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A question about expansion

  1. Apr 20, 2012 #1
    In an isotrophic and homogeneous cosmos, why would the expansion of space be specifically be vectored outward. Should it not also push galaxies together?
  2. jcsd
  3. Apr 20, 2012 #2
    The outward nature of the expansion is (in this case) unrelated to the isotropy and homogeneity of the universe. It could be either inward or outward, and still both isotropic and homogenous.

    Remember that isotropic means the same in all directions (i.e. no matter which direction you look, things look the same); and homogenous means the same in all places (i.e. no matter where you go, things look the same). As long as space was uniformly expanding or contracting, it would preserve the same symmetry.
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