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Hubble and the Law of Redshifts

  1. Sep 17, 2009 #1
    I've just started learning about Hubble, Red shifts, and how we measure the universe's expansion.

    It seems that he had two theories, that there is a stationary universe where the red shift from all light sources would be consistent or a theory in which the galaxies would be receding (and have a 13% dimmer light source?)

    The problem I have is that isn't red shift a measure of how fast a light source is receding from you?

    How can there be stationary galaxies that have the same red shift with a "linear relation"(whatever that means?) ?
     
  2. jcsd
  3. Sep 17, 2009 #2
    Here's hubble:
    "Since the corresponding velocity of recession is the same fraction of the velocity of light, the nebulae in the most distant cluster observed, if they are actually receding, will appear 13 per cent fainter than they would appear if they were stationary. The difference is small but, fortunately, the measures can be made with fair accuracy. The results may be stated simply. If the nebulae are stationary, the law of red shifts is sensibly linear; red shifts are a constant multiple of distances. In other words, each unit of light path contributes the same amount of red shift. On the other hand, if the nebulae are receding, and the dimming factors are applied, the scale of distances is altered, and the law of red shifts is no longer linear"
     
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