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Expansion and Time

  1. Jan 29, 2015 #1
    For two objects at distant parts of the galaxy, because of their relative velocity and the space between them increasing faster than light, does this factor into the time dilation they will experience?

    I'm tending to think not because the space they are on is relative and it is only space between them increasing?

    I'm not sure if that is right though, I was thinking of the implications of time across the universe, and if is true that the relative expansion space between two bodies dilates time, wouldn't it mean this time has already happened in some distant location of the universe?

    Thank you for your input,
  2. jcsd
  3. Jan 29, 2015 #2


    Staff: Mentor

    I think you mean two objects in different galaxies, very distant from each other, correct? If the two objects are in the same galaxy, the space between them is not increasing faster than light. (The interpretation of the expansion of the universe as "space between objects increasing" has its own issues, but even if those are disregarded, gravitationally bound objects like galaxies are not affected by the universe's expansion.)

    Time dilation as a concept does not apply in the universe as a whole.

    This isn't true.
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