Why Should Galaxy Collisions Have Been More Common in the Past

question 157

Multiple Choice

Why should galaxy collisions have been more common in the past than they are today?

• A)Galaxies were more active in the past and therefore would have collided with each other more frequently.
• B)Galaxies attracted each other more strongly in the past because they were more massive; they had not yet turned most of their mass into stars.
• C)Galaxies were much bigger in the past since they had not contracted completely.
• D)Galaxies were closer together in the past because the universe was smaller.

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