[MangoToupe]

This entire conversation seems silly without a time frame. Over a long enough time with continually interacting orbits, of course mass will coalesce. I don't think "merge" means "one time interaction that fully disperses the mass", anyway.

If they merge in 7 billion years, you think over the eg next 7 billion there won't be kinetic collisions? I'm skeptical.

[lIl-IIIl]

If they merge in 7 billion years, I wouldn't count a collision in year 13 billion as a result of colliding galaxies. It would be just a normal behavior of stars colliding in the new galaxy that was formed.

[MangoToupe]

Well, you certainly should—that's how causation works.