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B Expansion rate question

  1. Mar 15, 2016 #1
    I'm studying about accelerating expansion rate.

    I am reading that the rate of expansion is accelerating. Now the farther objects are from us the faster they are moving away from us due to expansion. Farther and farther, faster and faster. But that would occur even if the expansion rate is steady. Are they saying that the rate of the expansion itself it accelerating? And won't that mean that the time it takes for an object to move from say 10 billion light years to 11 billion light years from us will be longer now that say a billion years from now?

  2. jcsd
  3. Mar 15, 2016 #2


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    Staff: Mentor

    "the rate of expansion is accelerating" is not comparing different distances, it is comparing different times for the same object. If we consider an object where the distance increases by c/2 today, its distance will increase slightly faster tomorrow.
    That is yet another comparison, because there we would track different objects.
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