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QuizMultiple Choice

The Big Bang Theory — Quiz

Question 1 • Earth and Space Science

What is the best description of the relationship between the expansion of the universe and the redshift of light from galaxies?

Answer
A
The universe's expansion caused cooling that led to a redshift in the light emitted by galaxies.
B
The redshift of light from galaxies is historical evidence that the universe was once expanding rapidly.
C
The expansion of the universe causes a redshift of light from galaxies.
D
The redshift of light from galaxies has caused the universe to expand.

Explanation

As the universe expands, the space that light travels through stretches, increasing the light’s wavelength. A longer wavelength is shifted toward the red end of the spectrum, so the expansion of the universe causes galaxies’ light to be redshifted. Redshift is evidence of expansion, not what causes the universe to expand.

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