Name: Elias G.
How do galaxies hit each other if they are moving away
from each other?
Think of this as two different forces. One of the forces causes the galaxies
to separate (expansion of the universe) and the other force causes the
galaxies to get closer to each other (local gravity). The separating force
acts about at the same strength everywhere, but the one that brings galaxies
closer together is stronger if the galaxies are close together to begin with.
So what is happening is, the galaxies that are close together, tend to come
together and collide, while those that are far enough apart continue to get
Greg (Roberto Gregorius)
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Update: June 2012