Exam-style question
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What does a redshift in the light from distant galaxies indicate about their movement relative to Earth?.
Model answer
What a good answer should say
- A redshift indicates that the galaxies are moving away from Earth.
Explanation
Why this works
The evidence of redshift shows that the wavelengths of light from these galaxies are stretched, which is consistent with the Doppler effect for waves from a moving source. This implies that the universe is expanding, as more distant galaxies exhibit greater redshift.
Therefore, the conclusion is that the observed redshift supports the theory of an expanding universe.
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