The shift of the hydrogen absorption spectrum of a galaxy primarily provides evidence for the following:
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Motion of the galaxy - The redshift or blueshift of spectral lines indicates whether the galaxy is moving away from or towards us.
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Expansion of the universe - The overall redshift of galaxies supports the idea that the universe is expanding, as observed by the increasing distance of more distant galaxies.
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The Big Bang theory - The redshift data is consistent with predictions made by the Big Bang theory, which explains the expansion of the universe from an initial singularity.
Therefore, the correct answers are:
- motion of the galaxy
- expansion of the universe
- The Big Bang theory