In 4 billion years our galaxy will collide with Andromeda; NASA created this animation of what the c

[PoindexterOglethorpe]

12. I have discussed this with My Son The Astronomer any number of times.

He tells me that the current thinking is that no more than ten stars will actually collide when this happens. However, a lot more will be gravitionally interacting with each other.

And that the black holes in the center of each will eventually merge.

Astronomers already know that our galaxy has already absorbed some other galaxies because every so often there's a group of stars traveling in a different direction from the stars around them.

Another interesting fact. Eventually all the galaxies in our local cluster will join up and form one very giant galaxy. By that time, thanks to the expansion of the universe, all other galaxies will be so far away, they will no longer be visible; their light will not reach us. This will be many billions, perhaps trillions of years down the road. But what that will mean is that astronomers in the distant future will have no way of knowing that there is anything else in the universe besides their one enormous galaxy, and will have no way of figuring out how old the universe is. Kind of a scary thought.