they are now.

    Since the universe is expanding, though the light traveled 13 billion light years, the galaxies would have been closer than 13 billion light years when the light was emitted. And at the same time, they would be much further than that now.
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