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14. How do scientists know that the universe is expanding? The galaxies are moving away from each other, and the temperatures are decreasing. The galaxies are moving away from each other, and the temperatures are increasing. The galaxies are moving toward each other, and the temperatures are increasing. The galaxies are moving toward each other, and the temperatures are decreasing.

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the galaxies are moving away from each other and the temps are decreasing
Scientist know that the universe is expanding because of redshift which is a type of Doppler effect