galaxy > totally Cosmography Principle
  Cosmological principle is fully cosmological principle of further promotion. It is to the effect that: not only three-dimensional space is homogeneous and isotropic, the entire universe is exactly the same at different times. Evolution of the universe can be deduced according to state cosmology Robertson - Walker metric. Cosmological principle is the use of fully get metric steady state cosmology, using different metric can create a variety of cosmological model.
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