Why should galaxy collisions have been more common in the past than they are today?
A)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 and light.
B)Galaxies were much bigger in the past because they had not contracted completely.
C)Galaxies were closer together in the past because the universe was smaller.
D)Galaxy collisions shouldn't have been more common in the past than they are now.
E)Galaxies were more active in the past and therefore would have collided with each other more frequently.

Question

Quizplus · Accepted Answer

In the past, the universe was smaller, which means that galaxies were closer together. This increased proximity made it more likely for galaxies to collide with each other.

Why Should Galaxy Collisions Have Been More Common in the Past