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B How can I conceptualise light and the known universe

  1. Feb 28, 2017 #1
    I am having a large amount of trouble conceptualising the idea of light taking time to reach places, how we are seeing into the past when we look further out and the idea of the known universe.

    If someone could please elaborate on those points it would be much appreciated.
     
  2. jcsd
  3. Feb 28, 2017 #2

    Borg

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    It takes time for light to travel from its point of origin to its destination. What you are seeing is the light given off from an object at the time that it left that object.
     
  4. Feb 28, 2017 #3
    What Borg said is pretty much all there is to it. Light travels at the speed c, so it can only move through the universe at that speed. Keep in mind that what we see is simply light reflected off objects and travelling through spacetime at speed c to us.
     
  5. Feb 28, 2017 #4

    Borg

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    Another way to think about this...
    Imagine that someone 5 light years away takes a selfie and then could send that picture to you at the speed of light. It would take 5 years to reach you so you would be seeing what they looked like 5 years ago. Does that make more sense?
     
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